Disclosed is an improved hydraulic control comprising a fail-to-neutral module. As is conventional, the hydraulic control comprises a main spool and a fluid flow path comprising a bridge circuit including a driver stage. The fail-to-neutral module comprises means defining a fail-to-neutral orifice which (a) is located in the fluid flow path upstream of the bridge circuit and (b) has a relatively large flow area but a maximum dimension smaller than the smallest orifice in the pilot stage. Preferably the means comprise a pin positioned through a hole, the pin and the hole both being circular in cross-section and coaxial, and the fail-to-neutral orifice is the clearance between the pin and the boundary of the hole.
A throttle element installed in a blind bore of a connecting conduit which delivers fluid to cool an electromagnet. The throttle element includes a filter region upstream of a throttle which throttles flow of the fluid from an annular groove to the blind bore that connects with the electromagnet.
A hydraulic control valve has a valve block provided with a plurality of ports, a valve body formed with ports corresponding to the ports of the valve block, and a plate disposed between the valve block and the valve body. The plate has a flow passage for providing communication between the ports of the valve block and the ports of the valve body. A filter is disposed in the flow passage.
An electro-hydraulic pressure regulating valve including a tubular valve body, a partition in the valve body dividing the latter into a valve chamber and a solenoid chamber, a valve sleeve in the valve chamber with a piston slidable in the sleeve and defining a bias pressure chamber between the piston and the partition and a control pressure chamber on the opposite side of the piston, closed center regulating ports on the piston and the valve sleeve for regulating a supply pressure to a control pressure in the control pressure chamber, a bias pressure orifice between a supply pressure port and the bias pressure chamber, a fluid strainer between the supply pressure port and the bias pressure orifice, a relief orifice in the partition between the bias pressure chamber and a fluid sump, and a solenoid operated valve normally closing the relief orifice and operative when energized to open the relief orifice. The valve is suited for miniaturization and regulates control pressure as a function of bias pressure without exhausting significant quantities of supply pressure directly to the sump.
A transducer which provides a regulated pneumatic output as a function of an electric control input includes a housing, a gas regulator, and a particle trap. The housing has a passage therein, the passage including an inlet for receiving a pressurized gas supply and an outlet. The particle trap is disposed in the passage and includes a trap plate and a trap nozzle which directs gas against the trap plate so as to remove undesired entrained particles from the gas before it reaches the gas regulator.
An air filter (10) is provided by a housing (12) having an air inlet (26) and an air outlet (28), a main filter element (30) in the housing, a plastic outlet tube (44) having a sidewall (60) with a pressure tap opening (62) therethrough, a metal fitting (68) in the pressure tap opening and affixed to the plastic outlet tube, for receiving a pressure sensor connector (70), and an auxiliary filter element (74, 90) in the pressure tap opening (62) and affixed to the plastic outlet tube (44) and unaffixed to the metal fitting (68) such that the auxiliary filter element (74, 90) remains in the pressure tap opening (62) if the metal fitting (68) becomes dislodged from the plastic outlet tube (44) and falls out of the pressure tap opening (62), such that the auxiliary filter element (74, 90) continues to protect the clean side (38) of the main filter element (30) and eliminates a possible contaminating bypass thereto through the pressure tap opening (62).
