Hydraulic Cylinder Testing
Hydraulic cylinder testing is crucial in order to maintain optimal performance…
In hydraulic cylinder testing, measurements of any leakage need to be taken and to do this, the typical method is to pressurise the cylinder at the end of stroke. This hydraulic cylinder testing technique is known as the ‘end-of-stroke bypass test’.
The only major disadvantage to this test is that, as the name suggests, the only seals tested are the ones at either end of the cylinder – where there isn’t a lot of deterioration of the component. Realistically, the centre of the tube is most likely to be prone to more damage, therefore that’s where the test needs to be performed.
In a double-acting cylinder, a ‘mid-stroke bypass test’ is a suitable method to test the piston seals. One of the issues with this technique is how to control the cylinder; a hydraulic engineer has to hold the component mechanically to keep the cylinder in the centre. Even a smaller sized cylinder can generate 6 to 10 tonnes of force, so this method is very dangerous. With larger cylinders, this task is impossible.
The only test that is appropriate for this is something called hydrostatic testing. This is a test that is performed after the piston has been held hydraulically in any position that is required. The pressure intensification that is created helps to keep the piston in one position along the entire cylinder to make sure that all the seals are functional and there is no leakage. The only consequence this might have is if the pressure is allowed to build up at the piston end of the cylinder with the valve closed, the pressure at the rod end will to too great, which could cause disastrous failure.
In this case, a pressure relief valve must be used in the rod end when carrying out the hydrostatic test. This is vitally important for not only the protection of the machinery but also for the personal safety of the engineer carrying out the test. To perform this kind of hydraulic cylinder testing, the following steps must be carried out
- Ensure the cylinder is secured so that it is controlled;
- Clean hydraulic fluid must fill both sides of the cylinder – do this through the service ports;
- Connect all components – directional control valve, relief valve, ball valves and gauges;
- Remove any air from the cylinder by using the directional control valve and stroking the cylinder numerous times;
- Place the piston rod mid-stroke and close the ball valve;
- Direct the fluid flow to the side of the cylinder where the rod is located;
- Increase the setting on the relief valve until the pressure of the cylinder is seen on the gauge;
- Close both the ball valve and the directional control valve;
- Record the pressure of the cylinder from on both gauges and keep an eye on any changes.
Our catalogue showcases some of the hydraulic cylinders and other components that we regularly supply within our extensive range. It is only a small sample, however, so if you can’t find what you’re looking for complete our Stock Enquiry Form or call our sales team. They have over 75 years’ of technical experience between them and, as our library of customer testimonials shows, they know their stuff!