JLG G12-55A Service Manual - Manual (Page 136)

Hydraulic System
8-16 G10-55A, G12-55A
8.7.5 Service Brake Test
This procedure is used in order to determine if service
brake is functional. This procedure is not intended to
measure maximum brake performance. Brake holding
torque that is required to sustain an engine torque at a
specific engine rpm varies depending on machine
configuration. Variations are differences in engine
settings, power train efficiency and in brake holding
ability, etc.
Conduct the following service brake test on a dry level
surface, clear of any personnel and/or obstacles.
1. Place transmission control lever in (N) NEUTRAL,
engage the park brake, and start the engine.
2. Raise the boom to a travel position.
3. Depress the service brake, disengage the parking
brake and place the transmission control lever in
third gear forward.
4. Smoothly and controllably depress the throttle pedal.
Note: Do Not hold the accelerator pedal in the fully
depressed position for more than ten seconds. Damage
to the power train could occur.
5. Smoothly and controllably fully release the
throttle pedal.
6. Machine should remain stationary during test.
7. If machine does not remain stationary during this
test, contact the local distributor for proper service.
8. Engage park brake, place transmission control lever
in (N) NEUTRAL, lower boom and shut engine OFF.
8.7.6 Steering Orbitrol Valve
The steering orbitrol valve (7) is located at base of
steering wheel shaft, concealed by lower dash cover. The
valve is not serviceable and must be replaced in its
entirety if defective. For detailed information refer to
Section 4.3.1, “Steering Column and Orbitrol Valve.”
MY4280 7