Abstract: A reversible snap-action switch including a drive member and a switch-actuating driven member connected by a lost motion coupling. The relative position between the drive and driven members is shifted by substantially the lost motion distance as the drive member moves the driven member through a switching zone and then reverses its direction to return to its original position. In each direction of movement a bidirectional accelerating means imparts a snap-action motion to the drive member. This motion is coordinated with the position of the driven member so that switching occurs during the snap-action motion in each direction of movement, thereby inhibiting any hesitation in making or breaking the switch contacts. The invention also includes a cement-free mounting for the switch contacts.