Abstract: An air motor includes ceramic valves and valve plates to enhance performance and efficiency of the air motor.

Abstract: An air motor for a pump assembly including a drop tube communicating between an upper chamber port and a top plate port and including a longitudinal axis that is at an angle of between about 0° and 10° with respect to each of the upper chamber longitudinal axis and the top plate port longitudinal axis. The drop tube has a substantially constant internal diameter, a first generally bulbous end, a second generally bulbous end, and first and second slots defined in the respective first and second bulbous ends. First and second seals are positioned in the respective first and second slots, and the first and second seals air-tightly seal an outer surface of the drop tube within the upper chamber port and the top plate port.

Abstract: A pump assembly including an air motor includes a modular relief valve assembly connected to a motive fluid inlet of the air motor. The modular relief valve assembly has a housing that contains an actuator assembly, a ball valve assembly, a bleed valve, a first pressure adjustment assembly, and a second adjustment assembly. The housing includes a motive fluid inlet port, a pressure regulator outlet, a bleed valve port, an actuator support, a pressure adjustment chamber, and a ball valve chamber. The pressure regulator assembly includes at least one gauge that displays at least one measurement parameter.

Abstract: A first fluid channel for operating an actuator and a second fluid channel for operating an actuator are connected to a boom cylinder, including a boom rod side line, a boom head side line. A first and second supply line and a first and second discharge line of each of the first and second fluid channels, respectively, are connected to first and second meter-in control valve and first and second meter-out control valves, respectively. When the boom operating lever is returned an operating position to a neutral position, a pressure vibration generated in each fluid channel for operating the actuators is detected, and respective meter-in control valves and meter-out control valves are controlled to dampen the pressure vibration in each fluid channel.

Abstract: A hydraulic tilting device for tilting the cab of a vehicle between a driving position, in which the vehicle can be driven normally, and a tilted position, in which, for example, maintenance can be carried out on a vehicle engine positioned beneath the cab. The tilting device comprises a double-acting tilting cylinder having a first and a second connection, a reservoir for hydraulic fluid and a pump having a single pumping direction, which pump has a suction port which is in communication with the reservoir and a single delivery port for delivering pressurized hydraulic fluid. The tilting device has a valve, in inlet passage of which is connected to there delivery port of the pump, which valve has an actuable shut-off member, so that in a first position thereof the delivery port is connected to the first connection of the tilting cylinder and in the second position thereof the delivery port is connected to the second connection of the tilting cylinder.

Abstract: A swing cushion system of a work machine includes a directional flow device having a directional control member, a control device coupled to the directional flow device that outputs a signal to the directional flow device to shift the directional control member to dissipate energy in the fluid.

Abstract: A method that uses a dither signal for reducing hysteresis effect in a variable cam timing system is provided. The method includes the steps of: a) providing a dither signal having at least two switchable frequencies; b) determining the frequency characteristics of an engine speed; c) determining at least one frequency beating point in relation to a neighborhood of an engine crank RPM values; and d) changing the dither signal frequency when the engine is operating within the neighborhood of the engine crank RPM values. Thereby frequency beating effect is reduced.

Abstract: A fluid unit, for example a piston/cylinder unit, is supplied with fluid via a cyclically opened or closed on/off valve. The vacuum peaks occurring on the outlet side of the on/off valve when it is closed and the inertia forces of the flowing fluid are used to supply additional fluid to the fluid unit via a non-return valve leading from a low-pressure connection or reservoir to the fluid unit.

Abstract: In a pressure control valve, a filter member is disposed in a feedback path for feeding back fluid pressure in the corresponding control port to a pilot chamber for feedback controlling a position of the valve spool in cooperation with an electric or electromagnetic actuator. The filter member is so arranged as to remove foreign matter. The filter member also serves for regulating fluid flow in the feedback path.

Abstract: A solenoid operated control valve in an automatic transmission is operated by dither current. A flow rate of oil through the solenoid operated control valve is calculated. At least either one of the frequency and amplitude of the dither current is corrected by the flow rate. The solenoid operated control valve is operated by the dither current.

Abstract: A hydraulic circuit for controlling the deck swiveling speed of a working vehicle comprises a hydraulic actuator for driving the swivel deck, a flow control valve for controlling a rate of oil flow to the hydraulic actuator, and a direction control valve for switching an operating direction of the hydraulic actuator. The flow control and direction control valves are operatively connected to a swivel control lever. The greater amount of swivel control lever is operated toward a right or left swivel position, to the greater extent the flow control valve is shifted in a flow increasing direction. The direction control valve is operable to switch oil lines in response to an operation of the swivel control lever.

Abstract: A duty ratio for operating a solenoid is determined by calculating a duty ratio in each of basic periods and determining an operational time for which the solenoid is to be operated within each of the basic periods, based on the calculated duty ratio. When the duty ratio is reduced to the extent that the operational time is shorter than a minimum possible time of operation of the solenoid, an operational time for which the solenoid is to be operated is determined within a new period composed of a plurality of consecutive basic periods.

Abstract: A hydraulic control method which includes a step of changing the time rate of introduction per a predetermined unit time of pressurized oil into an oil passage connected to a hydraulically-operated load device, such as a clutch of an automatic transmission, from a first time rate to a second time rate, thereby changing the time-based average oil pressure inside the oil passage from a first oil pressure value to a second oil pressure value. The time rate of introduction of the pressurized oil into the oil passage is changed from the first time rate to the second time rate via a third pressurized oil introduction time rate corresponding to a third oil pressure value different from the first and second oil pressure values. If the second oil pressure value is greater than the first oil pressure value, the third pressurized oil introduction time rate is substantially 100%. If the second pressure value is smaller than the first, the third time rate is substantially 0%.

Abstract: A solenoid valve used as an expansion valve in a refrigeration circuit has an opening that varies as a function of the pulse width of a high frequency PWM (pulse width modulated) control signal. A transistor controls the electrical current delivered to the solenoid valve. The PWM control signal rapidly cycles the transistor on and off at a constant frequency that is sufficiently high to prevent the valve from having enough time within a cycle to move between fully open and closed. As a result, the valve balances at an intermediate position determined by the relative lengths of the on and off periods of each pulse cycle. The relative on-off pulse widths, often referred to as, "duty cycle", is varied in response to a temperature sensor to control the flow of refrigerant through the refrigeration circuit. The duty cycle is also adjusted to compensate for any variations in the supploy voltage applied across the solenoid valve.

Abstract: A digitally controlled air-over-hydraulic actuator includes a pneumatic cylinder and a hydraulic cylinder each having a separate piston and a common connecting rod. The pneumatic piston applies force to the connecting rod urging movement of the hydraulic piston. Bleeding of oil from one side of the hydraulic piston to the other is controlled by means of digital pulses applied to a digital valve that allows oil on either side of the hydraulic piston to flow to the other. The digital valve includes a moving piston having an oil passage that is momentarily aligned with ports to opposite sides of the hydraulic cylinder. A control system senses the differential pressure between opposite sides of the pneumatic piston to produce pulses that accelerate the digital valve piston past the ports, precisely controlling forced movement of the hydraulic piston.

Abstract: A control for a press for controlling the flow of fluid to two hydraulic actuators which applies a desired working force to or which positions the press platen in a desired position including a sub-control for introducing first and second super-imposed oscillations on the fluid of the actuators of equal amplitude and opposite phase to reduce internal friction in the actuators without disturbing the desired applied force or position of the platen.

Abstract: A sensing system for a vibration isolation table. A sensor responsive to the position of the tabletop is spaced apart from the tabletop and provides an output corresponding to the position of the tabletop. The output is modified to provide a control signal and a valve responsive to the modified signal controls the flow of air into and out of an air isolator which supports the load.

Abstract: A pressure regulating spool valve 10 having a body 25 within which a spool 20 is moved in a dither motion by a proportional solenoid 15 has a spool land 40 separating high and low pressure fluids and spanning and cooperating with a regulated port recess 51 in body 25 for variably opening high and low pressure windows 54 and 55. With opposite edges 52 and 53 of recess 51 spaced apart by a distance X, the opposite edges 42 and 43 of spool land 40 spaced apart by a distance Y, and the dither motion imposed on spool 20 by solenoid 15 having an axial excursion A, the relationship X.ltoreq.Y.ltoreq.(X+A) applies. This makes the alternating overlap of spool land 40 with recess edges 52 and 53 equal to or less than the dither excursion so that high and low pressure windows 54 and 55 of the regulated port 50 are opened for a predetermined portion of each half cycle of the dither motion.

Abstract: A sequencing valve mechanism utilized to control a pneumatic or hydraulic pressure medium from an on/off type pressure source to a two-chambered pneumatic or hydraulic appliance is disclosed. A pawl on a ratchet arm is driven around a ratchet island by the alternate application and withdrawal of pressure to the sequencing device. The ratchet arm is pivotally attached to a valve control arm which regulates a valve so as to control the output of a pressure source. The shapes of the ratchet island portions are such that two alternate applications and withdrawals of pressure are required for the pawl to complete one cycle about the island and, thereby, actuate the valve to different output positions only on alternate applications of pressure to the sequencing device.

Abstract: A steam turbine control system which includes a manual panel with pushbuttons for operator control of the steam admission valves. Each valve has its own control means and is responsive to pushbutton activation to govern its valve movement. If a pushbutton indicating valve opening or closing gets stuck, the operator pushes a pushbutton indicating opposite movement and the control means switches to a special control mode after a predetermined period of time. In the special mode valve movement stops after removal of the operator's finger pressure and valve movement is accomplished by activation of predetermined pairs of pushbuttons.

Abstract: Hydraulically operated turbine steam admission valves wherein each valve has its own microcomputer control. In the event the valve gets stuck due to possible contamination in the hydraulic system, the microcomputer control provides an oscillatory control signal to dither the valve. If the valve remains stuck after dithering action it is provided with a control signal of an initial magnitude greater than that normally required to close the valve.

Abstract: A pneumatic control system for machines that provides precise incremental or continuous direction, position, velocity and acceleration control of a variety of machine functions, such as rotary or linear motions, tool positioning and the like. A compressed air supply is maintained accurately at a preselected minimum pressure necessary for a particular operation, by a digitally pulsed air flow control system. Air flow and pressure to the associated actuating mechanisms is also controlled by a digital dithering technique using individual sharp pulses of air, each of which instantly breaks the static friction of the mechanism and causes a discrete precise increment of movement, with rapid consecutive pulses providing continuous motion. The direction, amount, acceleration and speed of travel are controlled by varying the pulse width and rate of air flow and pressure as necessary and for efficiency in air consumption.

Abstract: A method and device for controlling the fork of a synchromesh for a gear box. A command signal sent by the operator is converted into signals by a modulator whose output controls an electric valve to open and close several times in succession. The electric valve controls a jack which in turn controls the fork connected to a sliding gear associated with the synchromesh, whereby the instantaneous pressure of the fluid supplied to the jack is varied during the steps of approach, synchronization, and locking of the synchromesh.

Abstract: A hydraulic control system for the rolling rack of a three table bale wagon wherein the rolling rack is movable along the third table for supporting tiers of bales deposited on the third table by the second table, the control system including a single acting hydraulic cylinder for positively advancing the rolling rack to a first position wherein the third table is ready to receive tiers of bales, apparatus for selectively connecting the hydraulic cylinder with a source of hydraulic fluid under pressure for extending the hydraulic cylinder and thereby moving the rolling rack to the first position, and including a fluid flow line; selective apparatus connected with the fluid flow line for intermittent release of fluid pressure from the fluid flow line so that when mechanical pressure is exerted against the hydraulic cylinder in such a manner as to urge retraction of the cylinder, the retraction may be controlled by intermittent release of pressure from the fluid flow line.

Abstract: The invention relates to an actuator device for a motor vehicle speed-responsive system, the device being operable to actuate the throttle valve or the like of the internal combustion engine of the vehicle. The actuator device comprises a bellows device defining a first chamber partly bounded by a movable wall and a fixed wall, and communicating with two further chambers defined by associated housings carried by the said fixed wall. One of the further chambers contains a first electro-magnetic control valve fed by a D.C. voltage, and operable to control an orifice through which the first chamber communicates with atmosphere. The other of the further chambers contains a second electro-magnetic control valve fed both by said D.C. voltage and by a pulsed voltage, and operable to control both an orifice through which the first chamber communicates with atmosphere and an orifice through which the first chamber communicates with a source of gas at sub-atmospheric pressure.

Abstract: The pulsator for hydraulic systems controlling actuating mechanisms has a housing accommodating a pusher made in the form of a piston with a rod, a delivery valve, a pneumatic piston displacing in the cavity connected to the pneumatic control system. Above the pusher piston there is an upper cavity communicating with a high-pressure main, and under the piston there is a lower cavity communicating with the actuating mechanism via a non-return valve. A stem is provided between the rod and the piston. Also made above the pusher piston is an auxiliary cavity which is an extension of the upper cavity, defined by a leading edge and connected to the actuating mechanism. Above the lower cavity of the pusher piston there is an annular cavity disposed coaxially with said cavity, separated from said cavity by the leading edge, connected to the valve controlling resetting of the pusher.

Abstract: A demand compensated hydraulic system includes a pump responsive to a pressurized fluid in a demand feedback pilot line. The pilot line is connected to sense fluid demand between a hydraulic motor and an associated control valve which is closed by servo feedback from the motor. A dither is connected to the pilot line to continuously oscillate the pressurized fluid in the pilot line to prevent the occurrence of a situation wherein the flow across the control valve is sufficient to prevent the pump from going to a stand-by condition while being insufficient to operate the motor to close the valve to thereby cause the pump to go into the standby condition.

Abstract: A demand compensated hydraulic system includes a pump responsive to a pressurized fluid in a demand feedback pilot line. The pilot line is connected to sense fluid demand between a hydraulic motor and an associated control valve which is closed by servo feedback from the motor. A dither is connected to the pilot line to continuously oscillate the pressurized fluid in the pilot line to prevent the occurrence of a situation wherein the flow across the control valve is sufficient to prevent the pump from going to a stand-by condition while being insufficient to operate the motor to close the valve to thereby cause the pump to go into the standby condition.

Abstract: A control system for controlling a double-acting cylinder includes four pilot-operated, proportional-type poppet valves for controlling fluid flow between the cylinder, a pump and a reservoir. Four solenoid-controlled pilot valves operate the poppet valves in response to error signals generated by a control circuit. The control circuit receives a cylinder position feedback signal and an operator-generated command signal. The control circuit provides for float, shutdown, variable deadband and pressure adjustment operation.