Abstract: An improved rotary, gear within a gear transfer pump, including a pump housing having a circular pumping chamber communicating with a first port and a second port. An externally driven rotor is in meshing relationship with an internal idler gear. To enable the pump to handle an abrasive fluid medium or a non-homogenous pump fluid, an idler gear seal and a shaft seal are employed to contain pumped fluid within the pump chamber. A source of lubricating/flushing fluid is communicated to an idler gear bearing region and a shaft bearing. An idler gear seal includes a "flow resisting" side exposed to pump chamber fluid and a "flow passing" side exposed to lubricating/flushing fluid. The shaft seal includes a "flow resisting" side exposed to pump chamber pressure and a "flow-passing" side exposed to lubricating fluid. A cross-communicating fluid circuit maintains the "flow resisting " sides of both seals at substantially the same pressure.

Abstract: An externally driven rotor is rotatable within a pumping chamber and is located in meshing relationship with an internal idler gear. An annular bearing mounted within the housing in confronting relationship with a peripheral surface of the rotor, provides a bearing surface and supports radially directed loads exerted by unbalanced fluid force on the rotor. A pressure balancing circuit is provided for transferring pressurized fluid from a discharge region in the pump to a backside of the rotor to at least partially balance axial forces exerted on the rotor by pressurized fluid. To provide bi-rotational capability, a cross-communicating passage and check valves are used for controlling the flow of fluid into the pressure balancing circuit.

Abstract: An improved sealing apparatus for gear transfer pump of the type that includes a gear driven by a drive shaft connected to a drive source. The drive shaft extends through a backhead which includes a seal system for inhibiting fluid leakage between the drive shaft and the backhead. The seal system includes a tubular insert held at one end by a support element threadedly received in an end bore of the backhead and structure defined by the backhead which engages another portion of the insert and includes a secondary seal for inhibiting fluid leakage between the insert and the backhead. The insert includes structure for mounting at least a portion of the seal in predetermined alignment with the drive shaft. The drive shaft includes an abutment for locating a rotating portion of the seal for applications that include two-part seals. A seal cartridge is disclosed in which non-rotating and rotating portions of the seal form a single assembly that is installed as a unit into the backhead.