Skyjack SJ 3220, Service Manual

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SJ3220, SJ3226, SJ4720, SJ4726, SJ4732 223198ABA
Section 4 – Troubleshooting Information Hydraulic System
4.3-6 Platform Will Not Lower
1.
Defective Lift valve 3H-14.
Check valve. Replace if defective.
2.
Defective Holding valves 2H-13-1 and/or 2H-13-2.
(if equipped)
Clean valves. Replace if defective.
3.
Machine overloaded and Overload Lights PL-1
and PL-2 on Emergency Stop buttons flashing.
Check machine limits and reduce weight as
required. Refer to electrical troubleshooting.
4.3-7 Platform Drives Slow
1.
Free-wheeling valve V2 open or defective.
Close valve. Replace if defective.
2.
Flow divider/combiner FD1 defective or is
plugged.
Close valve and clean if necessary. Replace if
defective.
3.
Defective Speed valves 2H-18A-1 and/or
3H-18A-2.
Check valve. Replace if defective.
4.
Defective Counterbalance valve CB1.
Check valve. Replace if defective.
5.
Drive Motors M1 and/or M2 defective.
Check motors. Replace if defective.
4.3-8 Platform Will Not Drive in Forward or Reverse
1.
Open Free-Wheeling valve V2.
Close Valve. Replace if defective.
2.
Brakes are not released.
Check brakes. Replace if defective.
3.
Forward Drive valve 4H-16 or Reverse Drive valve
4H-15 is defective.
Check Valve. Replace if defective.
4.
Flow/Divider/Combiner valve FD1 defective or is
plugged.
Check Valve. Replace if defective.
5.
Defective Counterbalance valve CB1.
Check valve. Replace if defective.
6.
Drive Motors M1 and/or M2 defective. Check motors. Replace if defective.
4.3-9 Brake(s) will not Release (Pin Brakes)
1.
Brake valve 3H-17 is defective.
Check valve. Replace if defective.
2.
Defective or plugged Brake Orifice O6
(
SJ3220/26
) or Orifice O5 (
SJ4720/26/32
).
Check valve. Replace if defective.
3.
Leaking or defective Brake Cylinder.
Check cylinder. Replace or repair if defective.