Updated April 25, 2023 with solution
By Robert J. Sheaf, Founder/CEO of CFC Industrial Training
The circuit shown here is used to open and close the cage doors on a zoo enclosure. The staff would start the hydraulic system when they needed to open and close the gates. They then would shut it down when all the gates were closed.
After having trouble opening one of the larger cage doors, they spent time making sure there wasn’t a mechanical obstruction and that the gate wheels rotated freely. A local repair shop told them to increase the pressure on the electric motor-driven pump, but it would not go any higher. They tried increasing the setting on the relief valve and it also would not increase the pressure.
They tried to start the gas engine stand-by system but could not get that up and running, either. They also noticed the oil temperature kept climbing the longer they allowed the power unit to run.
Can you identify what was the problem? We welcome responses of all kinds directly to Robert Sheaf at email@example.com or to firstname.lastname@example.org. The solution will be provided next month, in conjunction with our February 2023 issue.
Posted April 25, 2023
Solution to pressure problems on a multi circuit system
The zoo enclosure problem was caused by the pilot-operated relief on the stand-by gas engine circuit. It had the control orifice partially blocked and relieved at a lower pressure than the cage doors required. The check valves were re-located after the stand-by filters on both systems to prevent this problem from happening again.
Filed Under: Components Oil Coolers, Pumps & Motors, Trending