John Deere 750B and 850B Crawler Bulldozers 1993 Technical and Repair Manual (P/N TM1476)

• Document and machine coverage: John Deere Technical Manual TM1476, dated May 11, 1994, is supplied as an 815-page PDF for 750B and 850B crawler bulldozers. Coverage includes 6505 all-hydraulic, 6520 and 6540 angle-dozer, and 6525 and 6545 bulldozer arrangements, along with standard, narrow-gauge, wide-track, long-track, and low-ground-pressure configurations.

• Undercarriage and final-drive work: Details wear measurement, pin-and-bushing service for lubricated and non-lubricated track chains, track-sag adjustment, roller and front-idler repair, recoil-spring and track-adjuster service, wear-strip replacement, sprocket work, planetary housings, and final-drive removal and overhaul.

• Hydrostatic transmission repair: Takes the transmission, pump, motor, charge and control pumps, pump displacement control valve (PDCV), motor displacement control valve (MDCV), manifold, steering/FNR/speed control valves, reservoir, filters, and oil cooler through removal, inspection, disassembly, assembly, adjustment, and installation.

• Engine, splitter-drive, and brake sections: Documents 750B and 850B engine removal and installation, oil-pan service, fuel-system bleeding, fan-belt tightener repair, cold-weather disconnect service, splitter-housing and input-shaft work, and park-brake and brake-valve repair.

• Blade equipment and implement hydraulics: Covers angle-dozer and bulldozer blades and frames, push beams, cutting edges and end bits, hydraulic pump and reservoir, dozer control and selector valves, quick-drop valve, relief valves, and lift and tilt cylinder repair.

• Electrical, cab, and climate systems: Includes serial-specific engine, instrument, and cab/ROPS electrical component layouts; Deutsch and Weather Pack connector repair; switches, senders, relays, charging and starting components; cab/ROPS service; R12 system cautions and leak checks; and R134a recovery, evacuation, charging, pressure diagnosis, and compressor work.

• Factory reference material: Provides assembly-specific torque data, lubricant and capacity tables, wear limits, clearances, shim and end-play specifications, relief-valve settings, leak-test criteria, exploded views, section views, an A/C pressure diagnostic chart, and dealer-fabricated tool drawings.

John Deere states that this repair manual is written for an experienced technician. The procedures assume shop-level lifting and pressing equipment, precision measuring tools, and the ability to identify matched, serial-specific parts, making the manual best suited to experienced heavy-equipment technicians rather than first-time mechanics.

Model and Serial-Number Detail

The specifications identify a 6068T engine in the 750B and a 6466A engine in the 850B. At machine serial number 731274, the manual changes its coverage for the lower steering linkage, charge pump, hydrostatic reservoir and transmission filters, speed-control and return-to-neutral linkage, park-brake linkage, neutral-start switch, and electrical component layouts. Later charge-pump construction is divided again at 750B serial 757030 and 850B serial 757352.

The bulldozer hydraulic section separates blade-lift cylinder repair and relief-valve specifications at serial 779602. It also distinguishes early and later control-valve and relief-valve construction. These breaks matter when selecting seals, valve parts, adjustment data, and the correct repair procedure.

Repair Depth, Illustrations, and Tools

Each service group begins with the applicable tools, service equipment, materials, parts kits, specifications, tolerances, and torque values. Section 99 supplies fabrication drawings for tools such as the DFRW20 compressor holding fixture, DFT1041 track-nut removal tool, DFT1078 final-drive lifting tool with DFT1079 adapter, and DSD140284/DSD130284 hydrostatic pump and motor repair stands.

Named visual references include the track-adjuster and front-idler exploded views, model-specific planet-housing and final-drive exploded views, the dozer hydraulic-pump cross section, blade-lift and blade-tilt control-valve section views, early/later relief-valve section views, and the air-conditioning pressure diagnostic chart.

Scope Limits and Repair Cautions

This is the machine repair volume, not the companion Operation and Test manual. John Deere directs many operational checks, post-transmission-repair startup procedures, transmission and hydraulic setup checks, and broader fault diagnosis to TM1332. Full internal engine repair also requires the applicable component manual: CTM8 for the 6068, CTM6 for the 6076, CTM4 for the 6414, or CTM1 for the 6466. Engine-accessory work and full undercarriage appraisal are cross-referenced to CTM11 and SP326.

The track-chain procedures warn that misaligned press tooling can broach pin and bushing bores, leaving the links unusable, while incorrectly oriented cross-drilled pins can break in service. After hydrostatic pump or motor repair, the cases must be prefilled and the separate TM1332 startup procedure followed; operating the units without oil can damage them.

Track-adjuster grease pressure, compressed recoil springs, suspended drivetrain and blade assemblies, hydraulic pressure, battery circuits, and refrigerant service all require the blocking, lifting, isolation, pressure-relief, and recovery precautions specified in TM1476.