General Information

The 2535 sliding fifth wheel models incorporate a Model 3500 fifth wheel (see Fig.), equipped with either an air-operated release slide, or a manual release slide. Sliding fifth wheel assemblies are mounted on a baseplate which permits forward and rear movement along notched rails. Plungers are meshed into teeth on the baseplate to lock the sliding mechanism. Disengagement of the sliding member is accomplished when the plungers are withdrawn (manually or air-operated), releasing the fifth wheel assembly so that it can be positioned for optimum weight distribution over the tractor axles.

Kingpin Lock Mechanism

Kingpin Control Handle

Mounting Bracket

Fig. 1, Holland Fifth Wheel

The air-operated release slide assembly (see Fig.) contains a double-ended air cylinder which locks and unlocks both sides of the sliding member at the same time. The air cylinder is activated by a two-position air-control valve in the tractor cab.

Note: Baseplate rails not shown.

Kingpin Lock Control Handle

Double-Ended Air Cylinder

Slide Plunger Release

Fig. 2, Air-Operated Release Slide Assembly

The manual release slide assembly (see Fig.) is equipped with a single release lever. Pulling on the release lever unlocks both plungers.

Note: Baseplate rails not shown.

Kingpin Lock Control Handle

Plunger Release Handle

Plunger Release Spring

Plunger

Fig. 3, Manual Release Slide

Type "B" Kingpin Lock Mechanism (see Fig.)

Closed Position, Locked

Open Position, Unlocked

Release Handle and Spring

Adjustment Nut

Lock Halves

Lock Pivot

Sliding Yoke

Fig. 4, Type "B" Kingpin Lock Mechanism (bottom view)

The Type "B" kingpin lock mechanism utilizes two spring-loaded lock halves. The final forward motion of the kingpin into the open lock halves forces the locks to close in a 360 degree grip around the shoulder and neck of the kingpin, positioning sliding yokes between the lock halves and tapered rib members of the fifth wheel understructure. The kingpin can be released only by manually operating the kingpin lock control handle. The adjustment nut will compensate for wear on the lock or kingpin.

Lockguard

The Holland lockguard is a device that prevents a false lockup, and is used on all models. The Lockguard is a spring-tensioned, smooth-surfaced tongue that the kingpin passes over and depresses when entering the lock mechanism. The Lockguard will prevent the locks from engaging before the kingpin fully enters the locks. If the kingpin enters the fifth wheel incorrectly and does not depress the tongue, the locks are unable to close.