I have a box store CH 80 gallon compressor that's 10+ YO. I use it pretty hard sand blasting and running air tools so it goes into a continuous run mode often. I replaced the pump 4 years ago with an Eaton double stage after the stock CH locked up. Now the motor is giving me problems; blew a start capacitor and after replacing that it's popping the thermal switch after about a 30 minute continuous run. It's a typical 5HP Emerson 56T frame running 3450 RPM. I know these motors are cheap and designed for light duty and not continuous. So, shopping for a replacement. Doesn't necessarily need to be a 56T frame or spin at 3450 since I can drill new holes if needed. Would actually prefer to slow it down a bit. Any suggestions?
Compressor Motor Suggestion
- Thread starter bfr57
- Start date
marinusdees
Well-known member
Baldor (or Leeson) 5 hp. Look on ebay. 1750 rpm.
The Tool Tyrant
ALLIANCE MEMBER
Just curious. Did you adjust the drive sheave to maintain the correct pump speed on the Eaton?
Jswain
Well-known member
Agree with the recommendation on a 1750rpm Baldor. Just make a note too as it probably won't have a thermal overload button in it so you will want to get a magnetic starter as well which is not a bad thing if you are a heavy user
redmondjp
Well-known member
Check out Surplus Center (catalog or website) - they often have decent deals on replacement compressor motors:
https://www.surpluscenter.com/
https://www.surpluscenter.com/
Firebrick43
Well-known member
A 1750 rpm WEG would be just as good as a baldor. A leeson is the best and sometimes you can find one for the same price. They are going to be a 182 or 184 frame size probably. If you look at your current motor plate, the FLA are probably not ~21 amps and there fore is not a true 5hp motor.
Jswain
Well-known member
If it's pretty dusty in that area you could try giving the motor a good blow through with an air hose, pull it out from the wall a bit more etc. A large 20" fan pointed at it helps cool it down pretty quick between cycles.
Thanks Jswain. I was thinking about a fan the other day. I have it outside in a enclosure that's well ventilated. I would have to pull a neutral line out to it to add a 110 VAC fan and maybe put a switch inside the garage. I also thought of adding a small light bulb tied into the pressure switch to let me know when it's running. At least my air cooling system is working with the aftercooler and air dryer! Not a drop of water anywhere.
Van Johnson112
Member
I bought this motor when I was rebuilding my compressor from tank up with a new Eaton pressure lubed pump. It’s reversible, rated for continuous duty, and it’s quite. After I bit the bullet and spent the cash I’m definitely happy with it.
NEW 5HP 184T FRAME WEG ELECTRIC MOT...=cm_sw_r_cp_api_glt_fabc_PNE8JWGMJ0F5508P8F9X
Sent from my iPhone using Garage Journal
NEW 5HP 184T FRAME WEG ELECTRIC MOT...=cm_sw_r_cp_api_glt_fabc_PNE8JWGMJ0F5508P8F9X
Sent from my iPhone using Garage Journal
matt_i
Well-known member
If you had a 3450 (2 pole) and get a 1725/1750 (4 pole) you will need to re-sheave the motor.
Typically the compressor sheave has fan blades cast into it and that's not an easy one to change.
I recommend taperlock sheaves (SDS/QD) as they squeeze the shaft and won't loosen up over time. The taperlock bushing has to be sized to the motor shaft. 1-1/8" is common for 5hp IIRC.
Typically the compressor sheave has fan blades cast into it and that's not an easy one to change.
I recommend taperlock sheaves (SDS/QD) as they squeeze the shaft and won't loosen up over time. The taperlock bushing has to be sized to the motor shaft. 1-1/8" is common for 5hp IIRC.
csp
Well-known member
We put a lot of farm duty motors on compressors especially outdoor ones here. Usually Teco motors cause that's what I get from my usual supplier. TEFC, continuous duty, sealed bearings. Pretty common thing for us to do on smaller receps like that, along with putting on mag starter and new pressure switches.
redmondjp
Well-known member
Just one caution - Totatally-Enclosed, Fan-Cooled (TEFC) motors typically have a lower service factor (1.0 instead of 1.15 or 1.25), meaning that they are less tolerant of being overloaded. This is because it is more difficult to get the heat out of the motor windings on this type of motor.
For dirty/dusty conditions or where it may get wet, using this type of motor is fine, but in most cases, you are better off with a conventional motor design with open windings as it will run cooler which results in the motor lasting longer due to less rapid winding insulation breakdown.
Also look at how many starts per hour a motor is rated for - often it is a fairly low number, say 5 starts per hour. During starting, up to 10 times the running current can briefly pass through the windings, resulting in a great deal of heat building up in the windings. The limit on the number of starts per hour is to allow that heat to get out of the motor (which happens most quickly when the motor is running with the internal fan blowing air through the housing), thereby limiting winding temperatures to a safe limit.
All that to say that TEFC is not "better" in every situation. There are downsides to it that should be understood.
LS6 Tommy
Well-known member
Not really helpful, but related and semi-funny. I had a guy tell me once if the motor is running the pump too fast, get a longer belt and remount the motor further away from the pump. He was adamant that since the longer belt had a larger diameter, it would turn the pump slower. Yes, he was an engineer...
Tommy
Tommy
The Tool Tyrant
ALLIANCE MEMBER
LS6 Tommy
Well-known member
STREETFIGHTER50
Well-known member
- Joined
- Sep 24, 2013
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Baldor motors are really good from what I’ve seen at many places.
nadogail
Well-known member
Cheap prices in Electric Motors and Paint do not indicate Bargains.
Just as Cheaply made Paint should be avoided, the "Savings" on a Cheaply Made Motor may go up in SMOKE.
Just as Cheaply made Paint should be avoided, the "Savings" on a Cheaply Made Motor may go up in SMOKE.
redmondjp
Well-known member
It hasn't been resolved on this thread yet as to whether the replacement pump was set up properly to match the available horsepower of the (now-failed) motor. That should be verified first, else the replacement motor may also fail in a similar manner.
Cautionary tip: motors still work when overloaded, until the overload protection (if any) kicks in, or until they fail. This is why the above step should not be overlooked.
If the existing pump needs an extra half HP at the speed and pressure that it is operating at, then the motor will try to deliver that extra power, even if it above its nameplate rating. This is a very common issue on frankencompressors.
Cautionary tip: motors still work when overloaded, until the overload protection (if any) kicks in, or until they fail. This is why the above step should not be overlooked.
If the existing pump needs an extra half HP at the speed and pressure that it is operating at, then the motor will try to deliver that extra power, even if it above its nameplate rating. This is a very common issue on frankencompressors.