Quote:
Originally Posted by fhhhstix
thicker oils will make hyd systems sluggish and build up excessive heat thinner less dense oil will dissipate heat quicker.
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No, that's not entirely correct. Heavier hydra oils are sluggish when cold, but once at operating temperature, they're fine. The heavier hydra oil purpose over thinner oils is for continuous duty in warmer climates, as thinner hydra oils will heat up too quickly, break down much sooner and loose their lubricity at higher temperatures which will lead to equipment failure. Lighter oils will also foam & become "spongy" if they get too hot!
My summertime tractors use Hydraul 56. With the Panther, as an example, the small hydraulic orbit motor that powers the fan on the airdrill @3000rpm will run for 3 to 4 hr intervals. Then another orbit motor to refill seed/fert tanks. Then seeding again for another stretch. The hydra oil never has a chance to cool much in a 14hr day, especially at 25° or more climate. A combo of steel piping, oil cooler ahead of engine rad and large oil reservior helps to keep temps within perameters. A lighter oil would cause the small orbit motors to run erractic and would likely trip an alarm during the heat of the day.
Some guys in our hobby, like rc guy Scott have used 30W engine oil in their model hyds while running outside during the summer heat greater than 25° b/c the 10W becomes like water & spins around the gears & does virtually nothing.