Modern passive mechanical amplifiers - Fundamental concepts

Mechanical action multipliers or passive amplifiers are mechanisms designed to obtain significant mechanical actions from readily available, usually human, mechanical actions. They are used to amplify forces or torques. Their use is universal, and their history is intertwined with that of mankind.

It should be noted that force multipliers should not be confused with true active mechanical amplifiers, which are servomechanisms. The latter gave rise to the mechanical brake servos widely used in the automotive industry before the Second World War (Hallot, Renault, Hispano-Suiza). In servomechanisms, energy is supplied from outside, and a distinction is made between control and actuation, with human effort practically limited to control. In what follows, we will only be talking about passive multiplier or amplifier mechanisms.

This article is the first in a series of three. We'll review a number of familiar examples, then look in detail at a typical amplifier, highlighting fundamental principles such as effort gain and speed gain.