MAINTENANCE OF FORKLIFTS - OD1660 - LESSON 1/TASK 1
(2) Priming the Hydraulic Pumps.
The procedure given here for
priming the hydraulic pump applies both to the main and the engine
The following hydraulic pump priming procedure is
recommended after installing any hydraulic pump.
(a) When priming the hydraulic pump, the hydraulic pressure
line is left loose or the pressure test pipe plug left out, and the
engine shut-off control is pulled out so that the engine will not
start. The engine is turned with the starter only, running the pump
until a gallon or more of oil pushes out.
(b) A pipe plug is installed or the hose line is closed. Then
the engine is started and run at idle only.
Do not operate the
hydraulic controls while the engine is idling.
(c) The engine is allowed to idle for several minutes. (On the
engine driven pump, the hydraulic brake accumulator pressure is
building, creating a load on the pump).
The engine should not be
These pumps will not tolerate air bubbles under
pressure without internal damage.
Bleeding of air from the hydraulic pumps before
start-up and then idling for several minutes
cannot be over emphasized.
(d) Actuate the hydraulic controls at idle speed, increasing
the engine speed until it reaches full operation.
Rear Steering Pump.
The rear steering pump is mounted on the
transfer case and supplies pressure for the rear steering only
(figure 8 on the following page).
After the pump has been removed
and disassembled, the following steps are performed: