John Deere JD644C Loader & JD646C Compactor – 1984 Technical Manual (P/N TM-1229)

John Deere Technical Manual TM-1229, revised March 1984, covers the JD644C Loader and JD646C Compactor. This is Deere’s actual-service publication; FOS manuals supply general theory and troubleshooting fundamentals, while the operator’s manuals provide more detailed routine servicing information.

Bookmarked PDF with Limited Text Search

Search and diagram detail: Text search works only in parts of the file because much of the embedded OCR is misrecognized. Large electrical and hydraulic schematics have no searchable text. Embedded bookmarks provide section and repair-group navigation. Small wiring labels require zooming, and some crowded connector markings remain indistinct.

One printable English PDF contains 1,378 pages, including two cover pages and 44 blank or header-only pages.

Powertrain Overhaul and Hydraulic Fault Finding

The following selected repair and testing topics give an overview of the manual. Further subjects include compactor-wheel cleat repair and articulated-frame pivot service.

• Engine repair: 6466A diesel removal, crankshaft and main bearings, valve train, connecting rods, pistons, cylinder block and liners, turbocharger, lubrication, and cooling components.

• Transmission and axles: Power-shift clutch overhaul, transmission controls, torque converter service, drive shafts, differentials, bearings, and planetary reduction gears.

• Hydraulics and steering: Main-pump and stroke-control-valve repair, metering-pump and steering-valve service, cylinder overhaul, pressure adjustment, and relief-valve testing.

• Brakes and loader: Service- and parking-brake repair, bleeding, accumulator charging, and loader pump, control-valve, boom, bucket, and hydraulic-cylinder service.

• Electrical diagnosis: Starting and charging circuit tests, lighting, gauges, indicators, and machine-control circuits, supported by wiring diagrams and electrical schematics.

• System testing: Section 90’s seven-step diagnostic method, pump-flow and leakage checks, power-train tests, and heating/air-conditioning diagnosis.

Deere wrote this manual for an experienced service technician; its procedures assume normal shop skills and access to lifting equipment, pressure gauges, and specified special tools.

Clutch Assemblies, Axle Setup, and Model Differences

Transmission detail: Step-by-step disassembly and assembly instructions distinguish reverse-, low-, and high-range power-shift clutches. They also cover output and shifter shafts, the transfer drive gear, transmission oil pump, control valve, cooler, filter, converter-out check valve, and clutch cut-off solenoid valve.

Mechanics and Rockwell universal joints receive separate treatment.

Differential setup: Input-quill and bevel-pinion work includes bearing and seal replacement, cone-point and preload adjustment, backlash setting, and differential-lock testing after repair. The ring gear and spiral bevel pinion shaft are specified as a matched replacement set.

Separate procedures address the 644C hydraulic differential lock and rear-axle disconnect linkage, and the 646C NO SPIN differential. Serial-dependent pump-drive and test data help match parts and diagnostic specifications to the machine’s configuration.

The transmission assembly instructions identify a specific damage risk: hammering the housing cover into place can damage the piston-housing seal ring.

Fuel-Injection Service and Its Repair Boundary

Fuel-system procedures cover injection-pump removal, installation and timing, system bleeding, and nozzle disassembly, cleaning, testing, and reassembly. Internal injection-pump repair and testing are referred to an authorized diesel injection service station or the separate TM-1215 publication, which is not included.

Steering, Brake, and Loader Hardware

Main hydraulic-pump and stroke-control-valve instructions distinguish pumps with and without a serial-number plate. Steering coverage adds the return filter, feedback cylinder, accumulator, and emergency-steering hardware. Rebuild details address spool orientation, keeping each relief valve’s original parts together, and air removal after service.

Brake sections extend to pedals, linkage, the brake valve, and inlet check valve. Loader hardware coverage includes reservoir overhaul, lift and tilt linkage, frames, boom repair, bucket teeth, cutting edges, and the multipurpose-bucket cylinder.

Raised equipment, articulated frames, heavy assemblies, and charged accumulators require the manual’s support, lock-bar, lifting, pressure-relief, and electrical-isolation precautions.

Circuit Diagnosis, Cab Systems, and Service References

Hydraulic testing separates closed-center steering/brake circuits from open-center loader circuits. Converter-out pressure, transmission lubrication, oil-cooler pressure-drop, and pump-flow tests support fault isolation before major assemblies are removed. Flow-testing cautions explain the risk of pump damage from a closed flow-meter loading valve.

Visual references include the Electrical Wiring Diagram, Electrical Schematic, Closed-Center Hydraulic System Schematic with Emergency Steering, Open-Center Hydraulic System Schematic, and Transmission Control Circuit, plus steering-return-filter and feedback-cylinder cross-sections.

Air-conditioning procedures address the original Refrigerant-12 system, including compressor service, expansion-valve and switch tests, leak testing, evacuation, and charging.

Reference tables supply customary and metric hardware torques, tube and hose fitting torques, capacities, pressure-test specifications, adjustment data, inspection and wear limits, and electrical test values.

Service-Gard tool references include the D-05144ST Transmission Adapter Plate, D-05223ST Repair Stand, D-01019AA Hydraulic Hand-Operated Pump, and JDH-46 Pressure Circuit Relief Valve Test Plug.

Differential and Turbocharger Specification Samples

The differential table lists input-yoke slotted-nut torque at 305–407 N·m (225–300 lb-ft), alongside the related input-quill and pinion setup data.

For turbocharger inspection, rotating-assembly axial end play is specified as 0.025–0.102 mm (0.001–0.004 in.). The section provides separate radial-bearing checks and disassembly, inspection, and assembly procedures.