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Forum topic by bbc557ci posted 08-22-2013 07:32 PM 1904 views 0 times favorited 9 replies Add to Favorites Watch
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595 posts in 2102 days

08-22-2013 07:32 PM

Few days ago I came accross a Sears compressor, belt driven, that looks like new. A neighbor had it at the end of his driveway with a For Sale sign on it. I knocked on the door and asked how much, and he said I could have it for $25.00. Neighbor said he bought it at a garage sale and could not use it, because it’s 220V. I looked and sure enough, the plug was for 220. So I said/asked if he was SURE he wanted only $25.00 for it, and he said $25 and get it out’a here. I brought it home and plugged it in, and it seems to work/run just fine!!

Now for the questions… It’s a Sears model 919.176850 and tagged as a 5 HP motor, but I don’t think it is actually 5 HP, but I just don’t know. Motor is 15 amp at 240 Volts and 3450 RPM’s. Seems like it would be closer to 2 HP ?? What do you all think?

Also, tag on the GE motor itself says “Compressor Duty”. What is the difference between compressor duty, and say a motor with similar specs, but for the type motor used on a table saw ?

Thanks in advance for your input.

-- Bill, central where near the "big apple"

9 replies so far

View chrisstef's profile


17428 posts in 3035 days

#1 posted 08-22-2013 07:35 PM

Sears / Craftsman is pretty notorious for misappropriating the HP of their equipment. At peak capacity it could probably push 5hp but in all reality 2hp is more like it.

-- Its not a crack, its a casting imperfection.

View toolie's profile


2135 posts in 2657 days

#2 posted 08-22-2013 07:47 PM

i wouldn’t guess the hp is much above 3 hp. a formerly owned 70s vintage unisaw had an OEM 3 hp baldor motor that drew 32A at 120v and 16A at 240v.

-- there's a solution to every just have to be willing to find it.

View PurpLev's profile


8536 posts in 3677 days

#3 posted 08-22-2013 07:48 PM

some mfg like to put on the motor the peak HP the motor can handle, but under normal load it is always far from that number as you mentioned.

compressor duty motors are rated to intermittent work as they come on and off… on and off in a repetitive cycle (motor turns on- runs to fill tank and stops, tank depleats – turns motor on… rinse and repeat). whereas motors that are rated for continueous duty like table saws are build to be turned on for a long period of time (cut material) and then turned off to ‘rest’ for a long period of time – so no on>off>on>off kind of work

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View Don W's profile

Don W

18756 posts in 2596 days

#4 posted 08-22-2013 07:50 PM

There was a thread a while ago where the whole “what’s the real hp ”. The short version of the whole thing was there is no standard so its anybody’s guess.

for $25 you did ok.

-- - Collecting is an investment in the past, and the future.

View bbc557ci's profile


595 posts in 2102 days

#5 posted 08-22-2013 08:13 PM

Thanks for the replies, and education!!

I just went out and read the tag on the GE motor. Tag on the motor says 230V and 13.1 AMP. Little different than the Sears tag stuck on the tank. I looked on the WWW and was able to print an owners manual. The motor in the manual looks identical to the motor on the compressor…..wierd but true ….

Don W, I have an oiless that can be heard for a country mile when running. I can’t stand the damn thing!! So I had been looking on Craigslist for a belt driven compresser for several months. Belt driven compressors that look like they haven’t been worked to death have been in the $200 to $250 range. So yeah, coming across this one for $25 makes me feel lucky. Maybe I should buy a lottery ticket!!

-- Bill, central where near the "big apple"

View crank49's profile


4032 posts in 2999 days

#6 posted 08-22-2013 08:14 PM

That is a capacitor start, induction motor and it is rated for 5 hp by its manufacturer.
The manual for that compressor states 15 amps and 240 volts; appears to be the original motor.
However, if you look up a new motor you will find a 3HP is typically 14.5 amps and a 5HP is typically 22amps.
Don’t know how Sears got GE to rate that motor 5HP.

The motors that Sears, and everybody else, grossly overrate are universal motors, like on vacuum cleaners, cheap aluminum and plastic table saws and portable tools.

Motors have several ratings defining the type service they are suited for.
General purpose.
Farm duty.
Compressor duty.
Has to do with how many times an hour they are designed to be started without over heating.
Also, whether they can start under a heavy load or not.
How long they need to run, for cooling purposes, before being turned off.

Compressor duty motors are usually very heavy duty motors because they normally have to start under load and they never get to run unloaded.

A table saw motor does not need the high starting torque so they can be general purpose or farm duty, but should be TEFC (total enclosed fan cooled). Also, most TS motors are going to be 3450 RPM.

View Shawn Masterson's profile

Shawn Masterson

1325 posts in 1977 days

#7 posted 08-23-2013 01:25 AM

I had a 60 gal compressor from rural king that was a 6.5 hp and drew 15 amps @220. Yeah my A**. my current 60 cal is a 2 stage and it is a 5 hp 25 amps @220. Most single phase 220 5 hp motors are 22-25 amps.

View bbc557ci's profile


595 posts in 2102 days

#8 posted 08-23-2013 01:45 AM

Well then, I guess it’s around 2-3 hp, which is plenty for what I use a compressor for.

And thanks once again for those detailed replies. I appreciate the schooling as much if not more than the bottom line answers!!

-- Bill, central where near the "big apple"

View TCCcabinetmaker's profile


932 posts in 2383 days

#9 posted 08-23-2013 03:07 AM

The problem is horse power isn’t really as important as the scfm of a compressor.

-- The mark of a good carpenter is not how few mistakes he makes, but rather how well he fixes them.

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