Theoretically the sum of the velocities of the three pistons on the discharge stroke in a low-fluctuation triplex pump should be a constant, and this can be achieved by means of the cam mechanism.

对于三缸低波动往复泵，理论上应使三个活塞在排出行程（吸入行程）中的速度之和为一常数，采用凸轮机构能达到这一目的。

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Each CAM must revolve once during the four-stroke cycle to open a valve.

在四行程循环时，每凸轮必须旋转打开一阀门。

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"Offering Cam Ranh Bay to foreign navies is a master stroke, " says Carlyle Thayer, a professor at the Australian Defence Force Academy at the University of New South Wales.

WSJ: Asia's New Arms Race