Abstract: A stator assembly for a progressive pump or motor, comprising a resilient material stator (10) having a helical bore (12) therethrough, the cylindrical outer surface (14) of the stator having a plurality of axially extending circumferentially spaced outward projections (16). A rigid generally tubular member (22) has cooperating recesses (24) and may be formed of a unitary tube or of a plurality of shell elements with a cooperating clamp arrangement (32-36). The side faces (18,20) of the projections are flat and either parallel to one another or are inclined towards one another in the radially outward direction.

Abstract: A flexible drive shaft for a helical gear pump having a rotor 10 in which the drive shaft 18 is formed with an enlarged, e.g. upset forged, head 20 and is provided with a plastics material coating 30. The drive shaft is held on to the rotor by bolts 40 passing through holes 28 in the head 20 and apertures 42 in a cap 32.