Chapter 7 Basic Hydraulic Circuits 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 off- working,which it will realize to save the energy,reduce the heating and get a long life of use. 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 pressure- venting)and the other is venting by flow rate(pump operating under zero or neat zero flow rates,is called flow-venting). Homepage List Upwards Downwards Retun Exit
Chapter 7 Basic Hydraulic Circuits 6 7.1.2 Pressure-venting circuits The function The methods 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. 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)
Chapter 7 Basic Hydraulie Cireuits 1.Pressure-venting by the neutral of a directional valve To system Play DVD TX✉ Fig.7-2a Pressure-venting by the neutral of a directional valve Play DVD Fig.7-2b Pressure-venting by a solenoid operated reliefvalve 3 Play DVD W☒& Fig.7-2c Pressure-venting by a pump limited pressure Play y吧 Fig.7-2d Pressure-venting by an accumulator Homepage List Upward达s Downwards Retumn Exit
Chapter 7 Basic Hydraulic Circuits 7 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
Chapter 7 Basic Hydraulic Circuits 2.Pressure-venting by pilot-operated relief valve As shown in Fig.7-2b. 3.Pressure-venting by a pump limited pressure As shown in Fig.7-2c. 4.Pressure-venting by an accumulator As shown in Fig.7-2d. 8 Homepage List Upwards Downwards Retumn Exit
Chapter 7 Basic Hydraulic Circuits 8 2. Pressure-venting by pilot -operated relief valve As shown in Fig.7-2b. 3. Pressure-venting by a pump limited pressure As shown in Fig.7-2c. 4. Pressure-venting by an accumulator As shown in Fig.7-2d
Chapter 7 Basic Hydraulic Cireuits 7.1.3 Pressure-reducing circuits The function:Used to drop a stable branch circuit pressure below the normal operating pressure of system. Usually a fixed pressure-reducing valve is installed to a branch circuit such as Fig.7-3a.Fig.7-3b is a two-stage pressure-reducing circuit To ensure a stable working speed,the lowest pressure should not be less than 0.5MPa,and the highest setting pressure should be at least less than 0.5MPa of the system pressure.When the actuator elements speed in a reducing-circuit needs to be regulated,the speed-regulating valve should be installed in the latter of the reducing-valve in order to avoid the affection of speed during the working. Homepage List Upwards Downwards Retumn Exit
Chapter 7 Basic Hydraulic Circuits 9 7.1.3 Pressure-reducing circuits The function: Used to drop a stable branch circuit pressure below the normal operating pressure of system. Usually a fixed pressure-reducing valve is installed to a branch circuit such as Fig. 7-3a. Fig. 7-3b is a two-stage pressure-reducing circuit. To ensure a stable working speed, the lowest pressure should not be less than 0.5MPa, and the highest setting pressure should be at least less than 0.5MPa of the system pressure. When the actuator elements speed in a reducing-circuit needs to be regulated, the speed-regulating valve should be installed in the latter of the reducing-valve in order to avoid the affection of speed during the working
Chapter 7 Basic Hydraulic Circuits To system To system a Play Play DVD DVD Fig.7-3 a)One-stage pressure-reducing b)Two-stage pressure-reducing 1,6-Pilot-operated pressure-reducing valve 2-Rated pressure-reducing valve 3-Check valve 4-Hydraulic cylinder 5-Two positions with two-ports directional valve 10 Homepage List Upwards Downwards Retumn Exit
Chapter 7 Basic Hydraulic Circuits 10 1,6- Pilot-operated pressure-reducing valve 2- Rated pressure-reducing valve 3- Check valve 4- Hydraulic cylinder 5-Two positions with two-ports directional valve Fig.7-3 a)One-stage pressure-reducing b) Two-stage pressure-reducing