Section XII. HYDRAULIC LIFT SYSTEM

Section XII. HYDRAULIC LIFT SYSTEM

This pump supplies hydraulic pressure to the

3-70. General

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

e. Inspection.

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

excessive wear.

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

NOTE

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

pressure.

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

hydraulic tank.

a. General. The main hydraulic pump is

mounted to the rear section of the transmission.

3-197