8 min read
By Todd Lewis
Hydraulic cylinders are mechanical actuators that provide functionality and directional force. They have numerous applications, from engineering vehicles to civil engineering and manufacturing equipment. Regular inspections and maintenance of hydraulic cylinders are necessary for this precision machinery to function effectively and efficiently.
Though they generally last for years, even with inspections, there are many hydraulic cylinder problems that can cause failure. Below are the 9 most common hydraulic cylinder failure causes that must be addressed in order to maintain effective hydraulic systems.
Along with the above reasons, according to statistical research published by MDPI in 2021, the most common causes of hydraulic cylinder failure are as follows: Fluid contamination and oil pollution contribute to about 41.1% of cylinder failures. Improper maintenance is the cause of approximately 12.6% of failures, while outsourced parts and physical damage to the cylinder cover 10% and 6.5% of failures, respectively. Intense oil viscosity and the wrong choice of filter are at fault for 5.2% and 1.7% of failures, respectively, while about 1.7% of failures are caused by excessive vibrations. 9% of the causes of hydraulic cylinder failure are uncertain.
Seals are the most easily damaged component of a cylinder. Cylinder seals are the weakest part of the cylinder and can fail for many reasons including scratched piston rods, breaking down from the heat, contaminated fluid, or pressure spikes.
Abrasives, incorrect fitting, and chemical erosion can also cause hydraulic cylinder piston seal failure and seal leakage. A hydraulic seal that has been damaged by any of these occurrences and experienced leakage can ruin the cylinder's ability to maintain a certain pressure.
One of the most common reasons for hydraulic cylinder failure is contaminated fluid. When foreign, abrasive particles become trapped in the fluid, they scratch the inside of the cylinder, ruin the finish of cylinder rods, block ports, and damage seals and fittings. Though hydraulic fluid does degrade with time, faulty wiper seals are generally the cause of accelerated fluid contamination.
Extreme temperatures affect the function of hydraulic cylinders:
A hydraulic cylinder is designed to apply linear force along an axis that is aligned with the cylinder. When hydraulic cylinders are installed improperly, the force is applied perpendicular to the intended direction and side loading occurs. Sideloading causes uneven wearing because the cylinder rod pushes and the piston drags with more force on one side than the other.
Moderate sideloading will accelerate the degradation of the hydraulic cylinder and the cylinder will need to be repaired sooner. However, excessive side loading and uneven wear to various components can have more catastrophic results, as it leads to the failure of the system and a potentially dangerous situation. In summation, with uneven loads, hydraulic cylinders fail.
There are a few causes for piston damage; it is possible the nut or piston retaining device will become looser over time and pistons will often wear out with time like any mechanical equipment. Also, side loading or contaminated fluid could cause damage to the pistons and piston rod. Ultimately, the piston damage will cause complete hydraulic cylinder failure and the device will lose power.
In order to perform effectively, it is essential to monitor and maintain precise and controlled internal hydraulic pressure. When there are pressure variations within the system that are not according to the manufacturer's specifications it could lead to potentially dangerous conditions. Regular checks and adjustments should be made to comply with the system's specifications.
Another common problem with hydraulic cylinders is corrosion; corrosion appears as rust and pitting on the piston rods and stages of the cylinder. Equipment is sometimes stored outdoors, with the cylinders extended, exposing the rods to the elements.
Over time, specks of rust will form and then develop into pits and as soon as the cylinder is retracted, the rod will destroy the seal of the cylinder. This problem can be eliminated by regularly using the cylinder so a micro oil film can form on the cylinder rod. Otherwise, hydraulic cylinder failure is inevitable.
Cylinder bore scoring presents as deep gouges or harsh scuffs to the interior of the bore walls. This will be most noticeable where the piston is in its fully extended position at the mouth of the barrel. In the fully extended position, there is less support which results in increased friction and forces. Cylinder bore scoring might occur if cylinders are not mounted properly or cannot accommodate alignment changes. Increased side-load forces, which lead to a crooked cylinder rod, can also cause cylinder bore scoring. Scoring is most often found in long-stroke cylinders.
Split welds are catastrophic failure signaled by separation or cracks in welded surfaces, like mounting points. They are generally believed to be a sign that atypical or excessive force has been applied to the cylinder.
There are many situations where this kind of damage might have occurred, from improper operation to external impact to the poor condition of the hydraulic system. A split weld should not be ignored, if untreated it could have unfortunate consequences, from damage to the equipment to potential injuries to personnel.
Hydraulic cylinders can fail for a number of reasons, from seal failure to pressure and temperature issues, and understanding why the cylinders can fail will reduce the chances it occurs. Regular checks are an essential part of ensuring the overall system is working safely and effectively.
However, if maintenance or repairs are necessary, Cylinders, Inc. can help you fix our cylinders quickly and affordably. If you notice problems with your hydraulic cylinders, talk to our experts to find out more and schedule your repairs.
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