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Hydraulics aren’t a new technology. We’ve used them in many industries since the 1800s, from construction to agriculture, forestry, mining and everywhere else where heavy duty muscle power is needed to get the job done.
Although we continue to refine the technology to improve performance, reliability and power, machinery can still develop problems. One of these problems in all hydraulic machinery is hydraulic drift. As with all performance issues, it impacts productivity and profits. In the case of drift, there’s also a health and safety risk for employees. Here’s how to identify and remedy any hydraulic drift issues.
What is hydraulic cylinder drift?
To understand how to identify hydraulic cylinder drift, it’s important to know how hydraulic machinery works. The cylinder is the muscle in the machine and delivers the power. A cylinder generates power by compressing hydraulic fluid within the casing.
Seals allow the cylinder to maintain a consistent pressure without leaks where the piston rod compresses the fluid. When in use, the rod and the piston move, pushing fluid through the cylinder to create constant pressure.
Hydraulic drift is where the cylinder retracts slowly while under load. It usually occurs when one or more components don’t function properly, causing uneven fluid pressure. On the surface, this won’t appear to be an issue. In heavy machinery, it can be a very serious problem and cause accidents.
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Leaks
A common cause of drift is when the rod seal develops a leak. This is where the rod enters the cylinder, usually at the top. In normal operation, the rod moves in and out of the cylinder. When it stops, the seal should prevent any loss of pressure or fluid from the cylinder. Fluid leaks are environmental and safety hazards and unwanted expenses.
Leaks in piston seals can also cause drift. These seals serve the necessary role of distributing hydraulic pressure. Any leak allows the pressure to equalise within the cylinder, which in turn lowers the efficiency and power and requires more fluid pressure to compensate. If there is too much pressure, valves can fail and cause cracks and further leaks.
Valves
A cylinder is a finely balanced and attuned piece of equipment. It operates within a specified range for each piece of machinery, depending on the task. Any variations outside those specifications present the risk of drift and damage.
There are two types of valves in a cylinder for holding pressure and relieving pressure. The first controls the rate at which fluid enters the cylinder. The second relieves the pressure if it exceeds the specified range. If working properly, the cylinder is self-regulating for pressure. If not, then you have an indirect cause for drift through damage and failure to other components, particularly seals.
Contaminated fluid
Contaminated fluid causes all sorts of problems in hydraulic systems. This is where dirt, dust or debris get into the fluid and into the working parts of the machinery. They add unwanted abrasion, change the fluid density and cause leaks, all of which cause premature wear on components. Again, this will contribute to drift.
What are the symptoms of drift?
Learn to look for signs of drift before you get landed with a costly repair bill.
As we know, any imbalance that makes the hydraulic system operate outside of its normal specifications causes strain, which leads to damage and potentially accidents for machine operators. At the very least, it causes performance issues, which means you’re not working as productively as you could. It’s best to identify and fix drift early.
How to fix drift
Not all hydraulic cylinders are made equal. A general purpose cylinder may fit your machine and appear to work, but it will be more susceptible to drift over time. The key to any operation is delivering the required power efficiently. A custom built cylinder that is designed to operate within the specifications of your industry is a better option.
You can prevent drift with regular maintenance. Hydraulic machinery can and will continue to perform at peak efficiency as long as you have a rigorous maintenance schedule to prevent problems before they occur. Maintenance is a planned, scheduled stoppage to work. Downtime for serious repairs isn’t.
Feel free to contact us for advice if you need help getting the right cylinder for your machinery and industrial applications.
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