| 摘要 |
In a tappet-driven single piston pump, piston side loads caused by return spring out-of- squareness are eliminated by effectively piloting the piston return spring, preferably the associated spring seat, by the tappet, thereby allowing the tappet to bear the spring side load. The piston engages and is returned by the spring seat, but radial clearance between the piston and spring seat is greater than radial clearance between the spring seat and tappet, thus eliminating side loading imparted to the piston. The spring seat can be considered a piston retainer, in which the piston is not closely attached to the retainer but instead exhibits a predefined radial clearance greater than the piloting clearance between the retainer and the tappet. |
