Belt that's supposed to slip...Ain't!

bobodu · Sep 6, 2004

Belt that\'s supposed to slip...Ain\'t!

I'm building an unstyled tractor out of stuff that I am scrounging up.One belt goes the from motor to freeaxled pulleys and another belt goes back to the tranny.I put an idler pulley on the belt coming from the motor to the freewheelers expecting the belt to slip until the idler is engaged.It ain't.....ought to have enough play in that puppy.I'm missing something easy here and don't have anything similar around.Oh Gawd...just remembered the wife's MTD. Umm..rather hear something from you guys than be caught looking under that thing /forums/images/graemlins/blush.gif

Egon · Sep 6, 2004

Re: Belt that\'s supposed to slip...Ain\'t!

Our 1975 Sears 16 HP garden tractor had belt drive just like you have described. Worked very well.

Is the belt you are using sized for the pulleys?

Egon

bobodu · Sep 6, 2004

Re: Belt that\'s supposed to slip...Ain\'t!

I'm guessing that's the problem here.The belt sits way deep on the motor pulley.

beenthere · Sep 6, 2004

Re: Belt that\'s supposed to slip...Ain\'t!

You may need a 'stop' or 'guide' on the backside of the belt on the side without the idler pulley. That keeps the belt straighter between the driven and drive pulley, and keeps it from dropping down into the drive pulley. Hope this makes sense. Without this guide, the belt will arch up too high on the side without the idler. That will cause it to grab. Just have the guide close enough to the belt that it doesn't touch when the idler is 'engaged'.

I may not interpret your problem, but wanted to give you my speculation of what I perceive your problem to be.
I've 'beenthere'. /forums/images/graemlins/wink.gif

bobodu · Sep 6, 2004

Re: Belt that\'s supposed to slip...Ain\'t!

Been thinking about that pin they have on some Briggs engines I've played with.Unfortunatly,that equipment is out on loan right now.I did find a pulley around here that was adjustable-width wise and bored it out to 3/4 inch.Alas,I had forgotten what a key shaft would do to hole when the pulley is not mechanically fixed.Drifted toward the slot.Gonna get another pulley.I thank you for letting me know where to put that stop, pin,guide,keeper thingy /forums/images/graemlins/wink.gif Pretty sure it was useful...but where! Got it now....i hope.

mrcaptainbob · Sep 7, 2004

Re: Belt that\'s supposed to slip...Ain\'t!

Maybe be not enough slack? That idler should be on the 'push' side of the power pulley. Sixty percent is the usual belt contact area on pulleys. More is better. So that should be your contact goal after idler engagement. Also, if you give your idler a good swing arc/distance then the belt should slip. If you can accomadate it, go with a slightly longer belt and increase the idler travel.

slowrev · Sep 7, 2004

Re: Belt that\'s supposed to slip...Ain\'t!

Are you using a utility type of belt of automotive type of belt ? The automotive type of belts will often not work properly in a slip required application.

bobodu · Sep 10, 2004

Re: Belt that\'s supposed to slip...Ain\'t!

Ok fellas..here we go again.Got a B size pulley to match the one on the bottom and a B belt 2 inches longer.Used dowels to push,pull and otherwise flex the belt trying to get the slip.I looked to my antique cultivator for clues and noticed the the drive pulley is MUCH smaller than the load pulley.As it sits now,I'm using two six inchers.I think my tiller is set up this way but the DPN (darned previous neighbor) still has it.Would the vertical run of the belt have a bearing on the problem? Of all the stupid,silly,furshliginer ..... /forums/images/graemlins/confused.gif

Egon · Sep 10, 2004

Re: Belt that\'s supposed to slip...Ain\'t!

On my sears with a belt drive the motor pulley was about 3" compared to 10" on the transmission.

Egon

Soundguy · Sep 11, 2004

Re: Belt that\'s supposed to slip...Ain\'t!

Here's an idea.. what about an electric clutch.. like off a riding lawnmower, or one of those trail mowers??

Heck.. an ac clutch if you could rig it?

Soundguy