There are many types of applications, specifically with heavy-duty equipment, where a standard hydraulic cylinder does not provide the stroke required to move the given load.
To design a cylinder that had a rod long enough to provide the lift would be impractical and ineffective, so an alternative design has to be used to provide the lift required by that allows the size of the hydraulic cylinder to remain small and compact.
The use of telescopic cylinders is ideal for these types of applications. These cylinders are commonly found on dump trucks, allowing the cylinder to extend the bump bed enough to allow for unloading, which also allows the retracted length of the cylinder rod to be short and fit into the design of the truck and box or bed.
There are many options in the design and mounting possibilities for these cylinders. They can have any number of stages, but the typical design is between two and five stages. The full extension of these cylinders can be up to twenty feet, which is often used in industrial and heavy-duty types of equipment and systems.
How They Work
All telescopic cylinders operate using a nesting type of design. The sections of the rod are graduated and fit into each other when retracted. When lengthened, the first stage has the largest diameter, with the successive stages slightly smaller to allow the movement for both extension and retraction. Most of these cylinders are mounted to the equipment using a center trunnion type of mount. This provides stability and secure positioning of the cylinder.
It is important when designing these cylinders to understand the force and the load. When designed correctly, they are effective at lifting and lowering based on the rated amount for the cylinder. Incorrect design of custom telescopic cylinders or the incorrect use of the cylinder can result in the rods bending and cylinder failure.
