One of the key advantages of direct-acting relief valves, in comparison to their pilot-operated cousins, is fast response. And their fast response makes direct-acting reliefs the valve of choice in situations where pressure spikes are possible and must be minimized. Secondary relief valves in an actuator circuit and the ‘spike relief’ for a variable-displacement pump are common examples.
But as … Read more
What is an acceptable level of oil loss for a hydraulic machine:
a). Zero
b). 2%
c). 5% or more?
In a perfect world, the right answer would of course be zero. But in reality, the true answer is 5% or more–of tank oil volume per year. And the reason I can say this with confidence is because total hydraulic … Read more
In chapter 13 of The Hydraulic Maintenance Handbook I discuss in detail the elimination of problems by engineering them out. An obvious example of this strategy is, if a hydraulic system has tapered thread adapters, their replacement with a more reliable type of connector eliminates the possibility of recurring leaks. Job done. And if an oil to water heat exchanger … Read more