Skyjack SJ 3220, Service Manual

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SJ3220, SJ3226, SJ4720, SJ4726, SJ4732 223198ABA
Section 4 – Troubleshooting Information Hydraulic System
4.3-10 Brake(s) will not Release (Wet Brakes)
1.
Brake Release valve 3H-17 is defective.
Check valve. Replace if defective.
2.
Brake Override valve V1 is defective.
Check valve. Replace if defective.
3.
Defective internal brake piston seals.
Check brake pack will maintain pressure. If
pressure is not maintained replace seals.
4.
Defective Brakes BR1 and/or BR2.
Inspect wheel assembly. Repair and replace as
necessary.
4.3-11 MEWP will not hold on a Grade (Wet Brakes)
1.
Worn or damaged brake discs.
Inspect brake discs for wear. Replace if worn or
damaged.
2.
Broken or damaged brake compression springs.
Check springs. Replace if defective.
3.
Defective Brakes BR1and/or BR2.
Inspect wheel assembly. Repair and replace as
necessary.
4.3-12 Platform does not Steer
1.
Right Steer valve 4H-23A and/or Left Steer valve
4H-24A is defective.
Check valves. Replace if defective.
2.
Steer cylinder C1 seal leaking.
Rebuild cylinder. Replace if damaged.
3.
Steering cylinder Orifice 01 is plugged.
Clean orifice. Replace if damaged.
4.
Mechanical binding in kingpins.
Check for binding. Repair as needed.
4.3-13 High/Low Torque Inoperative
1.
Speed valve 3H-18A-1 and/or 3H-18A-2 are stuck
or defective.
Clean valves and check operation. Replace if
defective.
2.
Differential valve 2H-18A is defective.
Clean valve and check operation. Replace if
defective.
4.3-14 Platform Power Deck Inoperative (if option installed)
1.
Platform Extend valve 4H-26 and/or Platform
Retract valve 4H-27 is defective.
Check valves. Replace if defective.
2.
Platform cylinders C5 and/or C6 (if installed) seal
leaking or is defective.
Rebuild cylinder(s). Replace if damaged.
3.
Mechanical binding in platform rails, rollers,
guides, etc.
Check for binding. Repair as needed.