 Hello friends, I am SP Mankani, assistant professor of Department of Mechanical Engineering, Valchian Institute of Technology, Solapur. Today we are going to study working of regenerative hydraulic circuits. At the end of this lecture, students will be able to understand the working of regenerative hydraulic circuit. So now this is regenerative hydraulic circuit. So here this one is a reservoir, filter, pump and motor is coupled to the pump and this is pressure relief valve and this is one is a 4 by 3 position operating spring loaded DC valve and here it is a piston and cylinder arrangements. So here initially we are going to be connected as a 4 by 3, 4 by 3 this direction control valve. So here at the center this is neutral and this one is one position one and this is position two. Just for reference purpose we are given as a position one and position two. So here when the oil is going to be pumped, so through the filter, through the filter this oil comes to this particularly P position. So from this P it is connected to the, is directly to the reservoir. So means this particularly as a center is a neutral position, neutral position. So and here this port one and port two. So as far as this one port one is connected to this one and port two is disconnected, port two is disconnected. So as it is a one, two, three, four, four ports and three positions direction control valve. So now the figure we are going to be once again referring as the oil is going to be pumping through this pump and that will come to this one position and that will back to the reservoir. This is a normal condition we are going to be considering it. Here this end is closed. So in case if it is going to be crossing the defined pressure, whatever the gauge pressure we are going to be setting if it is crossing that this defined pressure then this circuit is going to be coming in the working condition. Just we can observe here the flow is coming through this way and that is going to be shifted this position. This arrow mark is going to be shifted to this particular position. So because of the oil is going to be acting here, the pressure. So then this is going to be coming in the acting that time this particularly is connected then the oil is going to be coming back to the reservoir. So only this action is coming in the picture whenever it crosses the defined pressure. Otherwise it is going to be flowing through this way. So now going with the next we are just shifted the position to the this cross line. So means initially the position is directly connected that is a neutral condition. So now we are going to be by using this particular handle we are going to be shifting this to the position 2. So here is the position 2 we are going to consider it. So by this position so whatever the oil is going to be pumping through this filter. The filtered oil is coming through this pump. So the motor is coupled to this pump. So here this oil is flowing through this way. So here this is blocked. This position is blocked means the oil will not be flowing through this way. The port number 2 is concerned. So then this oil has to flow through this way. The oil has to flow this way. So when oil is flowing through this way so this is going to be acting this force on this particularly the back side of the piston that is a rod end side. So here this is going to act on the rod end side then it is going to be forcing in the this direction. So then this outlet so as this is inlet and this is becoming as a outlet. So as the oil is flowing this way this is inlet we are going to consider this is outlet. And oil when it is coming through this way so it is coming through this particularly connection. So this way then this oil is come through this one connection then it will come back to the reservoir. So here at this during this process the high pressure oil is flowing this way and the lower pressure oil is coming through this way. So that will come to the reservoir. So in this particularly regenerative circuits also called as a differential circuit also this is called as a differential circuit and also it is a bypass circuit otherwise it is a regenerative circuit. So we are going to be calling it as three names the differential circuit bypass circuit or a regenerative circuit. So here so when it is an extraction condition when it is an extraction condition means the piston is moving in this way and when it is a retardation position the piston is moving in this way. So now so based on that one so now here in the next diagram with the continuation of the same figure so just we have shifted to the position one. So as compared to the figure number one so here initially I have taken neutral condition now this is connected to the direction control position two and now it is a position one. The position one figure is indicating it as. So now the oil is coming through the filter to the pump so then high pressure this oil is come to through this particular way so it will come to this one. So whenever forcing this particularly piston in this direction in this direction so now in this what arrangement we have made as a regenerative circuit is so whatever the So even if you are going to be considering this as a P, P1 we can take and this as a PS PS I just I given the notation or otherwise you can give this as a PR as a rod side. So now here if you are going to be considering this as PR is greater than P1 PR is greater than P1 so this condition we are going to be considering with the basis as so here as the force is force is equal to pressure into area area is more in this side and area is less in this side as the rod is also there in this particular as a portion and because of that area is going to be considering here as a less and it is a more area. So this is going to be pushing it in this direction so because of that one you are going to consider PR is greater than P1 so means this whatever the piston is going to be moving in this way while the oil is flowing through this way high pressure oil so that time the piston is moving in this way when the piston is moving in this way so that time whatever the oil is there here so that will come through this way so that oil is coming through this way as a port 4 so when oil is coming through this way we are going to be connected that oil just it is a bypassing this oil we are going to be bypassing this oil in the previous diagram you have seen that is a directly connected to the reservoir so now it is going to be bypassed to this portion so from this particularly the oil is going to be added so means addition of oil is going to be taken place here the area is more and here the area is less and because of lesser area pressure will be more only we can pass this oil through this way toward this side we cannot pass this oil toward this side because this pressure is more so that is what we considered as a Fp is equal to P into area pressure into area so now this is force is equal to pressure into area and this is PR is a pressure at this side and P1 is a pressure at this side there is a blind end we are going to consider this is a blind end and this is a rod end so by considering this one we can pass the oil whichever at the higher pressure we are going to send it to this one and that will be the quantity here as a more and because of this rod and the area is less here and that oil is coming through this way as a higher pressure oil so by considering this one as a regenerative system so here what exactly are going to understand in this one as so while it is coming this way while it is coming this way so it is having as a more pressure is there here and because of that when it is coming this side it is at a lower pressure the application part of this one we are going to observe in the next diagram so now just you can observe the working model of regenerative hydraulic circuits in the first condition we are observing here as so just you can observe in the first condition it is a high pressure oil is moving inside the cylinder at the piston end side and the low pressure oil is coming through this way blue color I indicated here as a radical indicating it is a higher pressure at this condition directly motor is pumped through the motor it is going to be pumping and it is coming this side the oil is coming outlet because without any resistance it is coming this side so this is the blue color I indicated here just you can observe the next figure is bypassing this oil bypassing this soil the pressure at this end is more and that oil is going to be bypassed and passing through this pumped oil through the cylinder so now whatever the oil is coming here it is going to be pushing it back side so here just you can observe it here this is what the circuit you have just observed it is a GI figure you can just see this one is a higher pressure oil is coming through this way bypassed to this particularly the cylinder and here at the piston side even we are going to be calling it as a blind end side and this one is a rod end side so just you can observe here it is connected here it is closed so now the oil is going through this way and it is bypassed oil is going to be passing through this way the next what are the advantage of regenerative hydraulic circuit what are the advantage of regenerative hydraulic circuit the speed of the extension can be made greater than that of regular double acting cylinder the extending speed can be made greater than the retracting speed if the rod size is made small enough the example is power press machine so for the further information you may refer this website as well as oil hydraulics systems by SR Mujumdar thank you