Skyjack SJKB-40-D Operating Maintenance Instructions & Part List page 82

TROUBLE
NO PLATFORM LEVEL-
ING UP
NO PLATFORM LEVEL-
ING UP OR DOWN
PLATFORM DRIFTS
DOWN
PLATFORM WILL NOT
STAY LEVEL WITH
BOOM MOTION
BRAKES WILL NOT RE-
LEASE
BRAKES WILL NOT EN-
GAGE
NO DRIVE FORWARD
OR REVERSE
SJKB-40-D, SJKB-40-D/F
TROUBLESHOOTING (Cont.)
PROBABLE CAUSE
HYDRAULIC SYSTEM (Cont.)
1. Stuck or defective platform level
up valve 4H-41A.
2. Leveling master cylinder by
passing internally.
3. Stuck counter balance valve
CB13.
1. Plugged orifice.
1. Leaking or defective counter
balance valve CB12.
1. Leveling master cylinder by
passing internally.
2. Leaking or defective counter
balance valve CB12(down) or
CB13(up).
1. Defective brake valve 3H-26A.
2. Defective or misadjusted pressure
reducing valve PR1.
3. Defective relief valve RV8.
4. Stuck shuttle valve SV1.
1. Stuck or defective brake valve 3H-
26A.
2. Brakes out of adjustment.
3. Brake apply control valve FC2
closed.
1. Brakes will not release.
2. Defective relief valve RV5.
3. Defective pressure over-ride valve
P.O.R.1.
4. Defective or stuck directional
valve 4H-15 or 4H-16.
5. Defective main drive pump P1.
6. Defective drive motor M1.
1.
2.
3.
1.
1.
1.
2.
1.
2.
3.
4.
1.
2.
3.
1.
2.
3.
4.
5.
6.
JUN. 1999
REMEDY
Clean Valve. Replace if defective.
Rebuild cylinder. Replace if
damaged.
Clean Valve. Replace if defective.
Clean Orifice.
Check Valve. Replace if
defective.
Rebuild cylinder. Replace if
damaged.
Check Valve. Replace if
defective.
Check Valve. Replace if
defective.
Check Valve. Replace if
defective.
Check Valve. Replace if
defective.
Check Valve. Replace if
defective.
Check Valve. Replace if
defective.
Refer to section 5 for adjustment
procedure.
Refer to section 5 for adjustment
procedure.
Refer to section 5, "brake
diagnostics".
Refer to section 5 for test
procedure. Replace if defective.
Refer to section 5 for test
procedure. Replace if defective.
Check Valve. Replace if
defective.
Refer to section 5, "drive pump
diagnostics.
Refer to section 5, "drive motor
test procedures". Replace if
defective.
SECTION 4, Page 31