A telescopic hydraulic cylinder is more commonly referred to as a multistage cylinder. You can identify a telescopic hydraulic because it is comprised of multiple tubular rods. These rods are called sleeves. Usually, a telescopic hydraulic cylinder is going to have between four and five sleeves. The sleeves are designed to be sequentially smaller in diameter. They fit tightly inside each other.
When the hydraulic cylinder is put under pressure, the largest sleeve, also referred to as the main barrel, extends. When the barrel has extended as far out as it can, the next sleeve, also known as the stage, starts to extend. This process repeats until the cylinder extends the last stage known as the plunger.
Telescopic hydraulic cylinders are commonly manufactured in two ways. There are the single acting and the double acting cylinders. It is more common to use the single acting cylinder. It works thanks to gravity or another external force that causes the cylinder to retract. As soon as the hydraulic pressure is released, the hydraulic fluid is pushed out of the system and the cylinder will retract.
There are telescopic cylinders that are pneumatic, but it is a lot more common for them to be hydraulic. This is because of their capability to work when heavy loads are being transported. Some of the more common applications for telescopic cylinders are garbage trucks, dump trucks, and other machinery that are required to lift and move heavy loads.
