1912 Harvey power hammer patent

[Michael Moore]

Yoder/Pettingell-style but with solid links instead of the strapping to the head and adjustable mounts between the links and the leaf spring to vary the preload on the spring.

cheers,
Michael

[kit]

That's interesting.
I used chains instead of strapping on mine, it hadn't occured to me to use solid links.
Instinctively I think you would get more of a 'slap' action with straps or chains, which after all is most of the point of this kind of design, I wonder if that is the case?
I'm sitting here with one finger from each hand pointing at each other wanging them up and down pondering that one.

[Michael Moore]

Hi Kit,

the belting seems like it might add a little bit of extra springyness, but not something you could quantify very well.

The adjustable link pivots in this patent could be handy because the machines would likely have been running off of a line shaft and may not in those days have had a clutch for varying the speed. If they didn't, adjustments to the preload on the leaf spring might have been about all the tuning they could do, other than changing the weight of the upper hammer.

I've found lots of patents on sheetmetal machines but they tend to be folders/cutters/punches and not shaping hammers. Google Patents can sure supply hours of interesting reading!

cheers,
Michael

[kit]

the belting seems like it might add a little bit of extra springyness, but not something you could quantify very well.

I agree, just thinking that with webbing, when the links are moving just either side of horizontal they would allow the hammer to move up or down without compressing the spring as much as would happen with a solid link, I would imagine you'd have a larger 'soft' hit zone.
A lot to be said for a good slapper.