| 摘要 |
<p>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.</p> |
