VN Correct Pulley Size For Motor On Vn 12

Jason Annen

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As progress continues on my machine, it appears that the motor pulley on my machine appears to be way too small, like 2", plus it is only a single belt pulley. The pulley on the 41 vintage machine is much bigger at 4.375", double belt pulley with a 3/4" bore. I am assuming the larger pulley is correct, but I want to double check before trying to find one.

Jason
 
I've got a VN12 that I picked up for rebuilding-resale. Landed last week measure her up on Friday.
Please confirm you are looking for the step pulley on the motor side only.
Note: I'll measure whatever you need.

Daryl
MN
 
The pulley that is on the main drive motor.

Thanks,

Jason
 
Jason,

The pulley might be correct if you have a 2-pole, 2750 RPM motor, instead of the usual 4-pole, 1760 RPM motor. See if the spindle speeds are correct once you have it running, then worry about the pulley.

Cal
 
Cal Haines is generally a solid voice for clear reasoning and best practice.

Here is the data I offered, if it's helpful.
The VN12 I'm working on is a 3ph, 1.5hp, 1155rpm.
The 2 sheaved pulleys are:
Machine (Lower) 4.110inches OD
Motor pulley (Upper) 4.365inches OD

Advise should you need/want more data.

Daryl
MN
 
Powered it up today for the first time, much quieter than my other unit. The pulley combo on it seems to be correct, spindle speeds were pretty close, according to my old rpm meter. I do need a new belt for sure, but I am wondering if I should get a double pulley and run 2 belts, or just the one?

Jason
 
Powered it up today for the first time, much quieter than my other unit. The pulley combo on it seems to be correct, spindle speeds were pretty close, according to my old rpm meter. I do need a new belt for sure, but I am wondering if I should get a double pulley and run 2 belts, or just the one?

Jason
If you have a 2HP, motor you'll be fine with a single belt. The 16S (a descendant of the No. 12) uses a single belt. Even with a 3HP motor you're probably OK unless you're taking some real heavy cuts. If you go with two belts, be aware that you can't use just any belts, they need to be the type intended to be run in a multi-belt application.

Cal
 
Cal,
Makes sense that the belts need to be matched.
But why use a single belt?
It may work fine, but why would the manufacturer have used two if only one works well enough?

Daryl
MN
 
Who knows? Maybe grumpy old Bob the engineer just thought that double belts are always the way to go?

I would use it as is and if you can find the double pulley for a reasonable price, then replace it.

Jason's motor is probably not the original motor, so what he really needs it a 2 HP motor with the right pulley for its RPM.

Jason, is the motor single phase?

Cal
 
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