John Deere 640D Skidder & 648D Grapple Skidder Technical Manual (P/N TM1440)

This 969-page PDF contains the John Deere TM1440 technical manual, Repair, revised September 11, 1990, for the 640D Skidder and 648D Grapple Skidder. Coverage includes the 6414 (6-414T) turbocharged diesel and single- and dual-function boom grapple configurations. The repair procedures are suited to experienced heavy-equipment mechanics equipped for precision assembly, hydraulic testing, and lifting major components.

• Front and rear differentials: Axle assembly removal, carrier bearing preload adjustment, pinion cone-point setup, backlash and tooth-contact checks, and differential-lock oil and air tests.
• Power Shift transmission: C1/C2 clutch-pack, planetary assembly, and transfer-case overhaul, plus control-valve repair and compressed-air checks of clutch operation and sealing.
• Steering and brake service covers steering-valve and cylinder repair, secondary steering accumulators, service-brake bleeding, and park-brake disassembly and seal replacement.
• Main hydraulic procedures address the variable-displacement pump’s removal and installation, pressure-compensator and destroke components, and the separate hydraulic charge pump used on the 648D.
• Grapple repair includes control valves, the rotary manifold, rotate motor and shaft, boom and arch cylinders, and grapple dampener adjustment.
• Winch work covers clutch and brake assemblies, gear trains, telescoping drive shafts, drum-bearing adjustments, freespool checks, and gear-compartment seal tests.

Axle and Transmission Variants

The axle chapters distinguish S4 and S5 axle planetary carriers and include axle shaft-to-bearing cup grease dam wear specifications. Special outer-bearing greasing procedures address grease-dam damage on axles through serial 019616. Front differential input-shaft sealing changes at axle serial 020171, with separate illustrations for the earlier arrangement and later three-V-ring design.

Front differential drive-line procedures split at machine serials 517688/517689; rear drive-line procedures split at 517841/517842. These distinctions affect assembly details and fastening specifications. The manual also explains how incorrect rear drive-line joint alignment can cause excessive vibration and drivetrain failure.

Transmission coverage identifies old-style clutch disks and wavy plates versus later bronze-faced disks, including restrictions on mixing the two designs. Alternate removal procedures allow specified transfer-case and clutch/planetary repairs without removing the complete transmission. The separate engine-disconnect clutch section covers the pressure plate, disk, throw-out bearing, linkage, and release-lever adjustment.

Engine, Electrical, and Structural Repair

Engine procedures cover removal and installation, fuel-system bleeding, injection-pump timing, and replacement of the turbocharger, oil pump, water pump, and related external components. Injection-pump work is divided at engine serials 299999/300000, with Stanadyne DB4 procedures and application notes for the RE38913 drive-gear puller kit.

Electrical coverage includes battery load testing, Weather Pack connector repair, and terminal-to-wire references for the key switch, park-brake alarm, and gauges. The 65-amp Motorola alternator has disassembly, component testing, and reassembly procedures.

Structural work extends to engine/equipment frame separation, articulation-pivot service, and model-specific pivot-bore replacement. Stacking and trailbuilding blades, their control valves and cylinders, and cab/canopy removal are also covered. The grapple section explains how loose dampeners allow the grapple or tongs to strike the boom or machine and cause damage.

Winch Coverage and Companion Manuals

Separate repair procedures cover 8-inch- and 11-inch-drum winches. For the 4000 series winch, this volume documents removal, installation, cable attachment, and control-linkage adjustment; complete internal repair requires CTM-25.

This is the Repair volume. The separate Operation and Test manual provides the broader system-diagnostic procedures referenced throughout. Complete engine repair requires CTM-4, complete radial-piston pump repair requires CTM-7, and starting-motor and Delco Remy alternator repair requires CTM-11. Injection-nozzle repair and testing refer to TM-1214. These companion manuals are not included in this PDF.

Illustrations, Tools, and Service Data

Illustrations 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.

Reference charts cover metric and standard hardware tightening values, with component-specific tightening sequences, wear limits, clearances, spring-test specifications, electrical test values, and fluid-capacity data. Separate hydraulic cleanup procedures address the 640D transmission-hydraulic circuit and the 648D hydraulic system after major component failure.

The dealer-fabricated tool section supplies drawings for the JT38000 differential lifting tool, JT38003 rolling drag torque bar, and DF1057 axle adjusting tool.

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