History of Unit Rig

Unit Rig & Equipment Co. was founded in 1935 by a group of four Tulsa businessmen to manufacture oil drilling equipment, primarily well-servicing units and drawworks.

Between 1941 and 1945 the Company was involved quite heavily in the war effort although it continued to produce drawworks. After the close of World War II, the Company continued to build military products, including track-mounted entrenching machines and tank-mounted bridge launchers.

The original partnership was liquidated in 1946 - the Company was reorganized in 1947. On January 22, 1951 the late Ken W. Davis purchased all the stock of the corporation from the two remaining partners.

Unit Rig pioneered the development of the diesel electric drive, rear dump truck for use in open pit mining operations. Extensive experience acquired in applications of high horsepowered diesel engines to electric driven machinery on drilling rigs, encouraged Unit Rig to develop a new line of diesel electric powered mining trucks. The trucks were powered by a diesel engine turning a conventional generator which in turn provided power for DC motors in each of the rear wheels.

The prototype truck rolled out formally on January 27, 1960 and the first production models entered service in the last half of 1963. The truck was an immediate success gaining market share steadily.

In April 1984 Unit Rig purchased the Dart product line of wheel loaders and mechanical drive haulers. This high quality product line consists of the Dart 600C mechanical drive front end loader which has a 48,000 pound bucket capacity and end dump trucks ranging in capacity from 85 - 120 tons. The Dart line also includes tractor trailer bottom dump coal haulers with capacities from 120 to 160 tons.

In July 1988, TEREX Corporation purchased the U.S. and Canadian assets of the company and the stock of it's foreign subsidiaries, becoming a division of TEREX. In early 1998, the TEREX Corporation purchased O&K Mining, GmbH of Dortmund, Germany, a manufacturer of large hydraulic excavators, and combined it with Unit Rig to form TEREX Mining, a subsidiary of TEREX Corporation.

Unit Rig's current product line consists of a series of rear dump haulage trucks, with payload capacities ranging from 85 to 260 tons and bottom dump coal haulers with capacities of 180 to 270 tons. Unit Rig is the only large truck manufacturer to offer a completely new, high technology range of trucks. The Company has invested heavily in product development and offers new units at 120, 150, 170-190, 190-205, and 240-260 ton capacity. These new "MT" series trucks offer the advanced beam axle suspension arrangement, long frame life, very low maintenance requirement and high productivity cab together with a range of safety features not seen on competitive units.

The present principle markets for Unit Rig trucks are copper, coal, gold and iron mines. Currently Unit Rig has major customers on six continents.

Approximately 3,300 Unit Rig/Dart trucks and 400 Dart loaders have been sold in mining operations worldwide which is over 50% of the total world fleet.

TEREX Corporation, of Westport, Connecticut, is a diversified global manufacturer of a broad range of heavy equipment operating in two segments -- TEREX Earthmoving and TEREX Lifting. TEREX Earthmoving, in turn, consists of two divisions: TEREX Mining and TEREX Construction. TEREX Mining manufactures high capacity surface mining trucks under the Unit Rig brand name and large hydraulic excavators under the O&K brand name. TEREX Construction manufacturers rigid and articulated trucks for the construction industry under the TEREX and Payhauler brand names.

TEREX Lifting manufactures mobile cranes, aerial work platforms, utility aerial work devices, telescopic material handlers and truck mounted cranes and related products under the TEREX, Lorain, PPM, P&H, Marklift, Koehring, Simon, RO, Telelect and Square Shooter brand names.