John Deere 640D & 648D Skidder Repair Manual, 1988–1990 (P/N TM1440)

The John Deere technical repair manual P/N TM1440, revised September 11, 1990, covers the 640D Skidder and 648D Grapple Skidder, including single- and dual-function boom grapple configurations.

Text Search, Repair Bookmarks, and Drawing Detail

Search and illustration detail: An OCR text layer supports searches across the repair chapters, but some illustrated pages and drawing labels are not searchable. Recognition errors can affect numbers and identifiers. Embedded bookmarks reach sections and individual procedures; small drawing callouts and electrical connection tables benefit from zooming.

The download contains one printable 969-page PDF in English, including the original cover, revision notice, section contents, blank divider pages, and safety back cover.

Drivetrain, Hydraulic, and Grapple Repairs

The following selected repair topics show the manual’s scope. Additional subjects include PIP I/PIP II inspection checklists, cab-window replacement, seat repair, and heater service.

• Axles and differentials: Assembly removal, carrier-bearing preload, pinion cone-point adjustment, backlash and tooth-contact checks, plus differential-lock oil and air leakage tests.

• Power Shift transmission: Step-by-step procedures for C1/C2 clutch packs, planetary assemblies, and the transfer case, with control-valve repair and compressed-air clutch checks.

• Steering and brakes: Steering-valve and cylinder repair, secondary steering accumulators, service-brake bleeding, and park-brake disassembly and seal replacement.

• Main hydraulics: Pump removal and installation, pressure-compensator valve service, destroke components, and disassembly, inspection, and assembly of the separate 648D charge pump.

• Grapple equipment: Control-valve overhaul, rotary-manifold service, rotate-motor and shaft repair, boom and arch cylinder work, and dampener adjustment.

• Winches and drives: Clutch and brake repair, gear-train assembly, telescoping drive shafts, drum-bearing adjustment, freespool checks, and gear-compartment seal testing.

• Electrical components: Battery testing, Motorola alternator repair, Weather Pack connector service, and terminal-to-wire references for switches, alarms, and instruments.

The repair work is suited to experienced heavy-equipment mechanics with precision measuring tools, hydraulic service equipment, and lifting equipment for major assemblies.

Axle and Transmission Variants

Axle construction: Separate assembly instructions address S4 and S5 planetary carriers. The axle chapters also give shaft-to-bearing-cup grease-dam wear criteria, special outer-bearing greasing provisions through axle serial 019616, and front differential sealing changes at axle serial 020171.

Driveline selection: Front drive-line procedures divide at machine serials 517688/517689; rear procedures divide at 517841/517842. The serial-specific illustrations and fastening details help match the work to the installed arrangement. The rear drive-line instructions explain how incorrect joint alignment can produce vibration severe enough to damage drivetrain components.

Clutch packs: Earlier disks and wavy plates are distinguished from later bronze-faced disks, with specific restrictions on mixing designs. Alternate access procedures cover certain transfer-case and clutch/planetary repairs while the transmission remains in the frame.

The engine-disconnect clutch has its own procedures for the pressure plate, disk, throw-out bearing, linkage, and release-lever adjustment.

Engine and Fuel-System Work

The 6414 (6-414T) engine section covers engine removal and installation, fuel bleeding, injection-pump timing, and replacement of external components such as the turbocharger, oil pump, and water pump. Injection-pump procedures separate engines through serial 299999 from engines starting at 300000.

Stanadyne DB4 coverage identifies the applications for the RE38913 drive-gear puller kit. Internal injection-pump repair and testing are assigned to an authorized diesel injection repair station.

Engine repair limits: Full engine repair requires CTM-4. Injection-nozzle repair and testing procedures are referenced to TM-1214; neither companion publication is included.

Electrical Repair and Connections

The 65-amp Motorola alternator section goes beyond removal: it covers disassembly, brush and diode checks, stator and rotor testing, and reassembly requirements. Battery load testing and Weather Pack terminal work support component-level electrical service.

Connection references identify the wires used at the key switch, park-brake alarm, and gauges. Starting-motor and Delco Remy alternator repair require the separate CTM-11.

Hydraulic and Grapple Service

Accumulator service includes disassembly and nitrogen-charging procedures. Separate contamination-cleanup instructions address the 640D transmission-hydraulic circuit and the 648D hydraulic system following major component failure.

Grapple coverage distinguishes single- and dual-function boom arrangements. The rotary-manifold section includes leakage testing, while rotate-motor assembly addresses valve timing. Dampener adjustment notes explain how loose dampeners can let the grapple or tongs strike and damage the boom or machine.

Complete internal radial-piston pump repair requires CTM-7, which is not included.

Winch Repair and Diagnostic Limits

Separate internal repair sections cover 8-inch- and 11-inch-drum winches. The 4000 series winch coverage addresses removal, installation, cable attachment, and control-linkage adjustment; its complete internal repair requires the separate CTM-25.

This is the Repair volume. The referenced Operation and Test manual supplies broader system-diagnostic procedures and is not included in this download.

Frame Repairs, Illustrations, and Shop Tools

Structural procedures cover frame separation, articulation-pivot service, and model-specific pivot-bore replacement. Stacking and trailbuilding blade work includes control valves and cylinders, alongside cab/canopy removal procedures.

Illustration examples include the Motorola alternator exploded view and cross sections of the secondary steering valve, hydraulic charge pump, winch control valve, and dual-function boom/arch cylinders.

Metric and standard hardware charts accompany component-specific tightening sequences, wear limits, clearances, spring-test data, electrical test values, and fluid capacities. Dimensioned fabrication drawings cover the JT38000 differential lifting tool, JT38003 rolling drag torque bar, and DF1057 axle adjusting tool, supporting shop preparation for the documented work.

Technicians must ensure hydraulic pressure is safely relieved and the chassis is properly blocked before teardown.

Selected Differential Adjustment and Test Values

Differential adjustment data specify 0.05–0.10 mm (0.002–0.004 in.) carrier-bearing preload and 0.2–0.36 mm (0.008–0.014 in.) ring-gear backlash. The related procedures cover shim selection and tooth-contact checks.

For the differential-lock oil test, the specified oil-temperature range is 36–44°C (97–111°F). This condition accompanies the leakage measurement at the lock quill.