Abstract: An adjusting element with a closed first end, a cylinder, a piston displaceably arranged in the cylinder that divides the cylinder into a first work space remote of the first end and a second work space in proximity to the first end, and a piston rod which is arranged at one side of the piston and which projects through the first work space and is guided out of the cylinder concentric to or center longitudinal axis of the cylinder at a second end opposite from the first end so as to be sealed by a guiding and sealing device. The adjusting element has a device for detecting the piston rod position and/or the extended length of the adjusting element. The device for detecting the piston rod position includes a microswitch arranged at the cylinder and at least one switching element cooperating with the microswitch.

Abstract: A method of calibrating an electrically actuated hydraulic valve in a system that controls the flow of hydraulic fluid to a hydraulic cylinder connected to a machine element operates automatically. The system includes an ultrasonic sensor providing an indication of the position of the machine element. The calibration method includes the step of automatically applying a command signal to the hydraulic valve while monitoring the ultrasonic sensor to determine the level of the command signal required to cause the hydraulic cylinder to begin to move. The calibration method includes the additional step of automatically applying in succession a plurality of command signals of increasing level to the hydraulic valve while monitoring the ultrasonic sensor to determine the speed of movement of the hydraulic cylinder resulting from each of the command signals.

Abstract: Provided is a servovalve system for regulating fluid flowing within a fluid circuit. The servovalve system comprises a housing, a spool slidably disposed within the housing, a stepper motor operatively connected to the spool, and a controller and a position sensor electronically connected to the stepper motor. The controller generates driver signals representative of a desired amount of stepper motor rotation in order to cause the stepper motor to effectuate spool motion relative to the housing. The position sensor senses an actual amount of stepper motor rotation and generates a quantity of position signals representative thereof. The controller determines a signal ratio of the quantity of the position signals to the quantity of the driver signals and generates a diagnostic signal when the signal ratio reaches a threshold value representative of a predetermined level of mechanical resistance of spool motion relative to the housing.

Abstract: An electro-hydraulic servomotor includes: an electric motor (41) which rotates a drive shaft (51) in response to an inputted signal; a hydraulic motor (60) which rotates an output shaft (61) using hydraulic pressure of operation oil; a first geared shaft (53) rotatable along with the output shaft (61); a second geared shaft (52) threadingly engaged with the drive shaft (51) and meshed with the first geared shaft (53); and a spool (71) axially movable along with the second geared shaft (52) depending on a rotational difference between the drive shaft (51) and the first geared shaft (53), to control supply and discharge of the operation oil to and from the hydraulic motor. (60).

Abstract: A fluid operated machine is monitored and regulated by providing a logic with a memory for storing the timings of properly operating functions, and detectors the outputs of which are used to calculate the actual operating timings of the functions. The actual operating timings are compared to the timings in the memory, and if they deviate beyond acceptable tolerances a warning signal is given. In addition to monitoring the timings, the device will also open or close control flow valves to bring the operating speeds of functions within acceptable tolerances.

Abstract: An apparatus for compressing a workpiece is disclosed. The apparatus has a die to receive the workpiece in powdered or other form. An abutment holds the workpiece in a fixed position against the application of force, while a hydraulic cylinder is positioned to exert force against the die in the direction toward the abutment. A pump feeds hydraulic fluid to the hydraulic cylinder, and a pressure control valve is coupled to the hydraulic cylinder to control the maximum pressure in the hydraulic cylinder. The pressure control valve has a sealing member, a seat which engages the sealing member with the sealing member closing the outlet, a spring which urges the sealing member towards the seat, closing the outlet, and a backing member putting the spring under compression by maintaining a distance between the backing member and the seat. A stepping motor is rigidly mounted with respect to the seat.

Abstract: An apparatus for compressing a workpiece is disclosed. The apparatus has a die to receive the workpiece in powdered or other form. An abutment holds the workpiece in a fixed position against the application of force, while a hydraulic cylinder is positioned to exert force against the die in the direction toward the abutment. A pump feeds hydraulic fluid to the hydraulic cylinder, and a pressure control valve is coupled to the hydraulic cylinder to control the maximum pressure in the hydraulic cylinder. The pressure control valve has a sealing member, a seat which engages the sealing member with the sealing member closing the outlet, a spring which urges the sealing member towards the seat, closing the outlet, and a backing member putting the spring under compression by maintaining a distance between the backing member and the seat. A stepping motor is rigidly mounted with respect to the seat.

Abstract: An electrohydraulic servo system in which a microprocessor-based controller directs a pulse width modulated control signal to a servo valve for controlling flow of hydraulic fluid therethrough. Duration of each half-cycle in the pulse width modulated control signal is separately controlled by selectively incrementing or decrementing duration of the half-cycle in increments of the microprocessor clock period. Signal transition is controlled by a timer interrupt in which time required to enter the interrupt routine is measured following generation of the interrupt, and further operation is delayed by a complementary time, so that control signal transition takes place a fixed preselected number of clock periods after generation of a timer interrupt. In this way, timer interrupt latency is eliminated, and resolution of the pulse width modulated signal is enhanced through individual duration control of the signal half-cycles while maintaining a fixed modulated signal period.

Abstract: A novel digital servo valve system for use in displacing an actuator is capable of operating either in closed or open loop mode. The system includes a controller that compares computed values of actuator parameters with preselected parameter values and iteratively determines therefrom command signals for the servo valve. The servo valve is characterized by a ball screw mechanism that eliminates mechanical backlash and a torsion bar which increases radial and angular compliance. A servo valve provided according to the present invention also displays reduced flow forces using a simple, inexpensive valve body in combination with a uniquely configured displaceable spool.

Abstract: An electrohydraulic control system that includes a plurality of electrohydraulic devices coupled to a remote master controller by a high-speed serial communication bus. The bus has a serial differential transmission line, and a control line for indicating impending transmission of data from one controller and conditioning the other controllers to receive information. Sections of the communication bus are electrically isolated from each other, while maintaining data and control line signal integrity therebetween, by electro-optical interface modules that include transmitters and receivers interconnected by lengths of fiber optic line, and interface drivers having signal ports respectively interconnecting the fiber optic transmitters and receivers to associated sections of the communication bus.

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 fluidic power-assisted setting device has a setting motor having an output torque; a threaded spindle supported for rotation; a spindle nut threadedly mounted on the spindle for linear displacement; a setting member attached to the spindle nut for linear travel therewith; a gearing for transmitting the output torque of the setting motor to the spindle; a signalling device coupled to the gearing for generating an output signal when the linear force derived from the output torque of the setting motor is insufficient to overcome an external force opposing linear displacement of the setting member; and a fluidic power device including a hydraulic motor connected to the setting member for applying thereto a linear force to overcome the external force; and a hydraulic control valve hydraulically connecting the hydraulic motor with pressurized hydraulic fluid as a function of the output signal of the signalling device for causing the hydraulic motor to generate a force applied to the setting member for overcoming

Abstract: A universal control system for hydraulic cylinders to enable controlled increments of movement for varying uses including shaping members and lifting and lowering of loads. The lift control system is utilized to synchronize the raising or lowering of a load by, for example, four simultaneously-acting pump-operated hydraulic rams which have plural increments of movement. A sensor associated with the load adjacent each ram measures incremental movement of the load. A master controller controls the operation of the rams in accordance with the sensed increments and operates each pump simultaneously and independently until each pump achieves a preselected increment of movement of a ram, to maintain the load substantially level, followed by movement of all the rams through another increment of movement until the total lifting or lowering movement is achieved.

Abstract: A servomechnism made up of a relatively small number of components has a pintle that is moved back and forth by a hydraulic actuator, an input member disposed opposite to the pintle and capable of reciprocating parallel with the pintle, a spool capable of reciprocating parallel to both the input member and the pintle, a pair of idle gears pivoted to the spool, and a hydraulic circuit. The input member has a rack opposite to a rack formed on the pintle. The spool is mounted between these racks. The idle gears are in mesh with the racks. When the input member is moved to shift the spool out of its neutral position, the actuator is unlocked to return the spool to its neutral position.

Abstract: A fluid motor having a gerotor gear set includes a first member having internal teeth and a second member having external teeth. The second member is rotatably and orbitally mounted within the first member. The teeth of the first and second members cooperate to define a plurality of variable volume working chambers. Some of said working chambers expand and other of said working chambers contract upon relative rotatable and orbital movement between said first and second members. A plurality of electrically controlled valves are provided, each working chamber having an associated valve. Each valve selectively communicates, in one condition, its associated working chamber with an inlet passage, which is, in turn, connected to a source or pressurized fluid, or, in a second condition, its associated working chamber to an outlet passage, which is, in turn, connected to a reservoir. Each of the valves is responsive to a respective electrical control signal for placing the valve in the first or second condition.

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: An electrohydraulic system includes a plurality of electrohydraulic devices individually controlled by on-board microprocessor-based control electronics. Each individual device controller is connected to and addressable by a master controller for coordinating operation of the various devices. An electrohydraulic servo valve assembly includes a hydraulic manifold having a valve spool variably positionable therein under control of a torque motor. A microprocessor-based controller is connected to the torque motor and is mounted on the manifold by a cover which encloses and protects both the controller and the torque motor. A watchdog timer in the microprocessor-based controller monitors pulsewidth modulated signals to the torque motor for terminating operation in the event of signal loss. In a preferred embodiment of the invention, the servo valve assembly is coupled to a linear actuator which has its position monitored by an electroacoustic transducer.

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: An electric hydraulic control device for controlling hydraulic cylinders of work tools in a construction vehicle, in which control valves of the hydraulic cylinders are controlled in two ways. For some work tools which need not be controlled smoothly and finely, the corresponding control valves are controlled directly by an electric signal outputted according to the position of the operation levers, and for other work tools which must be controlled smoothly and finely, the corresponding control valves are controlled through an electric servo mechanism which is operated by an electric signal representative of the amount by which the operation lever is manipulated. In addition, there is provided a detector for detecting as to whether the transmission lever is in the locked condition, and electric systems of all of the control valves are rendered inoperative when the transmission lever is in the locked condition.

Abstract: Primary switches in bus cab, for instance, activate contacts in secondary switch group in rear transmission compartment to energize solenoids selectively pressurizing opposed cylinders to drive transmission shift operation to various positions.