Hart Parr was a very early American builder of gas tractors with the Hart Parr 30-60 being one of the more successful “Prairie” style tractors. However by 1919 the Prairie style tractors were obsolete being far too big and clumsy for the average farmer of the time.  The need was for smaller, more nimble tractors. Hart Parr’s first attempt to meet the needs of farmers at the time, the “Little Devil”, was a complete failure and the tractors were recalled. However, the right direction was taken in 1918 with the “New Hart Parr” 12-25 model, which formed the basis for all subsequent Hart-Parr tractors. The “New Hart Parr” was a tractor equipped with a two-cylinder, slow speed, water-cooled engine with force feed lubrication and open gears used to drive the rear wheels. The design after testing in Nebraska was re-rated at 15-30. A smaller model, the 10-20, was added to the range in 1921. The 10-20 and 15-30 were soon joined by a 22-40 in 1923. This tractor featured two 10-20 twin-cylinder engines side by side for a combined displacement of 616 cubic inches. 

The 22-40 was replaced in 1927 with the 28-50 model which duplicated the layout but which used 12-24 engines.

The Hart Parr 28-50 tractor was a four cylinder tractor with a cylinder bore of 5.5 inches and a stroke of 6.5 inches running at 850 rpm maximum. The engine appears to have been simply two 12-24 engines twinned. The tractor was fitted with a transmission offering two speeds ahead and one speed in reverse, a dry clutch, an automotive type coolant radiator which was not pressurized and an air cleaner. The tractor used water as the coolant.

The tractor was conventional in construction for the time, with a frame built up of structural steel components, riveted together with the engine, transmission and other components of the tractor then bolted to this frame.

The tractor was designed to operate a 36 inch separator or pull a 5 or 6 bottom plow. The 28-50 was also offered in industrial and road tractor versions. A canopy over the operators station was an option offered by Hart Parr. The 28-50 was also available in an industrial version with solid rubber tires.

Hart Parr built the 28-50 from 1927 to 1930.

The Museum collection holds two 28-50 tractors including one with a canopy SN 71566 donated by Mr. Murray Cleaver of Portage la Prairie, MB. The other 28-50 in the collection is SN 70529.