HYDRAULICS 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 H&P reviews sealing profile and material considerations that address four of the most prominent hydraulic cylinder efficiency challenges—fluid leaks, contamination, friction, and hydraulic fluid quality. By exploring these factors, we aim to identify effective strategies for enhancing hydraulic cylinder performance and reliability in various applications. 16 HYDRAULICS & PNEUMATICS October 2024 www.hpmag.co.uk Sealing solutions engineered for enhanced cylinder efficiency
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