Platform Will Not Lower; Platform Drives Slow; Platform Will Not Drive In Forward Or Reverse; Brake(S) Will Not Release (Pin Brakes) - Skyjack SJ3219 Service Manual

Hydraulic System

4.3-6 Platform Will Not Lower

1. Defective Lift valve 3H-14.
2. Defective Holding valve 2H-13.
3. Defective or plugged Lift Orifice O3.
4. Machine overloaded and Overload Lights PL-1
and PL-2 on Emergency Stop buttons flashing

4.3-7 Platform Drives Slow

1. Free-wheeling valve V2 open or defective.
2. Defective or plugged Drive Orifice O4.
3. Defective Counterbalance valve CB1.
4. Drive Motors M1 and/or M2 defective.

4.3-8 Platform Will Not Drive in Forward or Reverse

1. Free-Wheeling valve V2 is open or defective.
2. Brakes are not released.
3. Forward Drive valve 4H-16 or Reverse Drive valve
4H-15 is defective.
4. Defective or plugged Drive Orifice O4.
5. Defective Counter Balance valve CB1
6. Drive Motors M1 and/or M2 defective.

4.3-9 Brake(s) will not Release (Pin Brakes)

1. Brake Release valve 3H-17 is defective.
2. Defective or plugged Brake Orifice O5.
3. Leaking or defective Brake Cylinder.

4.3-10 Brake(s) will not Release (Wet Brakes)

1. Brake Release valve 3H-17 is defective.
2. Brake Override valve V1 is defective.
3. Defective internal brake piston seals.
4. Defective Brakes BR1 and/or BR2.
SJ3215, SJ3219
Section 4 – Troubleshooting Information
Check valve. Replace if defective.
Clean valve. Replace if defective.
Clean Orifice. Replace if defective.
Check machine limits and reduce weight as
required.
Refer to Electrical troubleshooting.
Close valve. Replace if defective.
Clean Orifice. Replace if defective.
Check valve. Replace if defective.
Check motors. Replace if defective.
Close valve. Replace if defective.
Check brakes. Replace if defective.
Check valves. Replace if defective.
Clean Orifice. Replace if defective.
Check valve. Replace if defective.
Check motors. Replace if defective.
Check valve. Replace if defective.
Check Orifice. Replace if defective.
Check cylinder. Replace or repair if defective.
Check valve. Replace if defective.
Check valve. Replace if defective.
Check brake pack will maintain pressure. If
pressure is not maintained replace seals.
Inspect wheel assembly. Repair and replace as
necessary.
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