By Martin Cuthbert, Managing Director, Webtec

For a busy company supporting mines and oilfields with hydraulic powered machinery, one factor second only to safety is maximising machine uptime. Fleets of mobile and industrial machines inevitably age and, in turn, become less reliable, reducing uptime and potentially damaging the company reputation. In this situation, the choices are clear: make large capital investment in new machinery, or attempt to get the most value from the machinery we own such as excavators, crushers, winches and mobile drilling rigs without compromising safety or reliability. It’s time to get smart with hydraulic maintenance. 

This challenge is typical of many that Webtec encounters when helping mobile and industrial machinery OEMs and operators with their measurement and control solutions. Customers find themselves in this position due to three common challenges that include: a team that lacks experience or the necessary training; the absence of a structured maintenance programme; and high operating costs.

Inexperienced team
The antidote to team inexperience is competence-based training. The company has long-standing relationships with training providers around the world to help companies build a team with skills and proficiency in hydraulic maintenance. 

When looking to identify an authorised training course, Webtec turns to relevant associations such as: CETOP in Europe; the NFPA (National Fluid Power Association) in the United States; the BFPA (British Fluid Power Association) in the UK; or the IFPS (International Fluid Power Society), which hold registers of accredited training organisations. Webtec is also an advisory member to the NFPC (National Fluid Power Centre) in the UK which offers in-person and online training as well as free online assessments to test prior knowledge.

No structured maintenance 
Any company looking to improve machine reliability needs to develop a structured maintenance programme that identifies the tasks and tools required to improve the situation.

If the maintenance manual for older machinery has gone missing, it may be necessary to develop one in-house, perhaps by reverse engineering a machine to determine its circuit and what maintenance it requires. This maintenance will fall into different categories: reactive (wait for it to go wrong and fix it); preventive (estimate when it will go wrong and fix before it does); predictive (monitor condition and fix when necessary); and proactive (try to stop it going wrong or minimise the consequences of a failure if it does).

Predictive maintenance differs from the others in that it involves online condition monitoring via the permanent installation of sensors. This is a topic for another day, whereas the focus here is on portable tools you can use for proactive, preventive and reactive maintenance.

Flow vs Pressure
To monitor pressure, the trusty tool of choice for many is a glycerine pressure gauge. But is that really the answer to everything? Consider the example of a 100% efficient pump running at 60 bar that feeds 100 l/min of hydraulic oil into a cylinder for lifting a weight in a cycle time of 5 seconds.




A pressure gauge won't indicate a problem with flow
If the technician puts the same glycerine pressure gauge on a pump that is only 50% efficient, the pump will still run at 60 bar even though it would only deliver 50 l/min of oil to the cylinder and take 10 seconds to lift the weight. Therefore, using a glycerine pressure gauge will not diagnose the fault because the pump’s operating pressure shows as the same value. You need to know the flow, because the flow determines the speed.

Webtec offers a trio of products when it comes to hydraulic testers: the RFIK, DHT and DHM series.




Webtec hydraulic testers
The RFIK is a purely mechanical tester, using the pressure drop to move a piston against a spring for operation that is independent of batteries or electronics. In contrast, DHT and DHM series testers use a turbine flow sensor, offering more precision and compatibility, as well as bi-directional flow measurement. The DHM also adds wireless connectivity, internal memory and real-time visualisation for advanced diagnostics. Importantly, all Webtec hydraulic testers measure flow, pressure and temperature. They also include an integral load valve and built-in Interpass® safety protection for complete peace of mind. 

High operating costs
With the right hydraulic tester it becomes possible to deliver regular cost-effective proactive, preventive and reactive maintenance as necessary.

The first area to target should be ensuring effective proactive maintenance, for example on construction machinery where tools should be commissioned before use. An excavator could switch attachments between machines on a daily basis. Operators simply assume that everything is interchangeable and will just work. However, it is not that straightforward. Unless you have a very modern excavator with an auto-setup feature, users should set up correct flow, pressure and back-pressure on each hydraulic excavator attachment before use.



Setting optimum flows and pressures for excavator attachments
Doing so will lead to enhanced performance, extended attachment operating life, reduced downtime, improved safety and lower costs. A Webtec DHT tester provides the optimal solution through inline installation at the end of a boom. The DHT will quickly and precisely check the flows and pressures that the excavator delivers.

Another example of proactive maintenance would be setting up a variable displacement axial piston pump in terms of its displacement limiter, standby (load sense) pressure and pressure limiter (compensator).

Off-line pump parameter adjustment

Again, Webtec’s DHT presents the ideal way forward.

The service manager also needs to ensure existing machinery is subject to regular checks, which links to their preventive maintenance strategy. Preventive maintenance could mean estimating the life of the pump (for example) to identify the optimal time for replacement. With preventive maintenance, the technician can take tests over time to see how the pump is performing compared with previous experiences and the OEM’s specification. Using a device such as the Webtec DHM tester also introduces the ability to perform datalogging and the transfer of results to a smartphone. This capability means historic data is automatically stored for future reference. 

Although typically a last resort, reactive maintenance still has its place simply because service managers need to make fault identification as efficient as possible during troubleshooting. Subsequently, if breakdowns occur, they can be dealt with quickly. 

Take the example of fault finding on a fan drive system for a pump or main excavator drive, where installing the Webtec RFIK hydraulic tester will pay dividends.



Flow testing a vehicle fan drive pump
As already explained, testing pumps at low pressure may appear to show the correct flow rate. However, with the help of the Webtec load valve, technicians can restrict the flow, elevating the working pressure to the pump’s normal operating level.



Using the loading valve to simulate pump working pressure
The user will subsequently see volumetric efficiency deteriorate more quickly if the pump is worn, in comparison with a new pump.

The outcome
By overcoming the three main challenges of an inexperienced team, the absence of a structured maintenance programme and high operating costs, a busy mining or oilfield services company operating a lot of hydraulic machinery can increase uptime and prevent possible damage to its reputation. Perhaps most importantly it can reduce costs and delay the need to buy new machinery.

Posted by Webtec

Streams: Company News   Community   Latest News