Abstract: A device for locking the throttle linkage of a vehicle comprises a bracket having a pair of aligned openings through which a rod of the linkage can pass. A lever pivotally mounted on the bracket has a free end for engaging the rod between the pair of openings so as to clamp the rod at that point and prevent actuation movement. The lever is moved by an air cylinder under control of a valve manually operable within the driver compartment. The driver therefore can adjust the engine rpm to an increased speed using the foot pedal and then lock the linkage at that position to allow the engine to run for a warming up period. The valve is then released to unclamp the linkage and allow normal driving movement of the linkage during operation of the vehicle.