Telescopic Cylinder Sizing and Selection
A telescopic cylinder delivers a long stroke from a short collapsed length because several stages run inside one another. The key factors are the number of stages, the stroke, the working pressure and the force curve that drops as the cylinder extends. This guide shows step by step how to size a telescopic cylinder for tippers, lift tables or crane duty.
View hydraulic cylindersHow does a telescopic cylinder work and when does it pay off?
A telescopic cylinder is built from several nested stages that extend one after another. This gives a stroke that is a multiple of the collapsed length - ideal when space is tight but a long stroke is needed. Single-acting versions are the most common: the load or a spring return retracts the cylinder once pressure is released.
Which parameters drive the sizing?
Four figures drive the sizing: the required total stroke, the maximum load, the available working pressure and the collapsed installed length. Load and pressure set the area needed for the first stage. The number of stages follows from the ratio of stroke to collapsed length, because each stage contributes only part of the total stroke.
- Set total stroke and collapsed length - this fixes the number of stages.
- Maximum load and working pressure set the area of the largest stage.
- Check extension speed against the pump flow rate.
- Account for side loads and guiding at long stroke.
Why does the force drop as it extends?
In a single-acting telescopic cylinder the largest stage extends first, then the smaller ones. Since force equals pressure times area, the smallest stage delivers the least force at the same pressure. The force therefore drops in steps while the flow demand stays constant, so speed increases toward the end. The application must handle this force curve over the full stroke.
Choose the working pressure so even the smallest stage lifts the load safely.
Compare cylindersClean hydraulic oil of the right viscosity protects seals and guides.
More on actuatorsFrequently asked questions
How many stages should my telescopic cylinder have?
The stage count depends on the ratio of total stroke to available collapsed length. For about 3:1 three to four stages usually suffice. More stages give more stroke but reduce the force of the smallest stage and add effort for guiding and sealing.
Why does the cylinder speed up as it extends?
The pump flow stays constant while the last stage to extend has a smaller area. The same oil volume on a smaller area means more travel per unit time, so speed rises and force falls at the same time.
Single-acting or double-acting - which is better?
Single-acting telescopic cylinders are simpler and cheaper and retract under load, ideal for tippers. Double-acting types need pressure to retract and suit cases where controlled retraction or motion against the load is required.
Find the right telescopic cylinder
Our hydraulics specialists help with stage count, stroke, working pressure and force curve for your application.
Vetted sizing
Recommendations from load case, pressure and field values.
Long stroke, little space
Stage count matched to the collapsed length.
Force over the stroke
Force curve and pressure reserve clearly explained.
Expert advice
Hydraulics specialists support your selection.