There are generally only two conditions which necessitate an oil change. One of these is oxidative degradation. And the only way to know if the oil’s life has expired based on this condition is to do regular oil analysis.
A hydraulic oil’s oxidative condition is determined by an absolute measure of its total acid concentration. When oxygen combines with hydrocarbon molecules a chain reaction occurs, which results in the formation of organic acids. These substances darken the oil, increase viscosity, reduce foaming resistance and air release, and form varnish and sludge. In other words, the oil becomes unserviceable.
The total acid number (AN) test result is expressed by the volume of the alkaline, potassium hydroxide (KOH) in milligrams (mg), required to neutralize the acidic components contained in one gram (gm) of used oil.… continue reading »
When positioning an air blast oil cooler, it should be situated so that it is at least half the fan diameter clear of any obstructions on both sides of the core. I recommend connecting the cooler so that oil flows from bottom to top, or if the tanks are on the sides, from lower connection (inlet) to upper connection (outlet). The reason for this is to purge all air from the unit quickly, and fill it completely, for maximum efficiency.
The other connection issue for air-blast oil coolers, which requires attention during initial installation, relates to whether it is single or double pass.… continue reading »
As a means of power transmission, hydraulics has many advantages. But overall efficiency is NOT one of them. A single-reduction gearbox has an efficiency of 98 to 99 percent, double-reduction 96 to 97 percent and triple-reduction 95 percent. And a chain drive in good condition has an efficiency of 97 to 98 percent.
A high-performance piston pump has an efficiency of 92 percent. If this pump drives a piston motor, the overall efficiency of this hydraulic drive, is 85 percent (0.92 x 0.92 x 100 = 85) – and this is without considering losses through valves and conductors.
And that’s good!… continue reading »