Transcript of What is a Load Sensing Pump?

welcome to lunchbox sessions bite-sized industrial training hey it's Carl here from lunchbox sessions.com this will be a brief introduction to load sensing pumps sometimes referred to as flow compensating our pump still has that very heavy spring that major adjustment called the pressure compensator or the pressure cut off for when we hit that really high top end pressure to make sure our system is protected but it also has a weaker spring called the load sensing adjustment or the flow compensator and that flow compensator is receiving information feedback if you will coming directly from the load our cylinder which right now is working at 300 PSI that's the pressure it takes to lift the cylinder and Rod and that 300 PSI is being fed back to the controller and giving that spring a boost I could tell that the spring is actually set to 300 PSI how did I figure that out I figured that out because our pump Outlet pressure is set at 600 so it's taking 300 from the load and adding it to the 300 spring setting and those two pressures add together those two forces add together to give us our regulated pump Outlet pressure of 600 PSI this is different from a pressure compensated pump which might be set at say 2,000 PSI at all times and therefore using a lot more input energy so in this particular case we've got a pump that sets its Outlet pressure just slightly higher than what's needed by the load we've got to have some kind of a flow controlling device in there this is our needle valve that's being used to set our desired cylinder stroke speed but let's have a look at what happens when I add a brick to the the brick stacker ah our load pressure has gone up to 600 but what happened to our pump Outlet pressure somehow it automatically adjusted from 600 up to 900 what we're finding out is that we're always maintaining a 300 PSI pressure differential sometimes referred to as a 300 PSI margin pressure when we're referring to load sense systems let's add one more brick and this time watch the delta Delta P gauge all the Delta P gauge fluctuates for a brief fraction of a second but quickly we find it returns to 300 PSI and we never really noticed any change in speed at the cylinder the cylinder just kept moving nice and steady and our pump found out that it needed to increase the outlet pressure setting automatically so what we found out is we can have a pump that is set at a pressure that's just a little higher than what's needed at the load instead of being always at the pressure cut off pressure which could be considerably higher and because we know we want steady speeds to our hydraulic cylinder we don't wish to see any fluctuation in speed every time we take a brick off the stack or every time we add a brick to the stack the pump knows to adjust itself accordingly so that the flow rate through the needle valve doesn't change that's the nature of a load sense system and that's a brief introduction to load sense pumps thanks for watching we have hundreds of interactive resources like this live schematic so you can try out your wild ideas without blowing anything up get started at lunchbox sessions.com