844/642 Telehandler HYDRAULICS

STEP 89

Step 90

If the pump, relief valve or any cylinders are repaired or replaced, repeat Steps 87, 88 and 89 to set the main control valve relief pressure at 3000 psi (207 bar).

Step 91

Shut off the engine. Remove the main relief valve (1) and turn the adjusting screw (2) clockwise to increase and counter clockwise to decrease the pressure.

NOTE: 1/2 turn of the adjusting screw (3) will change the pressure approximately 500 psi (35 bar).

Install the main relief valve cover.

Repeat Steps 87, 88 and 89 until the pressure gauge reads 3000 psi (207 bar).

If the pressure can be adjusted to 3000 psi (207 bar), proceed to Step 90.

If the pressure is more than 3000 psi (207 bar) and does not change when the adjusting screw (3) is turned counterclockwise, replace the main relief valve.

If the pressure is less than 3000 psi (207 bar) and does not increase when the adjusting screw is turned clockwise, go to the Pump Pressure Test in this manual before replacing the relief valve.

Template Name: OML_2_col

Template Date: 1994_04_22

0-00000

844/642 Telehandler HYDRAULICS

Joystick Control And Park Brake Pressure Test

STEP 92

If the forklift does not respond to the joystick controller and the problem is not the pump or cylinders, proceed to Step 102.

If the forklift does not respond to one of the joystick controller commands, proceed to the next step.

If the park brake does not respond to the park brake switch, proceed to Step 99.

Step 93

Remove the hose from the hydraulic solenoid of the function to be tested. Install a 1000 psi (69 bar) pressure gauge and hose between the hydraulic solenoid and the supply hose.

NOTE: The hose must be long enough to observe the pressure gauge from inside the cab or standing clear of the forklift.

Step 94

Start the engine and run at 1000 RPM. The park brake must be ON. Hold the joystick in the position of the solenoid to be tested. The pressure gauge should read 350 psi (24 bar).

If the pressure is 350 psi (24 bar) but there is no response to the joystick command, repair or replace the control solenoid or the control valve section.

If the pressure is less than 350 psi (24 bar), proceed to Step 96.

If the pressure is more than 350 psi (24 bar), proceed to the next step.

Step 95

Shut off the engine. Replace the flow divider. Repeat Step 94.

Template Name: OML_2_col

Date: 1994_04_22