overhead traveling crane
Electric control circuit for overhead traveling crane
1 Overview
There are two sets / 10.5m bridge cranes, designed for inspection and maintenance of machinery and vehicles for lifting purposes. As maintenance of the engine cylinder when the engine is correct, the electric hoist on the amount of increase and decrease the amount of requirements is very strict, in a position when the lift must be small, otherwise the cylinder can not be found. This requires that the electric hoist must have the jog control, but the electric hoist that buys from the factory comes to have this device, it does not have strict lifting amount, this is very inconvenient for car engine maintenance. As a result of this practical need, we bridge crane electrical control system improvements in the rise and fall of the electrical circuit to add an intermediate relay 1ZJ (or 2ZJ), while adding a combination switch LK, its working principle Is the use of AC contactor and intermediate relay power of the time difference, in order to achieve jog control.
2 working principle
When the total stop switch KK closed control circuit when the total power is turned on, the AC contactor QC as a result of the coil action, the main circuit in the QC main contact closure, The control loop is ready for operation.
3.1 No jog control is required
When a large amount of lift required to switch off the combination of LK, that is, its two groups with the contact LKl, LK. disconnect. When the press 3LA button AC contactor 3 C of the coil was electric, 3C main contact together, electric hoist was electric and rise, while connected to the down circuit in the 3C normally closed auxiliary contact disconnected to prevent the wrong electric hoist The relay contact IZJ of the jogging control circuit 3C is closed and the coil of the intermediate relay IZJ of the rising jogging control circuit is not energized and the intermediate relay IZJ is not operated, because the LKl is turned off. Motion control does not work. Just hold down the 3 LA button, the electric hoist has been rising to the upper limit point. Similarly, when pressed 4LA button AC contactor 4C of the coil was energized, 4C of the main contact closure, electric hoist was electric and down, while connected to the rising circuit in the 4C often trouble auxiliary contact disconnected to prevent electric The hoist malfunctions and rises. In this case, the normally open auxiliary contact of the jogging control circuit 4c is closed, but the LK is closed. So that the coil of the intermediate relay ZZJ of the rising jogging control circuit is not energized and the intermediate relay ZZJ is not operated, so the jogging control does not work. Just hold down the 4 LA button, the electric hoist has been reduced to the next limit point.
3.2 Jog control is required
When the minimum amount of lift required to put the combined switch LK, that is, its co-directional contact LKl, LK. At the same time connected, this time the jog control loop in the work of state. When the 3 LA button is pressed, the 3 C coil is energized, the 3C normally open contact and the main contact connected to the lift motor are closed. The motor rises and the IZJ coil is energized. The normally closed auxiliary contact is opened and the normally open auxiliary Contact closure, 3C coil power, 3C normally open contact and 3C main contact disconnected, the motor power failure and stop rising. At this time, only the release of the 3 LA button and then press again, the motor can rise again, because the motor was a very short time, so the rise is very small, so to achieve the jog control rise. Similarly, when pressed 4LA button 4C coil was electric, 4C normally open contact and connected to the main motor of the lift motor is closed, the motor down, while 2ZJ coil was electric, the normally closed auxiliary contact disconnected, normally open Auxiliary contact closed, 4C coil power, 4C normally open contacts and 4C main contact disconnected, the motor power loss and stop falling. At this time, only 4LA button and then release the press, the motor can decline again, because the motor was a very short time, so a small amount of decline, so to achieve the jog control decline. The two bridge cranes have been modified to operate well, providing great convenience for the auto repair work and improving the repair quality of automobiles and other machinery. But also improve the economic efficiency