Contaminants of hydraulic oil are broadly defined as any substance that impairs the proper functioning of the fluid. Air fits this definition and therefore when air becomes entrained in the oil, corrective action is required to prevent damage to both the oil and the other components in the hydraulic system.

Air can be present in four forms:

1. Free air – such as a pocket of air trapped in part of a system.
2. Dissolved air – hydraulic oil contains between 6 and 12 percent by volume of dissolved air.
3. Entrained air – air bubbles typically less than 1 mm in diameter dispersed in the oil.… continue reading »

If you read my previous blog post about hydraulics troubleshooting, you’ll recall I told the story of a monkey caught in an old Indian monkey trap. This story was an analogy for the importance of both knowledge AND process for a successful troubleshooting outcome. In response, one of our members sent me this:

“That is a great analogy. I am a USAF civilian (USAF retired) and work with military aircraft technicians as a field rep. I constantly hear from peers and leaders that personnel need system knowledge training and that is the end all to solve all troubleshooting problems. I have been trying to emphasize that the PROCESS and approach to troubleshooting is nearly as, or more important than, specific knowledge of a system.… continue reading »

One of our members wrote me this question:

“Our hydraulic power units are Kubota 86 hp and Deutz 76 hp 4 cylinder diesel systems. We use a 40 GPM gear pump with a flow divider valve to create two circuits of 20 GPM, each with a variable flow control. We have a diverter valve upstream to combine flows if needed. The gear pump can handle the trash in offshore oilfield hydraulics and is inexpensive compared to piston pumps. The pressure relief valve is set at 3000 PSI.

A gear-type flow divider would be better but is much more expensive. The flow controls we use are inexpensive – but the down side is they create unwanted heat.… continue reading »