In most hydraulic applications there are essentially two ways to get the required power output: high flow at (relatively) low pressure; and low flow at high pressure. This is because power is a product of flow and pressure; increase pressure and you can reduce flow proportionately but still get the same power output. For example, 100 liters/min at 200 bar equates to the same power output as 50 liters/min at 400 bar.

Higher pressures mean higher force and torque is available from smaller components. And because these components are smaller in displacement, higher speeds are possible from smaller flows. Smaller flows mean pipework, valving and even the hydraulic tank can be made smaller.… continue reading »

1. Abrasive wear is the scuffing and scoring of a lubricated surface. It can be further divided into two-body abrasion and three-body abrasion. Two-body abrasion occurs when two lubricated surfaces come into direct contact with each other–usually as a result of loss of the lubricating oil film. Three-body abrasion occurs when the clearance between two lubricated surfaces is bridged by one or more hard particles. In this case it’s the clearance-sized hard particles that are responsible for scoring the lubricated surface(s).

2. Adhesive wear is usually a progression of two-body abrasion. If the oil film between two lubricated surfaces moving relative to each other is lost, the two surfaces begin to scuff (two-body abrasion).… continue reading »

One of our members wrote me with this question:

“I’d like to hear your opinion about isolation valves on pump intake lines. Within our company there is an ongoing debate over whether we should use a more expensive ball valve or a cheaper butterfly valve?”

At the root of this question is the negative effect of turbulence in the pump intake line. The argument for using a ball valve as an intake line isolation valve is, when it’s open, the full bore of the valve is available for oil flow. So if you have a 2″ ball valve in a 2″ intake line, when the valve is open, from the oil’s point of view at least, it’s as if it wasn’t there at all.… continue reading »