Removing Cast Iron motor pulley/ brake drum

ripperj · Feb 5, 2018

I need to replace the motor bearings on my lathe. 5hp 3phase 112M frame size motor.
The triple V groove pulley and integrated brake drum appear to be shrunk fit to the motor shaft. There is a full length key. No Allens or separate hub.
The pulley is about 4.5” OD and the brake drum part is about 8” dia and 1.25” thick.The

rear of the drum part is relieved leaving about 1/2” rim and 1/2” thickness on the relieved part.
I ordered a OTC brake rotor/ drum puller. It only has two arms.

I have been soaking the shaft with Liquid Wrench.

I was planning on applying some tension with the puller and heating the V part of the pulley with Oxy/acetylene.

It may fall right off

, but I’m expecting it to be a PITA.

To reinstall I’m torn between boring the pulley a bit and tapping some set screws, and heating the pulley to 450 in my kitchen oven and hopefully dropping it on the shaft. A piece of 1/4” ply with a slot between the end bell and pulley would be about right to stop the pulley from going to far into the shaft.

Any advice other than don’t break it?

Thanks Keith

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ronf · Feb 5, 2018

You need a rose bud tip on the torch so you get the pulley hot fast with out heating the motor shaft, then you need some one on the puller with an air wrench to zip it off quick. The method you out lined to assemble it should work fine. I'm assuming there is no set screws hidden in the paint or dirt.

ewlsey · Feb 5, 2018

Your local electric motor rebuilder should be able to heat that up and press it off for you. Ditto on the install.

ripperj · Feb 5, 2018

I was thinking about the impact wrench, but was a bit nervous about breaking the rim of the drum.
I’ll try as described , if I couldn’t get it off that way I was going to drill (4) 1/2” holes just outside the pulley diameter and make a puller that used 1/2” tee-nuts. The force would be a applied a lot closer to the shaft.

Probably turn out to be one of those things that you later wonder why you were concerned

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Richard King · Feb 5, 2018

I am assuming you removed the set screw or could be 2 sets screws one on top of another in the pulley? You need one of these (below). Or one like this and a hyd. press. Your looking at breaking it if you use a puller if you have never done this type of thing before. Take it to a Engine rebuilder or an Electric motor repair shop as they have all the right tools. How much clearance is behind the pulley and motor cap?

I would also be very careful using a torch if your not familiar using one.

Bearing Splitter 1/4" to 15/16" at National Tool Warehouse

ripperj · Feb 5, 2018

There do not appear to be any set screws or screws of any type.

I’m not near the motor regarding clearance. Due to the curved shape of the motor end bell there is not a lot of room for a press plate if that’s what you are thinking. I’ll have to check later.

For what’s its worth I spent a couple years in an Electric Motor Repair shop, but all they pulleys I recall had separate tapered split bushings.

I did consider taking it to a motor shop, but I wasn’t sure the odds of it getting broken were any less.

Thanks for the reply

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atomarc · Feb 5, 2018

It's rare that there are no set screws, vary rare. Often they are hidden behind accumulated junk and not easily seen. Putting a puller on and tensioning it up while applying heat will do the deed for sure.

Using a impact is a good idea, not to oink on the puller but to buzz the sheave off fast when it comes loose. To reisntall, heat and drop on.

Stuart

petersen · Feb 5, 2018

If there are no set screws, explore whether the key

might be a taper key.

If so, you should be able to drive the pulley onto the

shaft a bit with a piece of pipe to release the taper.

Then pick out the key and the pulley should slide off more easily.

Taper keys are not very common these days, but many pulleys and hubs

are wrecked trying to pull off over a taper key.

Also; never place a pulley or hub up against a shoulder when using

a taper key. You need space behind it to knock it loose.

ripperj · Feb 5, 2018

I had not considered a taper key, I think I can see enough of the rear side to compare to the exposed front.

I’m going to take a much harder look for screws tonight, including at an angle from the rear of the hub, but I am pretty confident that there are none
Thanks gain for the support

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ewlsey · Feb 5, 2018

If it's a press fit pulley, consider drilling and tapping some holes in the front face to attach a puller. That's how most press fit pulleys I have come across are made. Much better than a the bearing splitter that could gouge the belt grooves or worse.

atomarc · Feb 5, 2018

Often knowing the brand motor or lathe will help one determine how much sophistication was involved in the motor construction and what method of sheave retention to look for. IMHO..tapered keys haven't been used since Christ was a kid, especially on a small electric motor.

Having no taper lock bushing and no set screws, the only other likely option would be a moderate shrink fit. A little heat and some gentle oink from a gear puller will solve the riddle.

I'm not sure I would be concerned about "gouging" cast iron but don't go nuts trying to muscle it off sans heat..or you'll have a bad hair day for sure. :eek:

Stuart

ripperj · Feb 5, 2018

It’s a “Kerry” brand 16x40, but it’s a 1984 year Namsun (South Korean). It’s similar to Wacheon in quality, but simpler

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Richard King · Feb 6, 2018

I would try to press off both housing and pulley with the splitter under the motor bell to support 360 degree's. If you drill and tap a hole you may get vibration later as the unit will not be balanced. I still think there are some set screws your missing under some crud. Was there a flat washer, lock washer and bolt holding the pulley onto the shaft as that could have eliminated a set screw?

LKeithR · Feb 6, 2018

I'd be leery of pulling on the outside of the brake drum. You'll undoubtedly have to put a lot of force on the outside to break the
assembly loose and you really risk the chance of breaking the drum--don't ask me how I know. :eek:

As Richard said, I'd get a
good bearing splitter and the appropriate two-point puller and start by grabbing the back of the pulley and seeing if it comes off
separately. Should make the job a lot easier and, if you do break something, it will be a lot easier to replace the pulley than the
brake drum.

If the pulley comes off and the drum is still putting up a fight you can drill and tap a couple holes in the drum as close to the
centre as practical and use the puller to yank it off. Pulling from as close the centre as possible will greatly reduce the bending
force on the drum...

ripperj · Feb 6, 2018

The drum and pulley are all machined from one piece. I confirmed that there are no set screws, nor was there a retaining bolt on the end of the shaft.
The key appears to be straight.
Richard- you last post appears that you recommend pulling the motor endbell and the drum/pulley in one shot? That does not seem to be the way to go as the motor end bell is relatively thin. I can recover from a broken brake drum fairly easily, but a broken endbell will require a new motor... if I misunderstood I apologize.
I would think I could lay out two or four 1/2” holes accurately enough that vibration would not be a big concern.

Thanks for the continued interest.
Keith

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Richard King · Feb 6, 2018

They must have made it so it could be removed. I am sure if I had it here I could get it apart. Good luck, I'm out of ideas for you.

bridgedog · Feb 6, 2018

If I was to do this I would use the bearing splitter. I would not go behind the pulley I would set it in the rear pulley groove. I have also ruined my share of parts but you must pitch if you are to catch. Good luck

iwananew10K · Feb 6, 2018

This might seem weird but there were some motors at the plat I worked at that had "set screws" that went in the end of the shaft that pushed the keys outward from ythe inside....terrible explanation and I'm sure there is a name for it....the set screws would get all plugged up with crap and if you didn't know they were there you would never see them.

It was actuall a very nice way of securing pulleys to shafts.

ripperj · Feb 6, 2018

Once in a while you get lucky.

Heated as best I could with a propane torch, tension on puller, wack puller with Three pound sledge, repeat a bunch of times. At one point it started moving nicely..... then I ran out of puller screw

Thanks for all the help

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ewlsey · Feb 6, 2018

All's well that ends well. What holds the key in?

Removing Cast Iron motor pulley/ brake drum

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Hot Rolled

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