 However, with the increasing speed of aircraft, the need to enable searchlights, anti-aircraft guns and naval guns to move ever faster to track their movement meant the some form of powered control was essential.Engineers were faced with the problem of making a heavy piece of equipment, such as a gun on its mounting carriage, track an input signal in a smooth and accurate fashion, with very little lag between changes in the input and the actual position of the gun mount.The gun needed to be aimed at the target at all times, and moving at the correct velocity to remain so.