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Specifications:  AC Model 720 Tractor




Power Lift System


Onan, Model CCKB



Hydraulic. 2.5 GPM (9.5 litres per minute) from the Hydrostatic Transmission charge pump.

Type Gasoline, 4 cycle, twin opposed cylinders
Cylinder Material Cast Iron   Relief Valve Pressure 550-700 PSI (3799-4828 kPa)

Horsepower @ 3600 RPM

19.5 (14.54kw)



Hand Operated

Bore and Stroke

3.25” (82.5mm) X 3.00” (76.2mm)


Hydraulic Cylinder

2.5 inch (63.5mm) diameter - 4 inch (102mm) stroke


49.8 cubic inches (816cc)


3 Point Hitch (Optional)

High Speed

3850 RPM No Load; 3600 RPM Full Load


Type Flexible Swinging draft hubs with ball couplers
Idle Speed 1200 RPM   SAE & ASAE Category Meets Category 0 dimensions
Valves Positive rotating Stellite facing on valve heads   Control Hydraulic, hand operated, same as power lift system
Valve Tappet Clearance Intake .007" (0.152mm); Exhaust .016" (0.406mm)   Drawbar
Valve Seats (Exhaust) Replaceable, Stellite faced   Type Single position - removable
Cooling System Pressure air cooled, axial flow blower   Height 13 inches (0.33 m)
Carburetor Zenith - Horizontal draft, adjustable main jet   Pin Size 3/4 inch (17mm)
Choke Manually operated Brakes Individual double disc type, can be locked together for simultaneous operation, parking brake is cam locking type.
Air Cleaner Replaceable Dry Element   Electrical System
Fuel Pump Diaphragm type   Battery 45 Ampere hour 12 volt, sealed terminals


Cam gear driven, adjustable mechanical flyball, pressure lubricated

  Alternator 20 Ampere flywheel alternator with silicon diode rectifier
Breaker Point Gap .020 inch (0.508mm)


Regulator Transistorized temperature compensated voltage regulator
Ignition Timing 20 before top dead center Protection 20 ampere circuit breaker

Spark Plug

Champion H-8 or Allis Chalmers No. 2067308


Lights Fender mounted sealed beams
Spark Plug Gap .025 inch (0.635mm) Dimensions

Lubrication System

Gear type oil pump, adjustable pressure relief valve, replaceable oil filter


56 inches (1.4m)

Length Overall 85 inches (2.2m)
Starting Motor

12 volt electric solenoid


Width (overall)

With Agricultural Tires (narrow setting) 43-1/4 inches (1.1m)
Power Train



With Agricultural Tires (wide setting) 48 inches (1.2m)
Clutch Foot pedal operated, double V-belt drive, clutch by varying center distance between pulleys   With Turf Tires 50-1/2 inches (1.3m)
Universal Joints Disc type, self aligning, no moving parts            With High Flotation Tires 56-1/2 inches (1.4m)

Hydrostatic Transmission

Sunstrand - Variable delivery piston pump with fixed stroke piston type motor.  Replaceable oil filter.


Ground Clearance (without drawbar)

15 inches (0.38m)

Gear Transmission 3-Speed Sliding Spur gear, Cast Iron transmission case, Rolling contact bearings Turning Radius (with Agricultural Tires at Wide Setting)
Differential 8 pinion, spur gear, non-adjustable limited slip.  Located in transmission case. Outside Front Tire Inside Rear Tire
Drop Housing Individual spur gears, rolling contact bearings, cast iron case. Without using brake 8 feet 3 feet
Using steering brake 6 feet 1 foot
Steering Recirculating ball screw, manual operation.  3.2 turns stop to stop.


Shipping Weight Approximately 1300 pounds (2860kg)


Standard lever operated seat, adjustable from operator position. 4 inches (102mm) travel, front to rear.  Spring mounted, inclined ramp.


Operating Weight (with 180 lb operator) Rear - 1000 pounds (2200kg)
Front - 480 pounds 91058kg)
Front PTO
12 volt electric solenoid actuated clutch, with automatic brake.  Speed equal to engine RPM.


Ground Speed Approximate, engine at 3600 RPM
First Gear Range 0-4.2 MPH Forward, 0-2.6 MPH Reverse

Rear PTO (Optional)


Second Gear Range 0-6.3 MPH Forward, 0-4.0 MPH Reverse
Third Gear Range 0=10.4 MPH Forward, 0-6.2 MPH Reverse

12 volt electric solenoid actuated.  Rated at 100 ft-lbs (135 N.M.)


Liquid Type and Capacity
Fuel Tank 3.8 gallons

Speed @ 3600 Engine RPM

2000 RPM


Engine Crankcase 3.5 quarts (above 32F, SAE 30; below 32F, SAE 5W-30)
Drive Involute splined shaft Transmission and Hydraulic System 6 quarts, Allis Chalmers Power Fluid 401 (Dextron)
Direction of Rotation Clockwise (viewed from the rear) Drop Housings, each 0.5 quarts, Allis Chalmers Gear Lube 715


Source:  AC Operator's Manual, MODEL 720 Lawn & Garden Tractors, Part Number 1657026, November 1976.




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