Kmk Wane

A 135kw motor at 1750 rpm can produce 540 ft-lbs of torque. What type of coupling is it? What is the coupling RPM? What torque and speed is your flexible coupling rated for? How did you check alignment? Did you check the shafts for runout?

My apologies for not responding to the clarifications requested earlier as I was not within internet reach. Anyway, I made a mistake when I said the motor was rated at 135 kW, in actual fact it is only 15 kW. The coupling that transmits the motor drive to the gear box is a flexible coupling of the compressive type with a brake unit attached on it. The high speed brake torque is 220 Nm, Output speed rotation is 5.9 rpm and the actual reduction ratio is 247.9:1. It will require approximately 63.413 kN to overcome the calculated resistance. Based on the calculations I have done the coupling which is rated to 240 Nm is sufficient for this application. I have been contemplating on what else can be wrong here that can cause catastrophic coupling failures. The flexible coupling currently used in this application is a Flendder brand.

I would appreciate any feedback and some direction on solving this problem.

Flender makes several types of flex couplings, None of which are called "the compressive type". Might it actually be one of these?

Also, what size is it?

The flennder coupling is a N-EUPEX DBDR 125, because the rubber inserts are compressed to transmit the torque, they have generally been classed as the compressive type coupling. The other form is the shear type, where the rubber tends to tear when transmitting torque.

Is the brake assembled correctly? If the orientation of used pads or shoes has been changed sometimes this can cause a brake to grab.

I did do a download of all work orders for the brakes on this drive and didn't find any major repairs on the brake unit. Preventative maintenance work done on the brakes included changing out worn pads with new ones. The old pads are discarded, we do not reuse the old pads even if they seem to be in good condition.

Check for loose mounts on the motor and whatever the coupling attaches to.

If even one bolt is loose it can cause a vibration or movement within the coupling itself typically this would create a lateral sheer stress to the coupling that is added to the rotating sheer of the motor. I had a similar problem and it turned out to be this.

Just a thought though.

Thanks for the hint, we will make sure that there are no losses mounts on the entire drive system.

What type of conveyor belt or roller. May have problems on one or couple of the conveyors the system is running. Could be as simple as a spill on the conveyor belt that is making the under side tacky, excessive belt tension, bad roller bearings. You mite want to look at what work had been preformed on the conveyor system prior to the coupling failures. I have all so seen roller conveyors where a section or two was added that caused such failures.

The coupling that is failing is part of a drive system that moves a shuttle frame at the end of a conveyor system. The conveyor drive system is different to the shuttle drive. The shuttle speed is about 0.25 m/s and is operated about 5 times a day for about 10 mins in each case.

I checked through the past work orders that were carried out on the whole shuttle system and the thing that I thougth could impact most on the coupling was the shuttle drive brake. However, no work out of the ordinary has been performed on the system.

Sir:

Rack and pinion.......

Do the rack teeth face up...or in a self cleaning mode face teeth horizontal or face down.......any conveyed material spillage,as indicated elsewhere, could load the rack with debris.......THE POINION COULD ALSO LOAD..BUT LESS LIKELY ... COULD BE INSTALLED UNDER THE RACK..AND SHIELDED IN PINION AREA.

MR. GUY

Mr GUY,

The rack is face down and is protected by a cover over it. However, I have noticed lots of spillage build up on the cover so have had it cleaned.