Re: Water Pump Failures

[Glenn Merrell <gmerrel@domain.elided>]

Hello Daryl,
	The hardening process is usually performed on the whole piece, as the piece
must be heated and maintained at temperature for a period of time, then cooled. 
It is difficult to harden only a portion of a piece, very labor intensive as
each piece must be isolated from the heat for the portion not being hardened,
or, made as a separate piece and fixed to the softer piece. In the latter case,
the shaft is made and the gear is machined and hardened in a separate process,
then attached to the shaft.  The flywheel is an example of this, where the
flywheel is softer than the ring gear, a separate piece pressed onto the
flywheel.

The jackshaft and water pump impeller shaft are one piece machined castings,
then machined to spec, hardened as required, then final ground to spec size.  A
lab should be able to test several areas on the metal surface for hardness,
checked in several ways.  There are hardness gauges that punch a known force
into the surface, and the resulting imprint is measured, infrared spectronomy,
grind tests that detect the color and type of sparks from the grindstone, etc.

So to specifically answer your questions, yes and yes.

Regards,
Glenn  Merrell
Triumph Stag Register USA VP

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Daryl Gatenby wrote:
> 
> Can an accurate hardness test, to determine what the hardness of the teeth
> would have been when new, be carried out on W/P gear teeth that are severely
> worn down to the point where maybe only 20-30% of the bulk of the teeth is
> left?
> 
> In the case of the Jackshaft gear teeth and W/P gear teeth is it as straight
> forward as testing the hardness of the shaft next to the teeth in order that
> an indicative gear tooth hardness can be obtained?