Engines and Clutches
EPA07 Aftertreatment System (ATS)
All on-road diesel engines built after December 31, 2006 (EPA07 engines) must meet strict new guidelines for reduced emissions of particulate matter and nitrogen oxides (NOx) from the exhaust. NOx is limited to just over 1 gram per brake horsepower hour (g/bhp-hr) and particulate matter cannot exceed 0.01 g/bhp-hr.
EPA07-compliant engines require ultralow-sulfur diesel (ULSD) fuel, and they should never be run on fuel with sulfur content higher than 15 ppm. In addition, they require low-ash engine oil. The following guidelines must be followed or the warranty may be compromised.
Use ultralow-sulfur diesel (ULSD) with 15 ppm sulfur content or less, based on ASTM D2622 test procedure.
Do not use fuel blended with used engine lube oil or kerosene.
Engine lube oil must have a sulfated ash level less than 1.0 wt %; currently referred to as CJ-4 oil.
The "exhaust system" in EPA07-compliant vehicles is called the aftertreatment system (ATS). The ATS varies according to engine manufacturer and vehicle configuration, but instead of a muffler, an aftertreatment system has a device that outwardly resembles a muffler, called the aftertreatment device (ATD).
IMPORTANT: See your engine operation manual for complete details and operation of the aftertreatment system.
Inside the ATD on Mercedes-Benz, Detroit Diesel, and Cummins engines, the exhaust first passes over the diesel oxidation catalyst (DOC), then it passes through the diesel particulate filter (DPF), which traps soot particles. If exhaust temperature is high enough, the trapped soot is reduced to ash, in a process called passive regeneration (regen). Passive regeneration occurs as the vehicle is driven normally under load; the driver is not even aware that it is happening. The harder an EPA07 engine works, the better it disposes of soot, as the exhaust heat alone is enough to burn the soot to ash. Over the course of a workday, however, passive regeneration cannot always keep the ATD filter clean, so the filter must undergo active regeneration . In active regeneration, extra fuel is injected into the exhaust stream to superheat the soot trapped in the DPF and turn it to ash. Active regeneration happens only when the vehicle is moving above a certain speed, determined by the engine manufacturer. Consult manufacturers' documentation for details.
Both active and passive regeneration happen automatically, without driver input.
NOTE: Caterpillar engines do not use a DOC; Cat engines burn diesel fuel at the regeneration head to superheat the exhaust and burn the trapped soot to ash. Engine software monitors and controls this process.
If conditions do not provide for at-speed active regeneration, the vehicle will need a driver-activated parked regeneration . The vehicle must be standing still, and the driver must initiate parked regen. Completing a parked regen takes 20 minutes to an hour, depending on ambient conditions.
DANGER
There are three warning lamps in the driver message center that alert the driver of the need to perform a parked regen, clean the filter, or of an engine fault that affects the emissions.
A slow (10-second) flash of the high exhaust system temperature (HEST) lamp, indicates a regeneration is in progress, and the driver is not controlling the engine idle speed.
A solid illuminated high exhaust system temperature (HEST) lamp, alerts the operator of high exhaust temperature during the regeneration process, when the speed is below 5 mph (8 km/h). The HEST lamp does not signify the need for any kind of vehicle or engine service; it only alerts the vehicle operator of high exhaust temperatures. Make sure the engine exhaust pipe outlet is not directed at any person, or at any surface or material that will melt, burn, or explode. See Fig. 7.1 .
Fig. 7.1, High Exhaust System Temperature (HEST) Lamp
WARNING
A solid yellow diesel particulate filter (DPF) lamp indicates that a parked regen is required soon, and should be scheduled for the earliest convenient time. See Fig. 7.2 . A blinking yellow DPF lamp indicates that a parked regen is required immediately, or an engine derate may occur.
Fig. 7.2, Diesel Particulate Filter (DPF) Status Lamp
A solid yellow malfunction indicator lamp (MIL) indicates an engine fault that affects the emissions. See Fig. 7.3 .
Diesel particulate filter servicing must be performed by an authorized technician, and a record must be maintained for warranty purposes. The record must include:
date of cleaning or replacement;
vehicle mileage;
particulate filter part number and serial number.
Fig. 7.3, Malfunction Indicator Lamp (MIL)
The request/inhibit regen switch ( Fig. 7.4 ), located on the dash, may have three selectable positions:
request regeneration;
default (can include appropriate normal state condition—either in an automatic regeneration or inhibit state);
inhibit regeneration.
NOTE: The regen switch can start an active regen only when at least one of two conditions exists: either the DPF light is lit, or the engine software calls for it. If neither of those conditions exist, the regen switch cannot cause a regeneration to happen.
The function of the switch will vary by the engine make and model in the vehicle. See the engine operation manual for switch operation details.
Fig. 7.4, Request/Inhibit Regen Switch
Engine Starting
For cold-weather starting, refer to "Ether Start System" in this chapter.
CAUTION
IMPORTANT: Ring gear and starter pinion damage caused by improper starting procedures is not warrantable.
Caterpillar
NOTE: Before starting the engine, read Chapter 2 in this manual for detailed information on how to read the instruments and operate the controls.
The information below contains guidelines for cold-weather starting. For additional information, refer to "Ether Start System."
WARNING
1.
Before engine start-up, perform the engine pretrip inspection and daily maintenance checks in Chapter 11 .
2.
Set the spring parking brakes.
3.
Turn the ignition switch to the on position. All the electronic gauges on the ICU (instrumentation control unit) complete a full sweep of their dials, the warning and indicator lights light up, and the buzzer sounds for three seconds.
NOTE: The engine electronics supply the correct amount of fuel for starting the engine. Pedal pressure is unnecessary.
4.
Turn the ignition switch to the start position. Do not press down on the throttle pedal. Release the switch the moment the engine starts. If the engine does not start after 30 seconds of cranking, turn the ignition switch off.
NOTE: Some starters are equipped with optional overcrank protection. If overcranking occurs, a thermostat breaks the electrical circuit to the starter motor until the motor has cooled. For air start systems, check the air supply before starting the engine. There must be 100 psi (689 kPa) of air pressure available.
5.
Wait two minutes to allow the starter motor to cool. Turn the ignition switch back to the on position and try to start the engine again.
CAUTION
6.
C-10, C-12, and C-15 engines may be operated at low load and speed once the engine oil pressure has reached 10 to 20 psi (69 to 138 kPa). When the engine has reached the normal operating temperature of 189°F (87°C), the engine may be operated at full load
Cummins and Detroit Diesel
NOTE: Before starting the engine, read Chapter 2 in this manual for detailed information on how to read the instruments and operate the controls. On vehicles equipped with a neutral start switch, the transmission must be in neutral before the engine can be started.
1.
Before engine start-up, perform the engine pretrip inspection and daily maintenance checks in Chapter 11 of this manual.
2.
Set the spring parking brakes.
CAUTION
3.
Set the throttle idle (hold down the clutch pedal).
4.
Make sure the transmission is in neutral.
CAUTION
5.
Turn on the ignition switch.
NOTE: A manual override knob, provided on the forward end of the electric shutdown valve, allows the valve to be opened in case of electric power failure. To use the override, open it by turning the knob fully clockwise. Return it to the run position after repair.
IMPORTANT: For Detroit Diesel engines, pumping the accelerator before or during cranking will not aid in starting. If the engine won't start, check the main engine power fuses; they may have blown. The fuses are located along the main engine electrical harness on the left frame rail, near the batteries. If needed, replace the fuses. Be sure to find the cause of the blown fuses as soon as possible.
NOTE: Some starters are equipped with an optional thermostat. If overcranking occurs, the thermostat breaks the electrical current to the starter motor until the motor has cooled.
6.
Press the start button. Release the button the moment the engine starts.
6.
If the vehicle is equipped with an automatic engine shutdown system with a manual override push button, press the override button while pressing the engine start button. Once the engine has started, release the engine start button, but continue to press the override push button until the warning bell stops.
6.
If the vehicle is equipped with a battery isolator system, and the gel cell battery is completely discharged, press and hold the battery boost push button while pressing the starter push button. This will temporarily disconnect the isolated battery while connecting the engine-starting batteries to the ignition switch for engine starting.
7.
When the engine is started, it takes a while to get the lubricating oil film reestablished between the shafts and bearings, and between the pistons and liners. Bring the engine up to operating speed gradually as it warms up and develops stable oil pressure.
7.
The oil pressure gauge indicates any drop in lubricating oil pressure or mechanical malfunction in the lubricating oil system. The operator should note the loss of oil pressure and shut down the engine before damage can occur.
8.
During the warm-up period, apply the load gradually until the oil temperature reaches 140°F (60°C). For an engine starting a loaded vehicle, the coolant temperature must be approximately 120°F (49°C).
Starting After Extended Shutdown or Oil Change
Do the following steps after an oil change or after the engine has been shut down for more than three days:
1.
Disconnect the wire from the fuel pump solenoid valve.
2.
Crank the engine until oil pressure shows on the gauge.
3.
Connect the wire to the fuel pump solenoid valve.
4.
Start the engine. Refer to "Engine Starting" above.
Ether Start System
Ether allows combustion with lower cylinder temperatures. A pressurized spray-can or a rag dampened with fluid will usually provide quick starting to as low as–10°F(–23°C). Below this temperature, some means of injecting a carbureted vapor directly into the intake manifold is necessary.
Caterpillar truck engines with direct injection are designed to start at temperatures above 10°F (–12°C) without using start systems. If the temperature is below 10°F (–12°C), a start system may be necessary and/or crankcase oil may need to be heated. Jacket water heaters are often used to assist starting in cold temperatures.
The cold start system, approved for use on Cummins engines, has been based upon starting aid capabilities to–25°F(–32°C).
WARNING
Cold-Weather Operation
IMPORTANT: If a winterfront is used on a vehicle with an electronic engine equipped with a charge air cooler, make sure that there are slit openings distributed across the face of the winterfront to allow airflow through the entire charge-air-cooler core. Do not use a winterfront with closed areas that block uniform air flow across any sections of the charge-air-cooler crossflow tubes. This will adversely affect the operation and durability of the charge air cooler.
Caterpillar
If the engine is in good mechanical condition and the precautions necessary for cold-weather operation are taken, ordinary cold weather will not cause difficulty in starting, or loss of efficiency.
If the engine does not start, prime the fuel system.
When the use of unblended No. 2 diesel fuel in winter cannot be avoided, install a thermostatically controlled fuel heater. Fuel heaters can prevent wax from clogging the fuel filters and formation of ice crystals from water in the fuel.
IMPORTANT: If a fuel heater is used, make sure it has thermostatic controls to prevent excessive heating of the fuel in warm weather. Excessive heating of fuel can cause a loss of engine power.
For cold-weather operation, use the following guidelines:
1.
When starting the engine in temperatures below 32°F (0°C), use engine lubricants of lower viscosity. See your engine operation and maintenance manual for specifications.
2.
When the temperature is below freezing, use sufficient antifreeze solution in the cooling system to prevent freezing. Refer to Group 20 of the Heavy-Duty Trucks Maintenance Manual for specifications.
3.
During cold weather, give more attention to the condition of the batteries. Test them frequently to ensure sufficient power for starting. Inspect all switches and connections in the electrical system and keep them in good condition to prevent losses through poor contacts. See Group 15 of the Heavy-Duty Trucks Service Manual for detailed information.
WARNING
4.
If so equipped, turn off the battery disconnect switch after the engine is stopped to prevent battery discharge while the starter motor is cooling.
4.
For starting below 0°F (–18°C), an optional cold-weather starting assist is recommended. For temperatures below–10°F(–23°C), consult your Caterpillar dealer for recommendations.
5.
When the customer parameters include cold mode operation and the coolant temperature is below 64°F (18°C), the system puts the engine in cold mode, limiting engine power, advancing timing, and adjusting the low idle to 600 rpm (for C-15 engines) or 800 rpm (for C-10 and C-12 engines) to improve warm-up time. The system will keep the engine in cold mode until the coolant temperature rises above 82°F (28°C). After the cold mode has been completed, operate the vehicle at low load and low rpm until the engine coolant reaches the normal operating temperature of 189°F (87°C).
6.
Fuel cloud point is the temperature at which wax crystals become visible, which is generally above the pour point of the fuel. To keep the fuel filter elements from plugging with wax crystals, the cloud point should be no higher than the lowest ambient temperature at which the engine must start.
Cummins
Satisfactory performance of a diesel engine operating in low ambient temperatures requires modification of the engine, surrounding equipment, operating practices, and maintenance procedures. The colder the temperatures, the greater the amount of modification required, and yet with the modifications applied the engines must still be capable of operation in warmer climates without extensive changes.
The following information is provided to engine owners, operators, and maintenance personnel on how the modifications can be applied to get satisfactory performance from their diesel engines.
There are three basic objectives:
Reasonable starting characteristics followed by practical and dependable warm-up of the engine and equipment.
A unit or installation which is as independent as possible from external influences.
Modifications which maintain satisfactory operating temperatures with a minimum increase in maintenance of the equipment and accessories.
If satisfactory engine temperature is not maintained, higher maintenance cost will result due to increased engine wear. Special provisions to overcome low temperatures are definitely necessary, whereas a change to a warmer climate normally requires only a minimum of revision. Most of the accessories should be designed in such a way that they can be disconnected so there is little effect on the engine when they are not in use.
The two most commonly used terms associated with preparation of equipment for low-temperature operation are "winterization" and "arctic specifications."
Winterization of the engine and/or components so that starting and operating are possible in the lowest temperature to be encountered, requires:
Proper lubrication with low-temperature lubricating oils.
Protection from the low-temperature air. The metal temperature does not change, but the rate of heat dissipation is affected.
Fuel of the proper grade for the lowest temperature.
Heat to raise the engine block and component temperatures to at least–25°F(–32°C) for starting in lower temperatures.
Electrical equipment capable of operating in the lowest expected temperature. All switches, connections, and batteries in the electrical system should be inspected and kept in good condition to prevent losses through poor contacts.
Arctic specifications refer to the design of material and specifications of components necessary for satisfactory engine operation in extremely low temperatures to–65°F(–54°C). Contact the nearest Freightliner dealer or Cummins engine dealer, to obtain the special items required.
CAUTION
IMPORTANT: Fuel heaters used on vehicles with Cummins PACE or CELECT engine systems could cause high fuel temperatures that affect engine performance and operation of the electronic engine controls. If a fuel heater is used, make sure it has thermostatic controls. If the fuel heater has a timer, set the timer to activate only for a limited period of time before the engine starts. Make sure the fuel heater is used only for starting the engine.
Detroit Diesel
Preparations made in advance of winter and maintenance performed during the cold months will help to ensure efficient engine starting and operation.
1.
Engine oil thickens as it gets colder, slowing cranking speed. When cold, multigrade oil offers less resistance to the cranking effort of the engine and permits sufficient rpm to be developed to start the engine. Refer to "Lubricating Oil Recommendations" in the Detroit Diesel Owner's and Operator's Guide for specific recommendations.
2.
When an engine equipped with a DDEC system is started at temperatures below 25°F (–4°C), the idle speed automatically increases to 900 rpm. The injection timing is also advanced to decrease white smoke. As the engine oil warms up, the idle speed gradually decreases. When the oil temperature reaches 122°F (50°C), both the idle speed and the injection timing return to normal.
3.
During cold weather, the batteries should be tested more frequently to ensure ample power for starting. All electrical connections should be tight and in good condition to prevent losses through loose or corroded connections.
4.
The ether start system should be properly charged and in good working order.
5.
Ethylene-glycol-base antifreeze is recommended. An inhibitor system is included in this type of antifreeze and the corrosion protection is sufficient as long as the recommended concentration range of 30 to 67 percent (antifreeze to water by volume) is employed. See Group 20 of the Heavy-Duty Trucks Maintenance Manual for cooling system capacity and quantity of antifreeze required for the lowest anticipated temperature.
6.
If the engine is to be operated in arctic temperatures, consult the nearest Freightliner dealer or an authorized Detroit Diesel engine dealer for information regarding availability of special cold weather equipment.
Engine Break-In
Every engine is tested on a dynamometer before shipment, eliminating the need for a break-in period. Before running the engine for the first time, follow the instructions in the Engine Operator's Manual.
Engine Operation
DANGER
All diesel engines have been built to comply with the requirements of the Federal (U.S.) Clean Air Act. Once an engine is placed in service, the responsibility for meeting both state and local regulations is with the owner/operator. Good operating practices, regular maintenance, and correct adjustments are factors that will help to stay within the regulations. Proper maintenance of the engine, which is the responsibility of the owner/operator, is essential to keep the emission levels low.
Engine Protection
On electronic engines, an engine-protection system monitors all engine sensors and electronic components, and recognizes system malfunctions. If a critical fault is detected, an amber check-engine warning lamp and a red stop-engine lamp illuminate.
The standard parameters that are monitored for engine protection are: low coolant level, high coolant temperature, low oil pressure, high soot level (DPF), and uncontrolled DPF regeneration.
Amber Check-Engine Warning Lamp
When the amber check-engine warning lamp comes on for any reason, the vehicle can still be operated, and the driver can proceed to the required destination. This condition should be reported to an authorized service center as soon as possible.
Red Stop-Engine Lamp
WARNING
The red stop-engine lamp illuminates to indicate that the engine-protection system has been activated. The conditions that will cause the red stop-engine lamp to come on are:
high coolant temperature
loss of coolant
low oil pressure
high soot level (DPF)
uncontrolled DPF regeneration
On some engines, the engine ECU will derate the engine, allowing it to run at low rpm and slow vehicle speed, until the vehicle can be driven to a safe location or to a service facility. On other engines, the engine ECU will first derate the engine, then if the condition does not improve, shut it down completely 30 seconds after the light comes on. The driver must safely bring the vehicle to a stop on the side of the road before the engine shuts down.
To restart the engine (override the shutdown command) turn the ignition switch to OFF, leave it there a few seconds, and turn the switch to START. The engine will run for a short period and shut down again if the condition does not improve.
IMPORTANT: Do not attempt to restart the engine while the vehicle is moving. Bring the vehicle to a safe stop and restart the engine with the vehicle stopped.
Stop-Engine Override Switch
If the vehicle is equipped with a stop-engine override (SEO) switch, it can be used to override the shutdown sequence. This override resets the shutdown timer, restoring power to the previous level before the red stop-engine lamp was illuminated. The switch must be recycled after five seconds to obtain a subsequent override.
CAUTION
Caterpillar Engine Operation
Proper operation and maintenance are key factors in obtaining the maximum life and economy of a vehicle engine. Follow the directions in the Caterpillar Operation and Maintenance Management Manual and this manual for trouble-free, economical engine operation.
1.
Operate the engine at low load. After normal oil pressure is reached and the temperature gauge begins to move, the engine may be operated at full load.
1.
Caterpillar electronic engines automatically idle at 900 to 1000 rpm for the correct warm up time after a cold engine start (less than 40°F [5°C]). These electronic engine systems will reduce the idle speed to 600 rpm when the engine is warm enough to drive the vehicle.
IMPORTANT: Fuel heaters used on vehicles with Caterpillar electronic engines could cause excessive fuel temperatures that affect engine performance and operation of the electronic engine controls. If a fuel heater is used, make sure it has thermostatic controls. If the fuel heater has a timer, set the timer to activate only for a limited period of time before the engine starts. Make sure the fuel heater is used only for starting the engine.
2.
Keep the engine speed to a minimum. An acceptable range is 1200 to 1600 rpm.
3.
Select a gear that allows a smooth, easy start without increasing engine speed above low idle or slipping the clutch. Engage the clutch smoothly. Jerky starts waste fuel and put stress on the drivetrain.
3.
It is not necessary to accelerate Caterpillar electronic engines to governed speed in the lower gears to get the vehicle moving, except in a high power demand situation such as starting on a grade.
4.
Continue to upshift until cruising speed is reached. Use only the rpm needed to make an upshift into the next gear. The engine speed needed to make an upshift increases as the vehicle speed increases or if upshifts are made on uphill grades. If the vehicle can be operated in a higher gear after reaching the desired speed, select the highest gear available that will pull the load. Experience with your vehicle will show you what rpm is needed to make upshifts under various conditions. This progressive shifting technique will lower fuel costs because the engine will be operating at the lowest rpm needed to pull the load.
4.
Caterpillar electronic engines can be programmed to limit engine rpm while the vehicle is operated in the lower and higher gears. This feature assists the driver in following progressive shifting techniques.
5.
On uphill grades, begin downshifting when the engine rpm falls to 1200 rpm. Fuel economy will be best if you let the engine lug back to around this speed before you downshift. Downshift until a gear is reached in which the engine will pull the load. Let the engine lug down if you can make it to the top of a hill without downshifting.
IMPORTANT: Don't let the engine exceed 2300 rpm (2100 rpm if equipped with an exhaust brake).
6.
On a downhill grade, do not coast or put the transmission in neutral. Select the correct gear that does not allow the engine to exceed its maximum speed. Use the brakes to limit the vehicle speed.
6.
A simple rule to follow is to select the same gear (or one gear lower) that would be needed to go up the grade.
7.
As with any engine, prolonged idling of Caterpillar engines is not recommended. An idling engine wastes fuel and if left unattended, is also unsafe.
7.
Caterpillar engines can be programmed to shut off automatically after a specified idling time. The vehicle transmission must be in neutral and the parking brake must be set for the automatic shutoff option to work.
Cruise Control
The cruise control is activated by the "On/Off" and "Set/Resume" switches on the dash ( Fig. 7.5 ) or by optional "Pause," "Resume," and "Set" buttons on the transmission shift knob ( Fig. 7.6 ). The minimum speed at which cruise control can be used on Caterpillar electronic engines is 30 mph (48 km/h). The minimum and maximum speed cruise control set limits can be programmed, by authorized personnel, into the ECM personality module.
- A. If equipped with Jacobs engine brake controls, the cruise switches may be installed here. The location may vary depending on other vehicle options.
Fig. 7.5, Cruise Control Switches, Standard Location
Fig. 7.6, Transmission Shift Knob Buttons
WARNING
CAUTION
1.
To cruise at a particular speed:
1.1
Flip the ON/OFF switch on the instrument control panel to ON.
1.2
Hold the throttle pedal until the speedometer indicates the desired speed.
1.3
Momentarily move the SET/RESUME switch on the instrument control panel to SET or push the SET button on the transmission shift knob.
2.
To disengage the cruise control:
2.1
Depress the brake pedal, or clutch pedal, or
2.2
Flip the ON/OFF switch on the instrument control panel to OFF or push the PAUSE button on the transmission shift knob.
3.
To resume a preselected cruise speed:
3.1
If the ON/OFF switch on the instrument control panel is in the OFF position, flip it to ON.
3.2
Momentarily move the SET/RESUME switch on the instrument control panel to RESUME, or push the RESUME button on the transmission shift knob. Cruise will return to the last speed selected.
3.2
To adjust cruise speed up or down, hold the SET/RESUME switch on the instrument control panel at SET to accelerate or at RESUME to decelerate until the desired speed is reached, or press the SET button on the transmission shift knob to accelerate or the RESUME button to decelerate until the desired speed is reached.
NOTE: The resume-vehicle-speed memory is not maintained if the ignition is shut off.
BrakeSaver, Optional
The BrakeSaver (optional on C-15 engines) permits the operator to control the speed reduction of the vehicle on grades, curves, or anytime speed reduction is necessary but long applications of the service brakes are not desired.
During downhill operation, the crankshaft is turned by the rear wheels (through the drivetrain). To reduce the speed of the vehicle, an application of braking force can be made to the crankshaft. The BrakeSaver does this by converting rotation energy into heat which is removed by the engine cooling system. The BrakeSaver is controlled by the driver, as necessary, by operating a lever on the instrument panel. Brake pressure increases as the lever is moved toward the ON position. An air pressure gauge provides a relative indication of the braking force. An oil temperature gauge indicates the heat in the BrakeSaver during its operation. If the temperature gauge indicates HOT, the BrakeSaver control lever must be moved to the OFF position. The oil temperature will decrease rapidly with the BrakeSaver off. When the temperature reaches normal, the BrakeSaver can be used.
CAUTION
Power Takeoff (PTO) Governor
Caterpillar electronic engines may be equipped with a PTO governor. This mode is used only when the vehicle is parked. The PTO mode is activated by the ON/OFF and SET/RESUME switches on the dash ( Fig. 7.5 ) or by optional PAUSE, RESUME, and SET buttons on the transmission shift knob ( Fig. 7.6 ).
1.
To engage the PTO:
1.1
Flip the ON/OFF switch on the instrument control panel to ON.
1.2
Hold the throttle pedal until the tachometer indicates the desired speed.
1.3
Momentarily move the SET/RESUME switch on the instrument control panel to SET, or push the SET button on the transmission shift knob.
2.
To disengage the PTO:
2.1
Depress the brake pedal, or clutch pedal, or
2.2
Flip the ON/OFF switch on the instrument control panel to OFF or press the PAUSE button on the shift knob.
3.
To resume a previously selected engine speed:
3.1
If the ON/OFF switch on the instrument control panel is in the OFF position, flip it to ON.
3.2
Momentarily move the SET/RESUME switch on the instrument control panel to RESUME, or press the RESUME button on the transmission shift knob.
3.2
To adjust engine speed up or down, hold the SET/RESUME switch on the instrument control panel at SET to accelerate or at RESUME to decelerate until the desired speed is reached, or press the SET button on the transmission shift knob to accelerate or the RESUME button to decelerate until the desired speed is reached.
NOTE: The resume-engine-speed memory is not maintained if the ignition is shut off.
Cummins Engine Operation
Cummins diesel engines have been built by Cummins to comply with the requirements of the Federal (U.S.) Clean Air Act. Once the engine is placed in service, the responsibility for meeting both state and local regulations is with the owner/operator. Good operating practices, regular maintenance, and proper adjustments are factors which will help to stay within the regulations.
Proper maintenance of the engine, which is the responsibility of the owner/operator, is essential to keep the emission levels low.
Follow the directions in the Cummins Operation and Maintenance Manual and this manual for trouble-free, economical vehicle engine operation.
1.
Cummins diesel engines produce high horsepower and peak torque characteristics at lower rpm. Because of this, it is not necessary to keep the engine "wound up" to deliver the required horsepower at the wheels. These characteristics may also result in less shifting, and make shifting at lower rpm (to peak torque) more practical.
2.
Depending on the vehicle gearing, the posted speed limit can sometimes allow operation in either of the top two gears; however, for improved operating efficiency (fuel economy and engine life), operate in the top gear at reduced rpm, rather than in the next lower gear at the maximum rpm.
3.
Cruise at partial throttle whenever road conditions and speed requirements permit. This driving technique permits operating within the most economical power range of the engine.
4.
When approaching a hill, open the throttle smoothly to start the upgrade at full power, then shift down as desired to maintain the maximum vehicle speed. The higher torque of Cummins engines may permit topping some grades without shifting.
5.
Cummins engines are designed to operate over a wide speed range. More frequent shifting than necessary does not allow proper utilization of this flexibility. The driver who stays in top gear and uses the wider speed range will achieve the best fuel economy.
6.
The Cummins diesel engine is effective as a brake on downhill grades, but care must be used not to overspeed the engine going downhill. The governor has no control over engine speed when it is being pushed by the loaded vehicle.
6.
Never turn off the ignition switch while going downhill. With the engine still in gear, fuel pressure will build up against the shutdown valve and may prevent it from opening when the ignition key is turned on.
CAUTION
7.
Use a combination of brakes and gears to keep the vehicle under control at all times and to keep the engine speed below the rated governed rpm.
Cruise Control
The cruise control is activated by the ON/OFF and SET/RESUME switches on the dash ( Fig. 7.5 ) or by optional PAUSE, RESUME, and SET buttons on the transmission shift knob ( Fig. 7.6 ). The minimum speed at which cruise control can be used on Cummins PACE and CELECT engines is 30 mph(48 km/h).
WARNING
CAUTION
1.
To cruise at a particular speed:
1.1
Flip the ON/OFF switch on the instrument control panel to ON.
1.2
Hold the throttle pedal until the speedometer indicates the desired speed.
1.3
Momentarily move the SET/RESUME switch on the instrument control panel to SET or push the SET button on the transmission shift knob.
2.
To disengage the cruise control:
2.1
Depress the brake pedal, or clutch pedal, or
2.2
Flip the ON/OFF switch on the instrument control panel to OFF or push the PAUSE button on the transmission shift knob.
3.
To resume a preselected cruise speed:
3.1
If the ON/OFF switch on the instrument control panel is in the OFF position, flip it to ON.
3.2
Momentarily move the SET/RESUME switch on the instrument control panel to RESUME, or push the RESUME button on the transmission shift knob. Cruise will return to the last speed selected.
3.2
To adjust cruise speed up or down, hold the SET/RESUME switch on the instrument control panel at SET to accelerate or at RESUME to decelerate until the desired speed is reached, or press the SET button on the transmission shift knob to accelerate or the RESUME button to decelerate until the desired speed is reached.
NOTE: The resume-vehicle-speed memory is not maintained if the ignition is shut off.
Power Takeoff (PTO) Governor
Cummins electronic engines may be equipped with a PTO governor. This mode is used only when the vehicle is parked. The PTO mode is activated by the ON/OFF and SET/RESUME switches on the dash ( Fig. 7.5 ) or by optional PAUSE, RESUME, and SET buttons on the transmission shift knob ( Fig. 7.6 ).
1.
To engage the PTO:
1.1
Flip the ON/OFF switch on the instrument control panel to ON.
1.2
Hold the throttle pedal until the tachometer indicates the desired speed.
1.3
Momentarily move the SET/RESUME switch on the instrument control panel to SET, or push the SET button on the transmission shift knob.
IMPORTANT: Two PTO engine speeds can be preset on PACE and CELECT engines. With the ON/OFF switch on, move the SET/RESUME switch to SET to reach the first preset value or, move the switch to RESUME for the second preset value. After one preset value has been selected, you must turn the ON/OFF switch off, then turn it back on before using the second preset value.
2.
To disengage the PTO:
2.1
Depress the brake pedal, clutch pedal, or throttle pedal (CELECT engines only), or
2.2
Flip the ON/OFF switch on the instrument control panel to OFF or press the PAUSE button on the shift knob.
3.
To resume a previously selected engine speed:
3.1
If the ON/OFF switch on the instrument control panel is in the OFF position, flip it to ON.
3.2
Momentarily move the SET/RESUME switch on the instrument control panel to RESUME, or press the RESUME button on the transmission shift knob.
3.3
To adjust engine speed up or down, hold the SET/RESUME switch on the instrument control panel at SET to accelerate or at RESUME to decelerate until the desired speed is reached, or press the SET button on the transmission shift knob to accelerate or the RESUME button to decelerate until the desired speed is reached.
NOTE: The resume-engine-speed memory is not maintained if the cruise control ON/OFF switch is turned OFF or if the ignition is shut off.
Detroit Diesel Engine Operation
Individual driving habits can make a difference in the performance and economy of any engine. The recommendations below call attention to the techniques that can be employed to save fuel and extend the operating efficiency and life of a new Detroit Diesel engine for the longest possible time.
All engines have an operating range in which the engine performs most efficiently. The operating range extends from maximum torque rpm at the low end to engine rated speed at the high end. Detroit Diesel engines deliver best fuel economy when operated in the low- and mid-speed segments of the efficiency range and produce maximum horsepower at rated speed, which is also the recommended maximum speed of the engine.
IMPORTANT: If a winterfront is used on a vehicle with an electronic engine equipped with a charge air cooler, make sure that there are slit openings distributed across the face of the winterfront to allow airflow through the entire charge-air-cooler core. Do not use a winterfront with closed areas that block uniform air flow across any sections of the charge-air-cooler crossflow tubes. This will adversely affect the operation and durability of the charge air cooler.
1.
It is seldom necessary to accelerate the engine to governed speed in the lower gears to get the vehicle moving, except in a high power demand situation such as starting on a grade.
1.
To conserve fuel, start off in low gear and develop only the engine speed needed to get rolling. Then, increase engine speed gradually as upward gear shifting progresses.
1.
As described by Detroit Diesel, this "progressive shifting" technique will get the vehicle up to the desired cruising speed while minimizing noise emission and maximizing fuel economy. A progressive shift pattern is illustrated in Fig. 7.7 .
- 1. Governed RPM
- 2. Engine RPM
- 3. Idle RPM
- 4. Miles (Kilometers) Per Hour
Fig. 7.7, Progressive Shift Pattern
NOTE: A momentary hesitation in throttle response will occur when a vehicle with a turbocharged engine is started on a grade. Do not disengage the clutch. The rpm will recover, and the vehicle will accelerate up the grade.
2.
For city driving, run in the highest gear possible and reduce engine speed. This enables you to operate at a safe speed for traffic conditions while using less fuel and reducing noise. Also, when slowing down for reduced speed zones, remain in your running gear and reduce engine rpm to stay within the speed limit. Avoid downshifting until you are ready to return to highway cruising speed.
3.
For highway cruising and for best fuel economy, run the engine at 80 to 90 percent of rated rpm to maintain highway speed. Engines with 1800 rpm ratings are exceptions and will provide fuel economy when run at their rated speed. Proper gear selection should permit cruising in the economy range with no appreciable sacrifice in desired highway speed.
3.
It is okay to operate below rated rpm at full throttle if you are satisfied with the way the vehicle performs. However, there are times when hilly terrain, high winds, or other conditions make it impractical to operate without reserve power. Such conditions are better met if the vehicle is operated in a lower gear with reserve power available for changes in terrain, wind, etc.
4.
The proper use of gears will shorten time on hills and minimize the amount of shifting. When starting up a hill, gradually depress the accelerator pedal all the way down and keep it there as the vehicle moves up the grade. If the engine continues to maintain a satisfactory road speed, remain in that gear for the entire grade.
4.
If the hill causes a steady decline in engine rpm, downshift as required until the engine can maintain a stable uphill speed. Make full use of each gear before going to a lower gear. By remaining in a gear until arriving at the speed of the next lower gear, the vehicle will top the grade in the best possible time on less fuel and fewer shifts.
5.
Because of their constant horsepower over a wide speed range, Detroit Diesel engines can be operated at full throttle at lower rpm than other engines. This offers benefits in fuel economy and engine life. And more than likely, it will be possible to top most grades without downshifting.
5.
When the vehicle starts into a grade, allow the engine to lug down to maximum torque rpm before downshifting. Downshift, if required, at maximum torque rpm also or at the predetermined road speed for the next lower gear.
5.
Do not be afraid to lug the engine down. It has more than enough torque at low rpm to keep a loaded vehicle moving against a grade and it won't harm the engine.
6.
The driver who is not familiar with the vehicle's shift points can greatly improve driving skill by learning them for all gears. By knowing rather than guessing where the shift points are, it is possible to avoid overspeeding the engine by downshifting too soon or missing the full use of a gear by downshifting too late. The shift points of any vehicle can be determined by a simple road-test method. Run the vehicle and determine the maximum road speed possible in every gear at the engine governed full-load speed setting.
6.
The top road speed possible in a gear would be the shift point for that gear. The results should be recorded in the proper order of shifting and displayed inside the cab.
CAUTION
7.
To slow the vehicle on downgrades and curves (using the engine), shift to a lower gear and allow the vehicle to decelerate in that gear. The engine provides maximum braking effect when running at the top end of the operating range, but it must not be allowed to exceed its full-load rated rpm. Continue to downshift as further reduction in vehicle speed is required. If the vehicle is above the allowable maximum speed of a lower gear, use the service brakes to slow the vehicle to an acceptable speed where the transmission may be downshifted safely. Again, the importance of knowing the shift points is demonstrated.
IMPORTANT: The engine governor has no control over engine rpm when the engine is being pushed by a loaded vehicle down a grade. Use service brakes and gears in combination on long grades to keep the vehicle speed under control and the engine rpm below full-load rated governed speed.
8.
Essential information regarding the operation and care of Allison automatic transmissions is contained in the Allison Driver's Handbook. Applying the knowledge presented will not only make driving easier, but will give the maximum benefits from an Allison-equipped vehicle.
8.
Maintenance literature is also available for drivers of Allison-equipped vehicles who desire trouble-free performance and maximum life from their equipment. These maintenance books are available from any authorized Detroit Diesel engine distributor.
9.
As with all engines, prolonged idling of Detroit Diesel engines is not recommended. An idling engine wastes fuel and left unattended, is also unsafe.
9.
A Detroit Diesel Electronic Control (DDEC) engine can be equipped to shut off automatically after 5 minutes of idling. The vehicle transmission must be in neutral and the parking brake must be set for the automatic shutoff option to work. To start the engine, follow the normal start-up procedure.
9.
Engines equipped with DDEC will idle fast when cold. As the engine warms up to operating temperature, the idle speed will decrease. Warm the engine until idle speed is normal before operating the vehicle.
Cruise Control
A DDEC engine may have cruise control. The minimum speed at which cruise control can be used is 35 mph (56 km/h).
The cruise control is activated by the ON/OFF and SET/RESUME switches on the dash ( Fig. 7.5 ) or by optional PAUSE, RESUME, and SET buttons on the transmission shift knob ( Fig. 7.6 ).
WARNING
CAUTION
1.
To cruise at a particular speed:
1.1
Flip the ON/OFF switch on the instrument control panel to ON.
1.2
Hold the throttle pedal until the speedometer indicates the desired speed.
1.3
Momentarily move the SET/RESUME switch on the instrument control panel to SET or push the SET button on the transmission shift knob.
2.
To deactivate the cruise control:
2.1
Depress the brake pedal, or clutch pedal, or
2.2
Flip the ON/OFF switch on the instrument control panel to OFF or push the PAUSE button on the transmission shift knob.
3.
To resume a preselected cruise speed:
3.1
If the ON/OFF switch on the instrument control panel is in the OFF position, flip it to ON.
3.2
Momentarily move the SET/RESUME switch on the instrument control panel to RESUME, or push the RESUME button on the transmission shift knob. Cruise will return to the last speed selected.
3.2
To adjust cruise speed up or down, hold the SET/RESUME switch on the instrument control panel at SET to accelerate or at RESUME to decelerate until the desired speed is reached, or press the SET button on the transmission shift knob to accelerate or the RESUME button to decelerate until the desired speed is reached.
NOTE: The resume vehicle speed memory is not maintained if the ignition is shut off or if the ON/OFF switch is off for more than 10 seconds.
Power Takeoff (PTO)
A power takeoff option is available for vehicles equipped with a DDEC system. The PTO operates only when the vehicle is at a standstill.
Some vehicles have separate controls for the PTO. In the case of a preset nonadjustable PTO engine speed, there is only an on/off switch labeled FAST IDLE. If the vehicle is equipped with a variable PTO engine speed, there are two controls: an on/off switch, and a potentiometer knob. Both of these are labeled GOVERNOR.
On other vehicles, the PTO mode is activated by the ON/OFF and SET/RESUME cruise control switches located on the instrument control panel on the dash ( Fig. 7.5 ), or by optional PAUSE, RESUME or SET buttons on the transmission shift knob ( Fig. 7.6 ).
1.
Operating the PTO With Separate PTO Controls:
1.1
Set the parking brake.
1.2
Turn on the switch labeled GOVERNOR (or FAST IDLE for vehicles with a preset PTO system).
1.3
For vehicles with a variable PTO, use the potentiometer knob to adjust the engine rpm.
2.
Operating the PTO Using Cruise Control Switches:
2.1
To engage the PTO, flip the ON/OFF switch on the instrument control panel to ON.
2.2
Hold the throttle pedal until the tachometer indicates the desired speed.
2.3
Momentarily move the SET/RESUME switch on the instrument control panel to SET or push the SET button on the transmission shift knob.
2.4
To disengage the PTO, depress the brake pedal, or clutch pedal, or flip the ON/OFF switch on the instrument control panel to OFF or press the PAUSE button on the shift knob.
3.
To resume a previously selected engine speed:
3.1
If the ON/OFF switch on the instrument control panel is in the OFF position, flip it to ON.
3.2
Momentarily move the SET/RESUME switch on the instrument control panel to RESUME or press the RESUME button on the transmission shift knob.
3.2
To adjust engine speed up or down, hold the SET/RESUME switch on the instrument control panel at SET to accelerate or at RESUME to decelerate until the desired speed is reached, or press the SET button on the transmission shift knob to accelerate or the RESUME button to decelerate until the desired speed is reached.
Optimized Idle®
The Optimized Idle option on DDEC III-equipped vehicles is a system that automatically stops and restarts the engine to accomplish the following:
Keep the engine oil temperature between 60 to 104°F (16 to 40°C)
Keep the battery charged
Keep the cab or sleeper at a constant, desired temperature (if equipped with a thermostat)
The benefits of the system include reduced engine idle time, fuel savings, reduction of exhaust emissions and noise, increased starter and engine life, and less chance of dead batteries due to electrical loads.
Optimized Idle operates in two modes. They are the engine mode or the thermostat mode. The engine mode keeps the battery charged and the engine oil temperature within factory set limits. The thermostat mode is the same as the engine mode, but also keeps the cab and sleeper at a constant preset temperature.
The engine mode is always activated when the system is operated. The thermostat mode is activated when the thermostat is turned on.
The thermostat mode controls the set point, which is the desired temperature of the cab and sleeper, and the comfort zone, which is the number of degrees from the set point before the engine needs to heat or cool the cab. There are three comfort zones: 4°F (2°C), 7°F (4°C), or 10°F (6°C).
Vehicles equipped with Optimized Idle have a label and light on the dashboard. The dash light is the bottom one on the vertical array of lights in the center dash panel, and the label is located on the "B" dash panel. See Fig. 7.8 for the label appearance. If equipped with the thermostat mode, a thermostat is located in the sleeper, above the bunk. See Fig. 7.9 .
Fig. 7.8, Optimized Idle Dash Label
- 1. Down Button
- 2. Up Button
- 3. Upper/Lower Temperature Icon
- 4. Temperature Display
- 5. Degrees Fahrenheit Indicator
- 6. Mode Button
- 7. Cooling Icon
- 8. Cool/Heat Selection Button
- 9. Heating Icon
- 10. Degrees Celsius Indicator
Fig. 7.9, Optimized Idle Thermostat
The thermostat consists of an LCD readout and four buttons.
The display normally shows the temperature of the sleeper, but changes accordingly as the buttons are pressed.
The button functions are as follows:
Up Button: increases the set point and comfort zone.
Down Button: decreases the set point and comfort zone.
Cool/Heat Button: detects either cooling or heating operation.
Mode Button: scrolls through the various functions. It can also be used to set desired temperature values.
1.
Activate Optimized Idle (engine mode) as follows:
1.1
Set the parking brake.
1.2
If it is tilted, close and secure the hood.
1.3
Start the engine and let it idle.
1.4
Put the transmission in neutral and in the high range, if so equipped.
1.5
Turn on the cruise control.
IMPORTANT: The cruise control must be turned on after the engine is idling. If it was previously turned on, turn off the cruise control, then turn it on again.
1.6
The dash light will begin blinking, indicating that Optimized Idle is active. The system is now in the engine mode, and after an initial phase in which the idle speeds up to 1000 or 1500 rpm (depending on the outside temperature), the engine will stop and start automatically to keep the battery charged and the engine oil warm. The dash light stays on and shines steadily at this point.
2.
Activate the thermostat mode (if so equipped) as follows:
NOTE: When the system is in the thermostat mode, it is also in the engine mode. It will continue to operate in the engine mode even if the thermostat mode is turned off.
2.1
With the system in the engine mode, set the cab and sleeper heater or air conditioner controls to the highest setting.
2.2
Turn on the thermostat by touching any of the four buttons. See Fig. 7.9 .
2.2
The display will flash the current sleeper temperature and the previous mode (cooling or heating) selected. If the cab needs to be cooled or heated, the cool/heat icon will flash.
2.3
Choose either cool or heat by pressing the Cool/Heat button. Make sure the selection matches that of the cab controls.
IMPORTANT: If the heat or cool selection of the thermostat does not match that of the cab, the system will idle and cycle excessively.
2.4
Select Fahrenheit or Celsius by pressing and holding the Mode button until either the "F" or "C" is displayed.
2.5
Select the temperature set point by pressing either the Up button or the Down button, as applicable. Holding the button will cause the display to count up or down rapidly. When the desired set point is displayed, release the button. The set point is stored in memory.
2.6
Select the temperature comfort zone by pressing the Mode button until the upper and lower temperature limit icon is displayed. Then use the Up or Down button to select one of the three comfort zones of 4°F (2°C), 7°F (4°C), or 10°F (6°C).
3.
To change the display to either Fahrenheit or Celsius, press the Mode button until only the F° or C° icon is flashing. Press the Up or Down button to change to the desired value. The main display will appear five seconds after the button is released.
4.
To deactivate the thermostat mode and return to just the engine mode, press the Mode button and hold it for three seconds.
5.
To shut down Optimized Idle completely, either turn off the ignition or use the drive away feature.
5.
The drive away feature allows the use of all the DDEC features. Use the drive away feature as follows:
5.1
If the engine is running: Release the parking brakes or put the transmission in gear.
5.1
If the engine is not running: Start the engine. Release the parking brakes or put the transmission into gear.
5.2
Let the engine return to base idle. The active light will turn off. Optimized Idle is now disabled and all the DDEC features are available.
Engine Shutdown
Caterpillar
CAUTION
1.
With the vehicle stopped, apply the parking brakes. Reduce the engine speed to low idle.
2.
Place the transmission shift lever in neutral.
3.
If the engine has been operating at low loads, run it at low idle for 30 seconds before stopping. If the engine has been operating at highway speed or at high loads, run it at low idle for three minutes to reduce and stabilize internal engine temperatures before stopping.
4.
Turn off the ignition key to shut down the engine.
5.
If equipped with an idle shutdown timer, it can be set to shut the engine down after a preset amount of time. Ninety seconds before the preset shutdown time, the CHECK ENGINE light will begin to flash at a rapid rate. If the clutch pedal or service brake indicates position change during this final ninety seconds, diagnostic lamp flashing, the idle shutdown timer will be disabled until reset.
6.
After stopping the engine, fill the fuel tank.
7.
Check the crankcase oil level while the engine is stopped. Maintain the oil level between the ADD and FULL marks on the dipstick.
8.
If freezing temperatures are expected, allow the engine jacket water expansion tank to cool, then check the coolant for proper antifreeze protection. The cooling system must be protected against freezing to the lowest expected outside temperature. Add permanent-type antifreeze, if required. For additional information, see Group 20 of the Heavy-Duty Trucks Maintenance Manual .
9.
Repair any leaks, perform minor adjustments, tighten loose bolts, etc. Observe the vehicle mileage or the service meter reading, if so equipped. Perform periodic maintenance as instructed in the Lubrication and Maintenance Chart in the Caterpillar Operation and Maintenance Management Manual .
Cummins
1.
With the vehicle stopped, apply the parking brakes and place the transmission in neutral.
2.
It is important to idle an engine three to five minutes before shutting it down. This allows the lubricating oil and the water to carry heat away from the combustion chamber, bearings, shafts, etc. This is especially important with turbocharged engines.
2.
Bearings and seals in the turbocharger are subjected to the high heat of combustion exhaust gases. While the engine is running, this heat is carried away by oil circulation, but if the engine is stopped suddenly, the turbocharger temperature may rise as much as 100°F (56°C). The extreme heat may cause bearings to seize or oil seals to leak.
3.
Do not idle the engine for excessively long periods. Long periods of idling are not good for an engine because the combustion chamber temperatures drop so low the fuel may not burn completely. This will cause carbon to clog the injector spray holes and piston rings, and may result in stuck valves.
3.
If the engine coolant temperature becomes too low, raw fuel will wash the lubricating oil off the cylinder walls and dilute the crankcase oil; therefore, all moving parts of the engine will suffer from poor lubrication.
4.
If the engine is not being used, shut it down by turning the ignition key off.
CAUTION
Detroit Diesel
1.
With the vehicle stopped, apply the parking brakes, and place the transmission in neutral.
2.
Allow the engine to run at half speed or slower, with no load, for four to five minutes to cool the engine gradually and uniformly.
3.
Shut down the engine by turning the ignition key off.
High-Altitude Operation
Cummins
Engines lose horsepower when operated at high altitude because the air is too thin to burn as much fuel as at sea level. This loss is about three percent for each 1000 feet (300 m) altitude above sea level for a naturally aspirated engine. Most turbocharged engines are rated for higher altitudes than naturally aspirated engines. An engine will have smoky exhaust at high altitudes unless a lower gear is used. The engine will not demand full fuel from the fuel system unless the engine is altitude-compensated by the use of a turbocharger. Shift gears as needed to avoid excessive exhaust smoke.
Bendix Cruise Control System, Optional
General Information
The Bendix cruise control system has two modes of operation: cruise control and stationary throttle control. The cruise control mode maintains a driver-selected speed above 20 mph (32 km/h). The stationary throttle control mode provides operator control of the engine throttle position when the vehicle is parked.
Cruise Control Operation
The cruise control is activated by the ON/OFF and SET/RESUME switches. See Fig. 7.5 . A light in the warning and indicator light module is on when the cruise control is engaged.
WARNING
CAUTION
1.
To cruise at a particular speed:
1.1
Flip the ON/OFF switch to ON.
1.2
Accelerate to the desired speed.
1.3
Push the SET/RESUME switch to SET.
NOTE: The cruise control will not work below 20 mph (32 km/h).
2.
To disengage the cruise control:
2.1
Flip the ON/OFF switch to OFF, or
2.2
Depress the brake pedal, or
2.3
Allow vehicle speed to drop below 20 mph (32 km/h).
2.3
To resume the preselected cruise speed, briefly push the SET/RESUME switch to RESUME. Cruise will return to the last speed selected.
NOTE: The resume vehicle speed memory is not maintained if the ignition is shut off or if the ON/OFF switch is flipped to OFF.
Cruise speed can be adjusted up or down by pushing the RESUME (accelerate) or SET (decelerate) switch until the desired speed is reached.
The vehicle can be accelerated normally with the cruise control engaged. Depress the throttle pedal as needed. When the throttle pedal is released, the vehicle will return to the set cruise speed.
Shifting can be done normally with the cruise control engaged. When the clutch pedal is depressed, the cruise control disengages, allowing the shift to be completed. When the clutch pedal is released, the cruise control reengages, and adjusts engine rpm to return to the selected speed.
Stationary Throttle Control Operation
This mode is used when the vehicle is parked, and is engaged by operating the ON/OFF and the SET/RESUME switches ( Fig. 7.5 ) as follows:
1.
With the engine idling, flip the ON/OFF switch to ON. A light in the warning and indicator light module will come on.
2.
Depress and release the RESUME switch until the desired rpm is reached.
NOTE: It may be necessary to depress and release the switch several times before engine speed increases.
3.
To reduce engine rpm, depress and release the SET switch until the desired rpm is reached.
4.
To disengage the stationary throttle control:
4.1
Flip the ON/OFF switch to OFF, or
4.2
Depress the clutch pedal.
IMPORTANT: In the throttle control mode, engine speed is controlled by positioning the engine throttle linkage. Engine governor characteristics and engine temperature may cause engine speed to vary. Don't leave the vehicle unattended for long periods of time while the stationary throttle control feature is being used.
Engine Braking System, Optional
Jacobs Engine Brake
A Jacobs engine brake is a hydraulic-electric engine attachment that converts a diesel engine into an air compressor. This is done by changing engine exhaust valve operation; it engages or disengages in less than one-fourth of a second. An engine brake is not a substitute for a service braking system, except in emergencies.
The controls consist of:
dual dash switches ( Fig. 7.10 ), which are on/off toggle switches;
Fig. 7.10, Engine Brake Switches
a clutch switch, which is a transmission-mounted microswitch that actuates when the driver removes his foot from the clutch pedal;
a throttle switch, which is an engine-mounted microswitch that actuates when the driver removes his foot from the throttle pedal.
Jacobs Engine Brake Operation
WARNING
To engage the engine brake, one or both of the dash switches must be on (up), and both the clutch and throttle pedals must be fully released. To disengage the engine brake, depress the throttle or clutch pedal, or turn both dash switches off (down). Depending on the engine type, dual dash switches enable the driver to operate the engine brake at one-third, two-thirds, and full capacity or at half and full capacity.
WARNING
Since the engine brake is most effective at rated engine speed, gear selection is very important. Gearing down the vehicle within the limits of the rated engine speed makes the engine brake more effective. Maximum braking occurs with the use of the lowest gear that does not exceed the rated engine speed. A rule of thumb for gear choice is to select the gear that normally would be used to climb an approaching downhill grade. Generally, this same gear can be used with the engine brake for a controlled descent of the hill.
"Control speed" is the speed at which the engine brake performs 100 percent of the required downhill braking, resulting in a constant speed of descent. The control speed varies, depending on vehicle weight and the downhill grade.
For faster descent, select a higher gear than that used for control speed. Service brakes must then be used intermittently to prevent engine overspeed and to maintain desired vehicle speed.
IMPORTANT: When descending a grade, remember that frequent use of service brakes causes them to become hot, which results in a reduction of their stopping ability. Grade descent speed should be such that the service brakes are used infrequently and that they remain cool, thus retaining their effectiveness.
A driver may descend slower than control speed by selecting a lower gear, one that will not overspeed the engine. The engine brake retarding force will then be sufficient to cause vehicle deceleration. Occasional deactivation of the engine brake may be necessary to maintain the designated road speed under these conditions.
The engine brake can be used to stop a vehicle if the service brakes quit working. By energizing the engine brake as soon as a service brake problem is apparent, a retarding effect is applied to the vehicle. As grade conditions permit, the driver can progressively downshift, using the engine brake in each gear. Eventually the engine brake will stop the vehicle.
WARNING
Whenever vehicle braking is required, the engine brake may be used with the service brakes. There is no time limit for operation of the engine brake.
1.
After the engine is warmed up and the vehicle is in motion, turn on the dash toggle switches (up position).
1.
On vehicles equipped with a Cummins NTC engine, select either the left-side switch (one-third engine brake retarding capacity), the right-side switch (two-thirds engine brake retarding capacity), or both switches (full engine brake retarding capacity).
1.
On vehicles equipped with a Cummins L10 or Caterpillar engine, select either the left-side switch or right-side switch (for one-half engine brake retarding capacity), or both switches (for full engine brake retarding capacity).
2.
The engine brake activates when the driver's feet are removed from both the clutch and throttle pedals. If it fails to activate, stop the vehicle in a safe spot and check the adjustment of the throttle and clutch switches. If no cause can be detected in the electrical system, check the engine brake system. See Group 01 of the Heavy-Duty Trucks Service Manual for instructions.
3.
To obtain maximum retarding, maintain the top governed speed of the engine through appropriate selection of gears when the engine brake is in use.
4.
When either the clutch or throttle pedal is depressed, the engine brake is deactivated.
CAUTION
Clutches
General Information
The major reason why clutches wear out too soon is excessive heat. Clutches are designed to absorb and dissipate more heat than encountered in typical operation. The temperatures developed in typical operation will not break down the clutch friction surfaces. However, if a clutch is slipped excessively or asked to do the job of a fluid coupling, high temperatures develop quickly and destroy the clutch. Temperatures generated between the flywheel, driven discs, and pressure plates can be high enough to cause the metal to flow and the friction facing material to char and burn.
Heat and wear are practically nonexistent when a clutch is fully engaged. But during the moment of engagement, when the clutch is picking up the load, it generates considerable heat. An improperly adjusted or slipping clutch will rapidly generate sufficient heat to destroy itself.
The most important items that a driver should be aware of to ensure long service life of the clutch include: starting in the right gear, clutch malfunctions, and when to adjust a clutch.
Clutch Operation
Eaton Valeo Clutch Break-In
With a newly installed Eaton Valeo clutch, the clutch may slip for a short time while the friction surfaces break-in. However, allowing the clutch to slip for more than two seconds can severely damage the clutch disc, pressure plate, and the flywheel.
During initial operation of a new vehicle or a vehicle with a new clutch, check for clutch slippage during acceleration. If the clutch slips, decelerate until the clutch does not slip. Allow the clutch to cool 15 to 30 seconds and then gradually accelerate again. If the clutch continues to slip, repeat the procedure. If necessary, repeat the procedure up to five times. If the clutch slips after five attempts, stop the vehicle. Allow the clutch to cool for at least one hour. Notify your Freightliner dealer of the problem.
CAUTION
Starting the Vehicle in the Proper Gear
An empty truck can be started in a higher transmission gear ratio than when partially or fully loaded. A good rule of thumb for the driver to follow is: select the gear combination that allows you to start moving with an idling engine, or, if necessary, just enough throttle to prevent stalling the engine. After the clutch is fully engaged, the engine should be accelerated to the correct rpm for the upshift into the next higher gear.
Gear Shifting Techniques
Many drivers upshift into the next gear, or even skip-shift into a higher gear, before the vehicle has reached the proper speed. This type of shifting is almost as bad as starting off in a gear that is too high since the engine rpm and vehicle speeds are too far apart, requiring the clutch to absorb the speed difference as heat. For transmission operating instructions, see Chapter 8 in this manual.
The clutch brake is applied by fully depressing the clutch pedal. Its purpose is to stop the transmission gears from rotating in order to engage the transmission gears quickly in making an initial start.
CAUTION
Excessive Vehicle Overload, or Overloading the Clutch
Clutches are designed for specific vehicle applications and loads. These limitations should not be exceeded.
CAUTION
Riding the Clutch Pedal
Riding the clutch pedal is very destructive to the clutch since partial clutch engagement permits slippage, generating excessive heat. Riding the clutch pedal will also put a constant thrust load on the release bearing, which can thin out the lubricant. Release bearing failures can be attributed to this type of misuse.
Holding the Vehicle on an Incline With a Slipping Clutch
A slipping clutch accumulates heat faster than it can be dissipated, resulting in early clutch failures. Never use the clutch as a hill holder.
Coasting With the Clutch Released (Pedal Depressed) and the Transmission in Gear
Coasting with the clutch released and the transmission in gear can cause high driven disc rpm through multiplication of ratios from the final drive and transmission.
WARNING
Engaging the Clutch While Coasting
Engaging the clutch while coasting can result in tremendous shock loads and possible damage to the clutch, as well as to the entire drivetrain.
Reporting Erratic Clutch Operation Promptly
Reporting erratic clutch operation as soon as possible will give maintenance personnel a chance to inspect and lubricate the clutch components, make necessary internal clutch and linkage adjustments, etc.
Clutch free pedal is a decreased resistance felt at the top of the clutch pedal stroke. See Fig. 7.11 . With the clutch pedal in this range, the clutch is fully engaged, and the only resistance to clutch pedal movement is the force of the return spring. If clutch free pedal is 3/4 inch (20 mm) or less, measured at the pedal, have the clutch adjusted.
- A. Free Pedal
Fig. 7.11, Clutch Free Pedal
Free pedal should be included and commented on daily in the driver's report since clutch free pedal is the maintenance department's guide to the condition of the clutch and the release mechanism.
See Group 25 of the Heavy-Duty Trucks Service Manual for clutch adjustment procedures and specifications.
CAUTION
Clutch brake squeeze is an increased resistance (greater than the force of the clutch spring) felt as the clutch pedal approaches the end of its stroke. If the gears grind when shifting into first or reverse gear with the clutch pedal fully depressed, the clutch is out of adjustment or the clutch brake is worn and needs to be replaced.
Clutch Adjustments
Clutches have an internal adjustment, and external linkage adjustment. See Group 25 of the Heavy-Duty Trucks Service Manual for clutch adjustment procedures and specifications.
CAUTION
Lubrication
The release bearing and linkage should be lubricated at frequent intervals. See Group 25 of the Heavy-Duty Trucks Maintenance Manual for intervals and procedures.
CAUTION