Friction belt drive design

[Tom Kitta]

So I have this somewhat semi complex friction drive as seen:

Here is the problem. The motor turning left is dragging the belts creating friction - it is hot within 30 seconds. The idler needs to move a lot to make the belts catch. Its as if the belts have super narrow sweet spot where they will not burn and the idler will make them catch.

Also I have a little run- away issue when the initial inertia is taken care off the power hammer just keeps on going - I have little friction in the system and thus very little energy is needed to keep moving.

Am I somehow on the right track?

Side note - I did not realize that so little tension is needed for these belts - did I do good going with 5/8? I went with 5/8 to make it more durable - also I did not think they will be so "stiff".

I am now working on making the hammer a bit stiffer as believe it or not I seem to have the 1/2" plate flexing a LOT - after like 10 strokes the hammer wants to walk out the door.

 

[140mower]

I suspect my words sre going to fail me, but here I go anyway. On a garden tractor you will find a belt guide that wraps around the drive pulley. When the drive is disengaged, the belt pushes back against the guide and clears the pulley. If you download a parts diagram of the drive pulley on a John Deere 110 garden tractor from the late 60's you will see what I mean. Seems simple, but it works.
Your motor needs a belt guide....

 

[historicalarms]

Im going to suggest your power hammer head is hitting solid at the end of every stroke , or the weight of it is causing the belt to slip just a smidge at the end of each stroke causing friction heating at every rotation and if it is running fast enough the heat isn't dissipating from the pulleys fast enough....the heat just keeps on building

 

[Tom Kitta]

OK, I try adding a belt guide - which I think is just a metal rod that will guide the belt closer to the pulley. Once I try it I let you guys know how it went.

 

[mbond]

Is it the motor that gets hot or the belts? I assume the belts

What you call the idler, is that cylinder on the left that is connected to threaded rod on some kind of arm? Probably the bottom of the vertical column is connected to a lever or some kind that you use to engage power to the hammer part (on the other side of the frame I think)

Assuming that that is right, and that the hammer part is probably heavy, heat in the belts suggests that they slip as the power is being applied. I don't see any break effect

If all of that makes sense, then I suggest that you have a geometry problem. The point at which your idler forces power on / lets power off should be more equidistant between other constraints on the belt. And the belt should have less slack overall. You can either adjust the parts that you have or add other rollers etc. but the point is that the power needs to be more firmly on when it is on, and more totally off when it is off - and not a narrow sweat spot

walking out the door is another question. making the machine heavier is the obvious first thing. Especially by adding sand or water into the lower portions. But it also highlights the problem with driving a power hammer with a 'direct' drive. It seems to be on the other side of the frame, but most power hammers have both a clutch (some kind of mechanism for operators to turn the power on and off) and something else that sits between the power and the hammer itself to absorb the large changes in forces as the hammer is drawn up, is accelerated down, makes an strike and repeats. I think often a flywheel meant to slip - such as a used tire - it used for this purpose. But I think there are a lot of choices, and it is hard to tell from only one picture