Sweep moldings are employed for molding parts whose shape is that of a surface of revolution. In the preliminary process, a base 1 and spindle 2 is well placed in the foundry floor. The sand is filled in and rammed until the excavation forms approximately the shape and size of the required casting. A sweep holder 5 is then placed in the spindle land the sweep 6 is attached by bolts and nuts. The surface of the mold is produced by the profile of the sweep as it is rotated about the spindle. After sweeping, the spindle is removed and the mold patched at the center. The gate is then cut and the mold is ready for pouring.
Steam Pressure at inlet to a steam turbine is reduced by throttling process to maintain the speed of the turbine constant at part load and hence this method of governing is called "Throttle Governing". Construction : Throttle governing system consists of a centrifugal governor, a lever , an oil pump , a pilot piston , control valve , a relay piston and a throttle valve. The throttle valve is moved by a relay piston. The relay piston is actuated by pilot piston control valve. There are two piston valves covering ports in the pilot piston control valve without any overlap. These piston valves are operated by lubricating oil supplied by a gear pump at 2 to 4 bar. The oil returns to the drain from this chamber. Working : When the turbine works on full rated load, the throttle valve will remain open. When the load is decreased, the energy output of the turbine becomes in excess and the turbine shaft speed increases. Hence, governor sleeve will lift. The upward movement of the
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