Compressor motor swap help!!

[TXNinAZ]

Finally found a good air compressor, but it was 3 phase. No problem, I'll get a new motor, and we'll be good. Problem. The frame Emglo/Jenny chose to use on this model is apparently uncommon, and now I'm unable to find a 5 hp motor with the right frame size in 1725-1750 RPM (bought a 3450 RPM 5hp Century motor, but a call to Jenny and they said I would regret using that without shrinking the pulley, which isn't possible because it's already quite a small pulley). Any suggestions?

I see that Leeson makes a frame transition base from my 145T to a 184U, but can't find any motors that fit my criteria with that frame, either. Plenty in a 184T frame, but that's not compatible with the 184U frame. I'd really hate to sell this one as-is and keep hunting for a different one, but I also don't want to mess with phase converting...any suggestions?

As purchased: Emglo GT2B-60V 2 HP, 3 phase, 1740 RPM, 145T motor frame
Looking for: 5 hp motor, 1725-1750 RPM

 

[Woodworker99]

If the compressor came with a 2 hp 3 phase motor why are you replacing it with a 5 hp single phase motor ? Why not use a 2 hp single phase motor. I thought U frame motors are still available.

 

[TXNinAZ]

If the compressor came with a 2 hp 3 phase motor why are you replacing it with a 5 hp single phase motor ? Why not use a 2 hp single phase motor. I thought U frame motors are still available.

Just looking for more output. Jenny sells that pump with a 5 hp motor and the tech support indicated it was fine to up the power. Just need the RPMs lower.

 

[TXNinAZ]

Motor plate for 3 phase motor.

 

[Woodworker99]

If the pump stays the same, using a 5 HP alone would not increase the air output. You would also have to change to a larger diameter motor pulley. Also, what about the starter- a 5 HP motor will draw more amps.

 

[bsaint]

Can you return the motor and get the right one?

145T motor isnt THAT uncommon but I don't think they make a 5 hp with a 145 frame.

 

[TXNinAZ]

If the pump stays the same, using a 5 HP alone would not increase the air output. You would also have to change to a larger diameter motor pulley. Also, what about the starter- a 5 HP motor will draw more amps.

I have the 3 phase starter on it now, but I was going to buy a new starter as well for the 5 hp motor. I didn't calculate the pulley change- thanks for pointing that out- totally spaced on it. Won't matter if I can't find a motor, though

 

[TXNinAZ]

Can you return the motor and get the right one?

145T motor isnt THAT uncommon but I don't think they make a 5 hp with a 145 frame.

Yes the supplier has no problem with returning/exchanging it, the issue is whether or not they can get a 5HP motor that only spins 1740 RPM. Since there doesn't appear to be a model that fits those specs, is there a solution to change the mount so that another motor will work.

 

[larry_g]

If you double the HP it seems reasonable that you would double the speed of the compressor head. So if your 5hp motor is 3450 then the same/old motor pulley should work just about right.

What you need from Emglo is a PUMP speed chart for the different hp motors. Then your going to have to know the pump pulley size and do the math to figure out the motor pulley size.

PUMP speed is the critical parameter here.

lg
no neat sig line

 

[TXNinAZ]

If you double the HP it seems reasonable that you would double the speed of the compressor head. So if your 5hp motor is 3450 then the same/old motor pulley should work just about right.

What you need from Emglo is a PUMP speed chart for the different hp motors. Then your going to have to know the pump pulley size and do the math to figure out the motor pulley size.

PUMP speed is the critical parameter here.

lg
no neat sig line

Thanks Larry. That's what I initially thought- a 5 hp motor should change the pump RPM from 450 (current pump speed, per the book), up to 900ish, with the same pulley. The guy at Jenny said if I ran the 5 hp 3450rpm motor, I'd be "rebuilding the pump all the time." I don't know if that means once every 500 hours or once every 5 hours. Since this is in my home shop, it's not going to kick on every 10 minutes for 40 hours a week.

 

[Woodworker99]

Since Emglo/Jenny said that model compressor can handle a 5 HP can you check if the bedplate holes or slots will match a 184T frame which is more common for a 5 Hp with a 1740 RPM. The larger frame motor would have a larger diameter shaft and a higher shaft axis - will the shaft clear the belt guard ?

 

[TXNinAZ]

Since Emglo/Jenny said that model compressor can handle a 5 HP can you check if the bedplate holes or slots will match a 184T frame which is more common for a 5 Hp with a 1740 RPM. The larger frame motor would have a larger diameter shaft and a higher shaft axis - will the shaft clear the belt guard ?

The belt guard shouldn't be an issue- it's just the mesh all on that side (no support bars or anything), so cutting it would take a few seconds with snips. The base plate only has one set of threaded mounting holes, plus another set of threaded holes that aren't in use If a motor could be mounted to them, it would be much, much bigger than the 145t.

 

[TXNinAZ]

Just measured- there are actually 2 sets of unused, threaded holes:

4 1/2 x 7 1/2
5 1/2 x 7 1/2

A 184T is 5.5" by 7.5" right? How would I size the pulley and belts if I went this route?

 

[larry_g]

(pump speed (desired)/ motor speed) X pump pulley dia = motor pulley dia.

900/3450 x 15" = 3.9" I would go with a 3.5 or 3.75" motor pulley.

lg
no neat sig line

 

[Woodworker99]

The motor mounts directly into threaded holes ? How would you make adjustments to the tension on the belts - as belts gets used they loose some tension and start to slip. Is there an idler pulley or the pump base itself is adjustable ?

 

[TXNinAZ]

(pump speed (desired)/ motor speed) X pump pulley dia = motor pulley dia.

900/3450 x 15" = 3.9" I would go with a 3.5 or 3.75" motor pulley.

lg
no neat sig line

Ha. It actually has a 3.5" pulley now.

 

[Woodworker99]

Oops! A 5 Hp 1740 RPM motor has a 186T frame right ?

 

[TXNinAZ]

The motor mounts directly into threaded holes ? How would you make adjustments to the tension on the belts - as belts gets used they loose some tension and start to slip. Is there an idler pulley or the pump base itself is adjustable ?

The motor has slots on its base plate so I assume that's the prescribed method of adding tension. The pump mounting location is also slotted.

 

[TXNinAZ]

Oops! A 5 Hp 1740 RPM motor has a 186T frame right ?

On eBay there's a Baldor 184t that's 5 hp and 1725 rpm.

 

[TXNinAZ]

So based on larry's formula: (900 [desired pump speed]/1725[5hp 184t motor speed])x13.25[pump pulley size]=6.91. Round down to 6.45", 1 1/8" ID. Would I need to get different belts, or will the existing ones be close enough to the right length?

Thanks for everyone's help on this- my GoogleFu let me down!

 

[Burgerkong]

What's stopping you from finding a 184T frame motor, getting an adjustable motor base and just bolting it (drill new holes) down on top of the mount? Looking at the frame sizes, you shouldn't have a problem fitting the adjustable base, there's enough clearance on the receiver mount.

 

[TXNinAZ]

What's stopping you from finding a 184T frame motor, getting an adjustable motor base and just bolting it (drill new holes) down on top of the mount? Looking at the frame sizes, you shouldn't have a problem fitting the adjustable base, there's enough clearance on the receiver mount.

After talking to Jenny again today, that's basically what I'm going to do, though the adjustable base isn't needed. For the 5 hp version of this compressor, they use a 184T frame motor, and all the base plates are the same for this compressor, so my new motor should bolt right up. Needed a new motor pulley and belts, but I'm ok with that.

Should end up with 43.3 CFM @ 40psi, and 24.4 cfm @ 90psi!! I've just been looking at the 175psi number (15.2) and thinking I'd be good, but damned, I'll have twice what I wanted when I started shopping!

Now to find a new starter...

 

[Burgerkong]

Are there adjustment slots on the new 184T motor? My 215T motor requires a base, it just has four tabs.

 

[TXNinAZ]

There is some adjustment in it. The mount points under the pump are slotted to allow for adjustment as well.