By Robert Sheaf, CFPAI/AJPP, CFPE, CFPS, CFPECS, CFPMT, CFPMIP, CFPMMH, CFPMIH, CFPMM, CFC Industrial Training
A new press was installed in a factory that makes steel bumpers for over-the-road tractors. The hydraulic power unit was supplied by a local hydraulic distributor that would only control the main ram supplied by the press manufacturer. The factory had a central system that would control all the auxiliary actuators on the press.
When everything was assembled on the plant floor and commissioning was started, they found that the main ram would not stay up in the neutral position. No matter what position the ram was stopped, it would fall to the fully extended position. They also lost pump pressure.
The power unit builder assured the customer that they tested the unit with one of their cylinders laying on their shop floor and it functioned well, extending and retracting as designed.
Any idea why the ram falls in the neutral position?
Solution to the previous problem:
Pressure-reducing Valve Would Not Reduce The Pressure
When pressure reducing valves adjustment knob is hard to turn, it normally is due to the spring chamber seeing hydraulic pressure. This pressure is also an additive to the spring adjustment setting. When we inspected the unit, we found the pressure supply and return connection were plumbed up backwards.
Robert Sheaf has more than 45 years troubleshooting, training and consulting in the fluid power field. Email email@example.com or visit his website at www.cfcindustrialtraining.com.