Abstract: A powered wheelchair has at least two power-steered, driven wheels (15,16,17,18). Preferably, all of the wheels (15,16,17,18) are driven and power-steered such that the wheelchair turns about a point on a transverse axis (X) of the vehicle, and may preferably also pivot on the spot. This turning is preferably achieved by a rotatable steering assembly (1) having steering drive cams (3,4), steering return cams (5,6) and flexible transmission members (13,14).

Abstract: A valve actuator is disclosed which comprises only two housings, namely a first housing defining a single enclosure for a reversible electric motor, electrical control gear associated with the motor and torque control means and travel limit switch mechanism, and a second housing comprising a gear box containing reduction gearing.

Abstract: A valve actuator has an electric driving motor for driving an output shaft through reduction gearing and a manual operator for driving the output shaft manually. A drive transfer device for transferring the drive from the electric motor to the manual operating means incorporates an electric switch which is operated by the initial movement of a manual operator of the drive transfer device to cause the motor if rotating to be brought to a stop. Continued movement of the manual operator causes the drive transfer device to transfer the drive to the output shaft from the electric motor to the manual operator. The drive transfer device advantageously includes a clutch between the motor shaft and a worm shaft forming part of the reduction gear. The driven clutch member may form an integral part of a unit which is slidable as a sleeve along the worm shaft but is keyed for rotation to the worm shaft, the unit also having a pinion for meshing with a drive gear forming part of the hand drive.

Abstract: A valve actuator comprises a variable speed motor, a speed control circuit for controlling the motor speed including speed selector means by means of which the desired motor speed can be set to different values by adjustment means. A torque limit control circuit is arranged to stop said motor when a pre-set torque limit has been exceeded. The torque limit control includes a torque sensor arranged to provide a measure of torque from one or more torque-related electrical parameters of the motor for example a torque related current flowing in the motor, and adjustment means for setting torque limit control circuit to different torque limits.

Abstract: This invention relates to a motorized actuator in which the motor shaft is drivably connected with the output shaft through an intermediate shaft assembly.The motor shaft assembly includes a worm and wormwheel which is formed with cut-outs each drivably receiving the extended ends of some of the teeth of a pinion which forms part of the intermediate shaft assembly. The pinion is at all times in driving engagement with a gear on the output shaft and is axially movable by a lever to disengage the motor drive so as to allow independent manual operation of the pinion and thereby the output shaft by a handwheel mounted on a shaft. The shaft is drivably coupled with a wormwheel which is in driving engagement with the pinion by means of the driving lugs.

Abstract: A piston-cylinder type actuator is provided with a fail-safe unit for returning the piston 10 to a fail-safe position in the event of failure of the power supply to the cylinder 12. The fail-safe device comprises a housing unit 27 which is detachably connected to the casing 18 of the actuator. The housing contains a pre-loaded spring 30 acting between the closed end 29 of the housing and a movable cap member 31 which is engaged by the piston rod 17. The cap member is retained in the housing by a fixed ring 32 which is connected to a flange 38 of the actuator. Removal of the fail-safe unit is prevented unless the piston is in its fail-safe position by means of a bayonet-type fitting comprising lugs 35 on the housing which are axially and rotatably engaged with locking recesses on the remote surface of the adaptor flange 38.