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Keeping Things Fluid


November 2017


Bosch Rexroth UK has issued its Fluid Rating List to help engineers understand the importance of choosing correctly rated hydraulic fluids to optimise performance and safety in hydraulic applications.

We often refer to hydraulic fluid as the “lifeblood” of hydraulic systems, because it not only transmits power through the system, but also transfers heat, lubricates and cools bearings, maintains pH, and removes water, oxygen and other contaminants. Ineffective hydraulic fluid can be both costly and harmful. Therefore choosing a high-quality hydraulic fluid is an important decision, and one that should not be rushed. Taking a few of the following factors into account will help when making a decision.

What kind of fluid do you need?

The range of hydraulic fluids has significantly expanded in recent years. Most hydraulic fluids are oil-based, the most popular of which is mineral oil. Synthetic, biodegradable and water-based fluids are also available. With so much choice, it is important that engineers think carefully about the setting, application and component materials of their hydraulic system.

What is your desired end-result?

Most people have three key expectations of their hydraulic fluid:

  • The fluid should last for as long as possible. Replacing hydraulic fluid is expensive, therefore it is difficult to achieve significant return on investment if a fluid needs changing every few weeks. Also, responsible disposal of waste oil is expensive.
  • The fluid should extend the lifespan of equipment by reducing the corrosion and wear or build-up of residue in core components of the hydraulic system.
  • Hydraulic fluid should optimise the efficiency of the systems by helping them to work smoothly, with increased capability and minimal need for operator intervention.

Users must look at their options and gather as much data as possible in order to match a fluid to its environment and applications.

Maintaining hydraulic fluid – from the inside-out

Once you’ve chosen the right fluid for the job, it’s important to maintain both the fluid in use and the fluid in storage in order for it to perform correctly.

Knowledge is power

Picking the right hydraulic fluid should not be left to chance. The hydraulic fluid should always exceed the minimum requirements and work as an efficient part of the system that ensures the productivity and longevity of the machinery.

Combine this with effective maintenance of the hydraulic fluid, and the “life-blood” of your systems can keep your hydraulics working for many years to come.

50 – 70 % of equipment failures are related to improper hydraulic fluid condition. Are you using the right fluid for your application? Magnifier

50 – 70 % of equipment failures are related to improper hydraulic fluid condition. Are you using the right fluid for your application?

Top five considerations

1 Optimize efficiencies by increasing capability and minimize need for operator intervention.

2 Extend the lifespan of equipment by reducing corrosion, wear and build-up of residue.

3 The right fluid will help reduce static build up.

4 Replacing hydraulic fluid is expensive, reduce the frequency with the right fluid for your application.

5 Maintaining optimal viscosity is key.

Keeping things fluid – a guide to best practice in hydraulic fluid selection and management is now available to download from .