Since their advent in the late 1800s, hydraulics have become an integral part of numerous industries. Whether you are involved in heavy construction or food processing, properly functioning hydraulic equipment is vital to the productivity of your business.
Despite advances in technology over the years, hydraulic equipment can still suffer from malfunctions, especially as machinery ages. One of the most commonly encountered problems is hydraulic cylinder drift. This issue can not only slow production speed but can also pose serious safety risks to your employees.
Fortunately, hydraulic cylinder drift is a straightforward malfunction that you can address with some proactive steps. Below, we will cover everything you need to know about hydraulic cylinder drift, including how to detect it and what to do about it when it happens.
What is Hydraulic Cylinder Drift?
While you undoubtedly know all of the ins and outs of your organization, you may not be familiar with the phrase “hydraulic cylinder drift.” The first step in overcoming drift is to have a good understanding of the basic function of your hydraulic equipment.
Hydraulic machinery utilizes cylinders to complete its tasks. The cylinder consists of an external casing, a piston, and a piston rod. Cylinders work by compressing a hydraulic fluid (usually oil) within the casing. Consistent and even pressure is maintained through the use of seals that prevent leaks at the rod entry point.
When you activate your hydraulic cylinder, the rod and piston will move, which changes the fluid volume within the cylinder. Ideally, the pressure within the chamber will remain constant once you have adjusted your machinery to the desired position. This is known as a hydraulic lock.
If your equipment is experiencing hydraulic cylinder drift, the cylinder will slowly retract while it’s under load. While this may only present a minor inconvenience in some applications, it can be catastrophic when this occurs with heavy equipment.
What Causes Drift to Occur?
In order to achieve a hydraulic lock, the fluid pressure within the cylinder must remain stable. This requires that your equipment’s valves are intact and piston and rod seals function as intended. A failure at one of these vital locations can create several problems, which will ultimately result in hydraulic cylinder drift.
Let’s start by taking a closer look at rod seal leaks since these are some of the most common issues and some of the easiest to detect. The rod seal is located at the top of the cylinder, right where the rod enters the pressurized chamber. When the rod stops moving, the seal should adhere to it and keep the fluid pressure stable.
If your rod seals are not functioning properly, you will experience hydraulic cylinder drift. Even worse, hydraulic fluid may escape from the system entirely. This can cause environmental and workplace hazards, such as slippery flooring. As you can see, the dangers of drift can quickly compound and result in a dangerous and unproductive work environment.
Piston seals are the second type of key component. The primary role of these seals is to ensure an equal distribution of hydraulic fluid pressure across the face of the piston.
A leak will allow pressure on both sides of the chamber to equalize. This severely decreases the efficiency of your equipment and will require higher fluid pressure. Pressure increases can cause your cylinder to greatly exceed the limitations of the pressure relief valve, resulting in cracks. The cracked valve will leak fluid and can contribute to hydraulic cylinder drift.
While under load, failing piston seals will place added strain on the valves of your equipment. Bad seals can also cause a slew of problems when you are retracting your cylinder. As the rod retracts out of the chamber, the piston is designed to block pressure from crossing it. If fluid passes over onto the other side, it can damage the rod seal.
Even though bad piston seals are not the root cause of drift, they can certainly contribute to it. If you have had to frequently replace rod seals on your equipment, the pistons may be the culprit.
Holding and Pressure Relief Valves
Despite the fact they are a less common culprit, you cannot overlook the importance of your holding and pressure relief valves. As its name implies, the pressure relief valve is intended to prevent the internal pressure of the cylinder from exceeding normal ranges. This protects vital components from damage. However, a leaky or damaged valve may not function as intended and can result in damage to your cylinder’s seals.
Holding valves or flow valves are used to control the rate at which hydraulic fluid enters the cylinder. If these valves work as they should, your equipment will self-regulate as you engage the hydraulic cylinders. When they are not in working order, you will experience a pressure imbalance. In severe cases, your equipment may not function at all.
Valve issues are indirect causes of hydraulic cylinder drift. However, it is important to keep in mind that any pressure imbalance can cause fluid to leak from the system. It can also put undue strain on rod seals, which will in turn cause drift.
The last culprit usually flies under the radar when you’re troubleshooting hydraulic equipment. Fluid contamination occurs when water or other fluids accidentally combine with your machine’s hydraulic fluid.
The seals and other components are designed to function properly with the specific viscosity of the appropriate hydraulic fluid. Foreign substances change the density of the oil and can allow it to seep past the seals. Contamination will also result in the oil compressing to a greater degree, which can cause small movement in the rod.
Signs of Cylinder Drift
Now that you have a better understanding of hydraulic cylinder drift, it is important to recognize the common indicators of its presence. This will allow you to service your equipment quickly and prevent the need for more serious repairs.
Drift occurs due to unintended positional changes that happen gradually under load. Some other signs of drift include:
- Excessive oil leaks, especially around the base of the rod
- Jerky or erratic movements
- “Stick-slip” or a stop in retraction followed by an abrupt slip or reduction in lift
- Machinery that appears to struggle to lift typical loads
- Frequently having to raise the lift to return it to the set height
If you are experiencing any of these problems with your equipment, then hydraulic cylinder drift is a likely cause. Failing to address drift quickly can cause a variety of problems to your equipment.
Over time, your machinery will have to work harder to perform the same tasks. This causes increased strain on various components, which can cause a need for more frequent repairs. The increased friction and wear on internal parts will ultimately cause a total cylinder failure.
Even if drift has not yet caused a complete equipment failure, it can make the performance of routine tasks more difficult. Shifting loads or inconsistent pressurization can slow the pace of work within your facility. Keep your employees safe and your business running smoothly by correcting drift immediately.
Remedies for Cylinder Drift
Do not let hydraulic cylinder drift derail your company or endanger your employees. Workplace accidents have serious legal and financial consequences. Fortunately, there are two key steps you can take to protect yourself from the dangers of a hydraulic equipment failure.
The first is to incorporate purpose-built cylinders into all of your equipment. General-use hydraulic cylinders may work for a time, but they are more prone to failures. Choosing hydraulic cylinders that are designed for your industry means that your cylinders will be more efficient and less likely to suffer from hydraulic cylinder drift.
Rapid-cycling processing equipment has different demands than slow, sustained hydraulic lifting devices. Various industries will expose their equipment to different contaminants, which must be accounted for during the design process. For example, the requirements of a marine hydraulic system will be vastly different than those placed on a food manufacturing device.
The second step to preventing hydraulic cylinder drift is to perform regular maintenance on all of your equipment. Industry-specific equipment is built to last and will do its job day in and day out, as long as you take proper care of it. Well-maintained equipment will keep your business’s operations running smoothly.
Experience the MAC Hydraulics Difference
Whether you are dealing with hydraulic cylinder drift or just want to make sure that your equipment is operating at peak performance, MAC Hydraulics can help. We provide mobile, on-site repair services for a variety of industries. Our experienced technicians can service hydraulic equipment for industries that include waste management, construction, food and beverage, manufacturing, railroad, and even aviation. When you need reliable hydraulic repair and service, contact MAC Hydraulics!