Fault finding quickly and accurately is very difficult when there is no system data and the hydraulic schematics are not complete. The backbone of any troubleshooting is data and without that it becomes very difficult to troubleshoot.
We were called to site to solve a problem with cylinders sometimes moving and then not, an intermittent problem. There were hydraulic schematics but no details of the set pressures of the pressure relief and pressure reducing valves. Downstream of the main control valve, connected to the cylinders there was also no pressure gauge. The system had a pressure reducing valve, accumulators and pilot operated check valves.
Fortunately the pump set had a pressure gauge on the outlet. When they tried to operate the cylinders the pressure gauge did not drop in pressure so that indicated there was not any loss in pressure so we could discount problems with the accumulators and pilot operated check valves. We then narrowed the problem down to the valves between the accumulator and the cylinders. Changing out the main directional control valve solved the problem. The investigation then moved onto why the valve had failed.
The system did not have enough test points to narrow down the issue and provide much needed data. Having a data logger and well positioned test points could have led to a faster solution. Too many hydraulic systems have a pressure gauge on the pump and no test points, which are vital for fault finding. Test points have a minimal purchase and installation cost and they are overlooked by many designers.
