Compressor Pulley Question? What style do I need (A, B, C, 3F, B60)?

[myridge]

My Quincy AirMaster QT-5 Baldor motor went out last week so I ordered a replacement Baldor L1410T with a 1 1/8" shaft. This is beefier than my old motor so I'll need a new pulley. I know I need a 7.5-8" pulley to work with my 13 or 14" pump pulley to get around 800-1000 RPM,

Now my trouble is I have no idea what to get I see Steel pulleys with welded or un-welded hubs, I see pulleys that need a bushing or sheave?

Then there in different belt style and width sizes, I don't know what this thing used how can I tell? what should I look for I see these on Grainger will they work? If I get the bushing?

Grainger Item V-Belt Pulley
Bore Type Split Taper Bushed Bore
Material Cast Iron
Number of Grooves 1
Outside Dia. 8"
3V Belt Pitch Dia. 7.95"
Fits Shaft Dia. 1/2" to 1-3/4"
Bushing Required P1
Construction Spoked
Set Screw Included No
For Use With 3V or 3VX Type V-belts

 

[Todd.Brock]

You will want to know exact sizes you are looking for. Surplus center is a good place for replacement sheaves. They are painted cast iron, Bore size is selectable. The belt size uses a system called datum diameter. It is typically based on the width of the belt. If you get a 6" pulley.


Sent from my iPhone using Tapatalk

 

[Todd.Brock]

You will want to know exact sizes you are looking for. Surplus center is a good place for replacement sheaves. They are painted cast iron, Bore size is selectable. The belt size uses a system called datum diameter. It is typically based on the width of the belt. If you get a 6" pulley diameter A maybe 5.8 and Diameter B is 5.6. The wider the belt, the higher it sits in the pulley. If you want an actual 6" with belt , you upsize to a 6.175 pulley.

Measure the pulley you have and the belt width. I would use the same diameter pulley in the 1 1/8 bore. You maybe off a little, but get as close as you can. This is all assuming your rpm's match on the new motor. 3450 vs 1725 RPM. If you had a 1725 motor and bought a 3450, your pulley would need to be twice as big and vice versa.


Sent from my iPhone using Tapatalk

Sent from my iPhone using Tapatalk

 

[myridge]

Still not sure what to measure. I looked at the old belt its a Bando Power King COG I don't see a size on it. But my by my measure its a 60" Also its about 3/4" wide

The old motor was a 3450rpm with a 3.5" pulley, My new motor is slower its 1725 RPM so to get close to the same RPM I'll need 7.5-8" I checked the Surplus Center and see some pulleys but I don't understand which one will work for me. Also the H style Bushing says 1.1875 is that bore 1 1/8th??

Will this work? H BUSHED BORE SINGLE GROOVE PULLEY
Brand new. Fractional HP, single groove, cast iron pulley. Use with a H-type split taper bushing (sold separately). For use with type "A" and "B" belts. Fully balanced.

 

[C96]

I know it’s already been done, but just curious as to why you didn’t replace the motor with an identical one and save yourself all this hassle?

 

[Major Ramifications]

If you use that pulley, you will need the H type split taper bushing in the correct bore size for your motor shaft.

 

[myridge]

High Cost and lower durability was the reasons. My Quincy used a non-standard Baldor 3450 rpm motor that was a special purpose motor and therefore almost $1000 to replace and very hard to find. And turns out the 3450rpm motor didn't have enough starting torque which is what caused it to fail and burn out its windings according to the repair shop. See the 1725 rpm has much higher starting torque and the slower motor will supposedly last longer and the cost was only $400 for a better more durable motor.

 

[myridge]

So will that pulley fit my belt and match my pump pulley? I understand I need a matching bushing that's ok. Just not sure on the size the way its worded here. Says 1.1825 instead of 1 1/8th is that the same? Math, fractions and measurements are not my thing, I just don't understand them or have never had them explained that made any sense to me.

 

[Todd.Brock]

You need a pulley like this. 1.125 equals 1 and 1/8" Google is your for fraction and decimal conversions.

I don't know the actual diameter you need, that is just an example., but read the page and it will give you some insight on belt widths and datum diameter. Use an online calculator that takes your flywheel diameter, motor pulley diameter, motor RPM, distance between the two pullies( it will calculate the size belt you need) and it will figure the pump RPM. Start with 7.5 " and see if it is the desired RPM. Adjust motor pulley value until you get the desired rpm for your pump. Find the closest size pulley and buy it. Fractions of inches shouldn't alter pump RPM too much , but check it in the calc to see if it stays in the desired range for pump speed. I don't have a link to one , but someone can chime in.
http://www.surpluscenter.com/Power-...5-O-D-1-1-8-BORE-1-GROOVE-PULLEY-1-BK80-F.axd

 

[myridge]

Perfect thank you, I took a good look and used some thinner to get the overspray off the belt and found some numbers. Says BX-55 on it.

Ok I think I got it, Found this link for pulley calculator and it says that with a 14" pump pulley 7.5" motor pulley at 1725 RPM at pulley center of 13" I should be at 924 Pump RPM, Thats good my max is 1060 and min is 400 Belt size is 60" so i will need a new belt too.

 

[metal4130]

When I built up my compressor I used a Browning split taper pulley. My Baldor motor was also a 1-1/8" and they can be found on eBay for a rather low price.

Is it going to be 1 belt or 2?

 

[Todd.Brock]

I'm sure the split taper pulley is cost effective. I have never used or priced one. I have only used the pullies I linked. They seemed cost effective to me. They are a nice unit. 2belt Version is about 35 biucks for the 7.75 diameter. The one linked was 23.

Was the old motor thermally protected or do you have a magnetic starter? Most 3450 RPM motors that I have seem are protected with a thermal reset button. Is your new motor thermally protected ?

 

[myridge]

Ok I am ordering the 7.75 fixed bore Pulley and according to the calculator I need a new 60" belt. My old belt was a BX-55 should I order a BX-60 Is there an advantage to the notched or COG BX over the standard B60? Added grip since its a single groove pump pulley?

 

[myridge]

I went ahead and ordered the BX-60 as that's what it had from the factory. To answer your question about thermal reset. Yes my old motor did have one but I plan to use a Siemens magnetic starter. I do not think the new motor has an internal thermal reset that I know of. But it hasn't arrived yet so I cannot confirm that just yet.

By my calculations the old pump RPM was 862, With this new configuration it will be slightly faster between 924-954 depending on Datum diameter. So will that produce more CFM?

Its still within range, pumps specs say between 400-1060 RPM

I may buy a 7.5 too just to see what works better it would be 877 RPM with a 7.5

Thanks for the help and suggestions

 

[pacmktg]

A cogged belt is designed to go around small pulleys. Most Fan and Compressor Mfgs have moved to cogged belts because they transmit more horsepower.

 

[Todd.Brock]

Glad to hear you are on your way! If you cant find the belt that you need or the size is slightly off, a good auto parts store like NAPA can find you a belt by size. I had to go back a second time to get a slightly longer belt when i was working on my bandsaw project. Either way, I dont suspect a cogged belt would hurt anything.

In regard to your CFM question, i suppose that theoretically, it would increase CFM to run at a higher CFM. Quincy should have stated specs at a certain RPM, especially if the pump is a 5 to 7.5 HP pump. I would stick to the pump speed recommended by Quincy personally. I dont think that you would see a huge jump in CFM. that is just my .02 though....

 

[b-body-bob]

From a Champion spec sheet, I see that higher horsepower motors turn the pump at a higher RPM, and produce more CFM.

The question is, can the motor you're using turn the pump at the RPM determined by the pulley and flywheel combination? If so, then yes you'll get more CFM because there are more strokes per unit time.

Although there is probably nothing to be inferred comparing my Champ to your Quincy, the pump on my compressor uses a Baldor L1430 5HP motor and the pump speed is 710 RPM.

The Champ 7hp motor turns the pump at 990 RPM and puts out an additional 8 CFM.