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Why Drive Shaft always broken?

Last updated: 10 Jul 2024
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Why Drive Shaft always broken?

Why Drive Shaft always broken?

Did you know inside the cooling tower there is one important part call Drive Shaft or someone just call it Shaft. This part will act as a transmission device from the Motor to the Gear Box in the form of a long rod across the middle of the cooling tower.

Picture 1 : The position of Drive Shaft in Cooling Tower

Having a properly functioning drive shaft can help to ensure the efficient of cooling tower operation and stable power transmission and cooling temperature

Normally, the Drive shaft has a lifetime about 10-15 years, but this year there were a lot of customers contacting us regarding buying the new Drive Shaft which in our opinion as a cooling tower designer it is not a normal case. Therefore, we have studied the root cause in order to solve the problem repeatedly and would like to share this in this article.

 

However, before getting into the article, let us introduce ourselves a little bit. We have written several articles before this in case someone has a chance to go through our article for the first time but to those who already have our fan page or follow many articles of ours already you can skip this part. 

We, Innovek Asia Co., Ltd., are the most successful and reliable cooling tower manufacturer in Thailand which qualified with the world class standard. Our aim is continuous development and constantly researching for new innovations. This can be proved from the trust we receive for both design with installation of cooling tower from the customer and including cooling tower repair from our expertise team with the experience of more than 15 years. Therefore, we can claim that we are the one stop service manufacturer with guarantees from several projects not only in the domestic market but overseas market as well.

Now we already know each other so lets go through the article.


Todays article as we mentioned above, we will talk about the abnormal condition of ordering the Drive Shaft. But before we discuss the root cause let us share the types of Drive Shaft first.

Type of Drive Shaft :

  • Universal joint drive shaft is a shaft that has been modified from a car drive shaft having a joint that makes this type of shaft can be offset mounted which can accommodate more misalignments than other shaft types.

The disadvantage of the Universal joint shafts is that this type of shaft is not suitable for long-term use because this shaft type is a modified shaft which causes the shaft to be heavy. If this shaft is too long, it will cause constant vibration. Therefore, this type of shaft is not popular nowadays.

Picture 2 : Universal joint drive shaft

 

  • Metal drive shaft is a flexible metal shaft developed from Universal Joint Drive Shaft. The misalignment from using joints has been changed to Bush to reduce the vibration. The shape of Bush looks like a round rubber ball similar to a ring sheath which is fitted with a nut.
The disadvantage of Metal drive shaft is that the shaft is made entirely from the metal causing it heavier than the Universal Joint Drive Shaft which more easily causes the unbalanced and also more expensive.

Picture 3 : Metal drive shaft
 
  • Composite drive shaft is a flexible shaft like a metal drive shaft, but the material is mainly made from Carbon Fiber which makes this type of shaft have a lighter weight and because it is made from fiberglass, so there is no chance of corrosion issue. This type of shaft has better support for misalignment compared to the first two types
Picture 4 : Composite drive shaft
 
So which type of Drive Shaft is the most frequently broken and ordered? From our primary data and analysis from past experience. Let us divide the cause into 2 groups.


The first group arises from the use of Universal Joint Drive Shaft or Metal Drive Shaft. The Gearbox is often broken because these 2 types of shafts have a high vibration value, there is vibration all the time, so it directly affects the Gear. Therefore, the Gearbox deteriorates and breaks faster. Another important issue is that the axle is heavy, if there is damage it will break and torn. The more disaster will happen when the parts may fall off and hit other devices which causes the inside cooling tower to be damaged.

The second group arises from the case where the Carbon Fiber Drive Shaft is used. In this case, there are quite a lot of reasons, accounting for as much as 80%. From the analysis there are several causes, let us divide the causes into 4 points in order to make it easy to understand.

  • Caused by incorrect installation of the Drive Shaft or improper installation. Most of the time they do not install as specified in the manual but they rely on their habit of installing the drive shaft rather than studying from the manual. Therefore, we recommend installing as the Manual given will be the best option.

  • Caused by poor alignment Drive shaft which caused the vibration. As mentioned above the Drive Shaft installed in the cooling tower is long, we recommend using the well-trained mechanic for alignment of the shafts that installed in the cooling tower. The Drive shaft setting in the cooling tower is different from setting the center of the shaft that is used in the pump.

  • Caused by Blade pass frequency, also known as BPF, means the frequency of vibration generated by the blade matching the natural frequency of the Drive Shaft. This causes the shaft to generate resonance which is a high resonance that may result in damage to the fan blade or shaft. If this case is found, the shaft must be replaced with a new model or the number of fan blades need to be replaced.
    We recommend selecting the correct type of Drive Shaft from the beginning or if after installation the problem arises, we recommend increasing the size of Drive Shaft because it will cost less than changing the fan blade.

  • Caused by Drive Shaft unbalance, which normally happens very rarely because of the new Drive Shaft that will be installed most of them are already counterbalanced from the factory. But in case it has been used for a long time there is a chance that an unbalance will occur
    We recommend checking the Drive Shaft regularly and if the Drive Shaft unbalance is found, it should be sent to have the Shaft rebalanced

After we did all the root cause analysis, we found out that the real reason is that it is important to choose the service provider. Even if there is a choice of the right type of shaft been use but if the installation is wrong not follow according to the manual or not set up properly because the wrong choice of selecting the service provider from the one who provide the cheap price which not have enough skill causing at the end there will be huge damage. If we choose a service provider who is highly experienced and well trained, it will cause maximum efficiency in work which is absolutely worth the price that you have to pay.

 
Before I wrap up todays article, Id like to give a guideline for Drive shafts maintenance method for readers to inspect the equipment youre looking after.

How to maintain Drive shafts :

  • Always inspect the Torque Bolt in accordance with the manufacturers Manual
  • Inspect the *Drive shafts exterior condition. If the fiber texture is apparent, it is advised to paint the shaft with UV protection to protect it from degeneration.*In the case of a composite drive shaft.
  • Check condition of the flex disc, if it is incomplete condition should be replaced to protect the problem with the equipment.
  • If you found a crack in the drive shaft, should replace it as soon as possible. If left for a long time a damaged drive shaft may fall apart. And may have additional damage to the other components such as fan blade and fan stack.
     
We do sincerely hope that this article will be useful to the readers, if you have any questions about cooling tower or you have any idea for our next article please feel free to suggest us or discuss with us via email coolingexpert@innovek.co.th We give you the advice with the correct answer without any cost.

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