KWG Double Acting Hydraulics Cylinder With Clevis And Fork

PistonThe piston is a short, cylinder-shaped metal component that separates the two sides of the cylinder barrel internally. The piston is usually machined with grooves to fit elastomeric or metal seals. These seals are often O-rings, U-cups, or cast iron rings. They prevent the pressurized hydraulic oil from passing by the piston to the chamber on the opposite side. This difference in pressure between the two sides of the piston causes the cylinder to extend and retract. Piston seals vary in design and material according to the pressure and temperature requirements that the hydraulic cylinder will see in service. Generally speaking, elastomeric seals, made from nitrile rubber or other materials, are best in lower temperature environments, while seals made of Viton are better for higher temperatures. The best seals for high temperatures are cast iron piston rings.Piston RodThe piston rod is typically a complex, chrome-plated piece of cold-rolled steel that attaches to the piston and extends from the cylinder through the rod-end head. In double rod-end hydraulic cylinders, the actuator has a rod extending from both sides of the piston and out both ends of the barrel. The piston rod connects the hydraulic actuator to the machine component doing the work. This connection can be in the form of a machine thread or a mounting attachment such as a rod-clevis or rod-eye. These mounting attachments can be threaded or welded to the piston rod or, sometimes, they are a machined part of the rod-end.Rod GlandThe hydraulic cylinder head is fitted with seals to prevent the pressurized hydraulic oil from leaking past the rod and head interface. This area is called the rod gland. It often has another seal called a rod wiper which prevents contaminants from entering the hydraulic cylinder when the extended rod retracts back into the cylinder. The rod gland also has a rod bearing. This bearing supports the weight of the piston rod and guides it as it passes back and forth through the rod gland. In some cases, especially in small hydraulic cylinders, the rod gland and the rod bearing are made from a single integral machined part.A hydraulic cylinder should be used for pushing and pulling only. No bending moments or side loads should be transmitted to the piston rod or the cylinder. For this reason, the ideal connection of a hydraulic cylinder is a single clevis with a spherical ball bearing. This allows the hydraulic actuator to move and allows for any misalignment between the actuator and the load it is pushing.