motor shaft repair 2

[humbleuser]

Hello everyone:

I have a 60HP Delco-Remy AC motor that is about 30 years old. The shaft broke on one end due to the hydraulic pump seizing (which needs to be rebuilt). I have yet to take the motor end caps off, but I was wondering if the shaft slides inside an "armature sleeve" or does the whole armature need to be taken out? Also, can the shaft be repaired or does it need to be replaced? Thanks.

 

[MikeHalloran]

I'd be surprised to find such a sleeve; it would just add cost and complexity in anticipation of an unlikely event.

Don't disassemble it, just take the intact motor to your local electric motor rebuilder. He can probably repair it better/ faster/ cheaper than you can.

Ask about making the repair frangible, so the pump drive spline(?) can be replaced without motor disassembly the next time the pump seizes. Or, not; you'll be gone by then. ;-)





Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA

 

[humbleuser]

Thanks, Mike. I really don't want to take the motor out if I don't have to. I would need to remove a bunch of hose, pipes, etc. to get it out. I was thinking about pulling the one end cap off and sliding the armature out (sounds easy enough). My question is it as easy as I'm thinking it is to do this? What needs to be removed within the motor to take out the armature? Again, thanks. BTW, this application is an injection molding machine.

 

[candu6]

If this is an induction motor then the task is simple: Remove one endbell and the rotor will slide right out. End bearings will be shrunk on either end of the shaft.

 

[humbleuser]

Thanks candu6. Is shaft repair and welding common? Never had this happen to me before. Thanks again.

 

[macmckim]

When your taking the rotor/shaft assembly apart from the motor frame by removing one of the endbell, also check on the opposite endbell to see if endbell has internal bearing cap. There were be 3-4 bolt heads around the bearing area. If you try to remove the rotor without removing these bolts, you may damage the motor.

Shaft repair is quite common and can be done by most motor repair shops. The costs will depend on where the shaft broke (in front of bearing or behind bearing). Some shops can stub a new shaft piece onto old shaft, or depending on damage, a new shaft will have to be made.

 

[mc5w]

Very likely you will have to replace the entire motor - a broken or bent shaft is basically a dead horse problem.

If this motor and hydraulic pump were built for each other before the days of C-faces you might have to replace both the motor and the pump. If it is too hard to attach a new motor to the existing pump that is your best option. Plumbing is very easy to reengineer, custome motor frames are not.

 

[humbleuser]

There are no bolts around the bearing and the end bell has 4 bolts only. When the rotor is pulled, are there brushes or anything else that could be damaged to worry about? Obviously, I never done this before and want to take the utmost precaution. Thanks to everyone for their valuable input.

 

[ScottyUK]

There should be no brushgear or anything much else in there if it is a standard 3-phase induction machine. Brushgear is found on DC, universal and synchronous machines, but I can't imagine why you would have any of those types on a hydraulic pump. Some 1-phase motors have a centrifugal switch which can be fiddly, but at 60HP you are way above the normal limit for a 1-phase machine so I would disgard this possibility also.

On the slim chance that anything is fitted internally, it is almost always located at behind the NDE endbell, so it would be apparent as soon as you pop the cover.







----------------------------------

If we learn from our mistakes,
I'm getting a great education!

 

[GopelT]

Here are a couple of thoughts. First: At 60 hp this motor is most certainly reshaftable. The rotor needs to be taken out and the rotor and broken piece of shaft need to be taken to a motor repair shop for the shaft to be pressed out of the rotor, measured up and a new shaft machined and pressed in. Replace the bearings also. An ounce of prevention.... when you pull the drive end endbell you may need to pull 2 or 3 screws first that are located in close proximity of the shaft. These bolts hold a bearing retainer in place. The rear endbell probably has the same thing. Pay attention to any bearing or shaft shims that might be there also. After reinserting the rotor back into the rear endbell you will need line up the drive end retainer to the screw holes in the endbell while replacing the endbell. Just cut 2 long (12 inch) pieces of threaded rod and screw them into the bearing retainer and fed them through the holes in the endbell as you slide the endbell into place. Remove the rod one at a time and install the screws. not a bad job at all..
have fun.

 

[macmckim]

Another item to try to check, dependingn on the motor's enclosure for the old Delco design (ODP enclosure or TEFC)
is some of the old Delco ODP motors have internal cooling fan on the DE side of the motor. The fan is larger than the rotor bore, so pulling the rotor from the non-drive end side of the motor, the fan will hit the winding.
If you can see inside the motor (its ODP) and can determine if motor has internal cooling fan. The TEFC motors do not have internal fans.

 

[electricpete]

Your old 60hp motor is 30 years old and has a broken shaft.

Assuming this is a run-of-the mill horizontal T-frame squirrel cage induction motor available off the shelf we would buy a new one for one or two thousand dollars and sell the old one for scrap.

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[electricpete]

Oops. I forgot you have problem with getting access to remove the motor.

If you go the rotor repair option make sure your shop knows what they're doing.

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[humbleuser]

Thanks everyone. I don't know if I mentioned it, but the motor is driving pumps on both ends (with one end having a broken shaft). Should this make a difference in all of the excellent advice given so far?

 

[itsmoked]

Nope no difference.

By the way, 60HP in an injection machine? That must be a dooser... 200 Ton?

 

[humbleuser]

250 Ton, Extended Platen, Accumalator, Hydrualic Clamp and it has an additional 20HP motor mounted on side of overhead oil tank for the injection boost/speed increase. It's an old machine but it runs great! Thanks.

 

[itsmoked]

Cool! Or, er, actually hot!

 

[mc5w]

A new motor would probably be more efficient than a 30 year old motor. It probably be worth your while to just replace this motor. At 30 years old there probably not any kind of strange mounting or coupling for the hydraulic pump, but I have encountered some specially built motors for lubraction pumps that cannot be replaced. In one instance of a dying lubrcation pump we just simply had to get a new lubrication pump from a different manufacturer and hook it up to a standard motor.

 

[stardelta]

I quote for and deal with repairs of this nature on a regular basis. Assuming its an AC motor a shaft replacement is the best option. Stub repairs and sleeves simply will not be strong enough for 60 hp especially if its a 2 pole machine. Shaft replacement is a routine procedure for a competent and I stress competent repair company but its a question of cost against options and benefits, and the repair will probably cost more than a modern replacement motor and mounting mods. Get the pump inspected first as it may be imposible to repair, if its snapped a 60hp shaft its almost certain to have caused some serious damge to the pump internals when it seized up. The whole motor would have to be removed from the pump and dismantled to allow the bearing housings/journals and other parts to be checked otherwise you are unlikely to get a guarantee. Also the pump driveshaft will need to be checked for damage. A detailed drawing would be made of all shaft dimensions then the broken shaft reminants would be bored out of the rotor pack. This method ensures no damage to the laminations. A new shaft would be roughed out and keywayed to fit the rotor pack. Insist on EN24T steel. Best to use controlled heat expansion on the pack when fitting the shaft and keep interference and pressure fitting to a minimum, again to avoid the risk of damage to the rotor pack. The D/E and N/D/E shaft extensions can then be finished turned, trued to the rotor and the whole assembly then balanced. Then its a couple of new bearings a winding overhaul and a final test.......Then the following month a big bill from the repair Co.!! We did one recently for a 175hp motor that was about 40 years old, it drove an industrial centrifuge and it was impossible to replace the motor or modify the machine, cost was about £3.5k. If I was in your position I would seriously consider approaching several reputable Hydraulic Engineering firms and getting quotes to replace the pump and motor with modern and more efficient replacements.

 

[Mendit]

Humbleuser
If this motor is a T frame, which it may not be as the AC Delco motors were often specials, throw it away and buy an energy efficient motor, the power savings will pay for the new motor in approx 3 years. Read the name plate before you buy new, make sure the motor you buy will do the job.
Many Delco motors have copper bar rotors and most standard motors in the HP range are now Aluminum di-cast. Check the code letter on the name plate. Codes E,F and G are normal.
These codes affect the starting current or Locked rotor current.