# Any idea for a replacement motor for Chicago Pneumatic Rotary Screw?



## Wulvie (Nov 5, 2021)

I bought a CP QRS5 at an auction with a bad motor. I contacted compressor shops and they want over $1,000 for a 5HP motor, and they have to wait forever for them.

It's a 5hp, single phase, 1 1/8" shaft motor. The label on this thing does not show a frame size, and I'm having a hard time finding a replacement. Any ideas? The capacitor box is on the top, not on the side. It's a WEG, cast iron housing with cooling fins. I can't use one with the box on the side as the compressor sides won't fit. Here's a picture of the label.

Any suggestions?


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## iowagold (Jan 22, 2020)

maybe something like this 
*click here for the north star compressor motor*
*it looks close 435.00
you can always change the pulley to match your belt.*


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## Wulvie (Nov 5, 2021)

Thanks. That one has the box on the side though, which won't fit in my compressor housing. 

Is there also a reason for cooling fins vs not having them? I'm wondering if a non-finned motor would overheat in there. It's a rotary screw compressor with a soundproofed enclosure, so not a ton of air movement.


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## oldcodger (Sep 13, 2021)

Have you had a motor shop look at your motor? Maybe it could be repaired.


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## Wulvie (Nov 5, 2021)

oldcodger said:


> Have you had a motor shop look at your motor? Maybe it could be repaired.


That was the first thing I did, the windings are all shot, he said it would cost more than a new motor to rewind it.

I was thinking of getting this https://www.amazon.com/gp/product/B0812BL7BP/ and using a bushing or adapter to size the shaft up to 1 1/8", but not sure if I need cooling fins on it.


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## stevon (Mar 5, 2019)

Wulvie,

One of these might work for you:









NEW! DAYTON 5 HP ELECTRIC MOTOR, 3450 RPM, 230V, FRAME: 184T, COSMETIC DAMAGE | eBay


Find many great new & used options and get the best deals for NEW! DAYTON 5 HP ELECTRIC MOTOR, 3450 RPM, 230V, FRAME: 184T, COSMETIC DAMAGE at the best online prices at eBay! Free shipping for many products!



www.ebay.com





5 HP AIR COMPRESSOR DUTY ELECTRIC MOTOR 184T FRAME 3450 RPM 1-PHASE 230 VOLT NEW 685650082318 | eBay

You can move the capacitors somewhere else if you have to and remote wire them. Most of the motors that I looked up in single phase have smooth bodies without fins, only heavy duty 3 phase motors seem to come finned. Your compressor just might just have a custom ordered/designed motor on the Chicago Pneumatic compressor. You could try a smooth body "Farm Duty" Service Factor 1.25, they handle heat better than a 1.15 or a 1.00 SF motor

Stephen




Wulvie said:


> I bought a CP QRS5 at an auction with a bad motor. I contacted compressor shops and they want over $1,000 for a 5HP motor, and they have to wait forever for them.
> 
> It's a 5hp, single phase, 1 1/8" shaft motor. The label on this thing does not show a frame size, and I'm having a hard time finding a replacement. Any ideas? The capacitor box is on the top, not on the side. It's a WEG, cast iron housing with cooling fins. I can't use one with the box on the side as the compressor sides won't fit. Here's a picture of the label.
> 
> ...


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## stevon (Mar 5, 2019)

stevon said:


> Wulvie,
> 
> One of these might work for you:
> 
> ...


Service factor description related to heat in the Baldor specifier guide:


https://www.baldor.com/~/media/files/brands/baldor-reliance/resources%20and%20support/specguide.ashx



5. SERVICE FACTOR: The service factor shown on the motor nameplate indicates the amount of continuous overload the motor can be subjected to, under nameplate conditions, without damaging the motor. When the voltage and frequency are at the same values as shown on the motor nameplate, the motor may be overloaded up to the horsepower indicated by multiplying the rated horsepower by the service factor. When operated at service factor load, the motor may have an efficiency, power factor, and speed slightly different from those shown on the nameplate. Service factor can also be used to determine if a motor can be operated continuously at altitudes higher than 3300 feet satisfactorily. At altitudes greater than 3300 feet, the lower density of air reduces the motor's cooling ability thereby causing the temperature of the motor to be higher. This higher temperature is compensated for by reducing the effective service factor to 1.0 on motors nameplated with a 1.15 service factor or greater. If the motor is operated outdoors at higher altitudes. it's sometimes possible to use full horsepower and full service factor since ambient temperatures are usually lower at those altitudes.


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## MacMcMacmac (9 mo ago)

You always need cooling fins on a TEFC motor or it will cook itself.


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