Gantry crane hydraulic lifting platform hydraulic system speed control loop mode analysis

Speed ​​control loop is door mounted  hoist crane   hydraulic lifting platform hydraulic system actuators velocity and velocity switching to achieve control loop. The main control methods are valve, pump control and actuator control in three ways. There are commonly used speed control loop speed control loop, fast loop, speed loop for access.
The basic principle of speed control loop pressure systems often need to adjust the hydraulic cylinders and hydraulic motor velocity to accommodate the host's duty cycle needs. Hydraulic cylinders and hydraulic motor speed depends on the displacement and input flow.
As can be seen, to control  hoist gantry crane  cylinder and motor speed can be achieved by changing the inflow of traffic can also be achieved by varying the displacement.
For  gantry crane  hydraulic lifting platform, hydraulic cylinders, the effective area by changing its A (equivalent displacement) to the governor is unrealistic, generally only method by changing the flow rate of speed. For variable motor, the governor can either change the flow can also change the motor displacement.
Therefore, the speed loop mainly in the following three ways:
1, Volume Control circuit: variable pump with adjustable or variable displacement motor to speed;
2, throttle circuit: pump oil from the quantitative, using flow into or out of the valve regulating the flow of the implementing agencies to achieve speed;
3, the volume throttle circuit, with limited pressure variable pump oil from the flow valve regulating the flow into the implementing agencies, and to the variable flow pump with adjustable flow control valve adapted to achieve speed.
Also can be applied to several dosing pumps in parallel, at different speeds needed to start an oil pump or several pumps to achieve grade governor.