英语翻译As a machine component,a shaft is commonly a cylindrical

英语翻译
As a machine component,a shaft is commonly a cylindrical bar that supports and rotates with devices for receiving and delivering rotary motion and torque.The crankshaft of a reciprocating engine receives its rotary motion from each of the cranks,via the pistons and connecting rods(the slider-crank mechanism),and delivers it by means of coupling,gears,chains or belts to the transmission,camshaft,pump and other devices.The camshaft,driven by a gear or chain from the crank-shaft delivers rotary motion to the valve actuating mechanism.
An axle is usually defined as a stationary cylindrical member on which wheels and pulleys can rotate,but the rotating shafts that drive the rear wheels of an automobile are also called axles,no doubt a carryover from horse-and-buggy days.It is common practice to speak of short shafts on machines as spindles,especially tool-carrying or work-carrying shafts on machine tools.
In the days when all machines in a shop were driven by one large electric motor or a prime mover,it was necessary to have long lineshafts running the length of the shop and supplying power,by belts,to shorter counter-shafts jackshaft,or headshafts.These lineshafts were assembled from separate lengths of shafting clamped together by rigid couplings.Although it is usually more convenient to drive each machine with a separate electric motor,and the present-day trend is in this direction,there are still some situations in which a group drive is more economical.

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