In 1929, tractor pioneer Hart-Parr, successful plow manufacturer Oliver, and two other work machinery manufacturers merged to form the new Oliver company. In 1930, the new Oliver Hart-Parr tractor models 18-27, 18-28, and 28-44 were introduced, featuring Waukesha engines. The Oliver Hart-Parr 70, introduced in 1935, was technically the successor to the 18-28 but had a more modern design. Its technology was enclosed under smooth (though still angular) sheet metal panels, a style that had become common in cars, and it had a 6-cylinder Continental engine.

The gauges were placed on the dashboard, and electric start and headlights were available as optional equipment. The HC model had a high-compression gasoline engine (27 hp) and the KD had a petrol engine (24 hp). There were 4+1 gears. The standard equipment included steering brakes that acted on the differential axles and also operated automatically when turning sharply. There was a Row-Crop version available with either one front wheel or two adjacent wheels, and a Standard model with a wide front axle and disc brakes.

In 1937 the design was changed to a very modern style, and a 6+1-speed transmission was offered for the rubber-tired version. The green color became lighter, and red was introduced as a decorative color. Now available was the streamlined tractor by which Oliver is still known in Finland. Hart-Parr was dropped from the name in 1938.

In 1940, the Oliver 60 was introduced, and the design of the Oliver 70 was modified to match the smaller model.

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