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Mark 7 idler shaft sheave diameter?

Posted: Mon Jun 24, 2024 6:53 pm
by mharmon
Does anyone know the OD of the poly v pulley on the Mark 7 idler shaft?

Re: Mark 7 idler shaft sheave diameter?

Posted: Mon Jun 24, 2024 8:52 pm
by JPG
od or pitch diameter? od = 1 167 " (Mark VII) Should be same on all models.

Re: Mark 7 idler shaft sheave diameter?

Posted: Mon Jun 24, 2024 10:53 pm
by mharmon
Thanks. I saw that the poly v belts are the same between a mark v and 7. Thanks for confirming that for me.

Re: Mark 7 idler shaft sheave diameter?

Posted: Mon Jun 24, 2024 11:39 pm
by JPG
A clarification: the Mark VII poly-v belts are wider than the other 'Marks' and 'fill' the drive shaft pulley. I do not have experience with the Power Pro Mark 7 belts. I have presumed the Power Pro idler shaft is the same od as the other 'Marks' since the idler shaft to drive shaft ratio (1.6) needs to be the same for all models.

Re: Mark 7 idler shaft sheave diameter?

Posted: Tue Jun 25, 2024 8:25 am
by DLB
JPG wrote: Mon Jun 24, 2024 11:39 pm A clarification: the Mark VII poly-v belts are wider than the other 'Marks' and 'fill' the drive shaft pulley. I do not have experience with the Power Pro Mark 7 belts. I have presumed the Power Pro idler shaft is the same od as the other 'Marks' since the idler shaft to drive shaft ratio (1.6) needs to be the same for all models.
It is the same or very close. I measured one at 1.170" OD. I believe the design PD is 30 mm.

That is interesting about the Mark VII using a wide poly-v belt.

- David

Re: Mark 7 idler shaft sheave diameter?

Posted: Tue Jun 25, 2024 10:26 am
by JPG
DLB wrote: Tue Jun 25, 2024 8:25 am
JPG wrote: Mon Jun 24, 2024 11:39 pm A clarification: the Mark VII poly-v belts are wider than the other 'Marks' and 'fill' the drive shaft pulley. I do not have experience with the Power Pro Mark 7 belts. I have presumed the Power Pro idler shaft is the same od as the other 'Marks' since the idler shaft to drive shaft ratio (1.6) needs to be the same for all models.
It is the same or very close. I measured one at 1.170" OD. I believe the design PD is 30 mm.

That is interesting about the Mark VII using a wide poly-v belt.

- David
I always wondered why the M5 poly-v belt was 4(?) ribs narrower than the drive shaft pulley. That led to the confusion of positioning.