Replacement motor advice for a Husky (CH) compressor

[gatorgrabber]

I picked up an excellent condition Husky (Campbell Hausfeld) 80gal compressor that lost its' motor to a power surge. The model # is HS7810. I took the motor to a well respected motor shop where they confirmed the windings are shot (so much for brushes!). So before I just blindly run out and replace what was installed (it's 5hp, 240v), should there be any other considerations I take into account? I've seen the same compressor running a 7.5hp, but is there any advantage to this? It's crazy how expensive motors have become, so a little research is in order. Any suggestions?

BTW, the compressor will see only light duty in a home shop; nothing commercial, no paint booth.

Thanks!

 

[healing]

BTW, the compressor will see only light duty in a home shop; nothing commercial, no paint booth.

My suggestion since a 7.5 is quite a bit more money than a 5 HP, I would stick with the 5hp. Especially since its for home use. I bought a new lesson 5hp off of evil bay a year ago, best price I found.

 

[gatorgrabber]

The only reason I'd look at the 7.5 is if a deal happened to come my way. Is there any reason to rule it out from an operational standpoint, other than wretched excess?

I neglected to ask if there are any preferences for motor manufacturer...or ones to steer clear of?

 

[gatorgrabber]

After several days of R&R (reading and research!), I've decided to take a slightly different approach to finding a replacement motor for this compressor. Since this unit came with a 'peak 7hp' motor (over-hyped 5hp is more like it), I'm considering going with a heavier duty motor such as one of the Baldors. I have plenty of mounting space, so that doesn't look to be a concern. The pulley will need replacing if the shaft is larger (currently 7/8"), but my question now lies with the motor speed. The factory motor was running near 3400rpm. Do I need to stay with that speed with my modest use in a home shop? It's a 2-stage compressor if that figures into the equation. I was thinking about a motor like the Baldor L1410T which spins at 1725rpm. Yes, a different ratio pulley can be used but is that really necessary? Any thoughts? Thanks!

BTW, my existing motor frame is a 56HZ.

 

[stonesfan68]

I'd go with a 7.5HP motor, too.

You'll definitely need a new motor pulley if you halve the speed of the motor. An air compressor performance is mostly linear, so 50% motor speed equals 50% compressor flow rate.

I wouldn't really worry about using an 1800 RPM motor versus a 3600 RPM motor in a home setting, especially since the motor won't be run at 7.5HP.

 

[gatorgrabber]

Good point regarding the compressor output. Do you have an opinion regarding the brand of motor? Since I tend to hold on to tools for years, I prefer to replace damaged parts with quality components when the need arises.

 

[gatorgrabber]

I've kind of narrowed the search to Leeson or Baldor; am I missing a brand I should be considering?

 

[stonesfan68]

Baldor is still a pretty good brand. I don't know much about Leeson.


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[rancherbill]

You have an entry level compressor. You have probably used half the life of the compressor.

Put a low cost correctly sized entry motor on that is rated for compressors. A bigger motor get you nothing unless you run the compressor faster. It will die quickly. Also you might have to get into re-wiring for a bigger motor.

 

[gatorgrabber]

This was a fairly new unit (1yr old in 2003) when lightning took it out, so it still has some time left on the clock. It was replaced as a unit and became garage art (enormous dust bunny) for the next decade until I liberated it. It was definitely more robust than the later versions using the same number. Since they came with both 5 and a 7.5hp motors, I was weighing one vs the other for my purposes as it's all that's required at this point.

 

[rancherbill]

That series came with both motors, but I doubt the interenal parts on the compressor are the same. The 7.5 would be a bigger bore.

 

[gatorgrabber]

It's not listed as such on the CH support PDF but that's entirely possible. I'm really not convinced that I have any need for a 7.5 as my needs are modest.

 

[EOC_Jason]

Check actual pump specs to see what size motor it can run. Sometimes two pumps might look the same, but internally are different.

 

[rsanter]

I would look for a used three phase motor.
Often they can be had cheap from people swapping them out
If it's cheaper to by that and a VFD then that's what I would do

Bob

 

[Davefr]

It's your money, but I'd ohm out your old motor to confirm that the windings are really bad. These things are pretty robust and it's kind of hard to believe a power glitch would destroy the windings.

Maybe it's just the capacitor that got zapped and the motor shop misdiagnosed the problem.

 

[Strouty]

I would look for a used three phase motor.
Often they can be had cheap from people swapping them out
If it's cheaper to by that and a VFD then that's what I would do

Bob

You would need a very large and expensive VFD to run a compressor.

If you change the motor to a larger size, you will probably need to change the magnetic starter as well. As others have said, just get an identical motor. Check at tractor supply, sometimes they have good deals. Ebay will also be a good bet. Make sure you get the same RPM as well as rotation and shaft size, that will be the least expensive option. A lot of motors are reversible, but if you get a non-reversible one and it is the wrong rotation, you will have issues. When you go from a 3600 to an 1800 (or vice versa) your pulley size is either half or double. The pump can only turn a certain RPM range, otherwise you are risking damage.

 

[gatorgrabber]

Let me try to respond in some kind of order. According to my conversation with CH, the pump is the same for both the 5 and the 7.5, at least for the year this was built. This really doesn't make much difference to me since I'm just going to go with a 5hp replacement motor. I briefly considered 3-phase but ruled it out due to the added complexities of not having that power on anything else in my shop. I can pick up a quality replacement single phase motor for less that $400, so that's the route I'm taking. Unless there's an advantage to going with a lower speed motor (and changing the pulley ratio), I'll just go with 3400rpm.

BTW, the unit was totally fried internally...kind of like someone dropped thermite into it! Nope, it's really dead.

 

[Strouty]

Sounds like you are on track, remember to check the rotation.

 

[gatorgrabber]

Absolutely!

BTW, can anyone give me an idea as to which brands are made in the USA? It's tricky to sort through the marketing BS.

 

[Garage Rat2]

1750 rpm 4 pole motors will develop more torque than 3450 2 pole motors, but you will need to double the diameter of the pulley on the motor to keep the same pump rpm. 3450 motors are usually installed by manufacturers as they are considerably lower in cost; less material for windings. Look at your old motor nameplate and see how many amps at voltage it used. That should be your guide to buying new motor, as HP values on compressors sometimes are marketing "inspired".

 

[gatorgrabber]

That's useful information, thanks. I'd prefer to operate the motor at a lower rpm. I don't have the old motor with me right now but they were playing marketing games with the HP, suggesting it produced a "7HP peak" when it was actually a 5HP motor.

 

[Jere]

Personally for 400 bucks I would buy a used compressor (or two for that kind of free cash) off of craigslist that had the motor you want. Then recoup some money buy selling the parts off you don't want or just keep some as spares. Those motors last a long time just check the bearings and make sure the motor runs before purchase. If you get an older motor you also get the benefit of honest ratings

 

[gatorgrabber]

Think of this more as a restoration exercise that gives me the exact compressor I want. Since I only have $75 in the entire compressor as it now sits, spending a little more for a good (new) motor still gives me a completed system for far less than just buying something else that has an unknown history. I've just taken the pump assembly apart and it's in excellent condition with very little wear. Once back together, this compressor should last me a good, long time. I'm very much a fan of rebuild over replace.

 

[CNGsaves]

Think your short list of motor brands might include:
. . . . Baldor, Leeson, AO Smith

Here's a 7.5 HP Baldor that I ran across on CL for $385
http://tulsa.craigslist.org/tls/4729154901.html

 

[mikehaugen]

Reliance motors are also quite good. But like everyone else, I'm sure there are different tiers of quality to meet different price points.

 

[gatorgrabber]

Thanks for the motor suggestions, I'll look into them.

 

[mark52621]

Leeson and Baldor are the two top brands. Marathon is also good. Just make sure the motor is rated "compressor" or "farm" duty. A service factor of 1.15 is also a plus.

I would go with a 1760 rpm motor and change pulley size. The same amount of work, you get a better motor, and it only costs ~ $15 for a pulley.

Also check frame size of the motor, not a big deal but the same frame size should be a direct replacement.

 

[stlrnt]

I purchased a used hs7810 and the shaft in the pump is lose.. bearings or bushings??? Don't know!! Can it be repaired?

The pump is no longer available everywhere I check.. is there a pump that I can replace it with? Also if it can be repaired who does that?

 

[dirtydogintex]

If rpm is reduced on a splash lube pump make certain the rpm does not drop below the mfg’s min recommended rpm.

About the only compressor duty motors worth a flip are Baldor.

 

[laser3kw]

In the compressor world, the manufactures play horsepower games just like the small engine manufactures. Check the FLA and rpm for the 5 hp and 7hp motors just to make sure they are not advertising a erroneous number.
If they indeed used the same pump with two different motor ratings, they may be using the higher hp to spin the pump faster for more cfm output ( and faster recovery time).
If that is the case, look at the parts break down for each. It wil state which pulleys are used on each motor. But be aware, they may also use a different pulley on the pump.
research, research, research.

 

[Citation]

I purchased a used hs7810 and the shaft in the pump is lose.. bearings or bushings??? Don't know!! Can it be repaired?

The pump is no longer available everywhere I check.. is there a pump that I can replace it with? Also if it can be repaired who does that?

I would suggest starting a new thread to ask the question. My web search suggests this is the same compressor my father has. Start a new thread and I'll give you my take (which is probably worth what you will pay for it... )