Abstract: Electro-pneumatic positioner with a pneumatically driven dual-chamber actuator having a pneumatic main air intake valve and a pneumatic main air discharge valve attached to a pressure pipe of the actuator. The positioner may also include a further main air intake valve and a further main air discharge valve attached to a further pressure pipe of the actuator. Each main valve has an actuating element, with the actuating element for the one and the further main air intake valves each being formed by a corresponding main valve. To manufacture an electro-pneumatic positioner of this type comparatively economically, the actuating element of the one main air discharge valve is formed by a feed pipe which connects the pressurized side of the one main air discharge valve to the interior of the reversing valve of the further main air intake valve.

Abstract: An assembly for reversing a fluid driven motor. The assembly includes a fluid driven motor, and a reversing valve that reverses inlet and exhaust porting to and from the fluid driven motor. An actuation device opens an actuation valve and a fluid supply valve. The actuation valve causes the reversing valve to reverse the inlet and exhaust porting to and from the fluid driven motor when the actuation device opens the actuation valve. The fluid supply valve allows fluid to flow through the fluid supply valve to the motor when the actuation device opens the fluid supply valve. The fluid supply valve also prevents fluid flow through the fluid supply valve to the fluid driven motor when the fluid supply valve is closed.

Abstract: A steer-by-driving control for controlling a hydrostatic steering unit to permit consistent operator input during forward and reverse travel has a valve assembly including a distribution valve and a pair of sleeve valves. The sleeve valves are rotatably mounted on the distribution valve and are interconnected by a gear arrangement. One sleeve valve is rotated by the operator in response to a steer request while the other sleeve member, due to the gearing, rotates oppositely. The distribution valve member controls fluid flow through forward and reverse steer passages formed in the sleeve valves to a signal valve for distribution to a control member of a hydrostatic unit. The distribution valve member is subjected to rotary input from the hydrostatic steering unit to stop fluid flow when the proper steer position has been reached. The signal valve is positioned according to the direction of the vehicle operation to selectively send the steer signals to the proper portions of the hydrostatic control.

Abstract: Disclosed is a representative agricultural implement towed by a tractor equipped by a hydraulic power source connected to a lift mechanism for raising and lowering the implement frame so as to vary the ground-working depth of the working tools. The frame carries a sensor responsive to changes in implement depth above and below a preselected norm. This sensor serves as the input for the inventive control valve and system so as to control the implement lift system automatically. The valve is designed as a four-position valve, with one of the positions serving dual modes so that the system produces fast and slow raising, fast and slow lowering and a neutral or balanced position. The valve has a pressure port connected to the pressure side of the tractor source via a manual valve to afford three of the four active positions with one setting of the manual valve. The fourth active position (fast raise) is achieved by changing the manual valve to reverse the pressure and return ports in the depth control valve.

Abstract: A fail-safe fluid control valve including a first sleeve accommodated in and fixed to a valve housing, a second valve also accommodated in and fixed to the valve housing in parallel relation with the first sleeve, a first valve spool slidably accommodated in the first sleeve, and a second valve spool slidably accommodated in the second sleeve. The first and second sleeves are properly formed with grooves and ports while the first and second valve spools are properly formed with large diameter portions spaced. When there occurs such an abnormal condition that the first valve spool and the first sleeve are jammed or stuck to each other, the second valve spool is adapted to be moved for actuating the fail-safe control valve under entirely the same condition as a normal condition.