JLG issued this book under document number 3120675, and the 102-page JLG 34HA service manual PDF you get here is that factory original, written for the 34HA aerial work platform rather than adapted from a lookalike model. Relay wiring diagrams and hydraulic schematics close out the book, tracing each circuit from the platform controls down through the turntable. Troubleshooting takes up better than a third of the pages, walking platform, boom, and turntable faults back to a cause, while the procedures chapter covers cylinder repair, swing bearing replacement, and torque hub work for both 2WD and 4WD axles. Set the main relief at 2750 PSI, then pull the swing bearing to turntable bolts to 220 ft. lbs., straight from the specifications chapter. A guessed torque on a boom lift puts people on the ground the hard way. Bookmarks and a live text layer land you on the right procedure in seconds.
What's Inside This JLG 34HA Manual
| System | Pages | Key Topics |
|---|---|---|
| List of Illustrations | 4-6 | Relay Wiring, Torque Chart, Serial Number Locations, Lubrication Chart, Boom Prop Configuration, Poly-Pak Seal Configuration, Horizontal Cutoff Switch Adjustment Procedure |
| Specifications | 7-16 | Capacities, Component Data, Performance Data, Torque Requirements, Lubrication, Pressure Settings, Cylinder Specifications, Major Component Weights |
| General Maintenance Guidelines | 17-20 | Safety and Workmanship, Cleanliness, Component Removal and Installation, Pressure-Fit Parts, Bearings, Relief Valves |
| Cylinder Procedures | 21-27 | Boom Prop Configurations, Cylinder Checking Procedures, Cylinder Repair, Cylinder Removal and Installation, Articulating Cylinder |
| Switch and Throttle Adjustments | 28-33 | Tilt Alarm Switch, Horizontal Cutoff Switch, Ford Engine Throttle Adjustments, Deutz Engine Throttle Adjustments |
| Pressure Settings and Swing Bearing | 34-42 | Pressure Setting Procedures, Racine Bang-Bang Valves, Swing Bearing Wear Tolerance, Swing Bearing Replacement, Swing Bearing Bolt Torquing |
| Drive Axle and Brake Maintenance | 43-55 | Torque Hub Disassembly, Torque Hub Assembly, Drive Torque Hub, Drive/Steer Axle, Swing Brake, Drive Brake |
| System Controls and Preventive Maintenance | 56-62 | Pq Controllers, Oscillating Axle Bleeding, Dual Fuel System, Free Wheeling Option, Preventive Maintenance Schedule |
| Troubleshooting | 63-102 | General, Platform Assembly Troubleshooting, Boom Assembly Troubleshooting, Turntable Assembly Troubleshooting |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Bearing To Chassis | 110 FT. LBS. (15.21 KGM) | p. 9 |
| Bearing To Turntable | 220 FT. LBS. (30.42 KGM) | p. 9 |
| Ford VSG 411 Engine Oil Capacity | 3.5 quarts | p. 7 |
| Deutz F2L1011 Engine Oil Capacity | 6.9 quarts | p. 7 |
| Main Relief Pressure (Ford/Deutz) | 2750 PSI | p. 10 |
| Steer Relief Pressure (2WD) | 1500 PSI | p. 10 |
| Steer Relief Pressure (4WD) | 2000 PSI | p. 10 |
| Telescope Relief Pressure (In) | 2000 PSI | p. 10 |
| Telescope Relief Pressure (Out) | 1500 PSI | p. 10 |
| Swing Bearing Bolt Torque (Inner Race) | 170 ft. lbs. | p. 42 |
| Swing Bearing Bolt Torque (Outer Race) | 80 ft. lbs. | p. 42 |
| Drive Brake Torque | 50-60 ft. lbs. | p. 54 |
JLG 34HA Common Problems This Manual Covers
JLG 34HA boom moves slow and jerky under load, hydraulic pump whining and losing power
Check hydraulic oil level and change the return filter first; a starved pump cavitates and whines. Tee a gauge into the main relief and confirm 2750 PSI, the setting listed on page 10, following the pressure setting procedures starting on page 34. Trace individual circuits against the hydraulic schematic on page 96 if only one function acts up.
Manual Section: Hydraulic System TroubleshootingDeutz engine won't start or cranks intermittently, fault light flashing three or five times
Load test the battery and clean both cable ends before chasing harness faults; a 3-flash code points at the charge system, 5 flashes at the start circuit. Verify crankcase oil level, the Deutz F2L1011 holds 6.9 quarts. If the starter stays dead, trace the ignition and relay circuits on the wiring diagram on page 87.
Manual Section: Turntable Assembly TroubleshootingBoom telescope weak under load, stalls partway out and extends slower than normal
Test the telescope relief before condemning the cylinder. Tee in a gauge and verify 1500 PSI on extend and 2000 PSI on retract, the settings listed on page 10, adjusting per the pressure setting procedures on page 34. If pressures are good, check the cylinder for internal bypass using the cylinder checking procedures on page 21.
Manual Section: Boom Assembly TroubleshootingClunking noise from the turntable when swinging, boom jerks and drifts side to side
Inspect the swing bearing before blaming the swing motor. Check bearing wear tolerance using the procedure in the swing bearing section starting on page 34, then torque inner race bolts to 170 ft. lbs. and outer race bolts to 80 ft. lbs. as specified on page 42. Replace any bolt that turns before reaching torque.
Manual Section: Pressure Settings and Swing Bearing p. 34Steering slow or hard in one direction, front wheels barely respond at idle
Verify steer relief pressure first: 1500 PSI on 2WD machines, 2000 PSI on 4WD, both listed on page 10. If pressure checks out, inspect the steer cylinder for internal bypass and the tie rod ends for slop. While you're under there, recheck wheel lug torque at 80 ft. lbs., the torque chart spec on page 9.
Manual Section: Chassis Assembly TroubleshootingFrequently Asked Questions
What is the torque specification for wheel lugs on the JLG 34HA?
The torque specification for wheel lugs on the JLG 34HA is 80 ft. lbs. (11.06 kgm). p. 9
What are the hydraulic oil capacity and viscosity recommendations for the JLG 34HA?
The hydraulic system has a capacity of approximately 22 U.S. gallons (83.28 l). JLG recommends Kendall 052 hydraulic oil, which has an SAE viscosity of 10W-20 and a viscosity index of 152. p. 7
What is the procedure for checking the steer cylinder for internal leakage?
To check for internal leakage, fully extend the cylinder, shut down the engine, and disconnect the hydraulic hose from the retract port. Activate the engine and the extend function; if leakage at the retract port exceeds 6-8 drops per minute, cylinder repairs are required. p. 20
What is the required interval for retorquing the swing bearing bolts on a JLG 34HA?
Swing bearing bolts must be retorqued after the first 200 hours of operation and every 500 hours thereafter. p. 9
What is the main relief valve pressure setting on a JLG 34HA with a Ford VSG-411 engine?
The main relief valve at the dump valve section for machines with a Ford VSG-411 engine should be set to 2750 PSI (193.33 kg/cm²). p. 10
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