Kenyon's pistonless steam engine indicator, 1878

Kenyon's pistonless steam engine indicator, 1878

In this steam engine indicator, patented in 1878 by Mr. J. W. Kenyon, a Bourdon tube takes the place of piston and spring. The motion, under varying pressure, of the free end of the tube is multiplied by a lever in the ratio of about 5: 1, and the pencil is constrained to move in a straight line by Watt's parallel motion applied as in Richards indicator. The connection between the tube and the parallel motion is by a rod with ball joints which enables the pencil to be drawn back from the paper on the drum when required. The drum is fitted with a stop motion, consisting of a small lever by which it can be raised sufficiently to disengage a short driving peg attached to the cord pulley.