Let’s face it, hydraulic cylinders are the bugbear of almost all industries, from manufacturing to forestry. They are the moving force behind most heavy loads, from excavators to bulldozers, but they can and do fail, usually at the worst times.
When a hydraulic cylinder fails, it is not just the cost of replacement or repairs; there is downtime and lost productivity. These failures can also affect your business’s reputation due to failure to perform specified tasks.
They are expensive to repair, especially the larger cylinders, but even more expensive to replace. Here are some of the main causes of why these vital components fail.
Seal Failure
Seals are the Achilles heel of hydraulic cylinders because they are made of soft material and can fail for so many reasons. The most common cause of seal failure is contaminated fluid, and this can occur in several ways.
Abrasive particles like dirt, dust, and even metal shavings can enter the system and act like sandpaper, wearing down the seals. Certain chemicals and additives can also chemically erode the seals, or water can weaken the lubrication of the hydraulic fluid and cause the seal to swell, shrink, or harden.
As if that wasn’t enough, pressure spikes can damage them, and the seal material can be forced into the clearance gaps between metal components, deforming or damaging it. Finally, temperature extremes can destroy the seal’s flexibility, causing it to harden and crack.
Contaminated Fluid
Once again, fluid contamination is the villain in hydraulic cylinder failure. It can be dirt, water, or even bacteria that can get in there and clog the workings with biofilm or degrade the hydraulic fluid properties. And yes, even air. Air can enter the fluid, causing aeration and cavitation, which can lead to erratic movements and further damage to the internal components.
Mostly, these contaminants cause abrasion in the cylinder, especially the piston rod and internal bore. These particles scratch the highly precise surfaces, degrading the seal and allowing leakage. Water can also get in there and corrode the metal and weaken the cylinder structure even further.
Physical Damage
Just like we break down under excessive stress or work overload, so do hydraulic cylinders. When operators apply force beyond the cylinder’s specified capacity, it can wreak havoc. I’m talking bending, buckling, and complete cylinder failure.
Sideloading happens when the cylinder is not precisely aligned to the load, which can cause damage to the rod or gland in a process called galling. Up next is overloading, where a load is too big for the rod, causing it to bend and further damage.
External damage also comes in different shapes and sizes. Objects falling on or colliding with the cylinder can bend the rod or dent the barrel. Either way, you might be out of pocket for repairs.
Corrosion
The most common form of corrosion is pitting corrosion, most often caused by water. It all starts with the cylinders being exposed to moist air, which can cause pitting in the piston rod. From there, it follows a chain reaction.
When the pitted rod retracts, the rough surface shreds the rod and the wiper seal. These damaged seals let in all those contaminants we spoke about earlier into the hydraulic fluid. In turn, it causes contamination in the fluid, which can damage the inner barrel walls, other seals, and parts. There you have: a destructive feedback loop that will land you at the repair shop.
Maintenance and Operation Errors
Unfortunately, we can’t always blame cylinder failure on general wear and tear. In many cases, improper maintenance is to blame. Smaller issues that can be rectified remain unnoticed, leading to more serious damage over time.
Ensuring you follow a strict maintenance schedule can dramatically lessen those unexpected downtimes caused by hydraulic cylinder failures.
Improper use of machinery is also often behind cylinder failure, such as pushing the cylinder past its operational limits or exposing it to harsh environments.
Signs Your Hydraulic Cylinder Needs Repair
- It’s leaking hydraulic fluid
- It’s operating slowly or irregularly
- There are unusual sounds or vibrations
- Your pressure is erratic
- Visible signs of damage
Should Your Company Consider Repairing Faulty Cylinders In-House?
Most construction companies do repair more minor cylinder repairs like simple re-seals and minor wear damage in-house, but typically send their cylinders with more complex issues to specialized hydraulic repair facilities for work that measures up to OEM standards.
So if you have or employ someone with the technical expertise and the equipment, it may pay to conduct minor repairs in-house.
However, you will need this fundamental equipment and these tools to do the job efficiently.
Hydraulic Cylinder Repair Bench
The hydraulic cylinder repair bench is your base of operations, a purpose-built platform to hold the cylinder in place while it is being repaired. It is constructed to bear the heavy weight and high-pressure components of hydraulic systems.
High-quality benches are versatile to handle a variety of cylinder sizes, built with a hydraulic power source, integrated tools, and advanced safety features. Some benches have on-board pressure testing, where you can test sealed cylinders before moving them off the bench.
Cylinder Honing Machine
This tool is essential for smoothing the interior surface of the cylinder bore of any scratches, high spots, or imperfections. It creates a uniform cross-hatch pattern for trapping and retaining lubricating oil.
Testing Tools
It is crucial to test the cylinder for pressure and flow after repairs. These testing tools include
a hydraulic pressure gauge, cylinder bore gauges, and a hydraulic flow meter.
Tools To Disassemble the Cylinder
Besides your basic tools like wrenches, pliers, mallets, hammers, and cleaning tools, you will need some specialized tools.
These include specialized spanner wrenches (face-pin, head-hook) for removing cylinder glands, which often have pinholes or slots. O-ring picks and impact wrenches are also a must-have.
Conclusion
If you want to repair minor cylinder damage in-house, ensure you have not only the technical knowledge but also the correct equipment to repair your cylinders safely and effectively.
