844/642 Telehandler HYDRAULICS

Boom Extend Cylinder Troubleshooting

NOTE: If the extend cylinder will extend but will not retract, replace the counterbalance valve on the extend cylinder.

Does the boom extend without a capacity load?

Test the pressure at the test port on MP on the.Follow the Control and Park Brake Pilot flow divider. Lower the boom to the end of thePressure Troubleshooting procedure. Is the cylinder stroke and hold. Does the pressureproblem in the controls? gauge read 3000 psi (207 bar)?

Repair or replace the malfunctioning control components.

Use an in-line pressure gauge to test the extend pressure at the extend cylinder. Does the pressure gauge read 2500 psi (172 bar)?

Repair or replace the extend cylinder.Adjust the extend pressure relief valve in the control valve and retest the extend pressure. Does the gauge read 2500 psi (172 bar)?

If the extend/retract does not work afterRepair or replace the extend control adjusting the relief valve, repair or replacevalve and/or the extend relief valve. the extend cylinder.

Use an in-line flowmeter to test the pressure at the EF port of the priority flow divider. Does the pressure gauge read 3000 psi (207 bar)?

Adjust the relief valve in the Main Control Valve.Remove and bench test the hydraulic pump. Open the load control valve of the flowmeter andDoes the hydraulic pump meet specifications? hold the joystick in the boom lower position. Does the gauge read 3000 psi (207 bar)?

Remove the flowmeter.Replace the relief valve in the Main Control Valve.

Replace the priorityRepair or replace the hydraulic pump. flow divider.

Template Name: OML_1_col 0-00000

Template Date: 1994_04_22