Does lug height change the final drive ratio on a snowmobile

[ArcticCrusher]

1 hour ago, f7ben said:

Crusher must have realized he was wrong and went the way of Snowrider

 

 

No worries Ben.

 

 

Edited September 11, 2016 by ArcticCrusher

[ckf]

[Zambroski]

10 minutes ago, ArcticCrusher said:

 

 

No worries Ben.

 

 

Holy fucking shit!

 

[Jimmy Snacks]

16 hours ago, ArcticCrusher said:

 

 

No worries Ben.

 

 

[Highmark]

On 9/10/2016 at 4:23 PM, ArcticCrusher said:

No, the belt thickness changes the final gear ratio by one half of the thickness.  It's basic physics.

This is correct pending type driver.  Convolute v. involute.  

In a previous thread I posted a former Polaris race engineer's opinion which said exactly this.   Funny how people know more than him or other engineers. 

Edited September 12, 2016 by Highmark

[f7ben]

6 hours ago, Highmark said:

This is correct pending type driver.  Convolute v. involute.  

In a previous thread I posted a former Polaris race engineer's opinion which said exactly this.   Funny how people know more than him or other engineers. 

The thickness of the belt is only relevant in a scenario where you are measuring speed or distance traveled for a given point on the belt ......where the belt only drives a tracked vehicle on the flat plane of the contact patch the belt thickness is irrelevant .....I spoke at length about this with some very smart people at work today...some that are involved in the same type of things our dear crusher is speaking of

[f7ben]

here is the best way to think of this .....along the flat section of rail where the track is actually moving the sled forward ......the inside and outside of the track are moving at the same exact rate ....therefore there is no difference regardless of thickness of the belt or lug height etc

 

Boom ....done

[jammin]

Yes. 

Neal

[f7ben]

Oh Hai Jasmineings

[ckf]

4 minutes ago, jammin said:

Yes. 

Neal

[GreenStreak]

physics says a taller lug track has more mass and weight therefore requiring more energy to spin it as fast as the smaller lug track. so it definitely affects speed and power output.

[f7ben]

13 minutes ago, GreenStreak said:

physics says a taller lug track has more mass and weight therefore requiring more energy to spin it as fast as the smaller lug track. so it definitely affects speed and power output.

That has nothing to do with gear ratio

[Legend]

13 minutes ago, GreenStreak said:

physics says a taller lug track has more mass and weight therefore requiring more energy to spin it as fast as the smaller lug track. so it definitely affects speed and power output.

Take a look at some of the mtn tracks weights. They are lighter than trail tracks.

 

Btw, No possible way a different lug height changes final drive ratio. It's impossible. And it's not rocket science. 

 

[BOHICA]

Check this shit out....  So I was at safeway getting my lunch this morning.  Got a sammich, a banana, a cup of grapes....green and red intermingled in the same cup,  and a buy one get one free yogurt parfait.....  So I got two!!!!  America, Fuck Yeah!!!  Anyways when I got to the check out stand I told my coworker, that I know people who are very very smart on an internet chat room.  So I told him that I could get the parfait with blue berries and strawberries go faster at the check stand then the free one that had strawberries and pineapple even though they are the same size....  I told them you have to think of a conveyor as a wheel and the larger it is the faster it goes due to the final ratio of the conveyor being changed by the thickness of the belt....  So I set the blue berry/strawberry parfait on a little plastic round tin thingy of icebreaker gum......  and the other one with pineapple and strawberries directly on the conveyor.  So my blue berry parfait was at least and inch taller or so do to being on a "thicker" belt.  I told my buddy prepared to be amazed!!!!!  And had the checker person turn on the conveyor.....  Well fuck me they both arrived to the checker person at the same time   I figured the blue berry one would have pulled out at least a 1 parfait cup lead being on the thicker belt or taller lug by the end but it didn't.  They stayed equal in the race the whole way.  

 

Edited September 13, 2016 by BOHICA

[ckf]

[f7ben]

Bohica for the win lolz

[Zambroski]

10 hours ago, BOHICA said:

Check this shit out....  So I was at safeway getting my lunch this morning.  Got a sammich, a banana, a cup of grapes....green and red intermingled in the same cup,  and a buy one get one free yogurt parfait.....  So I got two!!!!  America, Fuck Yeah!!!  Anyways when I got to the check out stand I told my coworker, that I know people who are very very smart on an internet chat room.  So I told him that I could get the parfait with blue berries and strawberries go faster at the check stand then the free one that had strawberries and pineapple even though they are the same size....  I told them you have to think of a conveyor as a wheel and the larger it is the faster it goes due to the final ratio of the conveyor being changed by the thickness of the belt....  So I set the blue berry/strawberry parfait on a little plastic round tin thingy of icebreaker gum......  and the other one with pineapple and strawberries directly on the conveyor.  So my blue berry parfait was at least and inch taller or so do to being on a "thicker" belt.  I told my buddy prepared to be amazed!!!!!  And had the checker person turn on the conveyor.....  Well fuck me they both arrived to the checker person at the same time   I figured the blue berry one would have pulled out at least a 1 parfait cup lead being on the thicker belt or taller lug by the end but it didn't.  They stayed equal in the race the whole way.  

 

Holy fucking shit!   Totally worth checking back in on this bizarre thread!

Be warned, you're going to get some flack for such a long post though.  

[Highmark]

17 hours ago, f7ben said:

The thickness of the belt is only relevant in a scenario where you are measuring speed or distance traveled for a given point on the belt ......where the belt only drives a tracked vehicle on the flat plane of the contact patch the belt thickness is irrelevant .....I spoke at length about this with some very smart people at work today...some that are involved in the same type of things our dear crusher is speaking of

From the former Polaris Race Engineer.

Track pitch diameter – sorry for the confusion, when I was talking sprocket OD I was referring to involute drive tracks.  95% or more of the tracks in my racing world are involute drive.  Therefore the effective OD (not the same as pitch diameter) of the sprocket is the same as the measured OD.  I realize that some of the present day tracks are convolute drive or combination of involute and convolute.  REGARDLESS – the pitch diameter of the track/sprocket combination is the same as the neutral axis in the track band or carcass.  The neutral axis is the same location as the tensile cord in the track.  Otherwise as the track bends around the sprocket, the cord would try to stretch and compress and that would lead to cord separation and track failure. If I remember correctly, the neutral axis is approx 45% of the distance from the inner surface of the track band to the outer surface of the track band.  The thickness of the track band is the thinnest section of the track, the majority of the track band thickness not counting where embossments and such are located.  Again, lug height is not a factor!!!

 

 

For convolute sprockets, it’s the same; the pitch diameter is located at the neutral axis or the cord line of the track.  Some feature on the convolute sprocket will support the inside surface of the track.  Either it’s the round cylinder just inside the sprocket teeth or it could be were the track clips sit in the base of the sprocket teeth – which makes it more difficult to determine sprocket effective OD, track thickness, and neutral axis location.   Regardless, the sprocket designer has taken this into account so all the driving teeth on the sprocket have even contact on the track lugs as the track bends around the sprockets.

 

 

In the case where you have a convolute sprocket and the effective sprocket OD and track are hard to measure, I would go back to the calculation where you take track pitch (distance from one track lug to the next) and number of driving teeth on the sprocket, to calculate ideal pitch line circumference and pitch diameter for your speed calculation.  That assumes the sprocket designer got it correctly which is a good assumption, otherwise your track is being driven by primarily one tooth on the sprocket and you have bigger problems than a speed calculation.  I emphasize number of drive teeth on the sprocket because it can be different than total number of teeth.  For instance, the current 2.52 pitch tracks have one sprocket tooth per lug because that’s all there is room for between track lugs.  However, my old speed track was 3.29 pitch and there were two sprocket teeth between each lug, the front side of the first lug was under load during acceleration, the back side of the second lug was under load during braking.  In this case a 12 tooth 3.29 sprocket has only 6 driving teeth.  The beauty of that is - with the speed tracks and stainless plates on the inside of the track, you could place the stud head and plate right between the sprocket teeth and run rows of studs inline with the sprockets.  When you try to do this on a 2.52 pitch track, the stud heads and plates get into the way of the sprocket teeth.  I know this is not the case with the 0.525 profile grouser bar tracks because you can use a stud with a flush profile head that can be run inline with the sprocket teeth but then you need to run the hyfax right on the rubber and in speed runs that means lots of slide rail lube – tanks, pumps, battery.  Track pitch is easy to measure, pick a spot along the rail where the track is flat or straight.  Measure from the base of one drive lug to the same spot on the next drive lug.  Most of today’s tracks are 2.52 pitch.  The Skidoo’s have an oddball pitch, something like 2.82”???

 

 

Hope this helps.  Just keep in mind, regardless of lug height, the pitch line in the track determines track length and vehicle speed and that is at the neutral axis or cord line (tensile cord) location in the track.

Edited September 13, 2016 by Highmark

[Legend]

That "Polaris race engineer" article is not only old, but that guy must have just started with Polaris 5 mins before he wrote that piece. 

 

He basically talks about very little pertaining to the topic of final drive. Obviously he is a recent college grad, with no knowledge of snowmobiles and is trying to act like he has all the answers. 

 

But in the end, he is correct that the lug height cannot change the final drive ratio. 

Edited September 13, 2016 by Legend

[Kev144]

No

[ckf]

I'm shocked that Ben has only been able to pull off 6 pages so far

[Capt.Storm]

a tank works the same way really.

 

[Highmark]

4 hours ago, Legend said:

That "Polaris race engineer" article is not only old, but that guy must have just started with Polaris 5 mins before he wrote that piece. 

 

He basically talks about very little pertaining to the topic of final drive. Obviously he is a recent college grad, with no knowledge of snowmobiles and is trying to act like he has all the answers. 

 

But in the end, he is correct that the lug height cannot change the final drive ratio. 

LMAO!   He worked for years at Polaris then over 2 decades with Deere before retiring and is now racing again.   He in fact held a few long standing NSSR records, well his wife did as the driver.  He has forgot more about engineering and sleds than you will ever know.   BTW are you an engineer?  Its not an "article" its an email he sent me when I asked him the question to prove MachZnot wrong.  

Edited September 13, 2016 by Highmark

[ckf]

Just now, Highmark said:

LMAO!   He worked for years at Polaris then over 2 decades with Deere.   He in fact held a few long standing NSSR records.  He has forgot more about engineering than you will ever know.   BTW are you an engineer?  Its not an "article" its an email he sent me when I asked him the question to prove MachZnot wrong.  

I kind of miss that old goofball

[f7ben]

7 minutes ago, ckf said:

I kind of miss that old goofball

x2....you should bring him back if he promises to behave