DemonRC
Senior Member
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- Houston, TX
No, they won't be in production this year. We'll get back on this project in late winter or early spring.
For those that don't know what a CVT is, a CVT is an infinitely variable transmission sometimes refered to as an IVT. I'll try to be as basic as possible and skip all the BS CVT terminology. The CVT is an invention of Divinci and is now commonly used in all types of recreational vehicles and a handful of automobiles like the Nissan Murano, Maxima, Audi's, etc. This belt type uses a centrifical force clutch to sandwich a belt between two pulley halves known as the "drive" pulley. As the force (rpm) increases, the pulley haves sqeeze together causing the belt to ride higher in the drive pulley. This causes the belt to ride lower in the 2nd pulley known as the "driven" pulley. This changes the gear ratio like raising the pinion gear tooth count and lowering the spur gear tooth count in a infinite series of steps.
There are drawbacks to using this tranmission, hence the reason why we are releasing a traditional 2 speed instead of a CVT. First, CVT belt drives are inefficient. They hover around the 85% efficiecy range. Compare that to a 93% range for gears and upward of 98% for timing belts. The reason is simple. The belt creates alot of friction on the pulley faces as it is turned within the pulley. Thinner belts help the issue but increase the 2nd major problem of a belt CVT which is poor torque transfer. Basically, it'll slip if too much torque is applied. So we applied more belt tension to stop the slippage which increases problem 1. There is a solution there and that is in a custom belt. We'll get back on producing that belt next year.
One thing you'll notice as that there is not alot of belt travel like you see in CVT's on scooters, motorcycles, etc. The setup you see right here is equivilent to a 3 tooth jump on a pinion and spur gear. We could actually run though about a 6 tooth jump on this same unit, however, we had to add some spacers to take up some of the belt slack which put a minimum cap on the low end. Basically, it won't allow the belt to drop down into the drive pulley all the way.
[ame=
[MEDIA=youtube]znV1UY-bbV4[/MEDIA][/ame]
For those that don't know what a CVT is, a CVT is an infinitely variable transmission sometimes refered to as an IVT. I'll try to be as basic as possible and skip all the BS CVT terminology. The CVT is an invention of Divinci and is now commonly used in all types of recreational vehicles and a handful of automobiles like the Nissan Murano, Maxima, Audi's, etc. This belt type uses a centrifical force clutch to sandwich a belt between two pulley halves known as the "drive" pulley. As the force (rpm) increases, the pulley haves sqeeze together causing the belt to ride higher in the drive pulley. This causes the belt to ride lower in the 2nd pulley known as the "driven" pulley. This changes the gear ratio like raising the pinion gear tooth count and lowering the spur gear tooth count in a infinite series of steps.
There are drawbacks to using this tranmission, hence the reason why we are releasing a traditional 2 speed instead of a CVT. First, CVT belt drives are inefficient. They hover around the 85% efficiecy range. Compare that to a 93% range for gears and upward of 98% for timing belts. The reason is simple. The belt creates alot of friction on the pulley faces as it is turned within the pulley. Thinner belts help the issue but increase the 2nd major problem of a belt CVT which is poor torque transfer. Basically, it'll slip if too much torque is applied. So we applied more belt tension to stop the slippage which increases problem 1. There is a solution there and that is in a custom belt. We'll get back on producing that belt next year.
One thing you'll notice as that there is not alot of belt travel like you see in CVT's on scooters, motorcycles, etc. The setup you see right here is equivilent to a 3 tooth jump on a pinion and spur gear. We could actually run though about a 6 tooth jump on this same unit, however, we had to add some spacers to take up some of the belt slack which put a minimum cap on the low end. Basically, it won't allow the belt to drop down into the drive pulley all the way.
[ame=
[MEDIA=youtube]znV1UY-bbV4[/MEDIA][/ame]
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