Lovejoy question

[Brewn4life]

To connect the output shaft of the electric motor to the milling shaft of my MM3, I use a love joy set up. Ok the output shaft of the motor is 5/8" and the input shaft of the mill is 1/2"..for ex.
So I would use a lovejoy hub with a 5/8" max. diam. And a hub with max. Diam. 1/2".
Both would need the OD the same size and the spider would have to have the same OD.
Is all this correct? And I take it get the strongest hub/sider set I can...say 100ftlb/trq+! I am thinking more like 200+ ftlbs/trq...always build for expansion.

 

[kjackson82]

Hubs come in sizes of shafts so for example you could have four hubs with id's of 3/8, 1/2, 5/8, & 7/8. They would all use a number 30 spider ( not exactly sure of exact number). So you can have to different shaft sizes connect with a lovejoy. Try McMaster Carr for exact sizing and part numbers.

 

[raouliii]

Yes. L numbers mate with each other and have the same OD. Here is the L type with keyway listing: http://catalog.lovejoy-inc.com/viewitems/standard-jaw-couplings-l-type/l-type-coupling-hubs-w-keyway-imperial? I have used L70s with a Hytrel spider.

A recommendation if I may.

I used the L70's on a MM2 mill and found that mating the mill to a coupler with a keyway is a much better option than one without a keyway. Simply file the key down in one dimension for a tight fit to the flat on the mill shaft. This allows you to tighten the set screw against the key, which provides much more surface contact with the flat of the shaft than without the key.

There have been reports of damaged shafts when only using a set screw against the flat.

 

[kjackson82]

I used the L70's on a MM2 mill and found that mating the mill to a coupler with a keyway is a much better option than one without a keyway. Simply file the key down in one dimension for a tight fit to the flat on the mill shaft. This allows you to tighten the set screw against the key, which provides much more surface contact with the flat of the shaft than without the key. There have been reports of damaged shafts when only using a set screw against the flat.

Agreed! Definitely the way to go. As far as the foot pounds, I don't think you need to beef that up. The spider is trapped pretty tight between the hubs and the torque of starting and stopping is what damages them. I don't believe you could start and stop it enough in your lifetime to damage the spider in this application. We have lovejoys on 100hp motors running pretty big pumps, gearboxes, fans, etc... and they last forever.

 

[kjackson82]

To add: the only ones I have actually seen tear up are in our applications of immediate forward - reversal swaps. The direction swaps a couple times per minute and there is quite a load being shifted. This shifting and torque heats the spider up allowing it to flex more and eventually just starts slowly getting eat away. The ones on single direction, such as fans, have been replaced due to rotting from being outside the plant. Never had a single direction get eat up, which is what you would be doing on a much smaller scale for the mill.

 

[Brewn4life]

Thanks for the reply's!