Hydraulic cylinder

It can be likened to a muscle in that, when the hydraulic system of a machine is activated, the cylinder is responsible for providing the motion.

The piston rod also has mounting attachments to connect the cylinder to the object or machine component that it is pushing or pulling.

Hydraulic cylinders can be used in any machine where high forces are required, one of the most familiar being earth-moving equipment such as excavators, back hoes and tractors to lift or lower the boom, arm, or bucket.

The cylinder barrel has features of smooth inside surface, high precision tolerance, durable in use, etc.

The cap is connected to the body by means of welding, threading, bolts, or tie rods.

The piston is machined with grooves to fit elastomeric or metal seals and bearing elements.

In double rod-end cylinders, the actuator has a rod extending from both sides of the piston and out both ends of the barrel.

The piston rod is highly ground and polished so as to provide a reliable seal and prevent leakage.

In some cases, especially in small hydraulic cylinders, the rod gland and the bearing elements are made from a single integral machined part.

Wipers/scrapers are used to eliminate contaminants such as moisture, dirt, and dust, which can cause extensive damage to cylinder walls, rods, seals, and other components.

The primary compounds used for wear bands are filled PTFE, woven fabric reinforced polyester resin, and bronze There are many component parts that make up the internal portion of a hydraulic cylinder.

Tie rod style cylinders can be completely disassembled for service and repair, and they are not always customizable.

[10] The National Fluid Power Association (NFPA) has standardized the dimensions of hydraulic tie-rod cylinders.

Welded cylinders have a narrower body and often a shorter overall length enabling them to fit better into the tight confines of machinery.

Welded cylinders do not suffer from failure due to tie rod stretch at high pressures and long strokes.

They are also used by heavy industry in cranes, oil rigs, and large off-road vehicles for above-ground mining operations.

The surfaces are often applied using coating techniques such as Chrome (Nickel) Plating, Lunac 2+ duplex, Laser Cladding, PTA welding and Thermal Spraying.

These coatings can be finished to the desirable surface roughness (Ra, Rz) where the seals give optimum performance.

It is for this reason that coating experts play a crucial role in selecting the optimum surface treatment procedure for protecting Hydraulic Cylinders.

Cylinders are used in different operational conditions and that makes it a challenge to find the right coating solution.

There is no single coating solution that successfully combats all the specific operational wear conditions.

As the common rods have a soft or mild steel core, their ends can be welded or machined for a screw thread.

This off-center strain can lead to bending of the rod in extreme cases, but more commonly causes leaking due to warping the circular seals into an oval shape.

[13] The strain of side loading can be directly reduced with the use of internal stop tubes which reduce the maximum extension length, leaving some distance between the piston and bore seal, and increasing leverage to resist warping of the seals.

Double pistons also spread out the forces of side loading while also reducing stroke length.

Generally, fixed mounts on the centerline of the cylinder are best for straight-line force transfer and avoiding wear.

Common types of mounting include: Flange mounts—Very strong and rigid, but have little tolerance for misalignment.

[15] Side-mounted cylinders—Easy to install and service, but the mounts produce a turning moment as the cylinder applies force to a load, increasing wear and tear.

Dowel pins hold it to the machine when operating at high pressure or under shock loading.

Clevis mounts can be used in any orientation and are generally recommended for short strokes and small- to medium-bore cylinders.