How to minimise hydraulic cylinder failure
Hydraulic cylinders are essential pieces of hydraulic engineering equipment. They are considered as common as pumps and motors combined, so if a hydraulic cylinder fails it can impact your entire operation. Minimising cylinder failure within hydraulic systems is important to avoid unnecessary lengthy equipment down time.
It is often stated that up to 25% of mechanical equipment failures are failures of design. If we apply this to hydraulic cylinders, as many as one in four hydraulic cylinders are not adequately designed for the given application they operate in. This does not mean that the cylinder is not capable of doing the job asked of it, it will usually, but not with an acceptable service life. If you are experiencing a particular hydraulic cylinder requiring frequent repair, you may need to address one or more design-related issues.
Bent rods are a common cause of rod seal failure. Bending of hydraulic cylinder rods can be caused by insufficient rod diameter or material strength, improper cylinder mounting arrangement or a combination of all three. Once a rod bends, excessive load is placed on the rod seal resulting in premature failure of the seal. At Berendsen we have the engineering expertise to calculate the permissible rod loading for cylinders in existing and new applications.
Ballooned Barrel Tubes
Ballooning of cylinder barrel tubes is usually caused by insufficient wall thickness and/or material strength for the cylinder’s operating pressure. Once the tube balloons, the correct tolerance between the piston seal and tube wall is lost and high-pressure fluid bypasses the seal. This high fluid velocity can result in erosion of the seal including localized heating caused by the pressure drop across the piston thus resulting in reduced seal life.
Insufficient Bearing Area
The internal bearing areas in the gland and at the piston are critical in carrying the thrust transferred to the cylinder. Insufficient internal bearing areas will result in excessive load being placed on the rod and piston seals. This results in deformation and ultimately premature failure of the seals.
The surface finish of the cylinder rod can have a dramatic effect on the life of the rod seal. If the surface roughness is too high, contaminant ingression is increased and an unacceptable level of leakage can result.
In the context of extending hydraulic cylinder service life, consider the surface of the cylinder rod as a lubricated wear surface and treat it accordingly. The installation of a boot to protect the rod surface and seals from impact damage and contaminants can also aid in extending cylinder life.
Regular Service & Maintenance
Regular service and maintenance of hydraulic systems is essential for removing contamination that will aid in the smooth running and longevity of major hydraulic equipment especially hydraulic cylinders. At Berendsen we have a dedicated team of service technicians that can aid in servicing and maintaining hydraulic systems to ensure cylinders continue to work to perfection.
Repair or Redesign?
Not all hydraulic cylinders are made equal. If you have hydraulic cylinders experiencing continuing failure or have suffered catastrophic failure it could be the result of poor design and modifications to the cylinder are likely required to overcome the vicious circle of failure and repair. Berendsen’s design enhancement service, through the use of the latest computer assisted design technology, can review all aspects of cylinder design and make any necessary design improvements to help reduce downtime and improve the lifespan of your equipment.