Pulley / Sheave question.

[Allan Speers]

I need a pulley for my Powermatic planer

The original spec is for a Browning 2 AK-41, which is a dual groove, 3.95" OD pulley that takes 4L V-belts. (and I can go as small as 3.4", which was the "Green" era PM 100's size)

These don't seem to be made any longer. I was looking on Ebay, hoping to find a used AK-41, but the only one was stupidly expensive. I found a nos Browning 2BK36 in the correct bore, and it is being advertised as correct for 4L v-belts. However, I checked this pulley on Amazon, and they have it listed for "A" and "B" belts.

I don't even know what that means. I get REALLY confused when it comes to pulleys & belts.

This is the pulley: http://www.amazon.com/Browning-2BK36X7-Finished-Sheave-Grooves/dp/B00271EKDI/ref=sr_1_1?s=industrial&ie=UTF8&qid=1433888893&sr=1-1&keywords=Browning+2BK36X7%2F8

Is this the wrong one? If so, what should I be looking for?

[Allan Speers]

Update:

I see now on another website the following description for that 2BK36:

"Outside Diameter: 3.7500"
Pitch Diameter of Belt Type 4L or A: 3.00"
Belt Pitch B Diameter: 3.40""

I assume this means that the true effective diameter with a 4L belt is only 3". - But then what is it with the AK-41?

Also, does this mean that "A" pulleys can be interchanged with "V" pulleys, that the grooves are identical?

[Dennis Ford]

Some pulleys fit only one size but many can handle a range of belt widths. "A" and "B" belts have the same included angle, "B" belts are wider so they ride higher up in the pulley than "A" belts. That changes the pitch diameter.
A good source for pulleys here:
http://www.surpluscenter.com/Pulleys/

[Jerry Bruette]

Allan

The sheave you picked on Amazon is actually for a B size belt that's what the B in 2BK36 means.

A belt designated as 4L has the same physical dimensions as a belt with the "A" size designation. The 4L is a fractional horsepower belt and the "A" belt is called a standard multiple belt.

Some sheave manufacturers will sell a "B" sized sheave and call it a multiple size sheave meaning a "A" or "B" belt will fit, and they will but, you're buying a sheave that's bigger in diameter with a deeper groove than what's needed.

You could order the sheave and a QD bushing of the proper size from McMaster-Carr for about $45. But you may not be familiar with how they go together.

TB Woods is another manufacturer of sheaves and their sheave with 7/8 bore and 3.75 OD is 2BK3678. It's another "multiple size" sheave, will fit "A" or "B" size belts.

You can try googling TB Woods 2AK3478

[Lee Schierer]

Your local industrial supply house (not an auto parts place) or "Gates" distributor would be highly qualified to help you locate the appropriate belt for your pulley.

[Allan Speers]

...... TB Woods is another manufacturer of sheaves and their sheave with 7/8 bore and 3.75 OD is 2BK3678. It's another "multiple size" sheave, will fit "A" or "B" size belts.

You can try googling TB Woods 2AK3478

Thanks, Jerry.

I found that TB Woods at Motion Industries. It's a little too small, but this same company actually sells the elusive Browning 2AK41 X 7/8. $80 (ouch) but at least it's available.

Also, now I know what the true working diameter of that pulley is, with a 4L (or "A") belt, (4.7") which is very important to know.
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New questions:

1: The TB Woods equivalent 2AK41 has this written about it:

“Fractional Horsepower Sheaves To Be Only Used With FHP (3L Or 4L) Type Belts. It Is Not Recommended To Use Classical Industrial V-Belts With This Sheave. “

So... what the heck does this mean to me? I want to use a notched (cogged) belt, or maybe one of those "joined" belts that negate the need for matched pairs (I'm still learning about belts)


2: Are the Chinese-made cast iron pulleys typically OK? They seem to work on lots of import machines, and even Leeson now sells them under their brand name. (Sad.)

Grizzly pulleys are still made in Taiwan (Ah, the good old days!) and they have a 4" diameter dual slot, balanced cast iron for $20 ! I don't want to cheap out, but the Grizzly ones are 1/4 the cost, so if they are just as good ... (IF they are.) The tires that came on my 21" Grizzly band saw were horrible, but I haven't seen reports of Grizzly pulleys falling apart, so as long as they are balanced ... (Maybe they are made of cheaper cast iron, and so wear faster?


3: I found a nos Browning variable-pitch sheave on EBay, (Not a Reeves, but the kind you lock down) which will cover the range I need. Are these considered as good? I'm thinking maybe they can't be accurately balanced, hence theoretically causing more vibration. Yes / no?

[Allan Speers]

well, belts are indeed another puzzle. Too many choices....

Anyway, right now I still DESPERATELY need answers to my last few questions, above.

Anyone?

[Jerry Bruette]

Allan

Sorry for the delayed answers, trying to take care of some investments tonight.

#1 Don't know why this is stated. But you could use the 4L belts instead of "A" belts although they are physically the same size, just measured differently for length.

#2 Good enough for Grizzly should be good enough for you.

#3 There would be no vibration with the variable pitch sheave. Only problem is you have no way of knowing what Pitch Diameter you have it set to, there are no markings indicating PD.
These sheaves are frequently used in HVAC or on blowers where you select the R.P.M.'s by opening or closing the sheave.

As for belts pick up some good Gates brand belts and your good to go.

Notches in belts do nothing more than let the belt get a better wrap on a small diameter sheave and let the belt run a little cooler.
A notched belt will have the letter "X" in the size AX27, BX60, CX80, would all be notched belts. The number after the letters is the length of the belt in inches measured on the pitch diameter for multiple V belts.

A FHP belt having a size designation like 4L170 would be a 17 inch belt measured on the outside of the belt.

Don't let the length of the belt throw you off though a A32 belt will work as well as a 4L320 belt, the length is so close between the two that it won't matter.

[Allan Speers]

Wow, great stuff, Jerry.

THANKS.

I think I'll get the vari-pitch pulley then, since the Grizzly is a tad large. (Although I don't know exactly what the effective pitch is with a pulley, only the O.D.)

I figure the exact pitch set on the vari-pitch sheave should be easy to suss, since I know the target head rpm. I can see how the motor spindle relates to the arbor spindle and calculate the rpm, then just dial-in the pulley setting.

------------------------------------

I see Gates belts recommended a lot, but also the cogged type. My arbor pulley is only 2.7" so I'm thinking cogged would be good. There's also the issue of exact length matching. I've seen some cogged DUAL belts, where the two belts are literally sort of "sewn" together so they have to be an exact match. Sounds like a winner, no?