| 摘要 |
A pump includes a pump housing, a rotating shaft extending through the pump housing, a plurality of pistons, and a plurality of control sleeves. Each piston may be at least partially, slidably contained within a respective piston sleeve. The pistons may also be be operably coupled to the rotating shaft such that rotation of the shaft rotates and reciprocates the pistons. Each control sleeve may be slidably disposed on a respective one of said piston sleeves and operable to selectively vary the amount of fluid delivered by the pump.
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