235,216. Metropolitan-Vickers Electrical Co., Ltd., (Assignees of Kasley, A. T.). June 9, 1924, [Convention date]. Fluid governors; fluid relays.-A constant fluid pressure, which can be regulated by an adjustable relief valve, is added to the load on a member responsive to fluid pressure which varies with the speed of the machine to be controlled in order to avoid the use of very strong or additional springs. Fluid-pressure set up by the engine-driven pump 13 acts beneath the head 42 of a pilot valve 34 positioned within the hollow relay piston 23, and also acts against the action of spring 49 on a piston 47, Fig. 2, which is connected to the pilot valve, and which fits loosely in cylinder 46, allowing leakage. The pressure behind the piston 47 is kept constant by a relief valve 54 whose loading spring is adjustable in order to set the governor for various speeds. An increase of speed causes the piston valve to rise, admitting fluid by ports 37, 26 beneath piston 23, and exhausting from above the piston by ports 24, 41, 27. The piston 23 moves to close the main stop valve and to take up neutral position in relation to the piston valve. A decrease of speed causes the operation to be reversed. The fluid relay may be dispensed with, the piston 47 acting directly on the main stop valve. In a modification, Fig. 4, the piston valve head 42 fits loosely in the cylindrical extension 29 on the piston 23, the relief valve 83 controlling the pressure above the head. The piston valve is also loaded by a tension spring 76. Specifications 207,803 and 209,403 are referred to.
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