U Joint angle limit

[cp1969]

As the angle increases, it becomes increasingly harder on the driving and driven pieces of equipment, too.

Believe it or not, output rpm is not constant when the angle between the two shafts is other than zero. Throughout one full turn of rotation, the output shaft lags, then leads, the input shaft in rotational speed. Whatever is attached to this shaft experiences this same, very rapid, change of speed. If the driven piece of equipment has a lot of intertia, (like a pull-behind rotary cutter, in a turn) it can really work the pto drive train in the tractor.

 

[California]

</font><font color="blue" class="small">( ...output rpm is not constant when the angle between the two shafts is other than zero. )</font>

This is true at the ujoints but to clarify, I think if the tractor pto and the implement input shaft are parallel then only the low-inertia driveshaft varies speed through a revolution. This is because the same angles at opposite ends of the driveshaft cancel each other. Only an implement that is tilted relative to the tractor would vary in speed. I think it is necessary to orient the ujoint yokes in the same axis to accomplish this.

 

[BIGUN]

I agree with California’s answer. The keyed slip joint on your BX1500 MMM drive shaft takes care of aligning its u-joints properly. If oriented improperly I think you would experience some serious vibration.