|
|
Posted by D Sherman [72.47.153.24] on Thursday, May 03, 2012 at 23:22:56 :
In Reply to: Re: Designed to break posted by John B [199.246.2.10] on Thursday, May 03, 2012 at 22:30:09 :
Yes, no doubt some were made flawed. They should have failed early, but sometimes they don't I broke a mainshaft in a 3053 transmission. I had a heavy load, but the engine is only about 140 HP and the 3053 mainshaft is about 2" diameter. Once I tore it down, I could see that there had been a crack in it for a long time before it propagated all the way and finally failed. On a part that's exposed to the weather it's really easy to look and see how much of the crack is rusty. On something that's well oiled, it's a bit harder to tell, but the recently broken part is still brighter. The failure analysis engineers have better ways to tell just how old a crack is and whether it was there right from the beginning.
In a really solid design, every part of the drivetrain should be able to survive the maximum amount of torque, including shock loads, that could be imposed by the stock engine. There should be no consideration of what's "designed to fail first" because nothing should fail. Usually that's the case. The problems come with the aftermarket modifications.
Nobody would think of putting 200 lbs/sq ft on the upstairs floor of a house that's designed for 40 lbs, or hanging a 5000 lb load from a 1000 lb-rated chain, but guys are always putting in bigger engines, bigger tires, etc, without consideration of the design strength of the drive train, the thought apparently being "It's pretty strong. It probably won't break. If it does, I'll beef it up." Fortunately broken axes and U joints aren't life-threatening.