Hydraulic and pneumatic pressure transmission
Chapter 7
Basic Hydraulic Circuits
vmax Rcmax 100 vmin
Chapter list
7.1 Pressure Control Circuits
7.2 Speed Control Circuits
1. Pressure-venting by the neutral of a directional valve
Fig.7-2a Pressure-venting by the neutral of a directional valve
Fig.7-2b Pressure-venting by a solenoid operated relief valve
Fig.7-2c Pressure-venting by a pump limited pressure
Fig.7-2d Pressure-venting by an accumulator
2. Pressure-venting by pilot -operated relief valve
As shown in Fig.7-2 regulated valves 4-Directional valve
2. Multistage pressure regulated circuits
As shown in Fig.7-1b.
3. Step less pressure regulated circuits
7.3 Directional Control Circuits
7.4 Multi-actuator Control Circuits
Introduction
Any hydraulic system is constituted by several basic hydraulic circuits. A hydraulic basic circuit is a group of components. Let’s classify: the functions in hydraulic system by: 1.pressure control circuits: control entire or partial operating pressure; 2.speed control circuits: control and regulate motion speed of actuator elements; 3.Directional control circuits: control and shift motion direction of actuator; 4.Multi-actuator control circuits: control and shift operating cycle between several actuators.
7.1.6 Pressure-holding circuits
7.1.1 Pressure regulated circuits
1. Pressure regulated from remote port
Fig.7-1 a)Pressure regulated from remote port b)Multistage pressure regulated circuit c) Step less pressure regulated circuit
The methods
There are two methods of unloaded pump: one is venting by pressure (pump operating under zero or near zero pressure, is called the pressureventing) and the other is venting by flow rate (pump operating under zero or neat zero flow rates, is called flow-venting).
7.1.1 Pressure regulated circuits 7.1.2 Pressure-venting circuits
7.1.3 Pressure-reducing circuits
7.1.4 Pressure-increasing circuits
7.1.5 Pressure counterbalance circuits
7.1 Pressure Control Circuits
Used to control and regulate the entire and partial pressure to realize a satisfied force and torque requirements, enhance working efficiency and improve the properties in a hydraulic system (six types shown in below) .
As shown in Fig.7-1c.
7.1.2 Pressure-venting circuits
The function
The function of a pressure venting circuit is to unload the pumping and to keep the pump idling when the hydraulic system is during the regular offworking, which it will realize to save the energy, reduce the heating and get a long life of use.