JLG 150HAX ANSI Service Manual - Manual (Page 134)

SECTION 6 - SCHEMATICS
6-6 – JLG Lift – 3120679
Boom will not extend.
Damaged wiring on control switch, solenoid
valve or proportional valve. Repair or replace wiring.
Solenoid valve or proportional valve not function-
ing properly. Repair or replace valve.
Control lever not functioning properly. Repair or replace lever.
Restricted or broken hydraulic line or fitting. Clean, repair or replace line or fitting.
Telescope cylinder not functioning properly. Repair or replace cylinder.
Pressure setting not correct. Check pressure/re-adjust as necessary.
Broken telescope chain.
(Main boom only.) Replace chain. (Main boom only.)
Boom extends and retracts erratically.
Hydraulic system oil low. Replenish oil as necessary.
Wear pads not adjusted or worn. Adjust or replace pads as required.
Restricted or broken hydraulic line or fitting. Clean, repair, or replace line or fitting.
Control lever not functioning properly. Replace lever.
Worn seals in telescope cylinder. Replace seals.
Cylinder not functioning properly. Replace cylinder.
Distorted boom section(s). Replace distorted section(s).
Chain sheaves worn/damaged.
(Main boom only.) Replace worn/damaged components.
(Main boom only.)
Boom chains loose. (Main boom only.) Tighten chains. (Torque to 50 ft. lb. [68 Nm] dry.).
(Main boom only.)
Counterbalance valve not functioning properly. Replace counterbalance valve.
Mid or fly section inoperative.
Broken drive chain. (Main boom only.) Repair or replace chain.
Mid and fly sections extend and retract erratically.
Drive chain out of adjustment. Adjust chain as required.
(Main boom only.)
Wear pads out of adjustment or worn. Adjust or replace pads as required.
Damaged/worn sheave or chain links.
(Main boom only.) Repair or replace chain or sheave as required.
(Main boom only.)
Mid or fly section distorted. Replace mid or fly section, as necessary.
Table 6-2.Boom Assembly - Troubleshooting
TROUBLE PROBABLE CAUSE REMEDY