By Martin Cuthbert, Managing Director, Webtec
Manufacturers of mobile hydraulic machines often have big goals, hoping to increase market share and harbouring ambitions of becoming the market leader. However, achieving this target can often prove challenging because key personnel have different agendas. Design engineers, for instance, are encouraged to lower the cost of sale (COS) and at the same time reduce CO2e (carbon dioxide equivalent emissions). Meanwhile, sales and marketing professionals want bona-fide ways of offering something new to stay ahead of the competition, and service managers want to drive better reliability. With so many conflicting interests, the task of reaching the end goal for mobile machine OEMs may seem daunting, but there is a clear and easy way through the maze: having a plan to optimise and maintain hydraulic efficiency.
The process begins by partnering with a proven and reputable manufacturer of hydraulic measurement and control products, a move that will help to boost brand image, increase sales and grow the business. A key piece of advice is to seek out a partner with thousands of users, preferably including many of the market’s largest mobile machine OEMs. This indicates trust and dependability.
Such a supplier is likely able to address a range of goals simultaneously, like reducing downtime, improving safety, reducing warranty claims, monitoring machine efficiency, improving control and monitoring the health of key hydraulic components such as pumps. To turn the concept into reality, Webtec has a proven three-step plan: assess the best combination of maintenance strategies; select standard or custom tools; and get lifetime support.
Maintaining an advantage
Industry takes advantage of many different maintenance strategies: reactive, proactive, preventative, and predictive. To explain in simple terms the role of each, consider a regular car.
Reactive maintenance is somewhat traditional but still has its place. It essentially involves keeping a monitored stock level of consumable products such as light bulbs or wiper blades, replacing the expired item at the next available opportunity. In contrast, proactive maintenance introduces a degree of anticipation by providing an on-the-spot solution, in the car example perhaps by carrying a spare wheel or using a run-flat tyre.
Preventative maintenance also uses the concept of anticipation by replacing a wear part after a predetermined number of running hours or miles, regardless of its actual condition. Then there is predictive maintenance, where sensors monitor brake pad wear and tyre pressures to ensure timely replacements or adjustments (based on actual condition) before issues arise.
The reality for the OEM service teams of hydraulic mobile machines is that all of these strategies should form part of planned maintenance regimes. To determine which mix will work best for what application, there is a simple decision-making hierarchy. It starts with thinking about proactive maintenance and whether there is a way to stop the machine /sub-assembly /component going wrong or minimising the consequences of a failure? If the answer is yes, then proactive maintenance provides the solution.
If the answer is no, predictive maintenance enters the frame: is it possible to monitor its condition and fix it when necessary? Again, a yes response indicates predictive maintenance as the optimal solution, whereas no means considering preventative maintenance: is there a way to estimate when it will fail and implement a fix before it does? A negative response to this question means the last resort is reactive maintenance and a likely troubleshooting exercise.
Often the right mix of maintenance strategies depends on the cost of machinery downtime. This is dictated by the type of machine and the industry where it’s being used. A hydraulic conveyor belt transporting aggregate away from the rock face of a mine might be critical and down-time could rapidly cost £100k+ / hour. In this case it makes sense to invest in more proactive and predictive solutions, such as duplicate power packs to provide redundancy and kidney-loop filtration to meet target oil cleanliness levels as well as oil flow, pressure and temperature condition monitoring.
On the other hand, on a non-critical hydraulic system with a low downtime cost of £1k / hour, it would be hard to justify adding permanently mounted sensors, it may be sufficient to carry out visual inspections and periodic equipment checks using a handheld digital pressure gauge and relying on a stock of common spare parts to reactively replace when needed.
What’s important is to assess the cost of inconvenience and machine downtime compared with the initial cost of the maintenance equipment and decide the appropriate maintenance mix.
Tools of the trade
To deliver the maintenance strategies a plethora of tools are available, including: condition monitoring devices for hydraulic flow, temperature, pressure, vibration, and hydraulic usage; portable testers and multimeters; and handheld dataloggers.
Many standard tools are suitable for everyday hydraulic applications, regardless of the chosen maintenance philosophy. Take the simple task of checking the flow rate of an excavator pump. In comparison with a new pump, the flow rate of a pump showing wear will reduce as pressure increases. It is important to carry out a P-Q test by checking the flow of the excavator pump at normal working pressure and test how the volumetric efficiency reduces with load. Here, a device like Webtec’s DHT (Digital Hydraulic Tester) features an integral loading valve to simulate working pressure during normal machine operation.
The risk is encountering pump failure before replacement occurs. At the same time, there is a need to avoid replacing the pump unnecessarily. So, under a preventative maintenance strategy, when is the optimal time to perform replacement? Examining previous failure data is a good starting point, assessing the number of failures against running hours. To help build a data map, the Webtec range of HPM hydraulic dataloggers can provide solutions for maintenance professionals on three different levels.
Firstly, these devices act as pressure dataloggers for simple applications, plugging into any standard pressure test point. It is possible to record pressure levels for up to 24 hours, with data available for download via a USB memory stick. On a second level, the HPM series can monitor additional system variables like pressure differential, flow rate, temperature, rpm and frequency. Users can therefore leverage the datalogger’s capabilities for hydraulic system set-up and more intensive fault finding. Again, data is downloadable via USB.
At a higher level, these instruments are suitable for multi-channel CAN bus communication or inputs from analogue sensors, providing the capability to monitor multiple parameters in complex mobile and industrial machinery. This is particularly useful for prototype machine assessment activities such as identifying potential issues associated with high-inertia loads.
Adopting a predictive maintenance approach means introducing continuous on-line monitoring of the excavator pump. By defining the performance benchmark for a new pump, it becomes possible to set an allowable level of performance degradation as running hours increase. With the use of a Webtec CTA in-line hydraulic flow monitor, maintenance professionals can see the moment when the pump reaches the maximum allowable level of performance degradation and replace it accordingly. This type of flow meter offers permanent installation on the mobile hydraulic machine, from where it transmits data to the cloud to allow the viewing of current system performance. Hydraulic flow is of course a critical component of calculating the overall energy efficiency of the pump.
Although a broad spectrum of standard tools is available, recent years have seen enquiries for custom products elevate. The task of customisation demands the design and manufacture of a better hydraulic measurement or control solution - typically by improving product fit, form or function - to suit a specific application.
When it comes to hydraulic measurement and control products, there is often no one-size-fits-all solution available off-the-shelf. In situations where a ‘special’ is necessary, the OEM has little choice but to seek expert suppliers able to provide custom solutions. However, as many mobile machine developers subsequently discover, there are few companies able to deliver the required levels of innovation, quality and speed of turnaround to meet the demands of important hydraulic projects. Furthermore, many assume the process will be arduous, with high levels of complexity and long lead times.
Webtec takes a different approach, making the route to product customisation straightforward. In many instances by following its Make it BLUE® approach the company can take the best-fit standard product and apply customisation according to requirements. Mobile hydraulic machine OEMs no longer have to compromise on functionality.
Chance of a lifetime
After assessing the best combination of maintenance strategies and deciding between standard or custom tools, the third and final step of the process is to get lifetime support. Following product delivery, the potential to receive continuous training and advice is paramount for ongoing success in the implementation of optimal hydraulic efficiency.
With these three steps, design engineers better understand the machine’s requirements, the sales team becomes confident in its promotion and service technicians know how to plan maintenance. Benefits also arise for the end users of mobile hydraulic machines, including lower energy consumption, reduced downtime and higher output. Highly satisfied end users typically equate to repeat business and enhanced brand reputation.
For further information visit www.webtec.com