Hydraulic System; All Functions Inoperative; All System Sluggish; Platform Drifts Down - Skyjack SJ3220 Service Manual

Hydraulic System

4.3 Hydraulic System

4.3-1 All Functions Inoperative

1. Electric Motor DCM1 not engaged.
2. Pump P1 defective.

4.3-2 All System Sluggish

1. System Relief Valve R1 defective or not adjusted
properly.
2. Hydraulic pump P1 worn.

4.3-3 Platform Drifts Down

1. Defective Lift cylinder seals at the gland.
2. Combination of stuck or defective Holding valves
2H-13-1 and/or 2H-13-2 and defective Relief
valves R3 and/or R4, if equipped.

4.3-4 Platform Lifts Slowly

1. Defective Lift valve 3H-14.
2. Lift Relief valve R2 is set incorrectly.
3. Defective Holding valves 2H-13-1 and/or 2H-13-2.
(If equipped)
4. Defective or plugged Lift Orifices O2 or O3.
(if equipped)

4.3-5 Platform Does Not Lift

1. Defective Lift valve 3H-14.
2. Hydraulic oil level too low.
3. Machine overloaded and Overload Lights PL-1
and PL-2 on Emergency Stop buttons flashing.
4. Defective or plugged Lift Orifices O2 or O3.
(if equipped)
5. Leaking or defective Lift cylinders C2 and/or C3.
(if equipped)
SJ3220, SJ3226, SJ4720, SJ4726, SJ4732
Section 4 – Troubleshooting Information
Refer to electrical troubleshooting.
Check system pressures and Pump P1
functionality. Replace if defective.
Adjust valve. Replace if defective.
Check system pressure and flow from Pump P1.
Replace if defective.
Replace if damaged.
Note: There are no piston seals, just wear rings.
Check valves. Replace if defective.
Check valve. Replace if defective.
Check pressures. Replace if defective.
Check Holding valves 2H-13-1 and 2H-13-2.
Replace if defective.
Clean Orifices. Replace if defective.
Check valve. Replace if defective.
Fully lower the platform. Fill hydraulic tank until
fluid is at or slightly above the top mark on the
sight glass.
Check machine limits and reduce weight as
required. Refer to electrical troubleshooting.
Clean Orifices. Replace if defective.
Check cylinders and/or Orifices. Replace if
defective.
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