2005/2006 I. Hydraulic and Pneumatic Systems1 System concepts Circuits with flow sources: Only one user can be delivered from one source Concepts:

2005/2006 I. Hydraulic and Pneumatic Systems2 System concepts Circuits with flow sources: Without restriction valve: The pump delivers under constant conditions. If the load changes, the rotational speed of the motor changes. If the load change is under a certain limit, the rpm change is small. If it is large (  p 2 ) then the rpm will go down drastically and the flow source is transformed into a pressure source. n1n1 n2n2 n0mn0m  p 0motor p1p1 p2p2 pp Q

2005/2006 I. Hydraulic and Pneumatic Systems3 System concepts Circuits with flow sources: What happens if we want to change the rpm of the motor at constant torque? Constant torque  constant  p m Changing rpm  changing Q a) Regulating the rpm or V g of the pump np1np1 Qm2Qm2 Qm1Qm1 pp pmpm Q np2np2

2005/2006 I. Hydraulic and Pneumatic Systems4 System concepts Circuits with flow sources: b) By restriction in series Δp p = Δp r + Δp m A 1 < A 2 < A 3 1.Q p = Q r = Q m 2.Q p = Q rv + Q r n m can be continuously adjusted pp Q pmpm prpr Ar1Ar1 Ar2Ar2 Ar3Ar3 pmpm pp Q nm2nm2 nm1nm1 Ar1Ar1 Ar2Ar2 Ar3Ar3 n m3 1 2

2005/2006 I. Hydraulic and Pneumatic Systems5 System concepts Circuits with flow sources: If the load changes, how does the motor rpm change by constant restriction valve opening? c) Parallel restriction valve Q p = Q r + Q m Δpm = Δpr ;Δpm = Δpr ; b) By restriction in series (cont.) pp A r =const Q Δp m = Δp r QmQm QrQr pp Q

2005/2006 I. Hydraulic and Pneumatic Systems6 System concepts Circuits with flow sources: The rpm can be changed by changing the restriction area. Here the load is constant c) Parallel restriction valve (cont.) Δp m = Δp r QmQm QrQr pp Q QpQp nmnm

2005/2006 I. Hydraulic and Pneumatic Systems7 System concepts Circuits with flow sources: If the load is not constant: The rpm change is much smaller pp Q We can use a flow control valve: c) Parallel restriction valve (cont.) QmQm QrQr Q pp

2005/2006 I. Hydraulic and Pneumatic Systems8 Examples Hydraulic press

2005/2006 I. Hydraulic and Pneumatic Systems9 Examples Synchronous drive

2005/2006 I. Hydraulic and Pneumatic Systems10 The End End of hydraulic part