Abstract: An electro hydrostatic actuator comprising a hydraulic pump driven by an electric motor to supply hydraulic fluid to a hydraulic actuator, the pump comprising an inlet and an outlet for the hydraulic fluid and an active flow path configured therebetween such that, in an active mode of operation when the pump is driven by the electric motor, hydraulic fluid is actively drawn in through the inlet and exhausted out through the outlet. The pump further comprises a bypass flow path configured to open between the inlet and outlet such that, in a damping mode of operation when the pump is not driven by the electric motor, hydraulic fluid is able to pass through the pump along the bypass flow path between the inlet and outlet. The hydraulic pump is a rotary piston pump comprising a pump barrel driven to rotate by a motor shaft.

Abstract: An electro hydrostatic actuator comprising a hydraulic pump driven by an electric motor to supply hydraulic fluid to a hydraulic actuator, the pump comprising an inlet and an outlet for the hydraulic fluid and an active flow path configured therebetween such that, in an active mode of operation when the pump is driven by the electric motor, hydraulic fluid is actively drawn in through the inlet and exhausted out through the outlet. The pump further comprises a bypass flow path configured to open between the inlet and outlet such that, in a damping mode of operation when the pump is not driven by the electric motor, hydraulic fluid is able to pass through the pump along the bypass flow path between the inlet and outlet. The hydraulic pump is a rotary piston pump comprising a pump barrel driven to rotate by a motor shaft.

Abstract: A linear screw actuator including, an outer housing which is fixed in use, an electric motor within the housing, the motor including a hollow rotatable output shaft, a rotatable but axially fixed nut driven by said output shaft, an elongate hollow axially translatable output member, said output member extending within said output shaft of said motor and cooperating with said rotatable nut, and, an elongate anchor member secured against rotation relative to said housing and extending within said output member, said anchor member cooperating with said output member to hold said output member against rotation whereby rotation of said nut relative to said output member causes axial translation of said non-rotatable output member relative to the housing.

Abstract: A linear screw actuator including, an outer housing which is fixed in use, an electric motor within the housing, the motor including a hollow rotatable output shaft, a rotatable but axially fixed nut driven by said output shaft, an elongate hollow axially translatable output member, said output member extending within said output shaft of said motor and cooperating with said rotatable nut, and, an elongate anchor member secured against rotation relative to said housing and extending within said output member, said anchor member cooperating with said output member to hold said output member against rotation whereby rotation of said nut relative to said output member causes axial translation of said non-rotatable output member relative to the housing.

Abstract: This unit is provided with two hydropneumatic jacks (2) having parallel vertical axes X--X and comprising bodies (5) adapted to be rigidly connected by a plate (3) and mounted slidably on rods (6) fixed to the chassis (7) of the vehicle. The plate (3) is sufficiently wide to allow if desired the passage of a transmission for the corresponding wheel. This arrangement improves the guiding of the wheels by holding them in fixed planes and enables them if desired to be made into driving and/or steered wheels.

Abstract: The hydropneumatic jack comprises a tubular body (14) closed at one end and open at the other end. A hollow rod (9) is slidably mounted in the body (14) in a sealed manner and in the rod is formed a first chamber (18) containing a freely slidable piston (19) which divides the chamber into two compartments (18a, 18 b) which are sealed off from each other, a second chamber (23) being defined between a transverse end wall (21) constituting the end of the hollow rod (9) and the inner wall of the body (14). The transverse end wall (21) is provided with a nozzle (22) putting the second chamber (23) in communication with the neighbouring compartment (18b) of hollow rod (9). The compartment (18b) and the second chamber (23) are filled with a hydraulic liquid under pressure and the second compartment (18a) is filled with a pressurized gas. This jack automatically and instantaneously corrects the decreases in tension of the track (1) in the static state, subsequent to wear or expansion of the track and rollers.

Abstract: Shock absorber (31) for a hydropneumatic vehicle suspension element, comprising a disk (32) fastened in an outer casing having ports (30, 38) for the passage of the hydraulic fluid, first elements (48, 49, 37a, 37b) allowing this passage in only one direction for some ports (30) and in the opposite direction for the other ports (38), and second elements (53, 54, 55) for fastening the first elements to the disk; the abovementioned first elements comprise, mounted on the two opposite faces of the disk (32), stacks (46, 47) of elastically flexible metal washers (46a-46c; 47a-47c) arranged in rigid annular deflectors (48, 49) located opposite the hydraulic-fluid passage ports (30, 38). The deflectors protect the flexible washers against any damage caused by the very high peaks of hydraulic pressure which occur on uneven ground.

Abstract: This valve comprises a tubular body (66) containing a hollow slide (68) mounted axially slidably in a sleeve (69), itself sliding in the body (66) along the axis (X--X) of the valve, a spring bearing on the body and pushing the slide (68) up against an annular end (73) of the sleeve (69), normally held by means of its opposite end (79) up against a cover (82) for closing the body (66) on the opposite side to its central orifice (67); the cover (82) and the sleeve (69) have radial ports (88, 81), the body (66) being contained in a tubular casing (34) having conduits (92, 96), fluid passages (89, 93, 94, 95, 40) also being provided to allow the valve to open in both directions as a result of the hydraulic pressure.

Abstract: The valve comprises a hollow body (36, 37, 40) provided with a first inlet or outlet opening (38) and a second outlet or inlet opening (41) for a hydraulic fluid, and the following elements:(a) a hollow slide (58) slidably mounted inside a hollow sleeve (56) slidably mounted in the body and coaxial with the slide (58);(b) an elastic element (61) bearing against the body (40) and biasing the slide into abutment against an annular end of the sleeve and the sleeve (56) into abutment against an annular seat (58) of the body;(c) and the annular bearing section (59) of the slide (58) on the sleeve (56) is less than the annular bearing section (57) of the sleeve on its seat (58), the sleeve being moreover provided with apertures (66) communicating with the first opening (38).This valve avoids deterioration of the suspension of a heavy vehicle travelling at high speed over uneven ground.

Abstract: A shock absorber having a hollow slide slidably mounted in a fixed member disposed in a sleeve inside the body, separated from the latter by an annular gap and having an opening which communicates with a conduit opening into an a hydraulic chamber. The fixed member is mounted with clearance in the sleeve and is provided with radial ports communicating with the interior of the slide which is biased against the fixed member by an elastic return member bearing on the body. The slide is arranged in such manner as to be capable of occupying alternately a first position, in which it closes any communication between the annular gap and the interior of the slide when the suspension element is subjected to a low frequency oscillation less than .sqroot.