Lift Axles
Lift axles are axles that can be lifted off the ground to reduce tire wear, rolling resistance, and toll charges when not required to distribute chassis load to meet the gross axle weight rating (GAWR) and bridge law requirements.
Fig. 1, Lift Axle Dash Switch
A manually controlled lift axle can be lowered by toggling up on the LIFT AXLE switch. See Fig.. The axle can be raised by toggling down on the LIFT AXLE switch. The switch will illuminate green when the axle is in the lowered position.
There are three types of axles that are manually lowered and raised using the LIFT AXLE switch:
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Steerable lift axle: will raise when the vehicle is put in reverse.
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Non-steerable lift axle: will maintain position when the vehicle is put in reverse.
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Lock-straight lift axle: will raise when the vehicle is put in reverse; the wheels lock in place when the lift axle is up.
There are also auto-deploying lift axles which automatically raise and lower given specific conditions:
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Reverse Autolift: the retractable axle might rise or stay in the fully-up position when the transmission is shifted into reverse.
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OptiMAAX: the retractable axle might move to or stay in the fully-down position on a loaded vehicle following a system malfunction, loss of power, or a perceived tampering attempt. The retractable axle will also lower to the fully-down position when payload reaches a certain weight.