1978–1987 John Deere 770A, 770AH, 772A, 772AH Motor Grader Technical Manual (P/N TM-1361)

John Deere TM-1361 (May 1987), formerly TM-1187, covers 770A, 770AH, 772A, and 772AH motor graders, including the hydrostatic front-wheel-drive equipment used on 772A/772AH machines.

Supplied as one 1,330-page PDF in English.

• Engine repair: Engine removal and installation, earlier-engine internal repair, fuel-injection timing, turbocharger service, and cooling-system procedures, with a separate-manual requirement for later engines.

• Power Shift and drivetrain: Transmission disassembly, clutch and planetary-pack repair, differential adjustment, tandem-drive service, and transfer-drive overhaul.

• Hydrostatic front-wheel drive: Standard- and high-speed configurations, pump and wheel-motor repair, electrical/hydraulic fault isolation, leakage tests, and neutral adjustments.

• Hydraulics, steering, and brakes: Main-pump and control-valve repair, pressure and flow testing, steering leakage checks, brake-accumulator tests, and brake bleeding.

• Grading equipment: Circle gearbox repair, moldboard/circle adjustments, blade-float controls, scarifier/ripper service, and Automatic Blade Control diagnosis.

• Electrical and cab systems: Starting and charging tests, instrument and control circuits, wiring diagrams, electrical schematics, and heating/air-conditioning diagnosis.

John Deere wrote this manual for experienced service technicians; basic service theory is covered in separate Fundamentals of Service manuals.

Engine Repair and Serial-Number Limits

Engine coverage includes removal and installation plus internal repair information for the 6531 engine through engine S/N 249595. It covers crankshaft and main bearings, valve gear, pistons and connecting rods, cylinder block and liners, cylinder head, and the oiling system.

Fuel-system procedures cover Roosa-Master Model DM injection-pump removal, installation, and timing, plus injection-nozzle testing and repair. Internal injection-pump repair is referred to TM-1109, which is not included.

Turbocharger, water-pump, thermostat, oil-cooler, and starting-motor work are also documented.

For the later 6466AT-06 engine, engine S/N 249596 and up, complete engine and fuel-system diagnosis, disassembly, inspection, repair, and assembly require the separate CTM-1 component manual, which is not included. The machine manual retains engine removal/installation and later-engine starter and fan-drive procedures.

Power Shift, Axles, and Final Drives

The direct-drive, eight-forward/four-reverse Power Shift section covers C1, C2, and C3 clutch assemblies, B1 through B4 brake units, compound planetary packs, reduction shafts, pumps, control valve, forward/reverse modulator, and clutch-disconnect controls. The Cross-Sectional View of Transmission identifies the internal assemblies.

Axle and final-drive coverage includes tandem housings, pivot housings, wheel axles, drive chains, planetary reductions, differential lock components, and powered front-wheel assemblies.

Differential repair includes cone-point setup, pinion-shaft adjustment, bearing preload, backlash, and tooth-bearing-pattern checks. The spiral bevel gear and bevel pinion are supplied as a matched set.

The assembly notes explain how incorrect tandem wheel-axle housing orientation can interrupt lubrication and damage the outer bearings. At the differential, allowing an external pressure/brake-line bulkhead fitting to turn can twist off the internal line.

HFWD Variants and Fault Isolation

Standard-speed HFWD operates through 1st–4th gears; the high-speed configuration operates through 1st–6th. The manual distinguishes their pumps and planetary drives and covers the electro-hydraulic actuator, flow divider, and solenoid manifold.

The propel-motor identification notes distinguish the E and F codes for standard- and high-speed equipment. This helps match the HFWD configuration before selecting parts or repair procedures.

Section 90 combines the HFWD Electrical Schematic with startup checks, wheel-motor and brake-cavity leakage tests, wheel-speed/aggressiveness adjustment, and pump/actuator neutral setup. Electrical testing references the D-01078AA HFWD Diagnostic Test Box.

Hydraulics, Grading Equipment, and Blade Control

Other repair sections cover steering cylinders and linkage, wet-disk service brakes, the parking brake, and main hydraulic pump and control valves. Diagnostic data covers standby and steering-priority pressures, brake-warning and accumulator checks, transmission clutch pressure, and HFWD charge/relief-pressure testing.

Grading coverage includes blade-lift and rear-steer functions, circle drive gearbox, moldboard/circle support adjustment, lift-arm locking system, and scarifier/ripper equipment. Hydraulic cycle-time charts cover blade lift, blade and circle side-shift, circle rotation, blade pitch, wheel lean, and rear frame steering.

The Hydraulic Schematic (JD770-A) shows the main circuit. Automatic Blade Control coverage includes grade/slope sensing, Honeywell hydraulic manifold variants, linkage checks, electrical diagnosis, and dedicated ABC test procedures. The ABC System Hydraulic Block Diagram and D-05289ST ABC Test Box references support that section.

Electrical Diagnosis and Service Data

The 24-volt electrical material covers starting and charging circuits, 42- and 50-amp alternator tests, gauge/indicator circuits, auxiliary hydraulic controls, air-conditioning circuits, wire routing, and a complete electrical schematic.

The Instrument Panel Wiring Diagram and Component Wiring Diagram supplement circuit diagnosis. The 770AH/772AH material identifies the fuel-injection-pump aneroid solenoid control circuit.

Predelivery checks and initial and recurring engine-oil/filter and transmission/hydraulic-filter schedules accompany component-specific torque tables, wear limits, fluid capacities, and electrical test specifications. Capacity tables distinguish engine-oil requirements at PIN 508636 and transmission/hydraulic requirements between 770A/770AH and 772A/772AH machines.

Lubrication data lists HY-GARD J20A for tandem drives, J20A/J20B temperature-dependent applications for transmission/hydraulic and HFWD systems, and SAE EP90 for the circle-drive gearbox.

Hydraulic and transmission testing references the D-01080AA Master Hydraulic System Analyzer and D-01084AA Tachometer/Temperature Reader.

Because these graders use stored brake-accumulator pressure, high-pressure hydraulics, and heavy drivetrain and blade assemblies, follow the manual's safety procedures, relieve system pressure, support raised equipment, and use appropriate lifting equipment before repair work.

PDF Search, Bookmarks, and Diagram Readability

The page total includes the cover, three unnumbered blank pages, foldout diagrams, and internal section blanks. Embedded OCR supports text search on most pages, but some diagrams and system-operation pages are not searchable; PDF bookmarks cover the repair and diagnostic sections. Small labels on the large wiring schematics require zooming.