Caution: residual pressure when machines are switched off!
Maintenance work on the hydraulics of machines involves risks and dangers - for example, due to the uncontrolled escape of the pressure fluid.
Figure 1 (circuit diagram): If you want to reach into line A1, you can retract the hydraulic cylinder as far as it will go. Line A1 is connected to the tank via the directional control valve (WV) and is therefore depressurised.
Figure 2: In mobile machines such as excavators, pipe fracture safety devices with a load-holding function are found on the boom cylinders and stick cylinders. They may only be dismantled when the pressure is safely released.
Lowering brake valve on a mobile machine
Gas pressure storage facilities pose an increased risk potential due to residual energy, as a compressible gas is used to store the oil volume.
The ability to read machine circuit diagrams is essential in order to check freedom from pressure.
Dipl.-Ing. (FH) Frank Weigel
Trainer Fluid Technology of the International Hydraulics Academy