Abstract: The machine casing (1) comprises at least two casing parts (2; 3, 4) assembled mechanically together by clamping members (5, 6), the two casing parts being both made from metal, one at least (2) of these two casing parts (first part) being subjected to deforming forces likely to cause relative micromovements of the two opposite faces of these two casing parts, said first part (2) being made from a metal of relatively low hardness. Between the opposite faces of the two casing parts is inserted a plate (7) corresponding to the contour of the opposite faces of the two casing parts but having an area substantially less than that of the surface of said opposite faces of the two casing parts; the plate (7) is made from a metal of a hardness greater than that of a metal forming said part (2) and the corresponding edge (8;9) of the plate is sufficiently sharp to bite into the metal of relatively low hardness.

Abstract: A gear pump or motor comprises a tubular casing having an internal shoulder and an inlet and outlet for working fluid. A pair of meshing gearwheels are each mounted in the casing between a pair of rigid bearings which are disposed one on either side of the shoulder adjacent respective end plates closing the ends of the casing. Screws passing through the shoulder are provided for clamping the shoulder between the bearings and end plates. In an unclamped condition of the shoulder, the difference between the axial lengths of the shoulder and the gearwheels is greater than a predetermined operating clearance between the gearwheels and the bearings. In a clamped condition of the shoulder in the normal operating conditions of the pump or motor, the shoulder is resiliently deformed to reduce the said difference to a value at most equal to the predetermined clearance.