Do these adapters refere to the runner ( normally connected to the reducer) and impeller (normally connected to the motor) which are reversed?

Given the above is true, it is unlikely. However, the coupling may generate unusually high momentary torque spikes associated with the reverse direction of the fluid vortex for the particular coupling model, given that I understand your description.

The high torque spikes may degrade the splice strength and cause premature splice failure.

This is not much worse than overfilling. ■

Sounds like one coupling bearing might have failed. This can cause a coupling half to misalign with respect to the other. The impeller and runner blades then collide causing desintegration of both halves of the coupling and their motor and/or reducer attachments.

Its one guess. ■

ADDED note:

THe coupling installation was noted to be incorrect. Alignment of the two halves is critical to "balance" the rotational inertia. A improper installation may cause undue rotational stress and premature failure of the coupling bearing which leads to my above comment. ■

Did the reducer manufacturer evaluate the "Reed Frequency" modal vibrations?

On ocassion, the reducer high speed shaft critical modal frequencies are coupled to the the high speed motor RPM. We have measured the fluid coupling vibration amplification. You need to either analyze the case or measure it in and perform a FFT on the data in order to eliminate the reduce/motor shaft stiffness as insufficient in diameter to control a critical modal coupling.

This coupling may result in a shaft failure, which seems unrelated to the coupling.

As you can note, you give some information and you received some information. It is sometimes better to state the facts and receive best opinions.

This is my last response to the problem. ■

Was the coupling mounted on the motor shaft or the gearbox shaft?

As the motor shaft has wider spacing on the bearings..it is better for the inner wheel rotating part to bemounted on the motor shaft.

The gearbox input shaft has closed spaced bearings and also smaller shaft diameter.

However, with this arrangement, the max. torque transmitted is usually higher than for the other way around.

We have had this issue.

The influecing factors are.

high overhung loads from coupling arrangement

alignment is critical - very hard to set up..

coupling dynamic balance is also important.

Thanks

James ■

Dear kamlesh

It is better to explain complete problem in one stroke so that you can get proper reply.

Still it is not known reason for gear box shaft damage and motor leg damage.

whether the gear box and motor shafts sizes and keyway sizes were same or sizes were different and started the conveyor

without properly fixing the shafts that caused accedent

Or

Fluid coupling was dalay chmber type

A R SINGH ■

Good morning Kamlesh..

Normally the fluid coupling is installed the "right way round" for practical reasons.

This is so that you can turn the coupling half (with the bolts) round so you can set the coupling at the right fill angle during maintenance and commissioning.

If you install the coupling the "wrong way round" you have to move the whole conveyor to turn this coupling half to the required angle.

Therefore you have to make sure you select the motor and gearbox shafts can take the different overhanging loads from the coupling. I have seen huge whirling of these shafts due to a big heavy TSS mounted on too smaller shafts.

I have also seen drive units with the couplings in the "wrong way round" for this very reason.

They actually worked, but not as smooth as if they would have been the " right way round", as the delay chamber is on the "slow" side, and Heaven help those poor maintenance chaps trying to check the oil level..

Regards

LSL Tekpro

Regards ■

Dear Shri Kamlesh,

There are various type of fluid couplings. What consequence can arise due to such wrong mounting will depend upon the particular design and arrangement of the coupling.

One important feature about the reputed make coupling is that the connection with the motor is made in such a way that, when motor is operated, and when load is standstill during initial phase, the motor and half coupling running makes the oil to rotate and thereby dissipation of heat energy is ensured even if the load does not move or takes longer time to move.

Everything is broken down in your case, which looks to be very surprising. If coupling mounting had caused overloading of the motor, the motor should have tripped by electrical protection system.

In case your coupling happened to be of delay-fill chamber type, and something went wrong at the oil entry aperture (connection) causing in-rush of large quantity of oil at the wrong time, can lead to overloading of the system.

It is important that right quantity of oil needs to be filled. consequences of overfilling can best be informed by the manufacturer of your coupling.

However the break down of the entire drive unit looks to be unusual. One has to really analyse the situation using the actual drawing of the coupling, drive arrangement etc. involving the coupling manufacturer. To me it seems any more statement could just amount to guess work.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyors.

Author of Book : Belt Feeder Design and Hopper Bin Silo

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25882916 ■

Further to my earlier reply, I am adding following information, which could be of use.

In case of delay fill fluid coupling, the motor side-coupling portion is holding majority of oil. The motor and this half coupling rotation injects the oil into working chamber by centrifugal force during starting. This gradually builds up the torque as per fluid coupling design, while keeping the forces within allowable limits. When the coupling is mounted in reverse order, the oil holding half coupling will rotate quite late (or may not rotate), because oil flow would be by gravity only. This would alter the torque characteristics altogether. If such flow happens to be erratic, it can cause jerks and abnormal situation. The best way is to discuss the matter with your supplier and understand the arising oil flow, in context of specific design.

In the event if you have different type of fluid coupling, you have to apply your mind and also involve your fluid coupling supplier for implications of oil flow pattern for the fluid coupling mounting you are referring. This oil flow pattern will enable to understand the response of the fluid coupling and consequent effect on the complete system.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyors.

Author of Book : Belt Feeder Design and Hopper Bin Silo

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25882916 ■