Abstract: A linkage is provided to simultaneously control two independent hydraulic drive motors for a vehicle, each having a control arm movable between a high speed position and a low speed position. The linkage comprises a control shaft having a pair of spaced-apart cam elements mounted thereon which engage each of the control arms to pivot them in opposite direction as the shaft is rotated. The linkage is also movable in an axial direction which thereby insures that both control arms reach corresponding high or low speed positions. For instance, if one control arm should reach a respective position prior to the time the other control arm reaches its corresponding position, further rotation of the shaft and cam elements therewith also results in axial movement thereof thus insuring that such other control arm reaches its corresponding position.