Voith Turbo-Transmissions

Turbo-Transmissions are hydrodynamic, multi-stage drive assemblies designed for rail vehicles using internal combustion engines. The first turbo-transmission was developed in 1932 by Voith in Heidenheim, Germany. Since then, improvements to turbo-transmissions have paralleled similar advances in diesel motors and today this combination plays a leading role worldwide, second only to the use of electrical drives.

Turbo-transmissions serve as a hydrodynamic link which converts a motor's mechanical energy into the kinetic energy of a fluid, via a torque-converter and fluid coupling, before producing the final rotary output. Here, the fluid is driven through rotor blade canals at high flow-rates and low pressure. This is where turbo-transmissions differ from similar hydrostatic transmissions, which operate using low flow-rates and high pressure according to the displacement principle.

Turbo-transmissions are hydrodynamic, multi-stage drive assemblies whose performance is based on the Föttinger principle of fluid dynamics. Torque-converters, fluid couplings and optional hydrodynamic retarders are the key components in these assemblies, which are ideally suited for powered rail vehicles.

The first turbo-transmission from 1932 used a relatively simple design. It consisted of a single torque-converter for the start-up phase and a fluid coupling for the travel phase which were both mounted on a common shaft. A key feature of this turbo-transmission was the filling and emptying of the hydrodynamic circuit, a principle which was first used in Föttinger marine transmissions. This offered the advantages of frictionless start-ups, frictionless gear shifting with constant traction, freewheeling through emptying of the hydrodynamic circuit, and more efficient operation of the fluid coupling.

Contrary to Föttinger however, Voith used low viscosity oil in the hydrodynamic circuit of its turbo-transmissions rather than water. In addition, various other improvements were made in the 1930s: The addition of a high-speed gear, a more compact housing, greater compatibility with different motor types, automation gear shifts, as well as cooling via a heat exchanger.

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