EOT Cranes

Is this the original state the crane was in? What did the KONE representative say the last time you called them to get over the problem?

Kone representives have not come, they are busy sending spare wheels

They need to send someone to investigate, Mildred. After all, it may be happening elsewhere.

Looks like they are busy sending shafts too! Who did install the spare parts and the last broken shaft?

Do you have a picture of the broken shaft ?

Yes . How can I send you ?

Put it in your answer = use the small camera sign which allows to send jpg pictures.

Send as well pictures as mentioned in my previous message.

If possible make a picture of each side of the broken section. If you have several shafts then make a couple of pictures.

It may be an overhung load problem. Has that been evaluated yet?

Pictures of the broken shaft and how the gear motor is coupled and mounted would be a help.

If this is a two speed motion then the most common cause is when the crane is deaccellarating. Shaft would look like it has spun and broken. This occurs when crane is taken from high speed motion to low speed motion. There MUST be a time delay before the crane goes into low speed. Normally the crane motion will be allowed to coast until it is coasting at normal low speed or less, then low speed will be energised. If low speed is energised when crane is travelling at high speed the twiting torque on the wheel is huge and spins the shaft.

Hope this helps. Let me know how you get on.

Possible driver/user error?

Are there any data logging made of load and motor usage statistics to allow such a check of the driver...if not available, install video cameras and use them to check up on the drivers....

I haven't worked on cranes since the '60s and they were not the youngest either (Ward/Lenard type), so I cannot be much of a help....

Hi Wahsoo, It would be better if you could have given more detailed information such as following:-

1.Capacity of crane, span, type of crane i.e single girder or double girder.

2.Duty of crane, medium duty or heavy duty.

3.Is there any VFD drive for slow starting or the motors are slip ring type.

Such L.T shaft failures mostly occur due to misalignment of the wheel or jerky start.

Better check wheel alignment and check the rails if there is abnormal wear on the rails on which this wheel is running. M/s Kone should have guided you properly instead of simply replacing wheel.

You indicate that a rail survey was done and the runway meets spec. While doing that did they check the crane itself? If the crane was not built correctly, the end trucks may not be parallel causing wheels to bind. You would see wear on both the wheel flanges and the rail in this case. Crane would also tend to "rack" as it travels which often causing squealling as wheels rub.

Another possibility is twist in the bridge beam. Again, if during the build, this wasn't checked, one wheel may be higher putting undue force on the opposite wheel and shaft.

How old is the crane? All Kone cranes in recent years come standard with VFD controls on the horizontal motions which would eliminate the 2 speed "jumping" mentioned above. The way their wheel/drive modules are made, it's not the weight of the drive motor on the shaft. We've installed a lot of those over 20 years and don't see this kind of problem so it's more likely a crane fabrication issue rather than a design issue of the motor mount.

BTW, I'm not a KONE employee or even a big fan, I just have a long history in the crane business and with KONE components.

Thank you sir. Actually three different drive wheels underwent fracture. Not a particular wheel.

Add some pictures of the rails and wheels it could help to see if the wheel are at the right angle.