Abstract: A hydraulic circuit for a backhoe loader having two double-acting cylinders for the arm and bucket of the loader and respective directional valves for the cylinders. There are heavy demands on the oil pump of the system when the two cylinders are moved simultaneously from one extreme position to another which requires substantially two whole cylinder volumes of oil. The cylinders are arranged in parallel relative to the pump. A first source of pressure medium displaced from one cylinder is used to perform work in the other cylinder and the other cylinder is also supplied with a second source of pressure medium directly from a pump. The line section through which the first source of pressure medium is supplied is shunted to a tank by valving apparatus upon a predetermined pressure being reached to freely accommodate the simultaneous movements of the cylinders.

Abstract: The handwheel of a vehicle is connected to a handwheel shaft which in turn is connected through a load torque isolating device (overrunning clutch) that acts in either of the two directions of rotation and is connected to a steering shaft that controls a hydraulic arrangement. The hydraulic arrangement controls a steering motor that in turn controls the direction of turning of the vehicle. A second motor is drivingly connected to the overrunning clutch to rotate the steering shaft when the second motor is operated but when the steering is controlled by the handwheel, movement of the second motor is prevented. The second motor is operable from a location remote from the vehicle. The overrunning clutch includes a hub connected to the steering shaft and is movable by the handwheel shaft, the hub being wedgable against the clutch housing for being driven by the second motor by two jamming rollers that each acts in one direction of rotation and can be released by rotating the handwheel shaft.

Abstract: A control valve is opened (moved from its neutral position) by rotation of a steering wheel to conduct fluid from a pump to a steering meter device that controls the amount of fluid fed to a steering motor arrangement. When the steering motor piston has been displaced by a distance corresponding to the angle of rotation of the steering wheel, the control valve is moved by the steering meter device from its opened condition to its neutral position. A pilot valve controlled actuating device is provided to short circuit the steering meter device to permit continued fluid flow from the pump to the steering motor device and provide a mechanical braking force to the meter device to block rotation thereof and thereby the movement of the control valve to its neutral position. The braking mechanism is resiliently urged to a non-braking position.

Abstract: A DNA sequence containing a ribosome binding site with a SD sequence AGGA and a start codon ATG, comprising a nucleotide sequence having the formula Y.sub.1 . . . Y.sub.m ZVAGGA X.sub.1, X.sub.2 . . . X.sub.n ATG wherein Y.sub.1 . . . Y.sub.m represents a promoter with one or more restriction enzyme sites, m being an integer corresponding to the number of base pairs in the promoter, each X, Y, Z and V is A, T, C or G; n is 9 to 13, and the sequence X.sub.1 . . . X.sub.n cannot contain a start codon.

Abstract: There is provided control apparatus for controlling fluid flow between a bidirectional motor, a pump and a container, and includes a control valve that has a slide operative between neutral and first and second operative positions. A compensating valve is provided in the supply conduit that holds the upstream pressure drop at the control valve substantially constant and is controlled by load pressure sensing circuitry. The load pressure circuitry includes two branches that are connected through a change over valve to the compensating valve. There is provided an over pressure valve and a throttle point in each branch, each branch being connected to a load pressure sensing orifice of the control valve housing and fluidly connected through the slide to one of the housing motor orifices, the one depending upon whether the slide is in its first or in its second position.

Abstract: A hydraulic control valve and sensing mechanism for controlling flow between a motor and a pump and container that includes a slide mounted in a housing bore for movement between a neutral position and two operative position. The slide has a central collar separated from end collars by slide grooves, profilings on diametric opposite sides of the slide grooves intersecting each groove. The housing bore has a pump groove supplied with pressure medium, axially opposite motor grooves connectable to motor conduits, and axially opposite the motor grooves from the pump grooves there are container grooves connectable to the container. The pressure sensing mechanism includes at least one pressure sensing orifice that is connected to the pressure to be sensed in an operative position of the slide but not being fluidly connected thereto when the slide is in its neutral position.

Abstract: A damping arrangement for damping the oscillations of valves which are controlled by pressure fluid and the control pressure conduits of which contain a throttle. A characteristic is that initial oscillations can be rapidly stabilized independently of the operating temperature of the pressure fluid. This is accomplished by the throttle having a throttle gap of which the height varies oppositely to the temperature of the pressure fluid so as to compensate fully or partially for changes in the hydraulic resistance that are occasioned by the temperature. The throttle gap is mostly traversed by laminar flow and consequently there is a high hydraulic throttling resistance even at low speeds of flow. The throttle is therefore also adapted effectively to damp small oscillations of the valve element so that the initial oscillations are rapidly stabilized.

Abstract: The invention relates to a steering control unit for a bidirectional servomotor which is connectable to steerable wheels. A steering wheel controlled quantity setting unit of a known type has ports connectable to a pump and a return tank and two control ports through which metered quantities of fluid flow to opposite sides of the servomotor and to other parts of the apparatus for actuating the servomotor. A directional control valve for selectivity directing pressurized fluid from a power circuit to opposite sides of the servomotor is controlled by a control circuit containing the setting unit. A utility valve having pressure regulating and control and power valve capabilities is provided. In cases wherein the quantity setting apparatus is remotely located from the regulating valve the length of the signal channels add to the reaction time.

Abstract: The invention relates to a steering control unit for a bidirectional servomotor which is connectable to steerable wheels. A steering wheel controlled quantity setting unit of a known type has ports connectable to a pump and a return tank and two control ports through which metered quantities of fluid flow to opposite sides of the servomotor and to other parts of the apparatus for actuating the servomotor. A directional control valve for selectively directing pressurized fluid from a power circuit to opposite sides of the servomotor is controlled by a control circuit containing the setting unit. A utility valve having the pressure regulating and control and power valve capabilities required for this type of apparatus is characterized by having only a single slide spool for performing all of these functions.

Abstract: The invention relates to a steering control unit for a bidirectional servomotor which is connectable to steerable wheels. A steering wheel controlled quantity setting unit of a known type has ports connectable to a pump and a return tank and two control ports through which metered quantities of fluid flow to opposite sides of the servomotor and to other parts of the apparatus for actuating the servomotor. A directional control valve for selectivity directing pressurized fluid from a power circuit to opposite sides of the servomotor is controlled by a control circuit containing the setting unit. A utility valve having the pressure regulating and control and power valve capabilities required for this type of apparatus is characterized by having only a single slide spool for performing all of these functions.

Abstract: The invention relates to hydraulic control apparatus for a servomotor of the type utilized for vehicle steering systems. Such apparatus has a control circuit controlled by a manually operated device such as a steering wheel and a power circuit connected between the servomotor and a power source such as a hydraulic pump. The power circuit includes resetting apparatus for throttling the return flow branch in a manner so that forces applied to the servomotor in the same direction as actuation are absorbed with a minimum of reactionary movement by the valves on the return flow side of the apparatus.

Abstract: The invention relates to a hydraulic control unit for a servomotor of the type used for vehicle steering systems. The unit has a control circuit with a power operated pump and a hand operated metering motor and an operating circuit with a power operated pump. The two circuits intersect upstream from the servomotor. A pressure comparison, throttling and proportioning valve is disposed between the outlets of the two pumps of the control and operating circuits. The proportioning valve is controlled by a differential pressure applied by the pumps and a spring which supplements the operating pump pressure. In the normal operating mode the proportioning valve allows a minor fractional flow of the pressurized fluid generated by the control pump to flow through the valve to the operating circuit.

Abstract: The invention relates to a hydraulic control apparatus of the type used in vehicle steering systems. In all such systems there is a reversible type hydraulic motor connected to the steering linkage. The motor has complementary expansible chambers. With the use of control means pressurized fluid is selectively delivered to one chamber which is caused to expand concomitantly with the collapsing of the other chamber from which fluid is returned to a sump. There is provided in the control and power circuit throttle valves having respective opening positions which correspond to the pressure difference on both sides of the valves. Between the passages which extend to the two control circuit throttle valves is a pressure comparator which is operable to vary the pressure upstream of the power circuit throttle valve in proportion to the pressure upstream of the control circuit throttle valve.

Abstract: The invention relates to a hydraulic control apparatus of the type used in vehicle steering systems. In all such systems there is a reversible type hydraulic motor connected to the steering linkage. The motor has complementary expansible chambers. With the use of control means pressurized fluid is selectively delivered to one chamber which is caused to expand concomitantly with the collapsing of the other chamber from which fluid is returned to a sump. Forces transmitted to the hydraulic motor through the steering linkage by reason of the wheels striking objects such as stones or curbs cause an objectionable effect by reason of fluid being forced out of the motor back into the system. This effect is avoided by providing two valve assemblies for the two ports of the reversible motor which function in the absence of a steering command as ordinary one way check valves which prevent the undesired flow of fluid from either of the motor ports.

Abstract: The invention relates to a control valve assembly for a hydrostatic control system such as power steering assembly. A common control valve assembly of this type has relatively rotatable inner and outer elements connected respectively to a vehicle steering wheel and a servomotor. Paired holes in the inner and outer element permit the flow of fluid therethrough when the unit is in its neutral position with the paired holes in respective registration. In hydrostatic steering system of this type impact is sometimes applied to the steering wheel when the working motor connected to the steered wheels is suddenly loaded, e.g. when the wheels strike a stone. Such impacts on the steering wheel are avoided by providing a one-way valve in a section of the working path through which fluid flows to the working motor. Pressure regulating valve means, excess pressure valve means and emergency control valve means are associated with the one-way valve assembly.