Abstract: A carbon-carbon composite material is made by providing an open-celled carbon foam preform, and densifying the preform with carbonaceous material. The open-celled carbon foam preform may be oxygen stabilized prior to carbonization, and the foam preform densified by CVD, HIP, PIC, VPI, pitch and resin injection, or any combination thereof. The carbon-carbon composite material can be heat treated to provide thermal management materials, structural materials, or a friction material for use in a brake or clutch mechanism.

Abstract: A pressuring valve having a housing with a bore therein for retaining concentric first and second pistons within a sleeve having an end wall with an entrance port connected to a first conduit. A spring within the bore urges a first face on the first piston toward a first seat which surrounds the entrance port and a second face on the second piston toward a second seat surrounding an annular opening in the first piston. The fluid pressure in the first conduit acts on the first face to overcome the spring and move the first piston away from the entrance port to allow fluid to flow to an exit port in the housing. This type flow continues until such time that the first piston fails to move when the fluid pressure thereafter acts on the second face to move the second piston and allow the fluid to flow to the exit by way of the annular opening and a plurality of axial opening in the first piston to maintain the fluid pressure in the first conduit substantially constant.

Abstract: The pressure differential release valve (130) comprises a three-part body having a first end member (132), an intermediate body member (133), and a second end member (134). The members (132, 133, 134) define an interior stepped bore (139) containing a differential area piston (141) and a poppet (161). The differential area piston (141) and poppet (161) have respective longitudinal through-openings (142, 162) and the poppet (161) engages a valve seat (168) of the body. The longitudinal through-opening (162) of the poppet (161) includes a ball valve (165) biased by a spring (166) into engagement with a valve seat (164) of the poppet (161). The piston (141) abuts the poppet (161) at an end (151) adjacent the valve seat (164) of the poppet (161). Fluid pressure received at an end (135) opening in the first end member (132) is transmitted through the body and exits an end opening (136) at the second end member (134).

Abstract: The power-assistance servo-motor (8) supported on a first end (9) of the master cylinder (1) incorporates a moveable wall structure (13) connected to a valve body (20), located at the other axial end of the master cylinder, by two rigid conduits (26, 27) which extend radially on the outside of the pistons (4, 5) of the master cylinder (1) and which respectively make the valve (18) communicate with each of the chambers (13, 16) of the servo-motor (8), the conduits (26, 27) passing so as to slide in a leak-proof manner through the continuous rear wall (12) of the servo-motor (8).