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JLG 120HX Service And Maintenance Manual

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View thousands of Crane Specifications on FreeCraneSpecs.com
Service and Maintenance Manual
Model
120HX
3120686
May 15, 2002
ANSI

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Table of Contents
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Summary of Contents for JLG 120HX

  • Page 1 View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com Service and Maintenance Manual Model 120HX 3120686 May 15, 2002 ANSI...
  • Page 2 View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com...

  • Page 3: A General

    Relieve system pressure by cycling the applicable control several times with the engine stopped and ignition on, to direct any line pressure back into the reservoir. Pressure 3120686 – JLG Lift –...
  • Page 4 View thousands of Crane Specifications on FreeCraneSpecs.com INTRODUCTION REVISON LOG July 1, 1992 - Original Issue June 1, 1995 - Revised January, 1999 - Revised August 9, 2001 - Revised May 15, 2002 - Revised – JLG Lift – 3120686...
  • Page 5 Hydraulic Oil ............. 1-5 3120686 – JLG Lift –...

  • Page 6: Table Of Contents

    Frame Jack Cylinders..........2-9 Cylinders w/Single Counterbalance Valves - Lift Cylinder, Telescope Cylinder, Extend-A-Reach Cylinder. 2-10 Cylinders w/Dual Counterbalance Valve - Axle Extension Cylinders, Telescope Cylinder, Platform Slave Level Cylinder 2-10 – JLG Lift – 3120686...
  • Page 7 RAMP Adjustment ............2-51 3120686 – JLG Lift –...
  • Page 8 Boom Marking Tape Installation ...........2-52 – JLG Lift –...
  • Page 9 Electrical System - Troubleshooting ..........3-20 3120686 – JLG Lift –...
  • Page 10 View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com TABLE OF CONTENTS (Continued) This page left blank intentionally. – JLG Lift – 3120686...

  • Page 11: Capacities

    Drive Brake - Spring applied, hydraulically released, Gradeability release pressure 140 psi (9.7 bar). 2WD - 25%. Drive Motor - 2 speed, 0.4 in.[3]/rev. (6.4 cm[3]/rev.) low speed, 0.2 in.[3]/rev. (2.5 cm[3]/rev.) high speed. 4WD - 40%. 3120686 – JLG Lift –...

  • Page 12: Turning Radius (4 Wheel Steer)

    Ground to 120’ to Ground Machine Width 505 to 637 seconds. 8 ft. 6 in. (2.6 m) w/axles retracted. 10 ft. 10 in. (3.3 m) w/ axles extended. Wheelbase 11 ft. 4-1/2 in. (3.5 m). – JLG Lift – 3120686...

  • Page 13: Function Speeds (Machines Built After S/N 38697)

    315 to 400 Seconds NOTE: See Section 2 for tightening sequence of turntable bearing bolts. NOTE: When maintenance becomes necessary or a fas- tener has loosened, refer to the Torque Chart Figure 1-1 to determine proper torque value. 3120686 – JLG Lift –...
  • Page 14 View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 1 - SPECIFICATIONS – JLG Lift – 3120686...

  • Page 15: Lubrication

    CC/SE, CC/SF, CD/SE, CD/SF, CE/SF or CE/ SG.l NOTE: Aside from JLG recommendations, it is not advisable Table 1-2. Single Viscosity Oil to mix oils of different brands or types, as they may not contain the same required additives or be of...
  • Page 16 View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 1 - SPECIFICATIONS – JLG Lift – 3120686...

  • Page 17: Lubrication Chart

    Swing Bearing Gear Master Cylinder - Rod End 1 Grease Fitting MPG - Pressure Gun 2 Grease Fittings MPG - Pressure Gun Boom Pivot Bearings Lift Cylinder - Rod End 1 Grease Fitting MPG - Pressure Gun 3120686 – JLG Lift –...

  • Page 18: Pressure Settings - Psi (Bar)

    Level Down Relief - 2000 (138) Rotate Relief - 2500 (172) Extend-A-Reach Up Relief - 3000 (207) Extend-A-Reach Down Relief - 1400 (97) Sequence (Load Sense) - 160 (11)* * Sequence pressure is pre-set and not normally adjusted. – JLG Lift – 3120686...

  • Page 19: Serial Number Locations

    14,400 (6,532) (12.7) (44.8) (7.6) Tires and Wheels) Axle Extend Cyl. (2) 29.0 Wheel and Tire Assembly 933 (423) (7.6) (73.7) (5.1) (Each) Steer Cylinder (2) Complete Machine - 4WD 44,004 (19,960) (7.6) (24.9) (3.8) 3120686 – JLG Lift –...

  • Page 20: Critical Stability Weights

    243 lb. (110 kg) DO NOT REPLACE ITEMS CRITICAL TO STABILITY, SUCH AS THE COUNTERWEIGHT OR FOAM-FILLED TIRES, WITH ITEMS OF DIF- FERENT WEIGHT OR SPECIFICATION. DO NOT MODIFY UNIT IN ANY WAY TO AFFECT STABILITY. 1-10 – JLG Lift – 3120686...

  • Page 21: Section 2. Procedures

    2. Discard bearings if the races and balls (or rollers) order to function properly. are pitted, scored, or burned. 3120686 – JLG Lift –...

  • Page 22: Gaskets

    NOTE: Metal particles may appear in the oil or filters of new machines due to the wear-in of meshing compo- nents. – JLG Lift – 3120686...

  • Page 23: Hydraulic Oil

    2. JLG recommends Kendall Hyken 052 hydraulic oil, Should any question arise regarding the use of greases in which has an SAE viscosity of 10W-20 and a viscos-...

  • Page 24: Manual Hydraulic Control Valves

    11. Repeat steps (2) thru (10) if necessary. 12. Check for proper operation of boom. Crossover Relief Valves JLG Industries, Inc. requires a complete boom disassem- Crossover relief valves are used in circuits where the actu- bly, per the instructions outlined in paragraph 2-11, Boom ator requires an operating pressure lower than that sup- Maintenance, every two years.
  • Page 25 View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 2 - PROCEDURES Figure 2-1. Boom Chain Adjustments 3120686 – JLG Lift –...

  • Page 26: Inspection Procedure

    RESULT IN UNCONTROLLED EXTENSION OR RETRACTION OF promptly. Do not repair chains; if a section of THE BOOM ASSEMBLY AND COULD CAUSE SERIOUS INJURY OR chain is damaged, replace the entire chain set. DEATH TO PERSONNEL OPERATING THE JLG BOOM LIFT. – JLG Lift – 3120686...
  • Page 27 Like fatigue cracks, these initiate at the Fatigue and ultimate strength failures on JLG Lifts are incurred as a result of severe abuse as point of highest stress (aperture) but tend to...

  • Page 28: Wear Pads

    If boom has retracted more than 1 inch (2.5 cm) and oil is leaking around rod- end of telescope cylinder (check with light and inspection mirror), seals are defective and require – JLG Lift – 3120686...

  • Page 29: Lift Cylinder

    E N S U R E T H AT H Y D R A U LI C L I N E S A R E C O N N E C TE D A S MARKED PRIOR TO BEING DISCONNECTED. 9. Connect hydraulic lines to control valve. 3120686 – JLG Lift –...

  • Page 30: Cylinders W/Single Counterbalance Valves - Lift Cylinder, Telescope Cylinder, Extend-A-Reach Cylinder

    6. If used, remove boom prop or lifting device from boom, activate hydraulic system and run cylinder through one complete cycle to check for leaks. 2-10 – JLG Lift – 3120686...

  • Page 31: Cylinder Removal And Installation

    14. Remove the two (2) extension chain adjusting nuts (3) bolts, washers and lockwashers which attach the at the aft end of the base boom. bracket to the aft end of the base boom. 3120686 – JLG Lift – 2-11...

  • Page 32: Lift Cylinder Removal

    20. Install boom end cover. 5. Place boom in the stowed position and shut down 21. Retract boom fully and place in stowed position. engine. Check hydraulic fluid level and adjust accordingly. 2-12 – JLG Lift – 3120686...

  • Page 33: Master Level Cylinder Removal

    Secure rod end attach pin with bolt, lockwasher and nut. 3120686 – JLG Lift – 2-13...

  • Page 34: Cleaning And Inspection

    4. Inspect inner surface of cylinder barrel tube for scor- ing or other damage. Check inside diameter for tapering or ovality. Replace if necessary. 5. Inspect threaded portion of barrel for damage. Dress threads as necessary. 2-14 – JLG Lift – 3120686...

  • Page 35: Assembly

    Dress piston surface or replace piston as necessary. NOTE: Prior to cylinder assembly, ensure that the proper cylinder seal kit is used. See your JLG Parts Manual. 7. Inspect seal and o-ring grooves in piston for burrs and sharp edges. Dress applicable surfaces as nec- essary.

  • Page 36: Cylinder Piston Nut Torque Specifications

    5 times with 2-16 – JLG Lift – 3120686...

  • Page 37: Boom Maintenance

    17. Using suitable straps, tie off outer mid section retract chains to underside of inner mid section as inner NOTE: Left or right is determined facing the machine from mid, outer mid and fly sections are exiting base sec- the platform. tion. 3120686 – JLG Lift – 2-17...
  • Page 38 View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 2 - PROCEDURES Figure 2-6. Boom Assembly - Sheet 1 of 2 2-18 – JLG Lift – 3120686...
  • Page 39 15. Chain Adjustment Assembly Fly Extend Chain 16. Upper Rear Wear Pad Fly Retract Chain 17. Adjustment & Jam Nuts Outer Mid Retract Chain 18. Safety Chain Figure 2-7. Boom Assembly - Sheet 2 of 2 3120686 – JLG Lift – 2-19...
  • Page 40 33. Carefully lift telescope cylinder clear of boom 47. Using suitable lifting equipment, carefully slide fly assembly and lower to ground or suitably supported section clear of outer mid section and lower to work area. ground or suitably supported work area. 2-20 – JLG Lift – 3120686...

  • Page 41: Inspection

    15. Place outer mid section extend chain assembly ing, cracking, separation of welds, or other damage. along telescope cylinder chain rest with chain adjust Replace boom sections as necessary. assembly hanging just below cylinder sheave. 3120686 – JLG Lift – 2-21...

  • Page 42: Installation

    1. Using suitable lifting equipment, position assembled in telescope cylinder trunnion and holes in aft end of boom on turntable so that boom pivot holes in both inner mid section. boom and turntable are aligned. 2-22 – JLG Lift – 3120686...
  • Page 43 If chattering is apparent, retract chain system requires adjustment. 12. Shut down machine systems. 13. Adjust extend and retract chain systems as required and secure adjustment locknuts. 14. As necessary, lubricate all points requiring lubrica- tion. 3120686 – JLG Lift – 2-23...

  • Page 44: Tilt Alarm Switch

    7. Individually push down on one corner at a time; there should be enough travel to cause the switch to trip. If the switch does not trip in all three tests, the WHITE BLACK YELLOW Figure 2-8. Tilt Switch Adjustment - Voltmeter 2-24 – JLG Lift – 3120686...

  • Page 45: Voltmeter Adjustment

    (mid) engine setting remains 4. Extend-A-Reach Relief. the same. If necessary, adjust slide pin to contact low (mid) engine limit switch at 1800 RPM. Shut a. Monitor pressure gauge at quick-connect on down engine. main valve. 3120686 – JLG Lift – 2-25...
  • Page 46 INJECTION PUMP THROTTLE LEVER STOP ADECO ACTUATOR ADECO ACTUATOR SLIDE PIN (1) ACTUATOR CABLE LIMIT SWITCH HIGH ENGINE LIMIT SWITCH LOW ENGINE SLIDE PIN (2) Figure 2-10. Throttle Checks and Adjustments - Deutz Engine 2-26 – JLG Lift – 3120686...

  • Page 47: Frame Valve

    2000 psi (138 bar). Tighten nut. h. Bottom out Rear Steer Left function. i. Loosen nut on rear steer left relief and adjust to 2000 psi (138 bar). Tighten nut. 2. Axle Extension/Retraction Relief. 3120686 – JLG Lift – 2-27...
  • Page 48 View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 2 - PROCEDURES Figure 2-11. Pressure Setting Adjustments - Main Valve - Machines Built Before S/N 38697 2-28 – JLG Lift – 3120686...
  • Page 49 View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 2 - PROCEDURES Figure 2-12. Pressure Setting Adjustments - Frame Valve - Machines Built Before S/N 38697 3120686 – JLG Lift – 2-29...
  • Page 50 View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 2 - PROCEDURES Figure 2-13. Pressure Setting Adjustments - Main Valve - Machines Built After S/N 38697 2-30 – JLG Lift – 3120686...
  • Page 51 View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 2 - PROCEDURES Figure 2-14. Pressure Setting Adjustments - Frame Valve - Machines Built After S/N 38697 3120686 – JLG Lift – 2-31...

  • Page 52: Swing Bearing

    NOTE: This check is designed to replace the existing bear- 0.0015" feeler gauge between the bolt head and ing bolt torque checks on JLG Lifts in service. This hardened washer at the arrow indicated position. check must be performed after the first 50 hours of machine operation and every 600 hours of machine operation thereafter.

  • Page 53: Wear Tolerance

    HYDRAULIC LINES AND PORTS SHOULD BE CAPPED IMMEDI- ATELY AFTER DISCONNECTING LINES TO AVOID THE ENTRY OF CONTAMINANTS INTO THE SYSTEM. Figure 2-16. Swing Bearing Tolerance Boom Placement 3120686 – JLG Lift – 2-33...
  • Page 54 Use a suitable tool to scribe a line on the inner IS IMPERATIVE THAT SUCH REPLACEMENT HARDWARE MEETS race of the swing bearing and on the underside JLG SPECIFICATIONS. USE OF GENUINE JLG HARDWARE IS of the turntable. This line will aid in aligning the HIGHLY RECOMMENDED.

  • Page 55: Swing Bearing Torque Values

    Using all applicable safety precautions, activate a. Remove two bolts (303) securing disconnect hydraulic system and functionally check swing cap (304) to cover and remove disconnect system for proper and safe operation. cover. 3120686 – JLG Lift – 2-35...
  • Page 56 View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 2 - PROCEDURES Figure 2-19. Drive Torque Hub 2-36 – JLG Lift – 3120686...

  • Page 57: Cleaning And Inspection

    9. Inspect mating surfaces of hub, ring gear and cover of hub counterbores. Discard seal and replace with for burrs and sharp edges. Dress applicable sur- new seal. faces or replace components as necessary. 3120686 – JLG Lift – 2-37...

  • Page 58: Assembly

    2. Position hub/spindle assembly (1) with large open end up. i. Place bearing cones (203) into cluster gear. 3. Lower internal gear (2) onto spindle. j. Place cluster gear into carrier with large gear up. 2-38 – JLG Lift – 3120686...
  • Page 59 (77 Nm). 13. Locate the one hole on underside of ring gear that has an “X” stamped beside it. This hole should be 21. Install coupling (19) into spindle onto input shaft. 3120686 – JLG Lift – 2-39...

  • Page 60: Swing Torque Hub

    (15). Assembly b. Using a suitable drift, carefully and gently tap shafts (15) from carrier (10), ensuring that nee- 1. If necessary, assemble hub and shaft assembly. 2-40 – JLG Lift – 3120686...

  • Page 61: Swing Torque Hub

    View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 2 - PROCEDURES Figure 2-20. Swing Torque Hub 3120686 – JLG Lift – 2-41...
  • Page 62 Align roll pin holes in both shaft (15) and carrier 17. Apply a light coating of petroleum jelly or multi-pur- (10) with chamfered portion of shaft hole upper- pose grease to outer thrust washers (8) and thrust most. bearing (9). 2-42 – JLG Lift – 3120686...

  • Page 63: Swing Brake

    DISCS (11, 14) AND FRICTION DISCS (12) SHOULD REMAIN DRY 7. Remove dowel pins (20), springs (15 & 16) and DURING INSTALLATION. NO OIL RESIDUE SHOULD BE ALLOWED spring retainer (17) from housing (21). TO CONTAMINATE DISC SURFACES. 3120686 – JLG Lift – 2-43...

  • Page 64: Swing Brake

    View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 2 - PROCEDURES Figure 2-21. Swing Brake 2-44 – JLG Lift – 3120686...

  • Page 65: Drive Brake

    (14), o-ring (28) and gasket (29) from end cover. 3. Remove piston (24) from end cover. 4. Remove o-ring (19), back-up ring (18), o-ring (21) and back-up ring (20) from piston. 5. Remove separator assemblies (9, 10) from housing. 3120686 – JLG Lift – 2-45...
  • Page 66 View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 2 - PROCEDURES Figure 2-22. Drive Brake, Mico 2-46 – JLG Lift – 3120686...

  • Page 67: Free Wheeling Option

    (13), being careful not to shear o- rings or back-up rings. 11. Install new case seal (11) in housing, then install bleeder screw (14), gasket (27) and o-ring (26) in end cover. 3120686 – JLG Lift – 2-47...

  • Page 68: Pq Controllers

    Tighten the setscrew on the gear and Table 2-5. Platform Controller Settings (Prior to S/N recheck for the proper mA readings. Repeat this 38697) step until the proper adjustment is obtained. Settings in mA Function Lift 1300 Swing 1300 2-48 – JLG Lift – 3120686...

  • Page 69: Trim Adjustment (S/N 38697 To Present)

    6. Operate controller until 1/2 of slide lock is out of the 20. Adjust the Ramp trimpot 6 turns clockwise. housing lock notch. Hold control handle in that posi- 21. Release footswitch. tion. 3120686 – JLG Lift – 2-49...
  • Page 70 6 and check ammeter reading. This reading will have changed due to HI trimpot adjustment, and must be readjusted back to the value shown in Table 2-6, Platform Controller Settings (S/N 38697 to Present). 2-50 – JLG Lift – 3120686...

  • Page 71: Ramp Adjustment

    12 in. (20-30 cm) is maintained. e. Release footswitch and stop machine. f. Seal ramp pot adjustment screw with a drop of enamel paint to prevent maladjustment due to vibration. g. Install controller and secure machine. 3120686 – JLG Lift – 2-51...

  • Page 72: Boom Marking Tape Installation

    4. Measure the voltage at TP9 and adjust potentiome- tor as outlined in step (c), be sure to use connector ter P3 until 5.0 Volts DC is measured at TP9. pins (1) and (4) on plug 2 on the circuit card. 2-52 – JLG Lift – 3120686...

  • Page 73: Operational Check

    If the boom angle is not within this range, contact the JLG Service Department for fur- ther assistance. Lift Down Speed Limit Adjustment The signals from these sensors (elevation angle and extension distance) are fed into a load radius card which 1.

  • Page 74: Overmoment Control System

    (via a relay in the overmoment control circuit card) to enable the descend function to operate at full speed. When this signal is removed, the descent function defaults to a creep speed. 2-54 – JLG Lift – 3120686...

  • Page 75: Overmoment Control Monitoring System

    Boom must not extend. Reset system machine will remain in this state until reset by a competent by activating toggle switch marked “R” located on person. right side of ground control station. 3120686 – JLG Lift – 2-55...

  • Page 76: Boom Length/Angle Sensor Configuration

    View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 2 - PROCEDURES Figure 2-27. Boom Length/Angle Sensor Configuration Figure 2-28. Load Radius Circuit Card 2-56 – JLG Lift – 3120686...

  • Page 77: Load Moment Limiting System Monitoring Circuit

    View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 2 - PROCEDURES Figure 2-26. Load Moment Limiting System Monitoring Circuit 3120686 – JLG Lift – 2-57...

  • Page 78: Load Management System Adjustment

    9. If boom does not stop at white tape or boom can be Installation extended after being retracted 10 feet (3 meters) without resetting, system must be repaired by JLG 1. Position boom to horizontal. authorized service personnel before machine can be 2.

  • Page 79: Preventive Maintenance And Inspection Schedule

    This machine requires periodic safety and maintenance and the "INTERVAL" at which the inspection is to take inspections by a JLG Dealer. A decal located on the turn- place. Under the "AREA" of the table, the various systems table affords a place to record (stamp) inspection dates.

  • Page 80: Preventive Maintenance And Inspection Schedule

    Placards and Decals Control Tags Valves 1,11 Carrier (Hoses and Cables) Pins 8, 12 Bushings 8, 12 Wear Pads 8, 12 1,5,6,13 Cylinders Boom Chain Adjusters 8, 12 Sheaves Radius Limit Tape 1, 2 Drift Test* 2-60 – JLG Lift – 3120686...
  • Page 81 Fuel Tank Cylinders 1,5,6,13 4, 12 Turntable Locking Pin Horizontal Limit Switch Oil Coupling Placards and Decals Tilt Alarm Switch 1, 7 Swing Bearing 9, 12 Swing Brake 1,5,6 1, 3, 5,6 Swing Hub 3120686 – JLG Lift – 2-61...
  • Page 82 Wheel and Tire Assembly 8,9,15 Drive Motors 1,5,6 1,5,6 Drive Torque Hubs Drive Brakes 1,5,6 Steer Cylinders 1,5,6,13 Steer Components 8, 12 Tie Rod Lock Pin Hydraulic Hoses Placards and Decals Wheel Bearings Swing Bearing/Worm Gear 2-62 – JLG Lift – 3120686...

  • Page 83: Section 3. Troubleshooting

    For aid in troubleshooting, refer to arising in the machine will be centered in the hydraulic the Illustrated Parts Manual for hydraulic diagrams of the and electrical systems. For this reason, every effort has various circuits 3120686 – JLG Lift –...
  • Page 84 Repair or replace pump. Restricted or broken hydraulic line or fitting. Clean, repair, or replace line or fitting. Slave cylinder not functioning properly. Repair or replace cylinder. Electrical failure. See proper wiring diagram. Orifice plugged. Clean orifice. – JLG Lift – 3120686...
  • Page 85 Determine cause and repair or replace valve. Electrical malfunction. See wiring diagram. Hydraulic system oil low. Replenish oil as necessary. Restricted or broken supply line on valve bank or Clean or replace line. hydraulic pump. 3120686 – JLG Lift –...
  • Page 86 Control valve not functioning properly. Repair or replace valve. Worn seals in lift cylinder. Replace seals. Cylinder not functioning properly. Repair or replace cylinder. Boom drifts down. Worn seals in lift cylinder. Replace seals. – JLG Lift – 3120686...
  • Page 87 Repair or replace control valve. Restricted or broken hydraulic line or fitting. Clean, repair, or replace line or fitting. Pressure setting incorrect. Check pressure/re-adjust as necessary. Telescope cylinder not functioning properly. Repair or replace cylinder. 3120686 – JLG Lift –...
  • Page 88 Poor ground on valves. See proper wiring diagram. No electric power to dump valve on cylinder. See proper wiring diagram. No electric power to valves. See proper wiring diagram. Internal damage to cylinder. Repair or replace cylinder. – JLG Lift – 3120686...
  • Page 89 Swing motor not functioning properly. Repair or replace swing control switch. Worn or broken teeth on swing gear or swing Replace gear(s) as required. motor pinion. Restrictor valves(s) plugged. Clean or replace restrictor valve. 3120686 – JLG Lift –...
  • Page 90 No electric power to dump valve. Repair or replace valve. Tower lift and upright raises and lowers erratically. Hydraulic system oil low. Replenish oil as required. Restricted or broken hydraulic line or fitting. Clean, repair, replace line. – JLG Lift – 3120686...
  • Page 91 Tower level master cylinder defective or leaking. Repair or replace master cylinder. Air in tower master cylinder. Fully cycle tower master cylinder 2-3 times. Seals worn or leaking in tower master cylinder. Repair master cylinder. 3120686 – JLG Lift –...
  • Page 92 Valve spool scored. Repair or replace valve. Excessive back pressure caused by restricted Remove line and clear obstruction or replace line return line to reservoir. as necessary. Damaged valve seals. Repair or replace valve as necessary. 3-10 – JLG Lift – 3120686...
  • Page 93 Damaged wiring on speed control switch or high Repair or replace wiring. engine solenoid. Drive controller not functioning properly. Replace controller. Actuator not functioning properly. Repair or replace solenoid. Excessive load on engine. Reduce load. 3120686 – JLG Lift – 3-11...
  • Page 94 Machine being moved up too steep a grade. Remove machine from grade and check that drive system operates correctly. Grade too steep. See WARNING Placard on platform for specified grades and sideslopes. Towing valve not closed. Close towing valve. 3-12 – JLG Lift – 3120686...
  • Page 95 Repair or replace motor(s). Circuit breaker open. Determine and correct cause; reset circuit breaker. Counterbalance valve sticking on return side. Adjust return counterbalance out 3 turns - cycle drive - return to original position. 3120686 – JLG Lift – 3-13...
  • Page 96 Damaged wiring on control switch or solenoid See proper wiring diagram. valve. Control switch not functioning properly. Replace switch. Restricted or broken hydraulic line on valve Clean, repair or replace line. bank, hydraulic pump or rotary coupling. (If equipped.) 3-14 – JLG Lift – 3120686...
  • Page 97 Take pressure reading at steer valve and adjust as necessary. Bent cylinder rod. Repair or replace cylinder. Damaged tie rod. Replace tie rod. Crossover relief valve sticking. Repair crossover relief valve. Cylinder packing defective. Repair or replace cylinder. 3120686 – JLG Lift – 3-15...
  • Page 98 Crossover relief valve set too low or not function- Reset, repair or replace valve as required. ing properly. Steer linkages loose. Tighten linkage. Steer wheel toe-in not set properly. Adjust toe-in for 1/4 inch overall. Spindle bushings badly worn. Replace bushings. 3-16 – JLG Lift – 3120686...
  • Page 99 Main relief valve set too low. Reset valve as required. Hydraulic system oil low. Replenish oil as necessary. Port relief set too high. Reset valve as required. Restricted or blocked return line. Repair or replace line. 3120686 – JLG Lift – 3-17...
  • Page 100 Determine and correct cause; reset circuit breaker. Engine is running. Shut down engine. Check valve in system leaking. Repair or replace check valve. Battery requires charging or will not hold a Charge or replace battery as required. charge. 3-18 – JLG Lift – 3120686...
  • Page 101 Control switch not functioning properly. Replace switch. Restricted or broken hydraulic line or fitting. Clean, repair or replace line or fitting. Pump motor solenoid not functioning properly. Replace solenoid. Pump motor not functioning properly. Repair or replace motor. 3120686 – JLG Lift – 3-19...
  • Page 102 Faulty ignition and/or starter circuit wiring. Check wiring continuity. See proper wiring dia- gram. Malfunctioning starter solenoid or motor. Replace solenoid or motor in accordance with applicable manufacturer’s manual. Faulty start switch. Replace switch. 3-20 – JLG Lift – 3120686...
  • Page 103 Function speed control will not function. Boom above horizontal. Lower boom. Horizontal limit switch malfunctioning. Repair or replace limit switch. Defective pump section. Repair or replace pump section. Electrical malfunction. See correct wiring diagram. 3120686 – JLG Lift – 3-21...

  • Page 104: Electrical Diagram - Boom Length Indicator

    View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 3 - TROUBLESHOOTING Figure 3-1. Electrical Diagram - Boom Length Indicator 3-22 – JLG Lift – 3120686...

  • Page 105: Electrical Schematic - Sheet 1 Of 4

    View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 3 - TROUBLESHOOTING Figure 3-2. Electrical Schematic - Sheet 1 of 4 3120686 – JLG Lift – 3-23...

  • Page 106: Electrical Schematic - Sheet 2 Of 4

    View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 3 - TROUBLESHOOTING 1870023B Figure 3-3. Electrical Schematic - Sheet 2 of 4 3-24 – JLG Lift – 3120686...

  • Page 107: Electrical Schematic - Sheet 3 Of 4

    View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 3 - TROUBLESHOOTING Figure 3-4. Electrical Schematic - Sheet 3 of 4 3120686 – JLG Lift – 3-25...

  • Page 108: Electrical Schematic - Sheet 4 Of 4

    View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 3 - TROUBLESHOOTING 1870023B Figure 3-5. Electrical Schematic - Sheet 4 of 4 3-26 – JLG Lift – 3120686...

  • Page 109: Hydraulic Schematic - (Sheet 1 Of 2)

    View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 3 - TROUBLESHOOTING Figure 3-6. Hydraulic Schematic - (Sheet 1 of 2) 3120686 – JLG Lift – 3-27...

  • Page 110: Hydraulic Schematic - (Sheet 2 Of 2)

    View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com SECTION 3 - TROUBLESHOOTING 2792377A Figure 3-7. Hydraulic Schematic - (Sheet 2 of 2) 3-28 – JLG Lift – 3120686...
  • Page 111 View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com...
  • Page 112 View thousands of Crane Specifications on FreeCraneSpecs.com View thousands of Crane Specifications on FreeCraneSpecs.com...

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