Method of making an internal gear pump

A method of manufacturing a pump comprising the steps of:

• providing a shaft comprising an inboard end and an outboard end, the inboard end being connected to a rotor, the shaft further comprising a first segment disposed between the outboard end and the rotor, the first segment having a first diameter, the shaft further comprising a second segment disposed between the first segment and the rotor, the second segment having a second diameter, the second diameter being greater than the first diameter,
• providing a casing comprising a pump chamber for accommodating the rotor, an open end and an outboard section for accommodating the shaft, the outboard section of the casing comprising a first recessed area defining a seal cavity, the outboard section of the casing further comprising a second recessed area for accommodating a stationary annular bushing, the bushing comprising an inside diameter that is larger than the second diameter of the second segment of the shaft,
• providing a seal assembly for mounting over the first segment of the shaft and within the seal cavity, the seal assembly having an outside diameter that is less than the inside diameter of the bushing and an inside diameter that is smaller than the second diameter of the second segment of the shaft,
• mounting the seal assembly over the first segment of the shaft so that the seal assembly abuts the second segment of the shaft,
• passing the outboard end of the shaft, the seal assembly and the first and second segments of the shaft through the pump chamber and the bushing until the rotor is disposed in the pump chamber, the second segment of the shaft is disposed within the bushing and the seal assembly is disposed within the seal cavity.