[TheForge] ALT Treadle Hammer Springs

[Jeffrey Polaski]

>A shock absorber defeats the purpose, they're intended 
>to damp rebound and you want your hammer head to 
>rebound.
Yes, that was the original thought and wouldn't make much sense...

Now that I think of it, I thought I saw a design for a junkyard hammer
that used a shock absorber or two to mount a weight for the hammer
head... li,ke the springs in a Little Giant. I don't remember where I
saw it, but I think there was a video. It looked like it would easily be
leathal to use, so maybe that's not such a good idea either...


Jeff Polaski

-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Jerry Frost
Sent: Wednesday, March 21, 2007 10:59 AM
To: artgawk at thegrid.net; Sponsored by ABANA
Subject: Re: [TheForge] ALT Treadle Hammer Springs

I have a little experience with pneumatic accumulators 
(spring analogs) and don't have an idea how well they'd 
work on a TH.

A shock absorber defeats the purpose, they're intended 
to damp rebound and you want your hammer head to 
rebound.

A pneumatic accumulator doesn't need to be heavy at 
all, there is a local car wash that uses them instead 
of garage door springs and they're 3" PVC. The garage 
doors feel a little odd but lift easily enough.

In theory pneumatic accumulators will replace 
mechanical springs in any linear application. In 
practice they don't do so well where they see a lot of 
movement as developed heat alters their action. A few 
years ago the head guy at Heavy Duty decided to replace 
the relief springs on the belly blades with a gas over 
hydraulic accumulator system. A belly blade used in a 
city needs to be able to give when you catch an 
obstacle like a high manhole, drop drain, etc. If 
there's no give in the blade they tend to get torn off 
doing considerable damage to all involved. Anyway, the 
gas over hyd accumulators worked okay for a while but 
after they got hot you couldn't lift them fast enough 
to avoid problems. They'd SHOOT down but creap up.

A little experimentation would answer the question 
regarding TH applications.

Frosty
-------------------------------
If it ain't forged
it ain't real.
Wrought iron is.
The FrostWorks

Meadow Lakes, AK.

http://www.artmetalradio.com/

From: "Peter Fels And Phoebe Palmer" 
<artgawk at thegrid.net>


>
>
> Jeffrey Polaski wrote:
>> Now that I read the message, I see I wasn't clear. 
>> I'm not sure what
>> they are called, but I was thinking of the big 
>> bag-type shocks, not the
>> regular car air-shocks.
>
> Shocks per-se sort of defeat the intended use. The 
> bladders are, in effect, compression springs but the 
> object here is to have a smooth, efficient, 
> frictionless way to make the hammer tup gravity 
> neutral...and the truck bladder doesn't sound all 
> that good.
> But a tightly inflated rubber ball in place of a 
> compression spring might work. There's more than one 
> way to use air for a spring and it'd be valuably 
> valveable.
> Looking at some independent front suspensions with 
> their double A arms moving in parallel and their 
> supplied spring and mounts ,has me wondering if we 
> aren't neglecting a ready-made treadle hammer 
> mechanism?
> Yeah, you'd wanna take off the shock absorber....pf
>  Those might work, too, but I'd think they would
>> wear out fairly fast.
> If you consider that 1/4 of the vehicle is riding on 
> that shock, and how many times a second it goes up 
> and down at freeway speeds, You'll see that wear 
> isn't going to be a big factor in a TH 
> application...pf
>>

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