Monthly Archives: July 2014

4 ways to reduce failures in hydraulic cylinders

hydraulic cylinder

An example of a hydraulic cylinder

As a product that’s used in a number of vehicles, hydraulic cylinders are as common as pumps and motors combined. If you use a lot of hydraulic equipment on a regular basis, then it’s more than likely going to be an expensive bill when the cylinder requires a repair. This can make up a considerable number of your overall operating costs, so taking these precautions should help the lower your bill and the damage dealt to the hydraulic cylinders.

According to various studies, a whopping 25% of mechanical equipment failures are down to a design flaw. If we apply this research to hydraulic cylinders, as many as one in four hydraulic cylinders are not designed for the application they’re currently operating in. This will just cause eventual breakdown of the machine or the hydraulic cylinder itself.

If you have any cylinders that don’t seem to last as long as they should, you may need to address one or more of the following issues:

Tube Ballooning

The cylinder tube can go through a process of ‘ballooning’, something which is usually caused by insufficient thickness of the wall and/or material strength in the cylinder’s operating pressure. Once the tube has ballooned, the tolerance between the piston seal and the tube wall is lost, which allows high-pressure fluid to bypass the seal. This fluid can actually erode the seal, with heating caused by the pressure drop across reduces the life of the seal. The end result is premature failure of the piston seal.

Bearing Area Is Insufficient

Given the surface of the bearing bands in the gland is insufficiently supporting the side thrust which is transferred to the cylinder, then an excessive load is placed on the rod and piston seals. This will result in the deformation of the seals, and ultimately, their failure.

The Finish of the Rod

The surface finish on the cylinder does have a significant effect on the life of the seal. Given the level of roughness on the surface is too low, the life can be reduced as a result. If the surface roughness is way too high, an unacceptable level of leakage is passes the road seal, which can result in poor performance.

In the sense of extending cylinder service life, you must think of the cylinder rod’s surface as a well lubricated, wear-surface, which you should treat accordingly.

In various applications, using an alternative rod surface treatment that has superior mechanical properties, which has conventional hard-chrome plating, such as nickel-chrome plating. These also have High Velocity Oxygen Fuel (HVOF) metal spraying, these can increase the service life of the rod and the seal.

Bent Rods

Bending cylinder rods can be caused by numerous insufficient rod diameter, even material strength. The improper cylinder mounting arrangement can cause damage to the rod. Once the rod bends, there are levels of deforming loads placed on the rod-seal. This increases the possibility of leakage and will ultimately result in the premature failure of the seal.

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