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  • Bented
    replied
    Originally posted by loose nut View Post
    I took a look at it today.

    Who designs this $#!~+
    Someone that was given the task of designing an air compressor with a very low target wholesale price.
    Any piece of simple machinery can be easily designed and manufactured "better" then what you have.

    More efficient
    Longer lasting
    Quieter
    More easily maintained
    Smaller
    Far more costly

    As a humorous side note, for 10 years or so I did a good deal of machine work for a large Pharma. distribution center, a sort and pick order operation. This place had a good deal of old conveyor/packaging equipment that used pneumatic controls spread all over the 100,000 sq. ft. building.
    After years of operating 24/7 there were so many small air leaks that the 25 hp screw compressor could not keep up.
    Finding and fixing the thousands of small leaks would take a great deal of time and also shut down sections of the process for repair.
    So they simply bought a 50 hp screw compressor and ran both at the same time, problem solved.
    Last edited by Bented; 04-03-2021, 08:06 PM.

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  • loose nut
    replied
    I took a look at it today.

    It has a one piece sheet metal guard and it has to go to remove the belt and pulley which is necessary to remove the motor. The belt and pulley need to be removed first but to remove the belt and pulley the guard needs to be removed first,. Who designs this $#!~+

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  • Dave C
    replied
    As said above, it's not that hard. Just take it slow and easy. Be careful when pulling the end bell off the shaft, you don't want to lose any of the washers that may be stuck to the bearing. Inspect the contacts on the switch. If they are good, inspect the actuator movement. Not much to do there other than cleaning it up and checking for broken parts, springs etc. Motor parts are available online.

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  • loose nut
    replied
    I have already watched that vid. I know the basics of how they work, just need to get the nerve to do it.

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  • loose nut
    replied
    The motor will start with pressure in the tank, pretty sure it is the switch.

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  • CPeter
    replied
    He said the it would start with no pressure in the tank, but if the tank had pressure it would not start. If it pumps up to full pressure and shuts off the the built in unloader in the pressure switch does its thing and releases the head pressure. It it shuts off prematurely, then the unloader does not get to do its job and the head pressure is too much for the motor to overcome. Is this s single or dual capacitor motor? They do make an inline unloader that relies on air flow to close it and when the air flow stops, it automatically opens and bleeds off the head pressure. Have you put an ammeter on the line in when it is trying to start? If it was the starting circuit in the motor, it seems like it would not start even with the belt off. If it was a bad tank check valve, then at full pressure, the unloader would drain the tank. A conundrum!!
    Peter

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  • Bented
    replied
    Originally posted by loose nut View Post
    Centrifugal clutch or switch that is used to energize the start winding of the electric motor. Sorry for the confusion.

    I figure the "switch" is stuck in the run position so the motor just hums but I can start the motor by giving the belt a pull and switching the compressor on why the motor is still revolving.
    Single phase AC does not generate a rotating magnetic field without help. When the coils are powered up at start there is no directional control so it tries to hold position, once in motion it will continue in that direction.

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  • chip's
    replied
    If the switch is ok, the unloader, as said above could cause the motor not to start because the head still had a load against it. If you can always get it started by spinning the belt it is probably a stuck switch at this point.

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  • The Metal Butcher
    replied
    Dad said to check your head unloader.

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  • rdfeil
    replied
    loose nut , Like said above, take the back cover off the motor and have a look. It is easy and simple, just go slow and easy with things. In most cases the cover will slip off easily after you remove the four through bolts. If it does not slip easily you can GENTLY tap it off with a dead blow hammer or any edge driving tool. Just go easy and rock from side to side. When the cover comes off make sure to keep track of any load springs that are between the bearing and the cover. They often stick to the grease on the bearing and then get lost when you are not looking . After that the switch is between the bearing and the rotor. There are several different designs, but all have a moving centrifugal activator and a switch with a lever that is pushed by the moving activator. The switch may be bad or the activator may be bad or stuck. I have seen many in dusty areas that have gotten stuck with grease and dirt over time. A simple cleaning and new grease and it is good to go. Keep us posted!!!

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  • I make chips
    replied
    Yep, time to pull the back cover off the motor and check the start switch. You'll likely find a bad connection or a burned contact. If a contact, try lightly sanding the surfaces to restore decent contact.

    Attached Files

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  • Dave C
    replied
    Check this out: How to Troubleshoot a Motor and Adjust Centrifugal Switches - Bing video

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  • loose nut
    replied
    Centrifugal clutch or switch that is used to energize the start winding of the electric motor. Sorry for the confusion.

    I figure the "switch" is stuck in the run position so the motor just hums but I can start the motor by giving the belt a pull and switching the compressor on why the motor is still revolving. The compressor, itself, works just fine, just a motor problem. I can use the compressor but I have to shut it off when the tank is full and then manually restart it when the tank runs down otherwise the motor won't start and it trips the breaker. It is a pain in the butt but still usable. I am a little gun shy about tearing a motor apart. As an electrician I would make a good plumber!

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  • rdfeil
    replied
    A couple of questions for clarity.... First, when you say 'clutch' so you mean clutch or do you mean start switch or something else? I have never seen a 5 Hp compressor with a true 'clutch'. Second, does the compressor EVER fail to start when the tank has 0 pressure or is the fail only when the tank has pressure? If it fails with 0 pressure and with a new capacitor it is now either a start switch or wiring issue. Most likely a switch. If it is only with pressure in the tank, then it is most likely an unload valve issue. The unload valve is often in the pressure switch and they do get clogged with oil and dirt. A good cleaning, with a solvent, can fix the problem.

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  • The Metal Butcher
    replied
    I had the exact same issue on a smaller compressor. Grandpa "fixed" it by cutting a hole in the belt guard to roll the pulley. Dad fixed it right. I will ask him what he did tomorrow.

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