Gov′ern-or cut-off.
An automatic arrangement in which the acceleration or retardation of the motion of the governor, due to changes of speed of the engine, is made to cut off the steam at an earlier or later period of the stroke of the piston, so that with the increased boiler-pressure or lighter work the steam shall be cut off earlier in the stroke, and when greater work is imposed on the engine or the steampressure flags, the steam-cylinder shall receive steam from the boiler during a larger proportion of the stroke of the piston. The combination of the governor with a cut-off valve-gear was first published in the “Repertory of patent inventions” for 1826, as the invention of James Whitelaw. There are many forms of this device, and the applications are made to slide and to puppet valves. In the illustration it is shown as applied to a cylindrical valve. The variable cam C on the stem which is raised or depressed by the vertical motions of the governor-balls makes two revolutions to each stroke of the engine. The two distinct fields of the cam have different radii, and act upon the short arm of a bell-crank lever D connected at its other end to the stem of a balanced cylinder-valve E, which governs the admission of steam to the cylinder. |
| Governor-valve. |
