Abstract: A method of testing a steerable wheel assembly incorporating a shock absorber strut, comprising providing a combined linear and rotary actuator, engaging a lower end of the assembly with the actuator so that the line of linear action of the actuator is aligned with the line of compression of the strut, operating the actuator to compress the strut, and operating the actuator in a rotary sense to apply a steering torque to the assembly. A linear actuator is engageable with the assembly via a load coupling to load the strut. The load coupling comprising a first part on the actuator adapted to engage a second part on the assembly, the two parts being adapted to provide a self-aligning action as the actuator engages the assembly. Preferably, one of the two parts comprises a tapered recess formation, and the other two parts comprises a tapered projecting formation engageable in the tapered recess formation.

Abstract: A closed loop control system for controlling an actuator operating on a moveable member, includes a control device controlling operation of the actuator, a sensor responsive to a condition such as loading of the moveable member as it is moved by the actuator and adapted to generate a corresponding feedback control signal SL, and a damping device having a damping effect on the response of the actuator to the feedback control signal, the damping effect being varied in accordance with the movement of the moveable member so as to vary the response of the actuator. The damping effect is increased in the region of stationary states to render the system more stable, and reduced therebetween to make the system more responsive at increased speeds, and thereby more conformal to a required performance profile. The position or velocity of the moveable member can be used to control the damping effect, or a timer can be used to control the damping effect.

Abstract: A method of testing a steerable wheel assembly incorporating a shock absorber strut, comprising providing a combined linear and rotary actuator, engaging a lower end of the assembly with the actuator so that the line of linear action of the actuator is aligned with the line of compression of the strut, operating the actuator to compress the strut, and operating the actuator in a rotary sense to apply a steering torque to the assembly. A linear actuator is engageable with the assembly via a load coupling to load the strut. The load coupling comprising a first part on the actuator adapted to engage a second part on the assembly, the two parts being adapted to provide a self-aligning action as the actuator engages the assembly. Preferably, one of the two parts comprises a tapered recess formation, and the other two parts comprises a tapered projecting formation engageable in the tapered recess formation.

Abstract: A closed loop control system for controlling an actuator operating on a moveable member, includes a control device controlling operation of the actuator, a sensor responsive to a condition such as loading of the moveable member as it is moved by the actuator and adapted to generate a corresponding feedback control signal SL, and a damping device having a damping effect on the response of the actuator to the feedback control signal, the damping effect being varied in accordance with the movement of the moveable member so as to vary the response of the actuator. The damping effect is increased in the region of stationary states to render the system more stable, and reduced therebetween to make the system more responsive at increased speeds, and thereby more conformal to a required performance profile. The position or velocity of the moveable member can be used to control the damping effect, or a timer can be used to control the damping effect.