The 20/5t Bridge Crane is a lifting equipment designed for hoisting and lowering heavy loads, as well as for horizontal movement of loads over short distances. As shown in Figure 9-96, it illustrates the electrical control circuit of the 20/5 (general hook crane). In the diagram, M5 represents the main winch motor.Command ControllerSA4 Control; MI is the auxiliary hoist motor, controlled by cam controller SA1; M2 is the trolley motor, controlled by SA2; M3 and M4 are the large vehicle motors, both controlled by cam controllers.
Zheji SA3 Control System
(1) Circuit operation during heavy load lifting
"Enhancement" features six gears. When the SA4 handle is shifted to the "Up 1" gear, S3, S4, S6, and S7 close, KM2, KM3, and KM4 are powered and attract, and the motor rotates in the forward direction.SequentialPower on, brake solenoid YA6 and YA5 energized.Brake ClampLoosen, short-circuit a segment of the rotor resistance, and the motor operates at the mechanical characteristics shown in Figure 9-97, upper 1 upper. This characteristic has a relatively low starting torque, typically unable to lift heavy loads, serving only as a tensioning wire rope and a preliminary stage to eliminate gear clearance in the hoist transmission system. When the main command controller handle is rotated sequentially,
At the second, third, fourth, fifth, and sixth gear shifts, the contactors KM5 to KM9 sequentially energize and engage, progressively short-circuiting the various sections of the rotor resistance. This causes the motor speed to gradually increase, achieving the mechanical characteristics shown in Figure 9-97, resulting in five different lifting speeds. Integers
2) The operation of the circuit during the lowering of heavy loads
Figure 9-97: When lifting and lowering heavy loads, the motor's mechanical characteristics change. During lowering, the main controller also features 6 gears. Depending on the weight of the load, the motor can operate in different states.If the overload descends, a low speed is required, and the motor can operate inReverse-pull, reversed connection brakingStatus;If the hook is empty or lightly loaded.Mandatory forced descent must be implemented.Among the six gear positions of the main command controller, the first three gears are J, down 1, and down 2.Brake descent; the last three gears, namely down 3, down 4, and down 5, are for strong descent. As the lever is moved from the zero position to the "J" gearAt the proper time, the S3, S6, S7, and S8 switches close, energizing and latching the KM2, KM4, and KM5, allowing the motor to engage.Positive CurrentNo Chinese content provided.Two segments of the winding resistance were removed, but the electromagnetic clamp held the hook tightly in place, preventing it from moving. When the handle was placed on the lower 1 and lower 2...At the gear shift, S3, S4, S6, and S7 close, KM3 is energized and latched, the electromagnetic brake is released, and KM5 and KM4 are sequentially de-energized.ReleaseCharacteristics CurveThe product becomes softer, obtaining the first and second characteristics of mechanical properties, while the motor operates in reverse traction mode.Engaged in manual mode. When the handle is set to positions 3, 4, and 5, S4, S5, S7, S8, S9, and S10 are activated.S11 and S12 sequentially closed, KM4, KM5, KM6, KM7, KM8, and KM9 sequentially powered on and attracted, resistance progressivelyGradual cutting, the motor speed increases step by step, and the motor operates under the three characteristics of strong decline at lower 3, lower 4, and lower 5.On the rise.
(3) Control of the secondary hook
The control of the secondary hook utilizes a cam.Controller SA1, featuring 10 gears, with five for ascending and five for descending.A single gear; employing a symmetrical connection method, where the controller handle is positioned for forward rotation.At the corresponding position of the reversal, the operation of the motor is completely the same.The forward gear position one is the preparatory gear, with the handle in position two.When shifting to 3rd, 4th, or 5th gear, the electric motor's speed gradually increases.Five gears down, the motor operates in high power mode under light load.The state of descent, if overloaded, causes the motor to operate in regenerative braking.Status, as shown in Figure 9-98.
(4) Cam controllers for large and small vehicles
Please provide the Chinese content to be translated.The control features of vehicles and small vehicles are essentially the same as those of the auxiliary hook.The difference is that the motor can only operate in forward and reverse electrical states.Light Load Force DropIt's impossible to operate in regenerative braking mode.
