BELT DRIVE DISCUSSION: PROS & CONS, COST/BENEFITS ... CHIME IN HERE.

[mikew5945]

do you have objective data ?

feel , and noticeable ,, are there any quantifiable values you can associate with those terms ?


If your going by hunch , I would suspect yes rotating mass in the motor and primary would allow the motor to spin up faster .. BUT only until the belt is engaged.

once the entire drivetrain is loaded from the motor to the snow . then it wouldn't matter.. the amount of resistance from the track spinning would be 100 times your reduced mass weight . so what was a small value of a idle speed motor load to a VERY VERY small value of a engaged load.

you sell and buy these lightweight drivetrain components ,so you drank the koolaid lol


when I was developing products , we would test them for consumer liking.
if the test variable would pass parody plus 10 points meaning 50 50 plus 10 points , then the juice might be worth the squeeze



to the loaded resistance argument:
nxt post

Wrong. Wrong. Wrong.
If life after loading a track doesn't matter then why do people buy a turbo?
There is a post above where CMX tested the belt drive against a chain drive. He used a drill to spin the track with a scale to tell the force used to turn the track and showed the amps used to power the drill. The math people can tell you what Horse Power is used to turn the track in both situations. The belt drive takes less HP to turn the track. This allows that unused HP to be used in spinning the track faster when loaded. This may be a small issue to you when you are playing with 180-300 HP. Now look at it when you are on just 60 HP. The benefit is now much greater.

 

[minet]

add

people buy turbos to add power


in the cmx experiment it showed less amps to turn over ON A STAND, there is a lot less resistance feedback spinning a track on a stand than when a sled is in snow pushing.. but you are right,, there is less amps drawn,, about 4 amps less if I recall.

ok now lets say that drill had the capacity to move the track in snow to the tune of 30 mph on a 60 hp sled . what would the amps be then.. ?
lets say 1000 amps on a belt drive 1006amps on a chain drive . that little bit is not worth 1000 $ to me.

belt drive is cool and it has some PROs, but my argument addresses just specifically the rotating mass being a significant reason to buy one.

 

[DITCHBANGER]

4amps is not very much for a grand let alone a tracke full of snow..heck that can just be that the chain was tightened a bit more than the belt during the test..ive never seen this test, but were the chain and belt tq'd the same amount?

 

[LPIdaho]

once the entire drivetrain is loaded from the motor to the snow . then it wouldn't matter..
the amount of resistance from the track spinning would be 100 times your reduced mass weight . so what was a small value of a idle speed motor load to a VERY VERY small value of a engaged load.

It would actually be once operating speed is reached, or full shift out of the clutches.
Less rotating mass isn't going to increase the top speed it just gets the vehicle to that top speed quicker.

 

[LPIdaho]

Here is an actual study for those that like to read

https://www.friction-facts.com/media/wysiwyg/Gates_Carbon_Belt_Drive_rev.pdf

 

[LPIdaho]

This study shows them to be equal in efficiency.
To me the reduced weight, rotational inertia and the ability to easily visually inspect the components is why I chose to run a belt drive PRO.

http://www.borgwarner.com/en/enews/Assets/2012_10_03_Engine%20Expo%202012.pdf

 

[kanedog]

Lightweight clutch covers, lightweight shafts, less rotating weight but then a track is 60lbs of rotating weight. Does losing 1lb of rotating weight on a belt drive compared to chain drive really matter when you have 60 lbs of track as rotating weight?
What say you?

 

[LPIdaho]

Lightweight clutch covers, lightweight shafts, less rotating weight but then a track is 60lbs of rotating weight. Does losing 1lb of rotating weight on a belt drive compared to chain drive really matter when you have 60 lbs of track as rotating weight?
What say you?

To me, absolutely matters! The energy it takes to spin up the clutches, for example, is independent of the track weight and vise versa.
And also because you are not rotating the fill weight of the track at all times. Only the portion around the drivers and rail tip and around the rear wheels and upper idlers. The rest of the track is moving relatively linear.

The Polaris LW crank is 2.5lb lighter(small compared to 60 lb of track) yet the race team has been winning hole shots like crazy and the racers have been raving about the increased throttle response and performance.

My drive train is almost 1.5lb lighter and the seat of the pants feel is dramatic. (because of the decreased rotational inertia not the weight it's self directly)

 

[GreenState]

If there is no benefit of reducing rotating mass, why not add more? Cast iron primary covers, chains from automotive CVTs, balanced lead-filled drive shafts, Kubota crank shafts?

There's no way adding rotational mass to your drivetrain would make your sled feel like it has less power and slower throttle response...

 

[mountainhorse]

You are exactly right!... adding mass will not add to performance.

Putting in a Duramax/Powerstroke/Cummins wont work either.

What are the weights and distances and how do they affect the performance in the end... are they major or minor. What are the tradeoffs?


.

 

[Snowmow]

If there is no benefit of reducing rotating mass, why not add more? Cast iron primary covers, chains from automotive CVTs, balanced lead-filled drive shafts, Kubota crank shafts?

There's no way adding rotational mass to your drivetrain would make your sled feel like it has less power and slower throttle response...

Reverse psychology. Works every time!!!

 

[mountainhorse]

IT'S A GOOD START!

Here's a video from CMX showing the efficiency of a belt drive.

https://www.youtube.com/watch?t=136&v=SNyq2spHkS0

I've watched the video from Mark Hoffman... and talked with him in person in detail about this.

He put some good effort into the setup and I've seen no one else do anything similar since.... Would be good to revisit this in a similar way with a more consistent method/subject.

It is a good start to methodology in getting an accurate idea about any improvement or detraction from performance in a belt drive.

The the test shown in the video...both machines are VERY different.

The test subjects... Stock Dragon, and a CMX first generation sled.

The CMX test-subject ran a shorter/different track, different track length, Different track width, shorter lug-height (taller lugs have more air resistance), The track was fully clipped (less hyfax friction) different drivers, much looser track tension, more tunnel clearance from D&R, different bearings, Lighter drive shaft, lighter jack shaft, different angle of attack, rail shape (kiked up or not), idler wheel diameter, etc etc... and we don't know the condition of the gears/chain/lube on the Dragon with chain.

ALL of those factors are important and will play a significant role in the outcome of the test.

I thought I saw a before and after video on the Dragon a while back using the same apparatus....and cant find it now.
But then again... that had many of the same differences in the setup/tension/etc. stock to CMXDS, so the drive cannot be isolated as the only factor.

The same test might be valuable "IF"...

The test were run on the same sled.

Simply adding an aftermarket drive to the test-subject-sled... like the TKI or Synchro drive...and use that sled as the only test subject.

It would be interesting to see differences in the two belt-drive kits as well.

Test conditions that would yield any meaningful result:
Use the same sled...only the secondary drive is changed.
Same driveshaft and drivers.
No changes whatsoever on the test sled besides adding the belt drive, test-to-test.
Same day... same test stand setup...back-to-back.
Confirm proper tension on the chain/belt.
Same gear/pulley ratio: 2.25:1 seems to common to both
Confirmed alignment of the input shaft on the motor.... best to use a double flex drive on the motor output and the jack-shaft input.
Same track, same suspension, same tension, properly tensioned chain and belt etc etc.



Also... the drive motor used would be best if it had a remote on/off switch rather than a trigger with variable speed and hand pressure that could be applied..

Now that type of test might give you an idea in the actual differences in the two drive systems.


.

 

[minet]

To me, absolutely matters! The energy it takes to spin up the clutches, for example, is independent of the track weight and vise versa.
And also because you are not rotating the fill weight of the track at all times. Only the portion around the drivers and rail tip and around the rear wheels and upper idlers. The rest of the track is moving relatively linear.

The Polaris LW crank is 2.5lb lighter(small compared to 60 lb of track) yet the race team has been winning hole shots like crazy and the racers have been raving about the increased throttle response and performance.

My drive train is almost 1.5lb lighter and the seat of the pants feel is dramatic. (because of the decreased rotational inertia not the weight it's self directly)

I appreciate your arguments and logic, but I want to point out that you sell a lot of light weight clutch components so profit from the theory that it matters.

as far as adding to the weight of drivetrain components with Kubota cranks and international harvester driveshafts. I would think there would be a point of diminishing returns on durability vs static weight gain. everything is a compromise

 

[minet]

Lightweight clutch covers, lightweight shafts, less rotating weight but then a track is 60lbs of rotating weight. Does losing 1lb of rotating weight on a belt drive compared to chain drive really matter when you have 60 lbs of track as rotating weight?
What say you?

its not just 60 lbs of track , most of the resistance will be from the snow. where the rubber meets the road so to speak.

 

[minet]

This study shows them to be equal in efficiency.
To me the reduced weight, rotational inertia and the ability to easily visually inspect the components is why I chose to run a belt drive PRO.

http://www.borgwarner.com/en/enews/Assets/2012_10_03_Engine%20Expo%202012.pdf

from this link ,, CONCLUSIONS

1. When both chain and belt drives are optimized they have similar efficiency

3. Chains are often the best solution for timing drives due to:
Minimized Package
Optimized Efficiency
Robustness Against Dynamic Instability
Proven Long Term Field Durability
Proven Adaptability Across Multiple Variants

 

[mtn-doo]

There is no question about efficiency with the belt drive. That is well known. The comments about mass HP and failures isn't the concern with bikes. Bikes are low HP and the belt drive technology is far beyond anything a bike could throw at it. From first hand experience, crash damage and alignment is the concern, not belt drive strength. The bikes are ridden hard and in crazy situations resulting in impacts and damage. The belt needs perfect alignment to stay functional. The chain and sprocket can limp out severely mis aligned. That will be the Achilles heel of the belt. A slight gain in performance? Yes. But the reliability or security after damage is the issue.

 

[CATSLEDMAN1]

chain vs belt vs gear vs helical gear

current sno bike technology appears may not be the best enviorment for a belt drive.....too flexy / too snowy / two wide.

The notion that a chain is the most efficient power transfer also doesn't apply to sno bikes....... too flexy / too snowy / too fast// too many o rings.

Sno bike chains work because they are cheap, handy and low tech. The application on sno bikes is counter to almost all the engineering data for good chain efficiency.

The evoutiion will have to be to snow proof two axis kind power transfer meaning shaft drives and eliminate two chains with one running in power dragging snow and ice.

 

[rab]

page 6 gives a bit of info

http://www.mtukrc.org/download/platteville/platteville_ic_design_paper_2014.pdf

 

[rab]

http://www.uwplatt.edu/files/sae/CSC_Documents/05_uw-platteville_design_paper.pdf

read a post on Doo Talk about another university having pretty much the same results with a 600 etec in norway

 

[mountainhorse]

These were not "University tests" but rather papers submitted by students for a grade and contest... I've done the same kind of thing for other projects in engineering coursework back when I was in my early 20's. I'd like to see the evaluation and review notes on these papers. There are very little sources quoted for any efficiency "claim" in the papers.

One of the papers actually is simply repeating the results of the other team from the same university student test results with a winch and scale. They are claiming that there was 30 lb (37%) reduction in pull resulting from the installation of a belt drive alone .... I find that hard to accept...especially with no test control stats posted... that part is vague at best.

I've also seen "test results" and video that was attempting to show increased efficiency of the belt compared to the chain... but all of those were using completely different sled configurations... different track (ply, lug height, durometer, clips etc etc) , different track-tension, different idler wheels, different track length, different hyfax, different angle of approach, different drivers and more.... I've yet to see a test result that was done, for example, the drill motor with amp-meter approach, that left the sled the same and had ONLY the drive changed from chain to belt. As a note: The university student project papers only used the drill/amp approach to compare different track/driver/idler combos... not secondary drives.


So again... I don't see any real engineering/scientific data using standardized testing to prove one way or the other... and come back to published research of the largest mfg of belt drives, Gates, that belt drives are approaching or equaling (not bettering) the efficiency of chain drive systems. (from links in the first post of this thread).




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