Sheave Angles

[Daveo99]

I'm wondering about multi angles on the clutch sheaves? Some of the clutches from Pro 4 and STM you can get multi angles. The TRA3 is like that also. I was wondering what the thought process behind that is? I would think if you have a 28 degree belt you would want a 14 degree sheave angle or a 12 degree sheave angle for a 24 degree belt.

 

[KnappAttack]

Less angle on the bottom bites the belt harder for less belt slippage where you need it most, more angle on the topped is more efficient for speed and release of the belt from the sheaves where you dont the grip as hard because the belts riding on the larger diameter portion. TAPP primary has progressive angles built in too. It can allow for more available OD doing this as well.

 

[Daveo99]

Less angle on the bottom bites the belt harder for less belt slippage where you need it most, more angle on the topped is more efficient for speed and release of the belt from the sheaves where you dont the grip as hard because the belts riding on the larger diameter portion. TAPP primary has progressive angles built in too. It can allow for more available OD doing this as well.

My next question is could you get the same results with ramp profile? Will the increased angle on the sheave on the larger diameter give better results than the ramp profile?

 

[KnappAttack]

My next question is could you get the same results with ramp profile? Will the increased angle on the sheave on the larger diameter give better results than the ramp profile?

Well perhaps. If you have max traction in a drag race type situation, you could alter the profile the weight and center of gravity on the weight to pinch the belt harder down low. I used to make my own weights to do just this as there were no weights made to stop the belt slippage to my liking, sometimes I would intentionally try to spin the track rather than hook up perfectly because belt slippage is more killer than anything for ET's. If you are spinning you don't need to pinch the belt so hard. More power needs more belt pinch of course too. This is for down low on the clutch.

More angle on the end of the sheaves is more efficient as it doesn't stay gripped on the belt as it tries to release from the sheaves. No amount of weight or profile can make up for better efficiency from that aspect of things. If you want efficiency, you don't want to steepen the angles on the end of the primary. Some have tried to do this to get more ratio or OD, but you give up efficiency here and defeat the purpose. Increasing the angle on the end increases the efficiency. So 14 degree is better than say a 13 degree on the clutch for the top end.

Shallower angles down low help to keep the belt gripped and pinched where it's needed to get rid of slippage, it takes more weight or helix to overcome this shallower angle. Steeper angles up top help with efficiency where it's needed for both speed and ET. Hope that helps.

 

[Trailleader]

There’s a lot of adjustment depending on conditions
Obviously with traction you’ll be more consistent
has anyone had experience with tapp secondary