Abstract: A manual override device for controlling at least one valve in a power system includes a rod having a first end and a second end. An attachment is configured to attach to a spool of the at least one valve and includes a clearance with respect to the first end of the rod so as to allow the attachment to move with the spool, during ordinary operation of the power system, without contacting the rod. A lever is connected to the second end of the rod and is configured to activate the manual override device by moving the rod in a longitudinal direction such that the first end of the rod makes contact with the attachment to move the spool.

Abstract: A control arrangement for use in a hydraulic control system including a control valve having at least two movable elements. The control arrangement is configured to control the positions of the two movable elements such that fluid from a common fluid pressure source is applied to both of the control surfaces of an actuator to drive the actuator. In an embodiment, the control surfaces have different effective areas.

Abstract: A control arrangement for use in a hydraulic control system including a control valve having at least two movable elements, such as spools or poppets, that is adapted to control a main flow through the control valve. The control arrangement further includes a control unit. In an embodiment the control arrangement is adapted to control the operation of the control valve in accordance with a first control scheme, monitor an operating parameter of the control system, and control the operation of the control valve in accordance with a second control scheme in the event that the value of the operating parameter falls outside of a predetermined range.

Abstract: A joystick actuator includes a fixed housing, a joystick member which is manually movable relative to the housing in at least one direction and which incorporates a light transmitter, a detection circuit within the housing incorporating at least two position sensing light detectors for receiving light of varying intensity from the light transmitter as the joystick member is moved in the at least one direction and a further light detector between the two position sensing light detectors. The actuator also includes parts in the detection circuit for making use of the output signal of the further light detector to linearize or substantially linearize the output signals of the position sensing light detectors. The detection circuit is arranged to provide an electrical output signal dependent on the light received by the light detectors and indicative of the position or rate of movement of the joystick member.