Phasing the Universal Joints on an Atlas Mill

Shootymacshootface said:
Those pictures are very telling. The u-joints need to be lined up to work together. I'm not an engineer, but I do know that u-joints have a working range. I am quite sure that when that table is lowered all the way downike that those u-joints are outside their working range. I'm sure that the designers of that machine made a compromise that was acceptable to them. Even with new properly aligned u-joints at that extreme angle you will get an uneven motion on the output end of the shaft. The closer the shaft gets to inline the smoother it will operate.
One last thing about drivelines is that when you are designing, say a pto, or the driveline on your latest hot rod build, you never want the drive shaft perfectly straight. The cross shaft bearings must be exercised.
Click to expand...

I’ve used my MFC table feed in both extreme directions. It works just fine if the output shafts are parallel and the cross pins are operating in the same plane. This is how a cardan shaft can provide constant velocity.

This particular example seems to illustrate a cardan shaft that was reassembled incorrectly at some time in the past.


Sent from my iPhone using Tapatalk
 
Yes, you need to disengage the hex shaft and re-clock that joint pair.

Sent from my SM-G892A using Tapatalk
 
While the previous video I embedded here illustrated a u-joint in action, here is an explanation from the engineering perspective. This actually explains why there is a velocity difference and how a two-joint, properly aligned shaft achieves constant velocity.

 
It is only 8:15 here this morning and I just learned a lot about drive shafts.

I had no idea about this, but always wondered whey driveshafts in front wheel drive cars were CV joints. Very interesting. Thank you for the lesson.
 
Yep. 4X4's have come a long way in the past 80-odd years. Most people today would think that there was something terribly wrong with the front axle if they drove an MB or GPW on dry pavement with the front axle engaged. Or for that matter, just about any 4X4 prior to the first Range Rover.
 
wa5cab said:
Yep. 4X4's have come a long way in the past 80-odd years. Most people today would think that there was something terribly wrong with the front axle if they drove an MB or GPW on dry pavement with the front axle engaged. Or for that matter, just about any 4X4 prior to the first Range Rover.
Click to expand...
Absolutely true, except for some medium duty trucks, specifically Ford's F350, 450, and 550's. Not sure about the other manufacturers, but Ford is still using u-joints on their front axles. They make them turn so sharp, that while in 4wd, you really have to hang onto the steering wheel if you have it turned anywhere near the locks. We had an F350 that broke the transfer case output shaft twice because the guy that was plowing with it was performing a 3 point turn on a wet road. Same exact place both times. The cause was the front wheels working against each other as they were speeding up and slowing down.
 
Thank you everyone. This has been tremendously helpful. I'll let you know when I have re-clocked the assembly. That will take some effort.
 
I re-clocked the lower joint and it now runs at a constant speed, as far as I can tell by eye. The 1/8" pin pressed out of the yoke easily. I was worried that the cast yoke might crack, but it was no problem at all.

Wish I knew the history behind the mill. The inner telescoping shaft appears to be shop made and there was only the one pin hole. So whoever made it did a good job, but put the pin hole in the wrong spot.
 
You must log in or register to reply here.
Back
Top