Resynchronizing an out-of-sync tower boom or bleeding the oscillating axle lockout cylinders is the job you'll be on within the hour, and the JLG 800A, 800AJ service manual PDF (OEM part 3120740, 452 pages) holds the factory procedure for both aerial work platforms. Electrical schematics and CANbus analyzer diagnostics take up roughly the last quarter of the book, while hydraulic schematics trace the pump, main valve and cylinder circuits you'll be pressure-setting. Chassis and turntable work is the biggest section, about a third of the manual, splitting drive brake, drive motor and swing hub rebuilds by serial number break so the procedure matches your machine. Change the hydraulic return and charge filters after the first 50 hours, then every 6 months or 300 hours; swing bearing bolts torque to 240 ft. lbs. (326 Nm) on both races. UMS calibration faults never happen at a convenient height. The bookmarked, searchable PDF goes wherever the machine is parked.
What's Inside This JLG 800A, 800AJ Manual
| System | Pages | Key Topics |
|---|
| Introduction - Maintenance Safety Precautions | 3-20 | Hydraulic System Safety, Maintenance |
| Specifications | 21-42 | Operating Specifications (Capacities) |
| General | 43-54 | Machine Preparation, Inspection |
| Chassis & Turntable | 55-212 | Tires & Wheels (Tire Inflation, Tire Damage, Tire Replacement, Wheel Replacement, Wheel Installation) |
| Platform and Rotator Assembly | 213-220 | Platform Support Removal, Platform Sections Replacement, Rotator and Slave Cylinder Removal, Upright Removal |
| Tower Boom Assembly | 221-235 | Tower Boom Assembly Removal, Tower Boom Assembly Installation, Hose Replacement, Limit Switch Adjustment |
| Wear Pads and Rotator Assembly | 236-242 | Wear Pad Replacement, Rotator Disassembly, Rotator Inspection, Rotator Assembly |
| Rotator Assembly (S/N 0300067538 to Present) | 243-252 | Rotator Disassembly, Rotator Inspection, Rotator Assembly, Counterbalance Valve Installation |
| Upright Monitoring System (UMS) | 253-276 | Drive Card Setup, Foot Switch Adjustment, UMS Re-Synchronizing, UMS Troubleshooting, Calibration Faults |
| Hydraulics Theory and Repair | 277-307 | Lubricating O-Rings, Cylinder Theory, Cylinder Checking Procedure, Cylinder Repair, Pressure Setting Procedures |
| Hydraulic Component Maintenance | 308-326 | Main Valve Components, Cylinder Removal and Installation, Hydraulic Pump Coupling Lubrication, Hydraulic Component Start-Up |
| JLG Control System and Electrical Schematics | 327-452 | CANbus Communications, Analyzer Diagnostics, Electrical Multimeter Basics, Electrical Schematics |
Quick Reference Specifications
| Specification | Value | Page |
|---|
| Swing Bearing Outer Race Torque | 240 ft. lbs. (326 Nm) | p. 102 |
| Rotator center bolt torque | 480 ft. lbs. (651 Nm) | p. 215 |
| Hydraulic Return Filter Replacement Interval | Change after first 50 hrs. and every 6 months or 300 hrs. thereafter | p. 31 |
| Hydraulic Charge Filter Replacement Interval | Change after first 50 hrs. and every 6 months or 300 hrs. thereafter | p. 31 |
| Battery voltage | 9.0V - 16.0V | p. 272 |
| Air Filter Replacement Interval | Every 6 months or 300 hours of operation | p. 33 |
| Swing Bearing Inner Race Torque | 240 ft. lbs. (326 Nm) | p. 102 |
| Rotator retaining bolts torque | 50 ft. lbs. (68 Nm) | p. 215 |
| UMS sensor frequency | 100Hz +/- 5Hz | p. 273 |
| UMS sensor duty cycle | 50% +/- 21% | p. 273 |
| Wheel Bolts Torque | 300 ft. lbs. (407 Nm) | p. 25 |
| Support to Rotator Bolts Torque | 50 ft. lbs. (68 Nm) | p. 25 |
