| 摘要 |
An actuating system is described for a phase change mechanism wherein the phase change mechanism comprises a rotatable phase change assembly and an actuator which rotates at the same speed as the assembly when the phase between a drive and a driven member is to be maintained constant and which is required to rotate relative to the phase change assembly to bring about a change in phase. The actuating system comprises reaction members 50, 52 coupled to the actuator 26 and braking means 54, 56 associated with the reaction members 50, 52. The reaction member when not braked is free to rotate with the phase change mechanism, but when braked each serves to vary the speed of the actuator 26 relative to speed of the phase change mechanism in a different sense. |
