Sealing solutions engineered for enhanced cylinder efficiency

04 November, 2024

Harnessing the power created by a fluid power system into usable linear motion is the fundamental function of every hydraulic cylinder. Hydraulic cylinders are used in a wide range of industrial applications across various markets. Some common industries include agriculture, construction and off highway, material handling, mining, and oil and gas.

Included in many of these systems is a large network of seals and sealing systems. Although seals typically make up less than five percent of the cost to manufacture the cylinder, they are critical to maintain the cylinder’s movement. However, several challenges can hinder their efficiency.

Fluid leaks

Leaks in seals or hoses can lead to loss of hydraulic fluid, reducing pressure and efficiency. But it is important to note that dynamic seals in hydraulic cylinders require small amounts of fluid at the seal lip to provide necessary and important boundary layer lubrication. Boundary layer lubrication is often visibly identifiable as a thin layer of hydraulic media that passes under the sealing lip to reduce both friction and heat, allowing the seal to operate longer.

This minimal boundary layer lubrication leakage is necessary for the optimum performance of hydraulic seals; however, the amount of leakage varies by application and the requirements of the end-user. High-performance hydraulic sealing material options help mitigate leakage issues.

Several materials are designed to enhance the performance of sealing solutions and help prevent leaks in a hydraulic system. Polyurethane seals, known for excellent wear resistance and flexibility and Nitrile (NBR) rubber are two examples. Composite seals that combine various materials to leverage the strengths of each also offer enhanced durability and leak prevention.

Contamination

Contaminated hydraulic fluid can cause wear and tear on components, leading to malfunctions and reduced performance. Rod wipers are commonly exposed to dirty environments, especially mobile equipment, and prevent contaminants such as dirt and moisture from entering the hydraulic system as the piston rod retracts. Contamination can cause significant damage to the rod, cylinder wall, seals, and other components in the hydraulic system, and is a major cause of premature seal and component failure.

Hallite’s 846 double-lipped, snap-in rod wiper is moulded in Hythane 181 high-performance polyurethane. The 842 is a single-lipped, snap-in rod wiper developed specifically for use in environments with heavy contamination, such as agriculture, off-highway equipment, forestry, the aggregate industry, and longwall mining. Both the 846 and 842 wipers feature Umbrella Wiper Technology— including a protective debris guard flap on the wiping lip that covers the gland housing and prevents the water and slurry trap that often occurs with conventional wipers.

Friction

Friction losses occur in fluid power components on industrial equipment due to the dynamic nature of their operation. For example, as hydraulic cylinders extend and retract on a bulldozer, friction can lead to greater energy requirements for operation potentially causing overheating.

Reducing friction in the components that interact with the machinery contributes to reducing energy consumption and improves the overall sustainability of the equipment. This has led companies to explore new types of lubrication, materials, and product geometries that offer less frictional drag. Hallite for example highlights that it is focused on reducing friction in hydraulic cylinder sealing systems by test methods to assess friction durability and understand the impact on longer term sealing properties. This has been the catalyst for the development of new seal profiles and materials, such as the 683 low friction rod seal, an asymmetric single-lipped rod seal designed with precision-trimmed sealing lips to provide a dry sealing solution in light and medium-duty applications. Its design provides low friction to help lower fuel consumption, reduce emissions and optimise performance.

Minimising friction through proper design, material selection, and maintenance can deliver optimal performance and longevity of hydraulic sealing components.

Hydraulic fluid quality

Using substandard fluid can affect lubrication and cooling, leading to premature wear and inefficiencies. Hydraulic fluid types are broadly defined by ISO6743-4 into three categories: biodegradable, mineral oil, and fire resistant. Therefore, it is important to properly pair sealing materials with hydraulic fluids. The right fluid and material combinations can ensure the longevity of hydraulic sealing systems to prevent downtime and minimize leaks caused by potential incompatibilities.

Using improper viscosity fluids can starve the seal of essential lubrication, resulting in excessive wear. On the other hand, the right viscosity ensures optimal lubrication, reducing friction between seals and their mating surfaces, which minimise wear and tear. This balance prevents overheating, allowing seals to maintain their shape and integrity over time, which also reduces the likelihood of leaks.

Finally, fluids with the correct viscosity facilitate efficient fluid flow, enhancing the overall responsiveness of the hydraulic system. By maintaining consistent pressure and reducing cavitation risks, proper viscosity fluids help protect seals from damage, ensuring reliable operation and extending the lifespan of hydraulic components.

When it comes to hydraulic sealing solutions that promote cylinder efficiency, there are several options depending on the application and operating environment. Solutions that address the most common challenges must consider design and material parameters that contribute to the greatest potential for successful performance.

For further information please visit: www.hallite.com

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