Classic Sears Mule Design

["Manic-Mechanic" 1,194]

I have an idea to engineer an attachment for a Sears Suburban/David Bradley 4-Wheel Tractor, utilizing the mule slot for running a compressor head. I have the late push lever & rod going to a slide bracket support for belt tension. I have everything roughed in but not secured as yet. I am wondering if I need a pulley somewhere along the belt to help disengage whenever the mule slide is retracted, allowing the engine pulley to rotate freely. Any thoughts would be greatly appreciated and successful idea pictured in the next phase of the design.

 

 

Oldman

[WHNJ701 4,165]

The 2 wheel david Bradley's had a compressor attachment, might want to look into that. I don't think it had an additional pulley 

 

Now go to chalk board and write "my hood is not a workbench" 10 times

["Manic-Mechanic" 1,194]

Ha, ha, ha! My hood is not a workbench! This is a totally not factory thing. The early david bradley 4 wheeled tractors didn't use a moving mule. That came out mid sixties. So this will slacken up but still turns a bit. I make it too loose the belt will just drop off. So, something is needed, may be an idler?

[R Scheer 502]

Maybe a belt guide?  Something along the lines of the drive belt on a Wheelhorse when you press the clutch?

 

Jhst a thought 

["Manic-Mechanic" 1,194]

I was thinking of the belt guard as well, even so, there is an idler pulley under that guard.

[echris 1,425]

5 hours ago, jabelman said:

Now go to chalk board and write "my hood is not a workbench" 10 times

I laughed way too hard at this. Nice.

[R Scheer 502]

Looking at the drawings, the idler wheel puts tension on the belt so you can move.  When you press the clutch it moves the idler wheel away from the belt.  It doesn't look like it helps hold the belt on the pulleys when you've engaged the clutch.

 

You're doing the same function as the idler wheel by sliding the compressor forward and back.

 

My question is how are you stopping the compressor from going overpressure, ie tractor running, compressor on, no load on compressor (no tool using air).  Might you be better going with an electric clutch?  This way you can fix the compressor in place, engage with a toggle switch, and possibly put a pressure switch in series so if the output pressure goes too high, the compressor will stop  and restart when the pressure drops below a set value.  Just thoughts

 

 

["Manic-Mechanic" 1,194]

There are manual overload valves that would allow discharge upon reaching set pressures, I've used them with other fuel driven systems. To use an electric clutch would be difficult to place with the drive pulley already in place.  (good idea though) I was thinking about a Sears Snow Blower attachment which was engaged in the same manner, however, while disengaged there is a pulley and a brake. This is why the components are not installed as yet, don't want to damage the frame or anything until this gets figured out. Just an idea I've had in my minds eye for many years, but no free time! Retired now, so........

[Razorback 1,035]

I don’t remember where I saw it or what kind of GT it was on, it was either a compressor or a generator that was mounted on the front on a metal plate on some sort of hinge. The weight of the compressor or generator was used to tension the belt (maybe even some additional weight on the plate?), with a lever/handle to provide just enough lift on the plate to take tension off of the belt.

 

Just providing that mental picture to consider in your design. 

Edited October 3, 2020 by Razorback

["Manic-Mechanic" 1,194]

Yes, the Sears mule has a rod which travels under the front end. The platform that compressor is on slides in and out for the desired tension. The lever has a double hinged linkage to remain tight once pushed forwards. This much I have reproduced onto this older machine. From this David Bradley on up the front slot remained the same, hence the press brake formed U to accommodate the slot. The issue is the belt while loose still rotates off the drive pulley. Puzzling since the belt drive below it works off the same principle and just simply stops when belt is slackened? Odd? Maybe it's because the drive belts are behind the pulley and this belt for the compressor, is forward of the drive pulley?

Edited October 3, 2020 by oldman

[R Scheer 502]

Possibly,  but are the belts the same construction.  I've read that some belts have too much friction, and don't release.  Something about rubber vs fabric covered.  Just another thought  that you've probably already thought of.

["Manic-Mechanic" 1,194]

No, not really. I generally get Kevlar. I haven't calculated the belt size as yet. The other belts on this are Kevlar. I know this isn't an absolute necessity, but it would be fun to get it operational.

 

Edited October 3, 2020 by oldman