Five Different Hydraulic Cylinder Types for Applications
Cylinder Construction Types
Differences in the design and manufacturing of cylinders depend primarily on what the industry and application are. Each type uses a different methodology on how the end caps are attached to the cylinder barrel as well as internal nuances. Barrel and end cap wall thickness also vary depending on materials used, cylinder construction, and operating pressures. The three most popular types of construction are tie-rod, welded rod, and telescopic. All these types can be either single or double-acting.
A tie-rod hydraulic cylinder uses threaded steel rods to hold two end caps to the ends of the cylinder barrel. Applications can use anywhere from 4 to 20 tie-rods depending on the bore diameter and operating pressure. A strong advantage of the tie-rod design is that it can be easily disassembled and examined for repair. Tie-rod cylinders are utilized in a large majority of industrial and heavy-duty manufacturing applications.
Welded Rod Cylinders
In a welded rod hydraulic cylinder, the barrel is welded directly to the end caps. The head cap can use a variety of retention methods such as threading or bolting. This design is generally well-received for mobile equipment due to the compact construction, internal bearing lengths, and duty cycle compared to tie-rod construction. However, the design does make inspection and repairs more difficult in the field due to requiring less conventional tools and equipment.
Telescopic hydraulic cylinders are typically used when a stroke length is required which is considerably longer than the retracted length. They are designed with a series of steel tubes, called stages, each progressively smaller in diameter and nested within each other.
Double-acting cylinders use hydraulic or pneumatic pressure to both extend and retract the rod or sleeve. Double-acting cylinders are more common than single-acting cylinders.
Single-acting hydraulic cylinders use hydraulic or pneumatic pressure to either extend or retract a single piston rod or sleeve from a cylinder. Generally, gravity or another external force returns the piston rod or sleeve to its no-pressurized state.