Hot Rods Curious tool

A friend just showed me a tool today that he has owned for many years. I had never seen one of these before. Anyone familiar with this tool?

 

Does it include the instructions? this is from the interwebs from a past auction of one

 

Yep it’s peening hammer. Used for peening (stress relief).

 

Is that intended to expand collapsed piston skirts? Reduce slap and noise?

 

No, it changes the surface structure of the material not its shape. In very very simplistic terms it makes it stronger

 

Actually, that's a little too simplistic. Peening as it is commonly used puts the surface in a state of compression which causes it to resist cracking. This makes the part more resistant to breaking but not really stronger. Peening a relatively thin section can also expand it which is why I speculated as to this tools purpose. We won't really know until someone comes up with the complete instruction sheet.

 

yes, the same instructions are inside the box. Dave

 

so of course you have to scan/photograph all of them and post here, for posterity...

 

So am I understanding this correctly, the hammer head moves like a hammer should while the handle doesn't move? All powered by air.

 

Good scans of the instruction sheets would be very helpful.

If the tool is still in working order, then a video (even a short one) of the tool in use on an old, scrap piston would be the "icing on the cake"!

 

Photos of the instructions.

 

Fantastic! Thanks for taking the time and effort to post this information. These older full skirt pistons seem to have been fitted differently than more modern slipper skirt styles. They don't seem to put any effort into peening the areas that are perpendicular to the pin bores.

 

Never saw that tool before. Thanks for posting all the info.

 

Very interesting. Thank you for posting.

 

This is correct. Peening results in the surface to have compressive stresses, which improves fatigue cracking resistance. It does not have enough depth to affect strength of the material, being only a few thousandths typically. Shot peening is a similar end result as this manual hammer peening. Valve springs are one example part that has shot peening done, as they obviously go through numerous cycles - which is what fatigue is. Thousands and thousands of stress cycles that are in the eleastic range (below the yield strength). Fatigue cracking is NOT because the metal got weaker, like when you think of your muscles fatigued from work. Totally different, but uses the same base word. Fatigue in metals is where there is repeated cyclic tensile stress, and a crack can initiate and propagate. Eventually this crack becomes too big and the part experiences catastrophic failure and breaks due to overload; since the remaining uncracked portion can not support the operating load.