Hydraulic Control Valve

TM 10-3930-631-34

pressure gage. When pressure reaches 1900 psi (133.5

kg-cm ) needle should stop indicating relief valve has

opened.

(3) If relief valve opens above or below 1900 psi

it must be adjusted.

(4) Remove acorn nut covering adjusting screw

at top front of lift control section. Loosen jam nut

securing adjusting screw.

(5) Hold lift control lever all the way to the rear

and adjust pressure. Turn adjusting screw clockwise to

increase pressure and coun- terclockwise to reduce

pressure.

(6) After pressure is properly adjusted, hold

adjusting screw and tighten jam nut to secure

adjustment.

(7) Push lift control lever forward to lower

carriage a short distance. Pull lever all the way to the

rear and hold in this position. Check gage. Relief valve

should open at 1900 psi. Install acorn nut.

(8) Turn master switch off, disconnect battery

receptacle and discharge capacitors.

(9) Disconnect pressure gage and install pipe

Figure 7-4. Checking low volume inlet pressure.

plug in valve.

(10)Install floor plate and center cover panel.

(3) Connect battery receptacle, sit on seat,

7-4. Hydraulic Control Valve

place directional control lever in neutral and turn master

a. Description. The hydraulic control valve (fig. 7-

switch on.

5) is made up of four sections. Inlet and housing

(4) Pull the tilt lever back to actuate the pump

sections enclose the three operating plunger sections.

and retract the tilt cylinders. Hold lever all the way back.

Three operating plunger sections are the side shift, tilt

(5) Observe pressure gage. When pressure

and lift sections. Relief valves are installed in the inlet

reading of 2100 psi (147.6 kg-cm2) is reached needle

and lift control sections.

should stop indicating relief valve opening.

(6) If relief valve opens below or above 2100

psi, relief valve must be adjusted.

(7) Remove acorn nut covering adjusting screw

(fig. 7-4). Acorn nut is located on bottom of inlet valve

section.

(8) Loosen jam nut on adjusting screw and hold

lever in full rearward position as in (4) above. Turn

adjusting

screw

clockwise

increase

counterclockwise to decrease pressure.

(9) When pressure is properly adjusted, hold

adjusting screw and tighten jam nut to secure

adjustment.

(10) Release tilt control lever and push lever

forward to relieve pressure. Pull lever to rear and again

check pressure setting. Relief valve should open at

2100 psi. Install acorn nut.

c. High Volume Pressure Adjustment.

(1) Do not remove pressure gage from inlet

section.

(2) While sitting on operator's seat and with

master switch on, pull lift control lever all the way to the

Figure 7-5. Control Valve.

rear. When mast reaches limit of extension, hold lever

all the way to the rear and observe

7-7