How to test a hydraulic cylinder?

A Brief Overview

100-ton hydraulic cylinders are utilized in a wide range of significant and minor applications. Hydraulic cylinders are used to move objects around, from your SUV’s trunk door to massive industrial cranes and everything in between.

Most 100-ton hydraulic cylinders employ an incompressible fluid, such as oil or hydraulic fluid, that has reached its maximum density. When a piston pushes down on the oil in a simple hydraulic system, the oil transfers the whole force to another piston, which is propelled up.

This force can be used to release valves, move digging equipment arms, or extend the boom of a 100-foot-high crane.

As you can expect, the greater the hydraulic pressure applied, the more critical that the parts operate effectively and safely. Giant cranes, for example, are used to lift and move important, heavy things like multi-ton bridge beams and heavy machinery.

The ability to rely on your 100-ton hydraulic cylinder is critical to the project’s safety. Regularly testing your hydraulic cylinders guarantees their functionality and helps extend their operational life regardless of your application.

While most firms outsource hydraulics testing to service companies, testing hydraulic parts in-house may save time and enhance efficiency. Our 100-ton hydraulic cylinder experts can design and manufacture a hydraulic cylinder testing system tailored to your specific requirements.

Conventional Way of Testing Hydraulic Cylinder

In a double-acting cylinder, the traditional method of evaluating the integrity of the piston seal is to pressurize the double-acting hydraulic cylinder after the stroke and measure any leakage through the seal.

The ‘end-of-stroke bypass test’ is a frequent term for this procedure. The primary drawback of the end-of-stroke bypass test is that it seldom detects cylinder tube ballooning produced by hoop stress.

In this post, I’ll show you how to utilize the intensification effect to check the integrity of a double-acting hydraulic cylinder’s piston seal. However, before undertaking this test technique, it is critical to thoroughly comprehend the dangers of pressure intensification in a hydraulic cylinder.

The traditional method of determining the integrity of a double-acting cylinder’s piston seal is to pressurize the 100-ton hydraulic cylinder after the stroke and measure any leaking beyond the seal. The “end-of-stroke bypass test” is a frequent term for this procedure.

The end-of-stroke bypass test has a severe drawback in that it often misses hoop stress-induced ballooning of the cylinder tube. Conducting a piston-seal bypass test mid-stroke is the best technique to check for ballooning of the cylinder tube. The main challenge is that the double-acting hydraulic cylinder’s force must be mechanically resisted, which is impossible to achieve with big diameter, high-pressure cylinders.

However, employing the intensification effect, a mid-stroke bypass test may be performed hydrostatically.

Basics of Testing Double Acting Hydraulic Cylinder

We need to know where a cylinder can leak before we start testing it. We’ll focus on double-acting cylinders because they’re the most frequent on earthmoving and stationary gear. If we exclude fittings and connections, which are technically not part of the cylinder, a double-acting hydraulic cylinder can leak in just two places.

There is an undeniable leakage at the gland seal, the opening through which the rod enters and exits. However, the leak at the piston seals inside is the source of the most 100-ton hydraulic cylinder action problems.

Stopping the piston at each end of the stroke, removing the hose at that end, and checking for leakage is a typical technique of testing the piston seals of a double-acting cylinder.

This full-stroke bypass testing only tests the seals at the ends of the 100-ton hydraulic cylinder tube, with minor wear and strain. The test should be carried out at the center of the barrel, where the problem of barrel ballooning arises.

The barrel expands until the seals lose contact with the inner bore, enabling oil to pass through. The seals are in connection with the barrel bore while the piston is at either end. Therefore a bypass test will be accepted at this point.

The test findings, however, reveal leakage somewhere near the center location. Any increase in tube diameter more than 0.010” will cause the seals to leak.

As a result, we’ll need to place the piston somewhere in the center and develop a test to reveal leaking past the seals. The “Rod Extension Test,” as I call it, is the most straightforward and most successful technique to perform this.

This test can even be performed on the system in real-time. It’s quick and easy to conduct, yet it’s just as effective as testing on the bench. Suppose In the piston end output port, there is a closed ball valve. A pressure relief valve (PRV) is attached to the supply line into the rod end port to prevent the cylinder from overprescribing.

Testing Procedure of 100-ton hydraulic cylinder

1. Take hold of the cylinder by securing it. It is under control if it is still on the machine.
2. On both sides of the piston, fill the cylinder with clean oil.
3. Connect an appropriate ball valve to the cylinder’s piston end.
4. With the ball valve open, repeatedly stroke the cylinder back and forth to remove all air from both sides.
5. Pressurize the rod end supply port to advance the piston to the middle of the cylinder, then seal the valve on the piston side port with the rod wholly extended.
6. Measure the length of the rod, then apply pressure on the rod end port while keeping an eye on it.
7. If oil is seeping from the wiper seal, the gland’s pressure seal is leaking.
8. The piston seals are leaking if the rod slides out of the cylinder.
9. If the rod slides in, the ball valve you placed on the opposite end is leaking.
10. Finding a leak doesn’t need much force.

Seals are more likely to leak at lower pressures than at higher pressures. The higher the pressure, the more complex the seal lip is forced against the cylinder wall, resulting in a better seal.

It will not work the other way around. Using a ball valve on the rod end port to provide pressure to the piston end port will not cause the rod to go in, indicating seal bypass. The higher amount of oil on the piston side prevents it from physically moving onto the smaller volume side of the rod end. So don’t do that; it’s hazardous.

Conclusion

Finally, you might have understood all about double-acting hydraulic cylinder testing. In case you want to seek professional advice, you can contact our 100-ton hydraulic cylinder experts.