Market Position:
The Allis-Chalmers D-21 was a powerful utility and row-crop tractor designed for demanding agricultural tasks, positioning it as a robust choice for mid-to-large scale farming operations.
Competitive Analysis:
Competed against similar-sized tractors from manufacturers like John Deere, International Harvester, and Ford, offering strong horsepower and reliable performance for its era.
Key Features:
Known for its powerful diesel engine, robust build, and often equipped with advanced features for its time, such as a Power Director transmission for on-the-go gear changes.
Manual Purpose:
This service manual is an essential resource for maintaining, troubleshooting, and repairing the Allis-Chalmers Model D-21 tractor, ensuring optimal performance and longevity.
Systems Covered:
Engine, Fuel System, Cooling System, Lubrication System, Ignition System, Clutch, Transmission, Power Director, PTO, Hydraulic System, Steering, Brakes, Electrical System, Front Axle, Rear Axle, Sheet Metal, Operator's Station, Troubleshooting
Estimated Page Count:
Approximately 300-400 pages (typical for this era's comprehensive manuals)
Manual Type:
Service Manual / Repair Manual
Engine Service:
Detailed procedures for engine disassembly, inspection, repair, and reassembly for all major engine components.
Fuel System Service:
Maintenance and repair of fuel injection pumps, injectors, fuel filters, and fuel lines.
Cooling System Service:
Radiator, water pump, thermostat, and fan maintenance and repair.
Lubrication System Service:
Oil pump, oil filter, and lubrication passages service.
Ignition System Service:
Spark plugs, ignition coils, distributors (if applicable), and wiring maintenance.
Clutch Service:
Clutch assembly removal, inspection, adjustment, and replacement.
Transmission Service:
Disassembly, inspection, repair, and reassembly of the main transmission, including gear sets and bearings.
Power Director Service:
Service and repair of the Power Director (hydraulic clutch) system.
Pto Service:
Maintenance and repair of the Power Take-Off (PTO) unit.
Hydraulic System Service:
Hydraulic pump, control valve, cylinders, hoses, and reservoir service and repair.
Steering System Service:
Maintenance and repair of the steering mechanism.
Brake System Service:
Brake pedal, linkage, and brake mechanism service and adjustment.
Electrical System Service:
Wiring diagrams, starter, generator/alternator, battery, lights, and instrumentation service.
Front Axle Service:
Front axle assembly, kingpins, and wheel bearings service.
Rear Axle Service:
Rear axle housing, differential, and final drive service.
Sheet Metal Service:
Repair and replacement of body panels and fenders.
Operators Station Service:
Seat, controls, and dashboard service.
Maintenance Procedures:
Includes detailed instructions for routine maintenance tasks such as lubrication, fluid changes, filter replacements, and adjustments.
Troubleshooting Guides:
Comprehensive diagnostic charts and procedures to identify and resolve common mechanical and electrical issues.
Repair Procedures:
Step-by-step instructions for dismantling, repairing, and reassembling all major components and systems of the tractor.
Overhaul Instructions:
Detailed guidance for complete engine, transmission, and hydraulic system overhauls.
Adjustment Procedures:
Specific instructions for adjusting clutch, brakes, PTO engagement, and other critical components.
Technical Depth:
Comprehensive. Covers everything from basic preventative maintenance and troubleshooting to complete component overhauls and rebuilds, suitable for both experienced mechanics and knowledgeable owners.
Engine Make Model:
Allis-Chalmers 4-cylinder Diesel (Specific model designation may vary based on exact D-21 variant)
Engine Displacement:
Approximately 260-270 cubic inches (4.3 - 4.4 Liters)
Engine Horsepower Drawbar:
Estimated 55-65 HP (Drawbar HP)
Engine Horsepower Pto:
Estimated 65-75 HP (PTO HP)
Engine Torque:
Significant torque output for heavy draft work.
Fuel Injection System:
Typically Roosa Master or similar rotary injection pump system.
Transmission Type Standard:
Constant Mesh Gear Transmission with Power Director (Multi-Speed)
Transmission Type Optional:
Not typically offered with alternative main transmissions, Power Director was a key feature.
Power Director Description:
A hydraulic clutch system that allowed for on-the-go shifting between two speed ranges within each gear, effectively doubling the number of forward gears.
Number Of Gears:
Typically 6 Forward Gears + 6 Reverse Gears (with Power Director engaged).
Wheelbase:
Varies based on configuration, typically around 80-90 inches.
Length:
Varies, generally around 120-140 inches without implements.
Width:
Varies based on rear wheel spacing, typically 60-80 inches.
Operating Weight:
Approximately 5,000 - 6,000 lbs (without ballast).
Drawbar Pull Capacity:
High, suitable for heavy tillage and draft operations.
Engine Oil Change Interval:
Typically every 100-200 operating hours or annually, depending on operating conditions and oil quality.
Air Filter Service Interval:
Service as needed based on operating environment (e.g., clean or replace when restriction indicator shows).
Fuel Filter Replacement Interval:
Typically every 250-500 operating hours or when fuel system issues arise.
Engine Oil Specification:
Refer to manual for exact grade (e.g., SAE 30 or 15W-40 diesel engine oil meeting API CD or equivalent).
Transmission Hydraulic Fluid Specification:
Refer to manual for specific type (e.g., UTTO - Universal Tractor Transmission Oil or specific Allis-Chalmers hydraulic fluid).
Coolant Specification:
Ethylene glycol-based antifreeze, typically a 50/50 mix with water, consult manual for specific type and corrosion inhibitors.
Common Issues:
Typical issues for tractors of this age can include wear in the transmission and Power Director clutch, hydraulic system leaks, engine injector pump calibration, and electrical system degradation.
Preventative Maintenance:
Regular lubrication, fluid level checks, and filter replacements are crucial for preventing common wear-related issues.
