July-August 2021

www.hpmag.co.uk HYDRAULICS & PNEUMATICS July/August 2021 25 often the last component considered when designing a system. To mitigate the risks of challenging routings, consider a flexible, corrugated hose design that has a tighter minimum bend radius, like Gates Multi Master GMV MegaFlex. Finally, hose routings can minimise the likelihood of leaks in a hydraulic system with proper termination selection. Always avoid stacking adapters to both minimise system cost and the risk of system leaks. To further demonstrate the value in optimised system routings, the product application engineers at Gates provided case studies to illustrate these points. In this first example, the customer asked for Gates’ help because they were having difficulty routing hoses through a channel in the Rear Drive. Upon further inspection, Gates engineers found a few opportunities: What Gates Engineers Observed Optimised Solution Tee grouping created challenges routing hoses through the channel Replace Tees with a manifold. Manifold design provided fixed points of reference for routing and improved aesthetics on the machine, plus they eliminate abrasion concerns from bundled tees. Bundled Tees were creating abrasion concerns 4+ connections at the same point were difficult to install. Gates QuickLok connections minimise leaks and enable fast and easy assembly. The before-and-after photos (3 and 4) show a cleaner system with improved performance and fewer leak points. Forgetting about safety Mistakes with high-pressure hydraulics can lead to critical injuries or even death. Here are some critical safety reminders about hydraulic systems and hydraulic hose assemblies: 1. Never touch a pressurised hydraulic hose. Rubbing your hand along a hose as a leak-detection technique, for instance, is just asking for trouble. 2. Similar to electrical systems, hydraulic systems can be energised even when the system appears to be in the ‘off’ setting. Therefore, always de-pressurise a hydraulic system prior to handling or replacing any system components. 3. When replacing a hydraulic assembly, always ensure the replacement assembly can meet the system performance requirements, including working pressure, temperature and fluid being conveyed. 4. For hydraulic hand tools, never carry the hand tool by the hose. This can lead to pinching and pinholes. 5. For line-of-sight hydraulic lines where an operator is working near the pressurised hydraulic assembly, line-of- sight sleeving should be used to protect the operator in the case of hose or assembly failures. Ignoring signs of wear Hydraulic assembly inspection should be included in any system preventive maintenance schedule. These inspections should monitor hydraulic assemblies for signs of wear, including cover damage like cracking and abrasion. Ideally, the system design would reduce the likelihood of damage, but when this damage is found to reach the hose reinforcement, the assembly must be replaced. Cover cracks can be caused by several issues. Exposure to extreme heat, particularly in engine compartments, can cause the exterior cover of the hose to become brittle and crack. Exposure to ozone, either from the sun or from high electrical charges, such as in welding equipment applications, can cause micro- cracks to appear on the surface of the hose. This is similar to ‘weathering’ that is seen in the sidewalls of tires. Ozone damage is typically seen first on the exterior of hose bends where the rubber compounds see their highest stresses. Once these cracks reach the hose reinforcement, the reinforcement is compromised because of potential damage due to moisture and debris. This damage can be mitigated by protecting hoses from high-electrical exposure and by choosing hoses with materials that are resistant to ozone. Cover abrasion is a constant challenge – particularly in congested hydraulic systems where it is challenging to isolate one hose from others or the machine frame in dynamic applications. The most obvious way to mitigate abrasion damage is to choose hose covers that are specially formulated with abrasion resistance. Specialised nitrile rubber compounds offer a mid-grade level of abrasion resistance, and extreme resistance to abrasion can be realised with a hose cover made of ultra-high molecular weight polyethylene film. It is also possible to assemble the hose in an 3. Re-designed manifold solution offers improved performance with a cleaner aesthetic In this second example, another customer was having issues with hydraulic fluid leaks at a hose-tube connection point. The Gates engineer located the root cause of the leakage issue – a bundle of hose-tube connections was very difficult to get wrenches on, causing installation challenges and ultimately these system leaks. The solution was crimp-on hose-tube connections that eliminated the leaks. This improvement also reduced the number of SKUs and resulted in a happy customer. 4. Crimp-On Hose-Tube connections eliminate leaks.