Abstract: A method of assembling a pump motor and preloading bearings of the motor including providing a housing, an end bell, first and second bearings each having a plurality of rolling elements disposed between an inner race and an outer race, a rotor assembly having a shaft, and a spring, securing the outer races to the housing and end bell, respectively, assembling the spring on the shaft, inserting the rotor assembly into the housing such that the spring bears against the inner race of the first bearing and the rotor assembly, attaching the end bell to the housing, and securing the inner race of each of the first and second bearings to the shaft.

Abstract: A valve assembly for a pump includes a pump chamber and a pump head having complementary recesses formed therein which cooperate to define a valve compartment including a pocket and an opposed seat. A flexible valve element is disposed between the recesses and adapted to move between a closed position against the seat which prevents fluid flow and an open position away from the valve seat which permits fluid flow. The dimensions of the valve compartment are selected to limit the movement of the valve element in the open position, which increases the pump efficiency and prevents damage to the valve element and/or valve overlap.

Abstract: A non-reciprocating motor adapted for driving a reciprocating load is assembled by selecting a housing, a first bearing, a second bearing, and a rotor assembly having a shaft, all having corresponding predetermined coefficients of thermal expansion. The first and second bearings are positioned in the housing. The rotor assembly is rotatably mounted in the housing with the shaft received in the first and second bearings, such that the rotor is in a first position in which it has a predetermined amount of axial and radial play relative to the housing. A biasing element is installed and forces the rotor assembly to a second position in which play is eliminated. Each race is then permanently secured such that the rotor assembly is retained in the second position over a temperature range of about minus 40 degrees to about 105 degrees Celsius.