Electric automatic deviation rectifying system of large span gantry crane

- May 25, 2018 -

Electric automatic deviation rectifying system for large span goliath gantry crane


Deviation is inevitable, so we need to rectify the deviation and minimize the deviation as far as possible. The main deviations of large span gantry cranes are as follows: such as the difference in running resistance caused by the track and parallel deviation of the big car, the deviation of the diameter of the wheel, the deviation of the motor speed, the fast and slow difference after the running of the rigid and flexible legs for a period of time, usually when the deviation is close to the span of 3/1000, the crane should be automatically reduced. Speed correction, the driver can also be manually corrected according to the deviation indicator; when the deviation exceeds the span of 3/1000, the deflected limiter will automatically break the control loop of the large car, so that the crane can stop automatically.


The commonly used method of automatic deviation of electric power is:

In order to automatically rectify the deviation of large span cranes, first, we should analyze the causes and phenomena of deviation, and then take corresponding corrective measures. There are some methods of electrical automatic correction:


1. When the speed of the motor on both sides of the rigid leg and the flexible leg is different, the average speed of the motor on the rigid leg is 1/1000 faster than the motor with the soft leg, which can be corrected by calculating the pulse number of the pulse encoder input to the PLC.

2, the angle between the main beam and the flexible leg is greater than or less than 90 degrees, which can be corrected by the angular displacement sensor installed on the top of the flexible leg.

3. By comparing the linear speed of the actual running of the wheel and the flexible leg, it can be rectified by the closed loop control method of the rubber friction rotating rotary encoder.

4. Some induction points are installed directly on the rail of a big car on the rigid leg side and the flexible leg side, and the approach of close switch is used to measure the close of the leg side and the leg side and input the PLC input end.


The principle of electrical automatic deviation

1, the basic programming and parameter setting method is to calculate the distance of the actual running of the wheel of a rigid (flexible) leg by the speed pulse - the number of the induction nuts on the fixed bolt on the rail press board of the crane is determined by the high performance close to the switch record. Distance from some electromagnetic induction points;

2, the actual operation speed of the close switch on the side of the first pulse is fast, and the pulse signal is immediately entered into the PLC input X17 (or X20), and the speed is immediately recorded and the correction is automatically controlled.

3, the method of automatic deviation is a quick method of slowing down. If the crane is running, the soft leg is fast, the flexible leg close to the switch is first inducted to the induction nut on the bolt, the flexible leg close to the switch control end is changed from constant to constant, so that the relay K510 is absorbed and the PLC input end X20 produces the input signal and can be compiled. Order: LD X20, ANI X17, OUT Y17, then the control terminal S9B of the flexible leg inverter input the deceleration control signal, the 4 motor of the flexible leg side is immediately decelerated, when the close switch of the leg side also detects the bolt induction nut, it automatically disconnects the input signal of the S9B, so that the soft, rigid leg side motor is simultaneously at the same time. Stable operation at the same speed;

4, if the crane is running, the rigid leg side is fast, the rigid leg proximity switch is first inducted to the nut on the bolt, the rigid leg close to the switch control end is changed from constant to constant, so that the relay K509 is absorbed and the PLC input terminal X17 produces the input signal, and the program can be programmed: LD X17, ANI X20, OUT Y16, then the rigid leg inverter The control terminal S9 input the deceleration control signal, and the 4 motor on the rigid leg side immediately decelerate operation. When the close switch of the leg side is also detected on the nut on the bolt, the input signal of the S9 is disconnected automatically, so that the rigid and flexible leg motor is stable at the same speed at the same speed.


Global positioning system GPS, but installation and maintenance costs are relatively high.


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