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Electric Motors/craftsman motor, repulsion induction type


hello, i have a craftsman repulsion induction 3/4 h.p. motor model # 315.5611 its reversable, 110 % 220 volt, dual shafts are 3/4 in. 3450 rpm, single phase,on tag says 12/6 for amps,below that where it just says sears roebuck & co. theres a # 03 in a box,im looking for any manual & a parts breakdown for this as i cant seem to find anything about it on the web,its runs great but would like to see if can get any parts still,thanks

John,   good idea to look before you might need a part, but looking at the voltage ratings, of 110/220  tells me this motor is most likely pre 1952       Voltage ratings started moving up in the 60s to 115/230  and now days most are rated 120/240   

Added to that it is repulsion induction, it is probably way obsolete,

As you can see in the old link above,  the model numbers were past 315.*****   and most had five digits past the period,   older motors as I recall had four digits,

has a classified section and other information about older obsoleted equipment,   

RI motors are very rugged, the design was used to gain the torque of a DC motor using more readily available AC for residential use.

The motor has a wound "rotor" which is often confused with an armature.  At a given rpm on start, there are several varieties of short circuiting devices,  some with a slang "necklace" that expanded internally in the commutator sections and shorted the windings,  making the rotor act like an induction rotor.

There are several other methods of shorting the rotating windings,  all fairly complex, and parts are very hard to find if available at all,  and would be found from a collector, other old motors that may be in non working order,  but as a modern stocked item,  you won't find any stocked parts now days.

The motor may have some value,  some are very collectable, so I would hang on to it.  If you are using it for a saw or other device, I would look to find a replacement motor of some kind and store the RI motor,

As far as repair,  it may have plain/sleeve type bearings,  these sometimes can be found, bearing stock  or oil lite type  material can be found and machined to size.

The stationary fields can always be wound,  the rotor windings can be rewound, and the segmented commutator can be fabricated, but it will not be a cheap process.

We repair probably three or four a year,  some the shorting device,  even the necklace can be machined to be reused,  brush springs and holders are hard to find,  but also can be fabricated if needed,   but again,  not a cheap venture.

The brushes can be fabricated,  not a huge process, but are not normally stocked.

Above I drilled down to the 315 prefix and it shows

315    Ryan
315    RYOBI / Ryobi Motor Products
315    Diehl Mfg Co (portable power tools, prior to Ryobi)

As a working motor, if in good shape without a lot of hours, it could work for years,  but motors of the vintage I think this is,  is probably not practical as an everyday motor and of more value to a collector on one of this vintage machinery sites,    

Hard to say if it is a motor only, most likely it came on a piece of equipment made for Sears by someone.

Depending on what you are using it for,  you might get by with a common 3/4 HP motor, maybe a capacitor start motor,  if it is a heavy starting load,  you may have to move up to a 1 HP or better to get the starting torque needed,    

At this point about all you can do is research these vintage sites, you might find an old manual,  but even then it will only show you parts that are obsolete.

We repair these depending on what the goal of the owner is,  if they are attempting to restore an old device using all original parts,  then we fabricate the parts, wind anything shorted, and restore it that way.

If they just need a motor to operate whatever equipment,  again it is often more cost effective to retrofit a more modern motor in place of the old RI motor,    leaving the parts available to be sold as the owner sees fit.

Wish I had more information, but I believe you are dealing with an antique, and as with antiques comes the research and costs needed to restore to that vintage OEM.

If you ever have problems with it,  we can do as described above, it just depends on your goals of the use,     and again, if you are just using it as a motor,  I would suggest you consider replacing it,  and or first,  offering the existing motor for sale, and see what value you have in that particular motor.

You can contact us at any time at    MEAR Services Inc,   816-650-4030.    We have volumes of old motor data, but nothing that shows up with the 315 number I could find.

Let me know if I can help you with any individual part, or help in repairing it,  there are books available that provide information on how to go about the dismantling and repair of these motors,   they are not like any standard induction motor.

Will Babbitt

President MEAR Services Inc

Electric Motors

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Three phase/ AC DC single phase motors, controls, any problems or failures, motor installation, performance issues, connections. All other electric motors/gearboxes/apparatus. Specialty repair concerns, obsolete motors and solutions. Other mechanical or specialty equipment. See my profile under Home/electrical at this site


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