Speed Indicator

Elliott
Speed Indicator
No. 21421
Elliott Brothers
(London) Limited.

This type of rotary speed indicator was designed by Young, a naval engineer, and made in large numbers by Elliott after 1917. This is a portable instrument for use with any rotating machinery; in use it is held against the rotating shaft using one of the adaptors supplied with the instrument.

Fixed versions were also supplied for ships' and other machinery. They were also supplied as miles per hour indicators for tramways, etc. In "Flight" Magazine for August 7th 1909 there is a picture of a similar looking Indicator used to check small propellers (boats or models) and it is stated to be "absolutely to be relied upon for its readings".

This unit includes a box and a set of input shaft adaptors, and is marked with two speed scales. The relevant adaptor is fitted to one of two input shafts on the side of the instrument's housing: one for the 500-2500 scale and the other for the 2000-10,000 scale.

The given dimensions are for the instrument with its case. The instrument alone weighs 470g, its face is 68mm diameter and is 82mm high (face to foot bumps and 82mm deep (input shafts to the opposite side)