Abstract: A system for controlling pressure of a fluid, specifically the pressure of servo oil delivered to a clutch which determines the torque transmitted by the clutch. The system includes a pump, a pressure regulating valve to provide servo oil at constant pressure from the pump, and a pilot valve controlled by a solenoid responsive to electric current to vary the pressure in a pilot fluid line supplied from the constant pressure line. The oil is delivered from the fixed pressure line to the clutch by a throttling flow control servo valve which can open for rapid filling of the clutch cylinder. This valve is biased to close by the delivered pressure and biased to open by the pilot pressure. It may also be biased to close by a spring, and in this case be restrained from completely closing, so that the valve assumes its minimum area when the delivered pressure is slightly less than the pilot pressure.

Abstract: A metering valve assembly for accurately controlling the flow of fluid independent of the pressure fluctuations at the input or at the output of the metering valve assembly. An electrical coil mounted on the assembly housing controls the position of an armature of an electromagnet in a permanent magnet field which, in conjunction with a nozzle assembly transmits pressure through suitable conduits to control a first slider valve. The displacement of the first slider valve controls the opening of a port area so that the flow through the port area is a function of the differential pressure developed across the port area with the output of the port directed through suitable conduit means to a second slider in the valve which is opposed to the upstream pressure of the metering valve.

Abstract: A combined load-sensing proportion and relay valve for an air brake system, comprising a valve disk having an exhaust hole in the axial center, and a control piston assembly for adjustably moving the valve disk to open the valve, characterized in that the control piston assembly consists of two pressure-sensitive pistons, the first of the pistons being formed with a downward projection having a valve seat at its lower end for face-to-face engagement with the valve seat, an indicated-pressure chamber communicated with an indicated-pressure inlet port is formed between the upper side of the first pressure-sensitive piston and the underside of the second piston, a control-pressure chamber communicated with a control-pressure inlet port is provided above the second pressure-sensitive piston, and engaging means is located between the first and second pistons.

Abstract: A two-stage fluid flow control valve system employing feedback such that the rate of flow of fluid through the load connections follows an input signal very closely over a wide dynamic range. The system employs poppet valves as flow sensors in the return line. The rate of flow of fluid through these sensors is a non-linear function of the pressure thereacross such that the change in pressure drop resulting from a given displacement from a set flow rate is greater at low ranges of flow than at high ranges. The result is closer control at low rates of flow where such control is normally more difficult to achieve.

Abstract: A pneumatic differential pressure sensor comprising a body with a hole which accommodates a pressed-in bushing, and a two-arm lever entering the body through the bushing so that one lever arm is inside the body and interacts with an element sensitive to the thermotechnical parameter while the other arm is outside the body. Secured to the bushing is a block carrying two clamps which serve as supporting elements for installing and fastening a zero corrector, a bellows and a nozzle-shutter element which interact with the other arm of the lever.

Abstract: In a force balance transmitter having a base structure provided with passages therein and a secondary assembly attached thereto that includes a pneumatically operated relay module detachably secured to the secondary assembly and having passages therein, the improvement of a fluid transfer member being disposed between the module and the base structure while interconnecting the passages of the base structure respectively to the passages of the module, the fluid transfer member being carried by the secondary assembly and having means floatingly interconnecting with the passages of the base structure to tend to isolate motion of at least that part of the base structure from the module.