Upright SL-26, Service & Parts Manual

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3. Service and Repair
3-6
Main Relief Valve
Figure 3-4: Hydraulic Manifold Assembly, Front View
Counterbalance Valves
1. Operate the work platform for 10-15 minutes to bring the hydraulic oil up to normal operating temperature.
2. Remove the gauge port cap and install the pressure gauge assembly.
3. Using two 1-ton jack stands and a 2-ton jack, jack the work platform up to raise the rear wheels off the
ground and block the machine securely.
4. Loosen the locknuts on Counterbalance Valves.
5. With the machine fully powered up depress the
DRIVE button on the upper control box, depress the
interlock lever and slowly pull the control lever to REVERSE to drive the wheels.
6. Adjust the Forward Counterbalance Valve by turning the adjustment screw until the pressure gauge
indicates 34.5 bar ( 500 psi ).
7. Slowly push the Control Lever to FORWARD to drive the wheels.
8. Adjust the Reverse Counterbalance Valve by turning the adjustment screw until the pressure gauge
indicates 34.5 bar ( 500 psi ).
9. Check the settings by slowly moving the Control Lever FORWARD , then REVERSE , checking the gauge to
ensure pressures are properly set. Re-adjust as needed.
10. Tighten locknuts on valves to 8N-m ( 6 ft-lbs ). Remove blocks and lower work platform to ground.
11. Remove the gauge from the gauge port and re-install cap.
12. Check for proper operation of the drive system and brake.
Fore/Aft Tilt Cylinder Relief Valve (CT4)
1. Operate the hydraulic system for five minutes.
2. Remove the quick disconnect plug and install a 0-100 bar (0-600 psi) pressure gauge.
3. Remove the plug from the end of the valve to expose the adjusting screw.
4. With the engine running, tilt the platform
fully forward using the fore/aft level switch.
5. While holding the level switch forward, set the pressure to 13 bar (500 psi) maximum by slowly turning the
adjusting screw, clockwise increases pressure.
6. Replace the valve plug.
7. Remove the gauge and reinstall the plug.
8. Level the platform.
1. Main Relief Valve
2. Overcentre Valves
3. Lift Coil 4. Steering Relief Valve
5. Test Port
6. Manual Brake Release Pump
1 2
3
4
5
1. Operate the hydraulic system 10 to 15 minutes
to warm the oil.
2. Remove the cap or loosen the locknut on the
Main Relief Valve.
3. Install a 0-250 bar ( 0-3000 psi ) pressure gauge
to the gauge port.
4. Select LIFT mode and elevate the machine fully.
5. While holding the Chassis Lift Button, adjust the
Main Relief Valve until the pressure gauge
reads 172 bar ( 2500 psi ).
6. Release the Chassis Lift Button.
7. Replace the cap, or tighten the locknut on the
Lift Relief Valve, and torque to 8N-m ( 6 ft-lbs ).
8. Lower the platform.
6