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a distributing shaft of a machine; a shaft with cams that impart motion to the separate mechanisms of the machine in a given sequence. For example, in internal combustion engines the camshaft allows opening and closing of the valves at the proper times; in fuel pumps the plungers are worked by cam action. Camshafts are stamped from steel or cast from high-strength cast iron. Camshaft cams and journals are hardened to a Rockwell C hardness of 53–62, after which they are ground and polished.
the part in the timing mechanism of a machine, instrument, or apparatus that ensures a definite order in the execution of functions and the cyclic recurrence of the operation. In internal-combustion engines, a camshaft is part of the valve-timing system and has a specified number of cams, which corresponds to the number of cylinders. It is rotated by a connecting mechanism from the crankshaft so that the operation of the valves and pistons is coordinated. In various automatic machines, camshafts are part of the control systems of production and operating processes that conform to a specified program. Programs can be changed by using replaceable camshafts corresponding to the appropriate operating cycle, or by using camshafts wih cams that can be moved along the shaft or turned to a certain angle, thus changing the eccentricity.