Mitigating risks in agricultural hydraulic hose applications

08 December, 2017

If more hose is required then the weight of the machine will increase, this is a key factor that directly correlates to operating costs. Many industries across the world are looking to ‘lighten’ machines in order to improve efficiency. The equation is quite simple – the greater the weight of the machine – the harder the internal combustion engine has to work – the harder the engine has to work - the harder the engine has to work the greater the fuel needed – the more fuel needed the higher the operating costs will be. It’s obvious that more weight is not acceptable. Standard hoses that can cope with high pressures need more levels of reinforcement and when more levels are added, hoses become stiff with a large bend radius. Our engineers are constantly looking to respond to this challenge and the latest evolution namely the two wire Dynamax EC881 has been designed to offer a 50% better bending radius (1/3 SAE 100R2 bend radius at 100degC).

Consider the pressure

Here at Eaton we have seen a market need over the last few years for increased operating pressures. This is mostly aligned with the OEM trend to offer compact machines, but with the same power and operating capabilities of their larger equivalents. During discussions with OEM customers they are increasingly telling us that their order books are changing to reflect huge growth in compact machines.

However, for OEMs this mean that they are actively seeking components that can cope with the higher pressures. Typically, standard EN857 Type 2SC size 8 hoses are qualified for working pressures up to 275 bar. This means that they are not ideal for deployment on higher pressure compact mobile machine applications, underspecified hoses are a severe risk to machine uptime and indeed operator safety.

The solution has been to specify four spiral hoses that offer more reinforcement, however they are less flexible, which is a problem with compact machines due to smaller installation space, and as stated above more hoses are needed to route around, which means more cost. The solution here is to work with a manufacturer who is evolving hose technology to cope with the higher pressure demand. In response to customer demand we are releasing two wire braided hoses (more flexibility) such as EC881 that are qualified up to 360 bars. Essentially, we have responded to the changing market dynamics and have worked closely with customers to design product that can cope.

Consider and minimise the abrasion risk

An obvious cause for this is the improper routing of hoses, essentially placing hoses in areas where they can chaff against a surface which has the potential to abrade. It can cause the outside cover of the hose to wear away, thus exposing the hose reinforcement to the outside environment. It then becomes prone to rust, which will eventually penetrate the hose thus causing it to leak. For OEMs it is imperative that the hose path is critically examined in the design phase to ensure the rub risk is minimised.

Where this isn’t possible isolators should always be used. However, there are instances where abrasion is unavoidable. In this case the best practice should be to specify hoses that feature abrasion resistant covers, such as Dura-Tuff covers. These, if utilised properly, can deliver eight times more protection when compared to synthetic hose covers. The key message here is reroute or re specify hoses that mitigate the risk.