cam 200 is provided with first and second cam faces 210 and 220 which are disposed with respect to each other at approximately right angles cam 200 is positioned in such a manner that cam faces 210 and 220 may be brought into contact with opposite edges of handle 140 as a result of rotation of cam 200 cam 200 is preferably driven by a central shaft 230 not shown which may be driven by an external source of motive power of course axle 130 may merely be extended through handle 140 as a substitute for shaft 230 alternatively cam 200 may be provided with circumferential gear teeth not shown which may be engaged to provide a source of motive power as a further alternative cam 200 may be provided with circumferential means for engaging a drive belt not shown which may be driven by an external source of motive power in a preferred embodiment shaft 230 protrudes from a gear box 300 arranged to provide reduction gearing to match the rotational speed and torque of a motor 310 to the desired actuation speed and force necessary to operate valve 100 by rotation of handle 140 though a 90 u00b0 arc the preferred embodiment uses a small direct current motor having a rotational speed of between 7 000 and 20 000 rpm for example a mabuchi rs 365ph or similar motor may be employed such motors are characterized by their high rotational velocity and low power requirements reduction gears in gear box 300 reduce this rotational speed to from 1 to 3 rpm so that handle 140.