Abstract: Gear pump, or Moineau pump, comprising two helical gears one inside the other, the internal helical gear, which is rotary (the rotor) having one tooth fewer than the external helical gear, which is stationary (the stator), characterized in that the rotor and the stator are made of respective materials which have respective coefficients of thermal expansion which lead to respective expansions of the rotor and of the stator which are such that an approximately constant clearance is maintained between the rotor and the stator over a range of ambient temperatures spanning between about 15.degree. C. and about 300.degree. C.

Abstract: Diasphragm pump having a delivery rate which can be continuously adjusted between a zero value and a maximum value, comprising:a continuously rotating eccentric drive member (6);a connecting rod (5) with a connecting-rod big end (11-14) fitted with a bearing (10) receiving, so as to rotate freely, the member (6) and the other end of which is coupled to a central area of the diaphragm (2);releasable coupling means in order to couple, in a selective manner, the connecting-rod big end to the member (6) during a desired fraction of stroke, which can be continuously adjusted by adjustment means (16-19).