| 摘要 |
A pump for a vehicle braking or traction control system integrated into a hydraulic control unit. The housing for the hydraulic control unit has at least one counterbore in which a cylindrical sleeve is disposed. The cylindrical sleeve has a counterbore which is open at one end and closed at the other. A piston is reciprocal in the counterbore by a motor driven cam. The piston, in conjunction with the closed end of the sleeve, forms a pumping chamber having an outlet port provided through the closed end of the sleeve. Low pressure brake fluid is received into the pumping chamber through an axial fluid passageway and a one-way check valve. A piston support land is provided on the internal surface of the cylindrical sleeve and a mating opposing land is provided on the external surface of the piston. The opposing land has a plurality of equally spaced annular grooves which entrap sufficient fluid to provide a uniform fluid film between the piston support and opposing lands.
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