A push-pull switch is commonly used as a manually operated controller for industrial electric motor control circuits. A push-pull switch is typically mounted in a front panel of a control enclosure. Push-pull switches are used in applications where push and pull actuation of the control circuit is desired, as opposed to single push button, rotary selector switch or knife switches, for example. A push-pull switch has a cap that actuates an electrical switch to open and close electrical circuits.
Prior push-pull switches used spring-loaded ball bearings to pop into side grooves. The cap was directly linked to a pushing part that actuated the electrical contact blocks. The ball bearings detented into side grooves, locating the position of the linkage to an in position, a middle position, or an out position.
Because of the direct linkage used in prior push-pull switches, switch contacts could move only about half of the distance normally travelled by a conventional push-button operator in moving from middle to in-positions, or middle to out-positions. This reduced the open air gap in the contact blocks, forcing a reduction in ampere rating for a standard contact block or the use of special early-make or late-break contact blocks. The use of a direct linkage also required that all contact blocks used with the push-pull switch operate simultaneously. This reduced the application options for individual push-pull switches. Also, spring-loaded ball bearings can be difficult to assemble.
The present invention is intended to overcome the problems discussed above, in a novel and simple manner.