Common faults of bridge cranes and their troubleshooting methods——

Common faults in mechanical transmission

1. The brake does not work well (the braking torque is small, the hook slipping phenomenon occurs in the hoisting mechanism) The car slipping phenomenon occurs in the running mechanism. The reason analysis and its solution are described as follows.

1) There is oil on the surface of the brake wheel, and the friction coefficient decreases, resulting in a decrease in the braking torque, so the car cannot be braked. It can be solved by cleaning the surface oil stains with kerosene or gasoline.

2) The brake shoe lining is severely worn and the rivets are exposed. When braking, the rivets are in contact with the surface of the brake wheel, which not only reduces the braking torque, but also pulls the surface of the brake wheel, causing great harm. Replace the brake shoe lining.

3) When the spring is not adjusted properly, the tension is small and the braking torque is reduced, and the brake cannot be braked, resulting in the phenomenon of slipping or slipping of the hook. Readjust the brake to increase the main spring tension.

4) The main spring is fatigued, the material is aged or cracked, there is no elasticity, the tension is significantly reduced and the car cannot be braked. The spring should be replaced with a new one and adjusted.

5) Improper installation of the brake, the brake frame and the brake wheel are not concentric or skewed, causing the hook or car to slip. Usually, first loosen the anchor bolts of the brake brake frame, and then tighten the brake to make the brake shoe hold the brake wheel. At this time, fill in the gap at the bottom of the suspended brake brake frame, and then tighten the anchor bolts. to achieve concentricity between the two.

6) Improper adjustment of the electromagnet stroke or a support under the horizontal rod of the long-stroke braking electromagnet, resulting in failure to brake the car. It is usually solved by readjusting the magnet stroke or removing the support.

7) The impeller of the hydraulic pusher does not rotate flexibly, resulting in the reduction of the braking torque. Adjust the impeller to eliminate the jamming resistance, and make the impeller rotate and slide to solve the problem.

2. The brake cannot be opened

The reasons for the brakes not opening and their elimination methods are as follows:

1) The tension of the main spring is too large and the magnetic pulling force of the electromagnet is the same as the tension of the main spring, so the brake cannot be opened. Readjust the brake so that the main spring tension is reduced.

2) The brake lever transmission system is stuck, and the release force is blocked in the transmission, so the brake cannot be opened. Check the transmission system and eliminate the jam phenomenon.

3) The brake screw of the brake is bent, and the top of the screw head cannot touch the moving iron core of the magnet, so the brake shoe cannot be pushed open. Disassemble the brake, remove the screw to straighten it or replace the screw.

4) The brake shoe lining sticks to the dirty working surface of the brake wheel. It can be solved by removing the dirt from the surface of the brake wheel.

5) The electromagnet coil is burnt or its wiring is broken, and the brake electromagnet has no magnetic pull. Replace the brake coil or connect the coil wiring.

6) The impeller of the hydraulic pusher is stuck. Clear the impeller jam fault.

7) The voltage drop of the line is too large, resulting in the voltage of the brake electromagnet coil being lower than 80% of the rated voltage, and the magnetic pulling force of the magnet is smaller than the tension of the main spring, so the brake cannot be opened. Clear the cause of the voltage drop and restore the normal voltage value to solve the problem.

3. When the brake is working, the brake shoe lining is hot, "smoke", and there is a burning smell, and the shoe lining wears quickly.

1) The gap between the brake shoe lining and the brake wheel is improperly adjusted, the gap is too small, and the shoe lining always contacts the working surface of the brake wheel during operation, resulting in friction and heat generation. Re-adjust the gap between the shoe lining and the brake wheel to make it uniform and completely disengaged during operation, and not to be disconnected from the brake wheel.

2) The auxiliary spring of the short-stroke brake fails, and the brake shoe cannot be pushed open, so that the brake shoe always sticks to the surface of the brake wheel to work, which is caused by long-term friction and heat generation. Replace the secondary spring and readjust the brake.

3) The brake frame and the brake wheel are not concentric, and the edge of the brake shoe cannot be separated from the working surface of the brake wheel, which is caused by friction and heat generation. Reinstall the brake to meet the requirements of concentricity.

4) The working surface of the brake wheel is rough, the brake shoe lining does not match the brake wheel, and the brake is not good. Refinish the brake wheel or replace the brake wheel.

4. The braking torque of the brake is unstable

1) The out-of-roundness of the brake wheel is out of tolerance, and the radial pulsation is large. During the braking process, the brake shoe periodically collides with the brake shoe and causes the change of the braking torque. Re-brake the brake wheel to make it meet the technical requirements or Just replace the qualified brake wheel.

2) The brake frame and the brake wheel are not concentric, and the brake wheel collides with the brake shoe during braking. Reinstall and adjust the brake bracket.

5. When the mechanism is running, the reducer vibrates on the bridge

1) The anchor bolts of the reducer base are loose and not fastened firmly. Tighten the anchor bolts to secure it.

2) The input shaft of the reducer and the motor shaft are not concentric or the output shaft of the reducer is not concentric with the driven workpiece shaft, which will cause the body of the reducer to tremble when it is running. Vibration can be eliminated by re-adjusting the reducer to meet the requirements of concentricity.

3) The rigidity of the supporting steel structure of the base of the reducer is poor, which causes deformation and vibration during operation. Reinforce the support frame to increase its rigidity.

6. The trolley is in a "three-legged" running state

The so-called three legs means that the trolley has three wheels in contact with the track of the trolley, and one wheel is suspended. Usually there are two situations:

1) The trolley always has a round of suspension at any position of the bridge. The reasons and exclusion methods are as follows:

① The gear manufacturing is unqualified, and the diameter is too small to exceed the tolerance range. Therefore, under the condition that the mounting axis of the frame is on the same horizontal plane, the gear is suspended.

Replacing the gear can solve or adjust the installation position of the axle to move it downwards and eliminate the suspension phenomenon.

② The diameters of the wheels are all qualified, but the installation accuracy of the wheels is poor, the axes of the four wheel axles are not on the same horizontal plane, and the axis of the gears is too high, so the phenomenon of suspension occurs. It can be solved by moving the axis of the suspended wheel down so that the axes of the four wheels are on the same horizontal plane.

③ The manufacture of the small frame is unsatisfactory or deformed, and this suspension angle produces the phenomenon of "lifting head". Correcting the small frame, eliminating the phenomenon of head-up, and meeting the qualified requirements can be completely solved.

2) The trolley has "three legs" phenomenon in one or two or three positions of the bridge, but it is normal in other positions. The reason is:

① The elevation difference between the two main beams of the same section exceeds the allowable range, causing the wheels placed above the main beam with low elevation to hang in the air.

② The installation quality of the trolley track is poor, and the elevation difference between the tops of the two rails on the same section exceeds the allowable range. Usually, it can be solved by adjusting the trolley rail to make the top elevation of the two trolley rails of the section consistent or within the tolerance range.

7. Slippage occurs when the trolley is running

1) There is oil or sand on the top surface of the track, and there is frost in outdoor work.

2) The quality of the wheel installation is poor, and there is a phenomenon of suspension, especially if the driving wheel is suspended or the wheel pressure is small. Adjust the installation position of the wheel and increase the driving wheel pressure.

3) The height difference between the tops of the two small rails in the same section is too large, resulting in a large difference in the wheel pressure of the driving wheel. Adjust the trolley track to meet the installation standard.

8. When the car starts, the body sways, and the vibration is very high

When the running motor of the trolley is a squirrel-cage motor, this phenomenon occurs when the driving wheel is unevenly pressed or one wheel is suspended due to its excessive start-up.

It can be solved by adjusting the wheel installation accuracy or adjusting the trolley track to meet the installation standard.

9. The wheel rim of the cart is gnawing on the road (the wheel rim is severely worn, and sometimes even derails and falls off the track)

There are a number of reasons for the truck to gnaw the road.

1) The wheel manufacturing is unqualified, especially the large difference between the diameters of the two driving wheels, which causes the line speed on both sides of the cart to be unequal, and the car body is inclined. After measuring the difference in the diameter of the driving wheel, remove the larger one and re-carry it to make it equal to the diameter of the other wheel, which can be solved after installation.

2) The difference between the transmission gaps in the transmission systems on both sides is too large, which causes the cart to be out of sync when it is started, resulting in the car body walking obliquely and gnawing the rails. When braking, due to the large gap difference, the cart is inclined to cause the phenomenon of gnawing. Check the transmission system on both sides, eliminate the excessive clearance, and make the transmission on both sides meet the technical requirements.

3) The installation accuracy of the wheels of the cart is poor, and the quality does not meet the technical requirements. Especially, the wheels are inclined in the horizontal direction to guide the cart to go obliquely, and the phenomenon of road gnawing is extremely serious.

Check the installation accuracy of the measuring wheel, find the wheel with horizontal deviation and readjust it so that the horizontal deviation is less than L/1000 (L-measurement chord length).

4) The bridge structure is deformed, causing the diagonal line of the cart to be out of tolerance, resulting in the appearance of a diamond shape, which causes the cart wheels to gnaw. Check and measure the relative difference of the diagonal of the two carts, determine the direction of correction, and usually use the flame correction method to correct the bridge frame, so that the diagonal tolerance of the cart meets the technical requirements. Sometimes it is also possible to adjust the wheel position to achieve the relative difference between the diagonals of the cart and meet the technical standards.

5) The installation quality of the cart track is poor, such as the difference in elevation is too large, the span exceeds the tolerance, etc., it will also cause the cart to gnaw the rail, adjust the cart track to make it meet the installation standard.

6) Improper adjustment of the brakes at both ends when driving separately, especially when one end of the brake is not safely opened, the resistances on both sides are inconsistent, causing the car body to walk obliquely and gnaw the road. Adjust the brakes at both ends so that they are fully opened during operation, and the braking torques at both ends are equal during braking.

7) The rotation speed of the motors on both sides is different, resulting in different linear speeds on both sides. The motors should be replaced to achieve synchronization.

8) There are oil stains, frost, sundries, etc. on the top surface of the track, which is also one of the factors that cause the cart to gnaw the road. Remove oil, frost, debris, etc.