Abstract: Reversible hydraulic motors drdiven by fluid from variable displacement pumps are useful in driving various mechanisms of earthmoving machines. It is desirable to control both the speed and direction of the motor with a single lever. The subject hydraulic control system includes a selector valve which has a fluid control section for directing pilot fluid to a reversing valve to reverse the direction of the motor. A signal control valve is mechanically actuated by movement of the selector valve to the operating position so that a regulated pressure control signal is directed to a displacement control of variable displacement pump to regulate the volumetric output of the pump and thus the operating speed of the motor.

Abstract: Spin on disposable filters are useful in removing contaminates from the fluid of fluid systems. Preventing axial elongation of the filter due to fluid pressure therein requires the use of thicker elements, thereby increasing the manufacturing cost. The subject twist on disposable filter includes a twist-lock connector device which captures a portion of a housing between cooperating members of the twist-lock connector device. The area of imbalance caused by seal placement is greatly reduced by the twist-lock connector device, thereby minimizing the forces tending to cause axial elongation of the filter. This permits the use of less expensive materials therein and simplifies the manufacturing procedure.

Abstract: Resilient mounting apparatuses are useful for isolating the engine generated vibrations and noise from the frame. The mushroom style resilient mounting apparatuses are generally over designed and add to the cost without any additional benefits. The subject resilient mounting apparatus includes a rebound pad designed to provide high fatigue capacity yet low initial stiffness in a small space and to permit the use of simple manufacturing processes to make it. The primary support includes a skirt which cooperates with the rebound pad to keep foreign material from migrating into an annular space. Thus the subject resilient mounting apparatus meets the functional requirements while avoiding the manufacturing complexity or the extra cost of unneeded material.

Abstract: Impact rippers are useful for ripping solid rock. The service life of the impactor can be extended if the impactor is operated only when the ripper shank is loaded sufficient to transmit the impact energy into the material being ripped. The subject control system uses control signals generated by a plurality of signal generating means when the ripper shanks are loaded above a predetermined level to control the operation of the hydraulically actuated impactors associated with such ripper shanks. The number of control signals being generated is also used to control the volume of fluid made available for use by the impactors being operated at an given time to control the operating speed thereof. Thus, only the impactor(s) associated with a ripper shank(s) loaded above the predetermined level is operated thereby avoiding non-productive and harmful impactor operation if the ripper shank(s) is not sufficiently loaded.

Abstract: Fluid control circuits commonly control actuation of a pair of cylinders for positioning an earthmoving blade. The known circuits for providing the three operating modes of the cylinders utilize a separate control valve for each cylinder thereby making precise positioning of the blade difficult since such positioning requires coordinated control of both valves. The subject fluid control circuit includes a selector valve for determining the direction of fluid flow to and from the head end and rod ends of the tilt cylinders and a single control valve for modulating and controlling the fluid flow from the pump to the cylinders. With this circuit, the selector valve can be prepositioned in the desired position prior to actuating the control valve so that dual cylinder tip, dual cylinder tilt, and single cylinder tilt of the blade is readily controlled by manipulation of only the single control valve.

Abstract: Test benches are useful, for example, for testing the operation of new or repaired pumps and motors. Current test benches involve directly driving the test pump with an electric motor, the horsepower of which must at least equal the horsepower rating of the test pump. The subject test bench utilizes an electric motor to drive a variable displacement pressure compensated pump. The discharge fluid from the pump drives a variable displacement hydraulic motor which in turn drives the test pump. The discharge fluid from the test pump is also directed to the hydraulic motor to add additional driving energy thereto in a regenerative manner. Thus, pumps having a higher horsepower rating several times greater than the horsepower rating of the electric motor can be effectively tested at their maximum rated displacement and pressure settings. The electric motor also drives another variable displacement pressure compensated pump, the discharge flow of which is directed to a test motor.

Abstract: A pressure-compensated flow-control valve with an adjustable limiting device controls the maximum speed of a fluid motor and eliminates an additional valving element found in prior art device. The flow control valve includes a flow limiting throttle opening integral with the flow control spool. The spool can be selectively rotated to adjust the effective size of the throttle opening thereby limiting flow through the valve. The spool establishes a constant rate of flow determined by the throttle opening or a directional control valve. By incorporation of the flow limiting function within the flow control spool, the overall cost and complexity of the pressure compensated flow control valve is reduced.

Abstract: Backhoes are useful for digging trenches, ditches, etc. However, a performance deficiency caused by the formation of voids in the hydraulic control motor occurs sometimes if the swinging mass of the backhoe is abruptly stopped by quickly moving the directional control valve to the neutral position. The present invention provides a control circuit having a charging valve for communicating pressurized fluid from the supply conduit connected to the pump to charge the makeup valves with pump discharge fluid to minimize or avoid the formation of voids when the directional control valve is moved to the neutral position to stop the swinging movement of the backhoe mechanism.

Abstract: The steering system of some lightweight vehicles are electronically controlled and have a manually operated mechanical control as a backup. Such manual backup control would not be adequate for large earthmoving, construction and industrial type vehicles. The subject steering system includes an electrically controlled circuit actuated by rotation of a steering wheel for controlling a main pilot operated steering valve as the primary steering control. A hydraulic control circuit is also actuated by rotation of the steering wheel for controlling the same steering valve as a backup control when the electrically controlled circuit is not active. The hydraulic steering circuit is disabled when the electrically controlled circuit is activated. By using the same steering valve as an integral part of both circuits, the complexity and cost of the overall steering control system is reduced.

Abstract: A signal valve (38) is connected to a supply conduit (16) connecting a pump (11) with a control valve (14) for transmitting an artificial load signal to a load signal chamber (34) of a pressure compensated unloader valve (27) when the control valve is at an operating position and the pressure in the supply conduit (16) is below a preselected value. This moves a valve member (31) of the unloader valve (27) to a blocking position causing essentially full pump flow to be directed to the hydraulic jack for decreasing the response time in situations wherein the hydraulic jack has cavitated and no positive load pressure signal is present.

Abstract: Spin on disposable filters are useful in removing contaminants from the fluid of fluid systems. Preventing axial elongation of the filter due to fluid pressure therein requires the use of thicker elements, thereby increasing the manufacturing cost. The subject twist or disposable filter includes a twist-lock connector device which captures a portion of a housing between interconnected members of the twist-lock connector device. The twist-lock connector device is adapted for axial sealing engagement with a mounting device and minimizes the area of imbalance, thereby minimizing the forces tending to cause axial elongation of the filter. This permits the use of less expensive materials therein and simplifies the manufacturing procedure.

Abstract: A method of forming a windowed unitary panel having a peripheral edge portion of a windowpane of glazing integrally embedded within a frame of high modulus plastic material includes heating the pane to a preselected temperature prior to its being positioned within a mold. The peripheral edge portion of the windowpane protrudes into the mold cavity so that the high modulus plastic material forming the frame encapsulates the peripheral edge portion. This prevents buckling of the windowpane since the preheated windowpane contracts simultaneously with the contraction of the rigid frame as it cools from the molding temperature to ambient.

Abstract: Metering slots in valve spools are useful for modulatably controlling fluid flow through a control valve. The current metering slot configurations used in a meter out condition have high flow forces acting on the spool or metering areas that open or increase in size rather slowly relative to the valve spool movement. The subject metering slot is formed by plunging a ball-end end mill cutter into a control face of a valve spool at an acute angle and then moving the cutter laterally to provide the desired width of the metering slot. The resulting metering slot provides a metering area that increases in size rather quickly with a rather small increment of movement of the spool with the flow forces generated by the fluid passing through the metering slot being relatively low.

Abstract: Recoil spring mechanisms are useful, for example, in relieving excessive tension in the track of track-type vehicles. Because the idler wheels recoil in a one-to-one relationship against a recoil spring, the tension in the track still increases drastically from when recoil first starts to full recoil. The subject variable leverage recoil mechanism has the idler wheel mounting bracket and first and second links arranged such that equal increments of movement of the idler wheel from a normal operating position toward a recoiled position results in progressively decreasing increments of compression of the recoil spring. This results in the idler wheel having a progressively increasing mechanical advantage over the recoil spring when the idler wheel move toward a recoiled position.

Abstract: Electro-hydraulic valve arrangements are useful in controlling a displacement control member of a variable displacement pump or motor. However, previous digital electro-hydraulic valves having brief pulse widths required special high speed solenoids to speed up the response time of the valve and resulted in increased cost of the valve. The subject digital electro-hydraulic valve arrangement includes a pair of on/off solenoid actuated valves arranged in series so that a flow path is initiated by a first of the valves and is disrupted by the second valve. The response times of the valves are equal such that directing an electrical signal to the second valve during the response time of the first valve results in extremely brief pulse widths of the valve arrangement. Using two solenoid actuated valves in this manner permits the use of less costly solenoid valves to provide very brief pulse widths through the total valve arrangement.

Abstract: Hydraulic motors are conventionally employed in rotating the upper structure of excavators and the like. Protection from inertia induced hydraulic shock loads of some hydraulic control circuits involves the use of a separate bypass valve which continuously interconnects the motor conduits. The subject control circuit includes a pair of shunt valves each of which establishes restricted communication between the first and second motor conduits in a particular direction at their normal spring biased position. This allows limited free swing of the upper structure when the directional control valve is shifted from an operating position to the neutral position. However, shifting the directional control valve to an operating position causes the appropriate one of the shunt valves to shift to a blocking position so that no interconnection between the motor conduits exist.

Abstract: Hydrostatic transmissions are commonly employed in the drive train of earthmoving and industrial vehicles. It is difficult to stop some such vehicles at a precise location on a slope due to the presence of a delay valve included in the controls for delaying application of a friction brake until the vehicle has been stopped by the hydrostatic transmission. In the present control system, a manual control valve (74) is moved to a first operative position and a hand control lever (25) is manipulated in combination therewith to reduce the displacement of a variable displacement pump (12) to establish a minimum drive condition sufficient to hold the vehicle motionless. Thereafter the manual control valve (74) can be moved to a second operative position to apply a friction brake (18) while the transmission maintains the vehicle motionless.

Abstract: Fuel injection apparatuses are used to inject fuel into the combustion chambers of compression ignition engines. The known mechanical drive arrangements for driving the distributor rotor and controlling beginning moment of fuel injection are complex, bulky and expensive to manufacture. The subject timing control for fuel injection apparatus includes a planetary gear arrangement driven by a pumping section and drivingly connected to a distributor rotor. A ring gear controls the timing phase relationship between the rotor and a delivery passage communicating the pumping section with the rotor. A riser of a flyweight assembly is mechanically connected to the ring gear so that the ring gear is positioned in accordance with the engine speed. The planetary gear arrangement is of simple construction requiring a minimum of space and is relatively inexpensive to manufacture.

Abstract: A wheel assembly (10) having self-contained tire mounting and demounting capabilities includes a closed torus tire (18) mountable on a wheel rim (11). The tire (18) is forced onto the wheel rim (11) by a plurality of retainers (25) which are driven into a plurality of mating slots (13) in the wheel rim by bolts (31). Similarly, the tire is forced off of the rim by screwing the bolts through threaded apertures in the retainers and against the wheel rim. Thus, the tire can be demounted from the wheel rim and that tire or another tire can be mounted on the wheel rim without removing the wheel rim from the vehicle.