Applications and Selection of Torque Converters

The purpose of this page is to provide a rough guide to help you select a torque converter based on net input horsepower and speed. However, a converter must also be matched to the characteristics of the driven machine and other factors such as stall torque ratio, engine lug, braking and cooling as well as other considerations. Contact our qualified staff for assistance with torque converter recommendations. Please be ready to provide information about your engine including net horsepower and governed speed, the characteristics of the driven machine and the performance expected under stipulated average and maximum conditions.

Torque Converter Selection Chart - Speed

Application Information

The impeller of the converter is a centrifugal pump and must obey the following basic laws:

  1. Input torque varies with the square of the input speed.
  2. Input horsepower varies with the cube of the input speed.
  3. Input horsepower varies with the fifth power of the diameter of the impeller.

To handle a complete range of engines from 40 to 1000 horsepower, most manufacturers such as Link Belt, Manitowoc and Twin Disc, make four size series of three-stage converter. In each series, there are torque converters available with different specific torque ratings, each covering a portion of the broad capacity range per series. This enables you to match the converter exactly to the engine to fully utilize the available horsepower. Separate specific torque ratings within a series are obtained by using a choice of four different impellers and, in certain applications, by using long third stage turbine blades.

Specific torque ratings (called MS Ratings) designate the torque capacity (symbolized by the letter "MS") of the impeller at 1700 input rpm and at the specific point where input and output torque are equal. MS ratings indicate the converter's capacity and the higher MS value for a given series, the higher the capacity.

Torque Converter Application Chart - Weight

A hydraulic torque converter permits and engine to operate at nearly constant governed speed to develop maximum horsepower. The horsepower output from the converter is reasonably over a wide range of output shaft speeds. The comparative curves in the chart above are based on field tests of a mechanical hoist. Please note that two transmission ratios were used to cover the full range of converter operation with a single ratio.

The following chart indicates typical performance characteristics based on a name brand hydraulic torque converter. Applications should be engineered to achieve maximum efficiency when the output speed is one-third to two-thirds of input, paying attention that torque multiplication diminishes as output speed approaches input.

Torque Ratio Chart