Topic: actual driveline

[marcritter]

We are talking driveshaft ( direct drive) like a sprinter is setup, right?

sorta only no torque tube.

No, you should look thru the build section at proven driveline layouts and copy what works and is dependable


ie: 700 and cart axle or 600/820 trans axle and jackshaft

any way someone could help with the search im having a hard time

[GTX21]

Thats gonna be hard with a mower orginated trans or trans axel

[jeffescortlx]

Twisted belt system simply won't hold up to the higher rpms of a racing mowchine, allow a slip clutch to work properly, and loses a good bit of hp in the twist...

I'd like to know more about this.
Why is RPM such a problem? I'm pretty sure I've seen factory lawn mower's use a twisted belt to drive the mower deck, and that see's just as high as RPM's as we do driving the wheels.
I know a slipper pullley clutch wont work, but a centrifugal clutch should.
And I'd be willing to bet that twisting a belt 90º will take a lot less power then a bevel gear set.

[Squidd]

 

Why is RPM such a problem? I'm pretty sure I've seen factory lawn mower's use a twisted belt to drive the mower deck, and that see's just as high as RPM's as we do driving the wheels.

Not even close in rpm....

[jeffescortlx]

Not even close in rpm....

What do you mean not even close? The deck pulley off the engine is quite large, and the blade pulley small. In fact, I'm very sure that the deck belt RPM is spinning just as fast (if not faster) as some of you guy's drive belt going to the tranny.

[Squidd]

Belt speed is not there if the motor doesn't go over 3650 rpm...

and decks run constant rpm not on the gas off the gas

[jeffescortlx]

Belt speed is not there if the motor doesn't go over 3650 rpm...

and decks run constant rpm not on the gas off the gas

Sure the motor pulley does'nt see any thing over 3650 rpm's, but having a 6" pulley drive a 3" pulley is over driven enough to say that the belt speed is quite high.
Deck speed is pretty constant once on, but it still needs to be engaged and disengaged.

[Old Goat]

I'm not sure how to do the math, but an 8" pulley on a motor turning 6500 rpm will have a way higher belt speed than a 6" mower deck drive pulley on a motor turning 3650 rpm.

[Old Goat]

The belt speed is determined by the engine pulley diameter and the engine speed.
I think I got it figured out. Here's what I came up with.... A mower engine with a 6" pulley spinning at 3650 rpms will have a belt speed of 95.51 feet per second. An engine with an 8" pulley spinning at 6500 rpms will have a belt speed of 226.78  feet per second. That's a pretty big difference.
Now I gotta go rest! My little pea brain is tired!

[birdman_express]

I'm not sure how to do the math, but an 8" pulley on a motor turning 6500 rpm will have a way higher belt speed than a 6" mower deck drive pulley on a motor turning 3650 rpm.

 

6500 @ 8" = 13606 FPM

3650 @ 6" = 5730 FPM

Not even close.

[jeffescortlx]

How many of you guy's are running a 8" engine pulley?


And, how do we know RPM is a problem for a twisted belt set up? Why is it when the belts are parallel they can spin what ever RPM you can throw at it, but if you twist one of the pulley's 90º all of a sudden 3651 RPM's will cause it to exsplode?

[Rooster]

How many of you guy's are running a 8" engine pulley?

Most of us

And, how do we know RPM is a problem for a twisted belt set up? Why is it when the belts are parallel they can spin what ever RPM you can throw at it, but if you twist one of the pulley's 90º all of a sudden 3651 RPM's will cause it to exsplode?

In case you haven't noticed, some guys play heck keeping belts on a race mower.
One of the things George recently taught me, and my mower demonstrated well, is the slap you get out of a belt when you let off the gas. Basically, your pulling on it very hard, when you quit pulling on it the belt section behind the pulley has alot of stress and momentum in it and comes slamming forward. with out a good guide set-up it will throw the belt right off of a pulley. Twisting the belt would make this alot worse.You do not have this problem stock because you don't have near the stress or momentum in the belt.

And the calculation for belt speed is: Diameter of Pulley X RPM X .262

This is called Surface Feet Per Minute, or SFM. It is one of the most important calculations we use in machining and is applicable to any spinning object.


As far as twisting the belt, with the power we are putting to them, you'll twits the cords.

[Toadworks]

More than the math you learned in third grade..... Here is a link to a great chart that has several formulas for calculating the types of forces we deal with in building these machines. Many times what looks like it will be strong enough to do a job actually isn't because of the monumental amounts of torque, force and RPM applied to them.

[birdman_express]

More than the math you learned in third grade..... Here is a link to

Where is the link?

[racingjohndeere55]

I see, several posts ran together, and I got distracted on this one,.

I hate when that happens