Torque amplifier

[1] It was intended to allow manual control of heavy equipment; e.g., industrial cranes, artillery, etc.

Vannevar Bush used Nieman's torque amplifier as part of his differential analyzer project at M.I.T in the early 1930s.

[2] Lord Kelvin had already discussed the possible construction of such calculators as early as the 1880s, but had been stymied by the limited output torque of the ball-and-disk integrators.

A capstan consists of a drum that is connected to a powerful rotary source, typically the steam engine of the ship, or an electric motor in modern examples.

To use the device, a rope is wrapped a few turns around the drum, with one end attached to a load, and the other hand-held by the user.

A single source of torque is supplied, typically from an electric motor, which is geared to power the two drums to spin in opposite directions.

As soon as the cage and the output shaft have moved to the correct position, the tension in the two ropes regains equilibrium and relative motion stops.

This amplified small gyro errors into signals large enough to move aircraft control surfaces.