Section XII. HYDRAULIC LIFT SYSTEM
This pump supplies hydraulic pressure to the
hydraulic lifting system.
The hydraulic lift system consists of the main
b. Removal. Refer to figure 3-141 and remove
hydraulic pump, hydraulic control valves, lift
main hydraulic pump.
cylinder, slave cylinder, tilt cylinder, extension
c. Disassembly. Refer to figure 3-142 and
cylinder, oscillation cylinder and the side shift
disassemble main hydraulic pump.
c y l i n d e r . The purpose of the hydraulic pump is to
p i c k up and force oil thru the hydraulic system, by
(1) Inspect housing for cracks, damage and
d i s p l a c i n g hydraulic oil from one side of the piston
t o the other side thru the sump tank. When oil is
(2) Inspect gears for damage.
forced into one end of a hydraulic cylinder it moves
(3) Inspect bearings for excessive wear.
t h e cylinder piston toward the opposite end of the
f. Reassembly. Refer to f i g u r e 3 - 1 4 2 a n d
cylinder. By this means it is possible to move a load
r e a s s e m b l e main hydraulic pump.
w h i c h is attached to the cylinder piston rod. All of
t h e hydraulic cylinders on the fork lift are of the
double acting type. The main control valve is in-
After overhaul, run pump for 30 minutes at 2000
rpm while pumping SAE No. 10 oil at 0 psi outlet
s t a l l e d in the hydraulic circuit, where it serves to
direct the hydraulic oil to selected points in the
hydraulic system. With all operating valve spools in
g . Test. B e n c h t e s t p u m p b y d r i v i n g i t a t 2 8 0 0
n e u t r a l position, oil flow from the pump will cir-
rpm, and load pump to 1800 psi. Pump capacities
c u l a t e freely through the various valve section back
are 6 gallons per minute for front outlet and 6
to the hydraulic reservoir.
gallons per minute at rear outlet.
3-71. Main Hydraulic Pump
h. Install. Refer to figure 3-141 and install main
a. General. The main hydraulic pump is
mounted to the rear section of the transmission.