Patent ID: 8602751

Claim:
A transfer pump comprising: a motor; a motor mount having a plurality of standoffs configured to engage the motor, and a tubular portion having an outer threaded portion and a center through channel; an outlet manifold comprising a manifold chamber having an open upper end that is sized to be sealingly engaged by the motor mount and a center aperture that is threaded to releasably engage the outer threaded portion of the motor mount, wherein the manifold chamber defines a plurality of inlet ports and an outlet port; an inner cylinder that sealingly attaches to the outlet manifold below the manifold chamber such that all of the inlet ports are disposed above and radially outwardly from the inner cylinder; a pressure cylinder having a proximal end that sealingly attaches to the outlet manifold below the manifold chamber and a distal end having a foot valve, such that all of the inlet ports are disposed above and radially inwardly from the pressure cylinder, the inner cylinder and the pressure cylinder defining an annular flow path that is fluidly connected to the manifold chamber through the plurality of inlet ports; a pump shaft assembly comprising an elongate shaft that is configured to be driven in reciprocating motion by the motor and extending through the outlet manifold, inner cylinder and pressure cylinder, the pump shaft assembly further comprising a small piston disposed in the inner cylinder and fixed to the elongate shaft and a large piston attached to a distal end of the elongate shaft, the large piston having a check valve, and wherein the small piston slidably engages the inner cylinder and the large piston slidably engages the pressure cylinder; wherein the outlet manifold further comprises a radial pressure relief port open to the atmosphere that provides a flow path to the inner cylinder.