Slide Extension, or Travel as it is also known, refers to how far a telescopic slide allows the application to move, and is often expressed as the percentage the slide can extend versus the closed length.
A slide specified as 100% extension will allow a movement approximately equal to the closed length of the slide. With 100% extension, typically a drawer would be able to extend out from the cabinet and fully allow access to the rear of the drawer. This sort of slide requires at least three sliding members, and some slides can offer up to 120% extension.
A 75% extension slide will allow a movement of approximately ¾ of the length of the closed slide. This means that the rear of the opened drawer may be covered, and so access is restricted. However, because only two sliding members are required, the slide design can be simpler, with a smaller cross section.
The following diagrams show the standard extensions:
75% extension – drawer opens approximately 75% of the total length of the slide:
100% extension – drawer opens the same amount as the slide length:
100%+ extension – over-travel is achieved. The drawer opens in excess of the slide length:
SL = Slide Length , TR = Travel
Whilst the majority of telescopic slides are designed with the Drawer Member flush with the front of the slide in the closed position, not all are. This means that the TR dimension shown, may actually be measured from behind the front of the slide.
Linear slides do not extend telescopically, and the moving member always travels within the slide length.