Telescopic cylinders are used in applications requiring long stroke but a short retracted length. The most common telescopic cylinder application is dump beds or trailers. They can fit between the frame rails of the chassis, but can extend far enough to dump even the longest beds.
Telescopic cylinders use nested barrels, each like both a rod and a barrel at the same time. The rod end itself is often hollow. Each barrel extends in stages, and the number of stages can vary between two or up to five or more. Stroke range varies vastly, but is most often between six and twenty feet.
The first stages of a telescopic cylinder have the most surface area to work with, so telescopic cylinders produce the most force at the beginning of their stroke. The more stages a telescopic cylinder has, the better it is able to produce more force over a wider range of its stroke.
Telescopic cylinders are usually mounted with center trunnion at the base end, although sometimes with a cross tube. The rod side of the cylinder is typically mounted with a pivot pin. Telescopic cylinders can be manufactured in single or double acting variations.