I work in a repair facility of electric motors and other machines.  Today our company was given a fairly recently patented gear box in which the main output shaft was badly damaged.  Upon looking at the sectional views, published on-line by the manufacturer, it seemed clear that part of the patent or patents was/were incorporated in this output shaft.   Our company was requested to make an entirely new output shaft with a couple of modifications to prevent future damage like what was caused.

My concern is that if our company were to make the shaft it would be liable for patent infringement.  Too, our customer might also be liable.  

Unlike a typical electrical motor shaft or conventional gear box in which the shaft designs are well establishied, and which our company reproduces on a regular basis, this one has significant elements that seem unique.  

The question is, would our company and that of our customer be liable if our company were to make the shaft?  Would it be prudent to request permission first from the manufacturer, as it does not offer replacement parts---only whole units?  

If the repair were only to recondition by replacing bearings, repair seal and bearing fits, and fix any stripped threads and the like, there would be no question that it would be permissible.  If the thing were old enough that the patents would likely be in the public domain, then again there would be no problem making a whole new part.  

This is in a very grey area of which I am reluctant to be a part.  

Is it permissible for me to make this shaft?  

I'm no lawyer, and certainly no patent lawyer, but it seems to me that building a part for repair purposes is a very different animal that building a part for general sales.

Plus, you're modifying the patented part, not making a direct copy.

The commercial aspect is where you might get in trouble.

This can be a very complicated issue that requires review of the patents or patents in reference to the requested product/machine.  Specifically, you need to know the extent to which the patents cover the overall product and/or the various components.  One can generally repair a product covered by a patent though the replacement/repair of worn out unpatented parts.  The ability to repair does not include the right to make parts that are covered by a patent.  Yes, there could be liability.  Speak to a patent lawyer if you think there is risk.