Vogele Basic Training Hydraulics & Electrics

H.8.0 Closed circuit
The hydraulic pump is fed with hydraulic fluid returning directly from the actuator (hydraulic motor).
The hydraulic fluid is under low pressure of roughly 10 to 30 bar and is raised to a higher pressure level
(high pressure) by the hydraulic pump before being fed back to the actuator again.
The advantages of this process are high speeds and filtering at a low pressure of just 10 to 20% of the volume
of the primary pump.
The circuit has high pressure and low pressure sides, which change with the direction of load.
The high pressure side is protected by pressure control valves, which relieve the pressure towards the
low pressure side.
The medium remains in the circuit.
Only the leakage at the hydraulic pump and hydraulic motor (depending on operating data) has to be replaced.
This is realized by a (usually) directly flange-connected auxiliary pump that permanently feeds a sufficient fluid
volume ( feed volume ) from a tank to the low pressure side via a non-return valve.
The unneeded volume flow of the feed pump working in the open circuit is returned to the tank via a feed
pressure control valve.
Volume flow variable
Pump,
variable
Motor,
variable