1970s–1990s Belarus MTZ 50, 80, 90, 500, 800, 900 Tractor Workshop Manual Set (P/N HN.21.AD.02)

The tractor sections cover the installed systems, while the embedded Danfoss publication adds component-level steering-unit service procedures.

Danfoss coverage limit: The steering excerpt jumps from pressure-relief valve assembly step 68 to step 72. It includes the OSPB exploded view, but the additional OSPC/OSPC LS exploded-view page listed in its contents is missing.

PDF Access and Wiring Detail

Search, navigation and small labels: The manual text is not searchable, and there are no embedded PDF bookmarks. Small wiring labels require zooming; some fine lettering and faint circuit lines remain difficult to read.

Supplied as one printable, English-language, 241-page PDF. The total includes six preliminary pages: the cover, one blank page, a conversion chart and three contents pages. The Danfoss excerpt is embedded in the steering chapter.

Engine, Drivetrain and Hydraulic Repair

The selected topics below show the main workshop coverage. Other material includes tire load and pressure charts and fuel-spray electric plug heater operation.

• Diesel engine repair: Cylinder-head disassembly, valve-seat reconditioning, piston and liner inspection, crankshaft removal, injector disassembly, and water-pump service.

• Clutch and transmission: Clutch overhaul and linkage adjustment, gearbox disassembly, shaft and bearing inspection, and service procedures for different gearshift mechanisms.

• Rear axle and PTO: Differential-lock adjustment, final-drive inspection, planetary PTO teardown, brake-band measurements, and PTO control adjustment.

• Brakes and front drive: Service and parking brake repair, steering-knuckle inspection, front axle reduction-gear service, and intermediate-support safety-clutch checks.

• Steering and hydraulics: Danfoss steering-unit service, hydraulic pump testing, distributor checks, ram leakage tests, and draft/position control adjustment.

• Electrical systems: Wiring diagrams for standard and modernized dashboards, starting and charging circuits, instrument connections, lighting, and auxiliary cab equipment.

This material is suited to mechanics familiar with component measurement and overhaul; hydraulic testing requires a test stand, pressure gauges and flow-measuring equipment.

Diesel Engine Inspection and Service

The engine sections describe D-50, D-60, D-240, D-242, D-243 and D-244 designs. They distinguish intake-manifold, crankshaft and injection-setting differences rather than treating every engine as identical.

Step-by-step procedures cover cylinder-head removal, valve-seat repair, injector nozzle disassembly and crankshaft work. Inspection tables address valve guides, spring loads, piston rings, cylinder liners and bearing fits. Having these component limits at the workbench supports decisions about reuse, machining or replacement during a rebuild.

The D-240 valve timing diagram supplements the timing-gear illustrations. Lubrication and cooling sections explain the centrifugal oil filter, oil pump, thermostat and water pump; 900 Series material also covers turbocharger oil-filter maintenance.

Injector handling: The disassembly instructions identify a locating pin that can be damaged if the specified sequence is ignored. Centrifugal-filter reassembly notes also address rotor indexing to preserve balance.

Transmission, PTO and Brake Work

Gearbox power-flow diagrams accompany the internal repair sections. Separate gearshift procedures distinguish the central-lever mechanism from the later side-shift designs, while clutch-control illustrations show arrangements before and after deletion of the clutch brake.

PTO coverage distinguishes the single-speed drive used on the 500 Series from the two-speed arrangement on the 800/900 Series. Planetary reducer drawings, differential tooth-contact charts and brake inspection tables support internal drivetrain work.

The clutch adjustment notes explain how insufficient pedal free travel can cause slipping and clutch failure.

Danfoss Steering and Implement Hydraulics

The Danfoss excerpt covers dismantling, inspection, seal installation and reassembly across the documented OSPB/OSPC steering variants. Tool illustrations identify the SJ 150-9000-2 holding tool and SJ 150-9000-11 seal assembly tool.

Hydraulic circuit diagrams explain the NSH32A-3 pump, R80-3/4-333 distributor, rear ram and draft/position control system. Distributor procedures include leakage, relief-valve and spool pop-out checks. The bypass-valve descriptions and separate component tests help distinguish pump-output problems from distributor or cylinder faults.

Adjustments also cover tractors equipped with the mixer control system.

Working on heavy machinery carries inherent risks. Always verify load capacities, secure the tractor on appropriate stands, and relieve hydraulic pressure before opening any lines to prevent severe injury.

Electrical Circuits and Component Operation

The electrical equipment diagrams trace harness connections through the dashboard, lighting and cab circuits. Separate schematics cover power supply and starting, while the 464.3701 generator circuit explains the rectifier and regulator arrangement.

Starter descriptions distinguish the documented motor designs and explain the interlocking relays and neutral safety switch. The alternator service notes limit routine attention to cleaning rather than internal repair.

Selected Clutch and PTO Inspection Data

The clutch adjustment section specifies pedal free travel of 1.5–2 inches (38–50 mm), measured at the pedal. It also explains the operating symptoms associated with incorrect clearance.

For the planetary PTO brake band, the inspection section gives a rated thickness of 7.78–8.20 mm and an allowable minimum of 7.2 mm. These are component inspection references accompanying the teardown and reassembly material.