Abstract: A metering valve for a work machine hydraulic system is disclosed. The metering valve has an inlet and an outlet, a main poppet, and a solenoid-operated pilot element. The main poppet is movable to pass fluid from the inlet to the outlet, and to block fluid from the inlet to the outlet. The solenoid-operated pilot element is movable between a first position at which pressurized fluid from the inlet pressurizes a control chamber in communication with a control end of the main poppet to urge the main poppet toward the flow-blocking position, and a second position at which the control chamber is communicated with a drain to move the main poppet toward the flow-passing position. The metering valve also has a relief valve element configured to drain pressurized fluid from the control chamber to move the main poppet toward the flow-passing position in response to a pressure at the inlet exceeding a predetermined pressure.

Abstract: The present fluid cylinder includes a cylinder body having a cylindrical internal cavity therein with a longitudinal axis therethrough, the internal cavity being adapted for disposition of a piston and rod assembly for axial movement therein. The cylinder includes a member such as an end cap enclosing an axial end of the internal cavity, the member having a sensor port or passage therethrough extending between an internal opening communicating with the internal cavity and an external opening. A sensor is disposed in the internal opening of the sensor port or passage, and a sensor electronics module is disposed therein between the sensor and the external opening. The sensor is operable for sensing an axial distance of the piston or the rod from a predetermined location when disposed in the internal cavity and outputting signals representative of the distance to the sensor electronics module which includes circuitry for retrieving the signals.

Abstract: The present fluid cylinder includes a cylinder body having a cylindrical internal cavity therein with a longitudinal axis therethrough, the internal cavity being adapted for disposition of a piston and rod assembly for axial movement therein. The cylinder includes a member such as an end cap enclosing an axial end of the internal cavity, the member having a sensor port or passage therethrough extending between an internal opening communicating with the internal cavity and an external opening. A sensor is disposed in the internal opening of the sensor port or passage, and a sensor electronics module is disposed therein between the sensor and the external opening. The sensor is operable for sensing an axial distance of the piston or the rod from a predetermined location when disposed in the internal cavity and outputting signals representative of the distance to the sensor electronics module which includes circuitry for retrieving the signals.

Abstract: Improvement of the ability to detect selected resonant frequencies associated with the position of the piston in a piston position sensing system using electromagnetic waves in the fluid in a hydraulic cylinder is achieved by positioning the electric signal input and output probes with 90 degree separation around the circumferential periphery of the cylinder to suppress coupling into unwanted modes that diminish detectability of particular resonant frequency signals, In a coaxial sensing system "dummy" probes at 90 degree separation to each other and 90 degree separation to the input and output probes operate to improve symmetry and resonance shape and to suppress unwanted modes.

Abstract: A coaxial capacitor contacting and sealing structure, for electrical continuity between parts that move in relation to each other at the ends of a cavity within a hydraulic cylinder employing electromagnetic wave position sensing. The structure employs a contacting and sealing member having a high surface conductivity that is mounted in one of the parts. The mounting of the contacting and sealing member provides force for pressure contact in oil between the parts and to enhance electrical continuity with the part in which the contacting and sealing member is located.

Abstract: A contacting and sealing structure, for electrical continuity, noise reduction and leakage reduction between parts that move in relation to each other at the ends of the cavity within a hydraulic cylinder employing electromagnetic wave position sensing, is provided by employing two springs having garter and canted coil spring functions that are retained in side by side grooves in one of the parts so that the spring coils extend directly across the intersection of the parts.

Abstract: A drive system is provided for driving a rotatable seed drum of a seed planter which includes a fan for supplying air under pressure to the drum. The drum drive system includes an alternator which is mechanically driven, preferably from a drive for the planter fan, and which has output terminals connected to a motor mechanically connected to the seed drum. A ground speed signal generator is mechanically connected to a ground-engaging wheel to develop a signal which has an amplitude proportional to ground speed and which is applied through an adjustable resistance to a field winding of the alternator after passing through a control box. A drum speed signal generator arrangement is provided for developing a drum speed signal having an amplitude inversely proportional to the speed of rotation of the seed drum. This signal is also directed to the control box. Preferably, the signal generators include reluctance generator devices.

Abstract: A control system is provided for a hydraulically operated tractor hitch assembly including a rockshaft operated by a main cylinder which is controlled through a spool valve operated by a pilot cylinder which is controlled, in turn, through a solenoid operated pilot valve. The pilot valve is selectively controlled from first and second detector circuits through a gating circuit which is controlled by a third detector circuit which responds to a first error signal developed by comparing a command signal which corresponds to a rockshaft target position and a first feedback signal which corresponds to the actual rockshaft position and which is generated by a potentiometer connected to the rockshaft.