real benefits of belt drive
- Thread starter minet
- Start date
How much weight was saved on the Pro between 2012 to 13 from just going from a chain to a belt? It seems like it would be pretty negligible.
For me, it's the design that matters more than anything.
Improper chain deflection is a huge power loss that people overlook all the time.
I've run some sleds without adjusters. The chains and gearing where just perfect.(However new chains were needed every few hundred kms) I doubt in those circumstances the efficiency % changes much. However heat and drag is created which leads to a loss of power(Power = energy)
However in the case that one has to run a adjuster and because deflection changes often with a wearing chain, I believe the belt drive helps in that regard.
The transfer of energy is more efficient with a belt drive. Heat, slippage, mal-adjustment all robs energy(HP and Torque) and if you can eliminate or at least decrease it, the more energy gets transferred to where we want it to go(the track)
Improper chain deflection is a huge power loss that people overlook all the time.
I've run some sleds without adjusters. The chains and gearing where just perfect.(However new chains were needed every few hundred kms) I doubt in those circumstances the efficiency % changes much. However heat and drag is created which leads to a loss of power(Power = energy)
However in the case that one has to run a adjuster and because deflection changes often with a wearing chain, I believe the belt drive helps in that regard.
The transfer of energy is more efficient with a belt drive. Heat, slippage, mal-adjustment all robs energy(HP and Torque) and if you can eliminate or at least decrease it, the more energy gets transferred to where we want it to go(the track)
M
minet
Well-known member
For Ricky Bobby question.
Up to the primary. Sure less mass.would rev you up faster. Until you get good belt engagement
But in the real world conditions when all aspects of the driveline is engaged there are just so many variable s to.pin point mass as a gain. Snow conditions . Rider weight. . Everything. In a perfectly controlled environment on a track dyno. You may be able to prove a gain..
That's my theory. . It has holes but it makes the most sense to me. And everyone is just buying into hype
Up to the primary. Sure less mass.would rev you up faster. Until you get good belt engagement
But in the real world conditions when all aspects of the driveline is engaged there are just so many variable s to.pin point mass as a gain. Snow conditions . Rider weight. . Everything. In a perfectly controlled environment on a track dyno. You may be able to prove a gain..
That's my theory. . It has holes but it makes the most sense to me. And everyone is just buying into hype
J
Jaynelson
Well-known member
I don't care where you save it, but saving any rotating mass will always have a greater benefit for acceleration/deceleration than saving stationary mass. Sleds, cars, blenders, all will benefit from increased acceleration from a decrease in rotating mass and/or efficiency of a rotating assembly (as Reeb explained). It's physics 101....not really up for debate.
Now, whether or not it's worthwhile on a sled is a different question. I've ridden newer Pro's with the belt drive, and would say they have a noticeably more direct feeling to the drive; I would say it's noticeable. That said, I totally agree it's splitting hairs with all the other variables, but that argument is really no different for many other mods....can you really notice the HP differences for can, slightly different pipe, slightly different track, etc, etc. Everyone will say they can, but often that is simply cost justification after the fact.
Now, whether or not it's worthwhile on a sled is a different question. I've ridden newer Pro's with the belt drive, and would say they have a noticeably more direct feeling to the drive; I would say it's noticeable. That said, I totally agree it's splitting hairs with all the other variables, but that argument is really no different for many other mods....can you really notice the HP differences for can, slightly different pipe, slightly different track, etc, etc. Everyone will say they can, but often that is simply cost justification after the fact.
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M
minet
Well-known member
yah that makes sence, but i think that is more of an academic argument than actual performance results
conventional drive train format ..
engine fixed to primary
secondary fixed to all downstream components and track
belt is the dynamic tie between
the power ultimately is released to make the track spin, there is inherit drag and loss of efficiency with every transfer point.
primary to belt
secondary to jackshaft belt slip
chain / belt power transfer from jack shaft to drive shaft
there is room for improvement and increased efficiency within all those power transfer points on a sled..
the key component of my argument is the power transfer from the track to the ground.
snow pack composition, and all natural sciences that go into the creation of a snowflake and the matrix that forms them together..
we all know track speed is not the same as ground speed
track speed is what all the components efficiency produce, ground speed is the end result.
if we were concerned with rotating mass we would all be running 121s with .375 or shorter lug high ,, this would produce the highest track speed.
low inherit rotating mass and * key attribute* low resistance feedback from the snow to the track.
but we run 2 inch , 2.25 2.5 and now 3 inch tracks ,, 144 152 164 174 lengths
the longer the track , the deeper the lug the more resistance feedback is translated from the track to the snow.. pushing us forward, faster, and higher
lets for sake of argument there is 5 lbs of inherit drag or efficiency loss from the secondary to driveshaft drivers ..you can measure that with the track off and turn the secondary by hand and see how hard it is for you to make the drivers turn by rotating the secondary by hand.
now put the track on the drivers and get it all ready to run..
then turn the secondary by hand with the sled in 2 feet of fresh powder and the track is a 174 x3 16 wide .. how easy will that bee to turn the secondary by hand?
ok that is resistance feedback. and i would take a stab and say its 50 lbs ,,
ok before the track was on there was 5 lb resistance ,, now there is 55 lb resistance..
lets say a belt drive is twice as efficient as a chain .. brings that down to 2.5.. track still produces the same amount of feedback
so
chain drive 55 lb resistance
belt drive 52.5 lb resistance
kind of spending a pound to save a penny
conventional drive train format ..
engine fixed to primary
secondary fixed to all downstream components and track
belt is the dynamic tie between
the power ultimately is released to make the track spin, there is inherit drag and loss of efficiency with every transfer point.
primary to belt
secondary to jackshaft belt slip
chain / belt power transfer from jack shaft to drive shaft
there is room for improvement and increased efficiency within all those power transfer points on a sled..
the key component of my argument is the power transfer from the track to the ground.
snow pack composition, and all natural sciences that go into the creation of a snowflake and the matrix that forms them together..
we all know track speed is not the same as ground speed
track speed is what all the components efficiency produce, ground speed is the end result.
if we were concerned with rotating mass we would all be running 121s with .375 or shorter lug high ,, this would produce the highest track speed.
low inherit rotating mass and * key attribute* low resistance feedback from the snow to the track.
but we run 2 inch , 2.25 2.5 and now 3 inch tracks ,, 144 152 164 174 lengths
the longer the track , the deeper the lug the more resistance feedback is translated from the track to the snow.. pushing us forward, faster, and higher
lets for sake of argument there is 5 lbs of inherit drag or efficiency loss from the secondary to driveshaft drivers ..you can measure that with the track off and turn the secondary by hand and see how hard it is for you to make the drivers turn by rotating the secondary by hand.
now put the track on the drivers and get it all ready to run..
then turn the secondary by hand with the sled in 2 feet of fresh powder and the track is a 174 x3 16 wide .. how easy will that bee to turn the secondary by hand?
ok that is resistance feedback. and i would take a stab and say its 50 lbs ,,
ok before the track was on there was 5 lb resistance ,, now there is 55 lb resistance..
lets say a belt drive is twice as efficient as a chain .. brings that down to 2.5.. track still produces the same amount of feedback
so
chain drive 55 lb resistance
belt drive 52.5 lb resistance
kind of spending a pound to save a penny
I'm going to be building a few resto mod sleds this summer just for fun. It'll be interesting to see how much drag each component actually adds to the entire system. I'll use my uber scientific fish scale to measure my results. I think it'll give me a much better understanding as to what area of the drivetrain I should be focusing on when it comes to efficiency and maximizing it.
G
geo
Well-known member
Biggest benefit to me is ever since I saw the first belt drive on a sled I've wanted one lol.
It came stock but I needed to spend a couple more bucks to gear it down. That was a bigger benefit.
In the end, when I'm having a hoot in nut deep snow, I don't care about the physics of it. But it looks purdy and I'm closer to another dream of a 400 lb sled.
It came stock but I needed to spend a couple more bucks to gear it down. That was a bigger benefit.
In the end, when I'm having a hoot in nut deep snow, I don't care about the physics of it. But it looks purdy and I'm closer to another dream of a 400 lb sled.
Rode a couple of 12 pros, felt doggy to ride. Rode a couple of 13 pros feels snappy, only major change, belt drive. It must work. Put one on my cat, feels better to me. Thought maybe it was in my head trying to justify the cost. Let a couple of guys ride it, without telling them it has a belt drive, first response was "great throttle response". They work IMO
S
snengineer
Well-known member
rotating mass could be an exponential relationship, not sure if it is but if it is then that changes things big time.
D
Deep Powder Guy
Banned
There are just way to many variables in the CVT (primary, secondary, chain or belt drive) component of a snowmobile to make any valid claims regarding rotating mass. At the end of the day a snowmobile like any moving vehicle is one rotating mass which is at the mercy of how the vehicle is being used....if all we did on our snowmobiles were to go down perfectly straight groomed trail at 40 mph than perhaps rotating mass can be accounted for but for many that's just not the case especially for the masses that flex there sleds through chest deep powder in a variety of snow density conditions. Although I'm not 100% convinced the belt drive is better I will concede that saving weight is always beneficial for the "overall" vehicles rotating mass.
DPG
DPG
M
minet
Well-known member
great thoughts,
contemplating this further
pre full primary belt engage , i can see a motor could spool up to that point quicker.. .2 seconds? idano
once the rest of the drivetrain in engauged from primary to the snow is still the same,, kinda
two things that get me,
rehashing the previous
terminal velocity ,
the total sum of resistance feedback from the snow to primary
i don't think that would change much from chain to belt and if so negligible, track still produces identical feedback
power passes through a static system be it belt or chain ( gear/tooth )
belt or chain has no effect on secondary and primary dynamics
2nd point
spool up / inertia
it takes more power to start moving a heavier object and increase its speed than a lighter. but again the difference in resistance from the snow to the primary is near the same.
the difference is the total weight of the chain and gears vs total weight of the belt and gears
both are static to upstream ( secondary/jackshaft ) and downstream( drivers /driveshaft)
arbitrary number used in first post*
so does 52.5 lb spool up quicker than 55 lbs ,, yup but how measurable
will 52.5 lb have a higher terminal velocity ( topspeed ) than 55 lb , yup but how measurable
do any other motor sports have a set precedence post drive train engagement ?
lightweight flywheel sure ,, until pressure plate / clutch engage on a standard transmission. never heard of a lightweight pressure plate, carbon fiber drive shafts, CV axles, ring and pinon gears?
, MPG and efficiency / performance is at the forefront of the market influences.
some cars are designed to be lightweight to reduce total weight for mpg or hp/lb ratio ect .. there are not many lightweight rims or tires mentioned as marketable attributes. and most high performance cars use larger and wider tires to increase the traction
just rambling now , losing overall weight of a sled ,, great,, and measurable performance
losing 2.5 lbs of rotating mass after the primary is engaged , i argue is more hype than measurable performance.
but as said earlier, they are trick and sexy and i still want one, for the coolness factor and the overall weight loss
contemplating this further
pre full primary belt engage , i can see a motor could spool up to that point quicker.. .2 seconds? idano
once the rest of the drivetrain in engauged from primary to the snow is still the same,, kinda
two things that get me,
rehashing the previous
terminal velocity ,
the total sum of resistance feedback from the snow to primary
i don't think that would change much from chain to belt and if so negligible, track still produces identical feedback
power passes through a static system be it belt or chain ( gear/tooth )
belt or chain has no effect on secondary and primary dynamics
2nd point
spool up / inertia
it takes more power to start moving a heavier object and increase its speed than a lighter. but again the difference in resistance from the snow to the primary is near the same.
the difference is the total weight of the chain and gears vs total weight of the belt and gears
both are static to upstream ( secondary/jackshaft ) and downstream( drivers /driveshaft)
arbitrary number used in first post*
so does 52.5 lb spool up quicker than 55 lbs ,, yup but how measurable
will 52.5 lb have a higher terminal velocity ( topspeed ) than 55 lb , yup but how measurable
do any other motor sports have a set precedence post drive train engagement ?
lightweight flywheel sure ,, until pressure plate / clutch engage on a standard transmission. never heard of a lightweight pressure plate, carbon fiber drive shafts, CV axles, ring and pinon gears?
, MPG and efficiency / performance is at the forefront of the market influences.
some cars are designed to be lightweight to reduce total weight for mpg or hp/lb ratio ect .. there are not many lightweight rims or tires mentioned as marketable attributes. and most high performance cars use larger and wider tires to increase the traction
just rambling now , losing overall weight of a sled ,, great,, and measurable performance
losing 2.5 lbs of rotating mass after the primary is engaged , i argue is more hype than measurable performance.
but as said earlier, they are trick and sexy and i still want one, for the coolness factor and the overall weight loss
One does not have to look very hard to find the benefits of the lightest drive train that will reliably do the job. A few minutes on Google and look what has been done in drag racing. In an effort to keep shaving times with the same car, same engine, same tune. Race teams have tapped the high end transmission builders to save weight and parasitic drag from the rotating internals. Many have been stuffing the smaller lighter 404 internals into other housings. Some have gone as far as making billet aluminum 404 internals (planetary gears included) to drop the inerta value to gain acceleration and reduce parasitic drag.
This thinking in my opinion is a direct carry over to the demise of the chain case and all it's weight and parasitic drag (pin to plate as well as plate to sprocket friction as well as the drag of slinging the oil around after draging the chain thru the bath). I've run triple roller chain and aluminum sprockets for years to cut the inertia and parasitic drag to a minimum but going to the belt drive is the next step. Now that they finally have the belts strong enough to handle the stresses that a sled dishes out.
The other plus to belts is less HP lost due to heat generation. A sled with a chain case, even a well maintained one. Will boil off the oil in a good day of riding (why they only run genuine Dino oil in the iron dog sleds, the synthics don't survive the heat generation and boil off in short order). While belt tooth profile and proper design play a large role in the amount of heat generated in a belt drive, a properly designed and tensioned system will never get much over 150 degrees F. 100 plus degrees cooler than a chain case in similar conditions.
Ultimately I'd like to see a system that is under 10-15 pounds of total rotating weight from crank shaft to track. I have one on the drawing board currently but the technology is still too expensive to bring it to production, at this point.
Most current systems are pushing 40-50 pounds crankshaft to track.
This thinking in my opinion is a direct carry over to the demise of the chain case and all it's weight and parasitic drag (pin to plate as well as plate to sprocket friction as well as the drag of slinging the oil around after draging the chain thru the bath). I've run triple roller chain and aluminum sprockets for years to cut the inertia and parasitic drag to a minimum but going to the belt drive is the next step. Now that they finally have the belts strong enough to handle the stresses that a sled dishes out.
The other plus to belts is less HP lost due to heat generation. A sled with a chain case, even a well maintained one. Will boil off the oil in a good day of riding (why they only run genuine Dino oil in the iron dog sleds, the synthics don't survive the heat generation and boil off in short order). While belt tooth profile and proper design play a large role in the amount of heat generated in a belt drive, a properly designed and tensioned system will never get much over 150 degrees F. 100 plus degrees cooler than a chain case in similar conditions.
Ultimately I'd like to see a system that is under 10-15 pounds of total rotating weight from crank shaft to track. I have one on the drawing board currently but the technology is still too expensive to bring it to production, at this point.
Most current systems are pushing 40-50 pounds crankshaft to track.
Just a thought here, but I was under the impression that a Diamond Lite Drive, driveshaft, brake, and secondary was in the neighborhood of 27lbs. I might be wrong but that number rings a bell.
That number may be accurate, I have not weighed that one. My guess would be without secondary, but regardless, add the primary and the belt and you are pushing 40#'s.
My system is without both the primary, secondary, and drive belt as it eliminates all of that and achieves the CVT function in a completely different way, everything takes place inside the drive shaft to further centralize / self cancel the gyroscopic effects and centralize the mass.
It's not exponential but it is inversely proportional.
Inertia is to rotation what mass is to linear motion.
So if you went from an Inertia of 5kg*m^2 to 4 kg*m^2 the second one would accelerate at 5/4 times faster (25% higher).
Or to achieve the same acceleration it would take the square root of (5/4) or ~ 12% less input (energy).
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minet
Well-known member
loud handle, what you are designing sounds a lot like a viscous coupling differential.
interesting concept , removing the jack shaft all together
oh and im sure in the most extreme of performance applications where .001 thousands of a second determine a Win or a loss such as in drag racing. i agree all out performance every bit of weight loss to the drive system would be best.
same could be said for the space shuttle . all out spare no expense performance such as these extreme engineering examples.. i totally agree.
and thank you for your input
interesting concept , removing the jack shaft all together
oh and im sure in the most extreme of performance applications where .001 thousands of a second determine a Win or a loss such as in drag racing. i agree all out performance every bit of weight loss to the drive system would be best.
same could be said for the space shuttle . all out spare no expense performance such as these extreme engineering examples.. i totally agree.
and thank you for your input
My intellectual property lawyer told me not to discuss any specifics until it is patented, but not viscous in design.
I concur that for most people the difference between the drivetrain designs is indistinguishable. Shortly after getting into sleds, I started racing and being very mechanically inclined I started looking for ways to get an edge over others. Essentially trying to use technology to over come my deficiencies as a rider. I never really achieved that goal but now thirty years later and having invested about half a million, and thousands of hours of thought and CAD drawings and research, over the years. I think I'm getting close. : ) Winning was easy to achieve when I farmed the piloting to friends with more natural ability than I have.
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