Abstract: An apparatus for controlling a primary actuator comprises a primary moveable link connected to the primary actuator, a secondary actuator, and a secondary moveable link connected to the secondary actuator. The secondary moveable link is engageable and disengageable with the primary moveable link and the primary and secondary links are guided for movement along a predefined path. The user of the apparatus is able to control the engagement and disengagement of the primary and secondary links such that movement of the secondary actuator is transferred to the primary actuator when the links are engaged and such that movement of the secondary actuator is not transferred to the primary actuator when the links are disengaged.