A Bumpy ride

At Indrotech we feel it our duty to educate the industry on what faults we look for on a problematic driveshaft and how and why we rectify it.

Here is a fault that we find with a typical truck drive shafts.

The fault either comes from neglect to service it, normal wear and tear and believe it or not, even as new from the Original Manufacturer. This fault creates a massive vibration causing failure to the shaft components like; universal joints, centre bearings and even the driveshaft itself. That’s why we always stress that shafts need to run geometrically true to avoid this from happening.

Our first step is to look at the overall concentricity of the assembly starting from the straightness of the tube to the concentricity of the other components welded to either end of the tube. It does get technical and tedious to fix but it must be right, otherwise we come up with the problem that you saw in the video.

The benefit of our procedures is reducing this obvious runout down to 4 thousandths of an inch, equivalent to 1/10th of a millimetre. This is a standard service we practice within our Manufacturing Process let alone our Balancing Procedure.

This procedure helps with our final balancing process that in turn eliminates any vibration in the truck that is caused by the driveshaft. In the video we are running the shaft only at a couple of hundred RPM, imagine what effect it would have running at 3 or 4 thousand RPM. It would be dangerous on the road and more than just a bumpy ride for the driver; it could be catastrophic!

Please refer to our last post so you can see how a shaft, whether a single piece, 2 piece, 3 piece or 4 piece should run. 3 piece driveshaft balancing


What a wonderful feature

Dynamically balancing a closed face rotor is pretty straight forward when it comes to the theory behind it.

You have a full 360-degree area to correct from in 2 planes for instance; a flywheel or a wide roller. Things tend to get more complex when an item does not have a full disc, to make that correction, but rather a number of equal or unequal components around an axis that form a diameter such as a bi or trilobe rotor.

Back in the day, when machines were not as clever as today’s, to determine the position of a balance weight that sat mid-air between these components was tedious. Generally, the correction points on these units sit mid-air between the lobes never on a lobe. To attach that problem, you had two options. You either guess what portion of the total weight goes on one lobe and the remaining on the next one, or you do it properly with vector diagrams, trigonometry and calculations…

Today, technology has advanced so much that the machine solves all those calculations for you. Our CAB690 Schenck measuring unit is brilliant in doing this; provided the operator enters the right information. The operator tells the machine how many components or lobes there are on each plane, what angle they sit on and where our zero position is in relation to the first lobe. It’s as easy as that…


So all we need to do is concentrate on balancing and bring up the ‘green flags’ to tell us we have reached our tolerance.

What a wonderful feature…

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