An assembly of a hydraulic motor and of a brake is already known, comprising: a motor frame; a cylinder-block mounted to rotate about an axis of rotation and maintained axially in position at least in one direction with respect to the frame by means of a bearing device, and provided with a plane communication face perpendicular to the axis of rotation; an internal fluid distributor valve, provided with a plane distribution face, generally in abutment on the communication face of the cylinder-block, jacks capable of containing fluids under pressure, being interposed between the frame and the internal fluid distributor valve and capable of generating a thrust for abutment of the distribution face against the communication face; two groups of braking members fast in rotation, the braking members of a first of the two groups with the motor frame, and the braking members of the second group with a brake shaft itself fast in rotation with the cylinder block; an axial thrust member for controlling braking, with displacement parallel to the axis of rotation, coupled to the brake shaft so as to be fast therewith with respect to a translation of said thrust member parallel to the axis of rotation, of direction opposite that of the thrust for abutment of the distribution face against the communication face; a device for controlling the braking coupled to the thrust member and capable of generating thereon an axial braking thrust; and a brake-release jack coupled between the motor frame and the thrust member, with effect antagonistic to that of the braking control device, capable of generating on the thrust member an axial thrust of direction opposite that of the thrust for abutment of the distribution face against the communication face.
It is ascertained that the bearing device must be capable of withstanding a considerable axial thrust: that transmitted to the cylinder-block by the internal fluid distributor valve during abutment of the distribution face of the internal distributor valve on the communication face of the cylinder-block. The dimensions of the bearing device might be reduced or its operative life might be increased if, during nominal running of the motor, with the maximum nominal pressure provided, an effort antagonistic to that of said thrust for abutment of the distribution face on the communication face were developed and applied to the cylinder-block to reduce and even cancel the effect of said thrust.
It is also ascertained that, in an assembly of a motor and of a brake, the motor may function only if the action of the brake is cancelled or only when an effort of brake-release is generated.
The invention contemplates bringing these observations together and, by transmitting in the appropriate direction the brake-release effort which exists simultaneously with the thrust for abutment of the distribution face of the internal distributor valve on the communication face of the cylinder-block, in obtaining the partial or total neutralization of the latter by the former.