Oliver 90

Beginning with the Hart-Parr 28–44, the series was the most powerful Oliver tractor offering, capable of heavy plowing.

Initial development proceeded on parallel lines, with the 28–44 offered with low and high-compression engine options that became the Oliver 90 and 99, respectively.

Built in Charles City, Iowa, the 28–44 was itself a scaled-up Hart-Parr 18-36, with a 443-cubic-inch (7,260-cubic-centimetre) engine with 48 horsepower (36 kW) gross, and a weight of 6,415 pounds (2,910 kg).

The 99's production was moved from the main Oliver plant in Charles City, Iowa to South Bend, Indiana.

Options were added for six-cylinder and diesel engines, and the tractors received styled sheet metal.

All three were re-styled,more squared-off in appearance, with green bodies and a green-tinged white for grilles and wheels.

[11][12] The Oliver 990 replaced the General Motors-engined Super 99, with an upgrade in rated RPM, allowing seven plows with 93 horsepower (69 kW) gross.

[13][14] The Oliver 995 Lugmatic added more RPM and a torque converter to the 990 for better performance under load, and was rated for 12 to 14 plows.