Just had a slip joint shatter on pto driveline on a sterling water truck. The driveline is new. The old driveline failed. I don't have any pictures of the old one. But I think it was a u joint failure. The pump is also new. And I can spin it with my hand. Anybody have a theory? I'm scratching my head
I suspect Chineasium parts. I recommend only using Spicer 1310 series parts or re-branded Spicer NAPA. Maybe the pump has a serious vibration, or the new shaft wasn’t balanced. Or, the shaft is too long and the slip coupling has no slip. (He said shaft, huh huh) That slip coupling is very dry. It should greasy. So, greasy. This thread is greasy.
I’ve seen a fair number of discount PTO shafts catastrophically fail on newly up-fitted trucks. Had one launched from a new 4,500 gallon fuel truck while the driver was doing a delivery at the Girdwood Fire Station. The short end landed 30-40 yards into a muskeg. Driver was lucky it didn’t kneecap him.
I replaced a gailed one that was those little tiny one u joints with a larger shaft that ran a 40gpm hydro pump that was set at 3000 psi. In other words is that enough shaft. I went to the local farm supply and got tge biggest size i could that they had yokes to fit the shaft
Tiny little one is probably a 1210 series. 1 1/16” cap x 2 7/16”. 40gpm at 3000 psi works out to be 80hp. A 1310 series u joint is rated to 400ft/lbs of continuous torque. We would need to know how fast the pTO shaft is spinning to calculate any further. Doubtful a 1210 could handle that pump.
It didnt made it about a month of use before i made it bigger
I don't know. I went back and tried to do some failure analysis on the shrapnel this afternoon. I did notice that I somehow forgot to grease the slip joint. But the pump only ran for about 3or 4 minutes before the shaft failure and it ran so smooth that I got out of the cab to make sure that it was turning. I don't know what series the shaft yokes are but they were reused from the original driveline. Looking at the damaged pieces it looks like the slip joint made contact with the ground and that is what shattered it so the failure seems to be on the PTO side yoke where it broke at the key way. Right now I am thinking that either that yoke got damaged when the original driveline failed (and neither I or the driveline shop noticed) or that (its possible) I over torqued the set screw and broke it without noticing. Shaft has a balance weight on it and I have been using this shop for 15 or 20 years and many, many drivelines (though, never one this small). And they are pretty meticulous. To the point where, even if they have the driveline in their hand, they always make me go back and measure the distance shaft end to shaft end. That always annoys me, but to be honest... After 20 years you would think that I would remember to do that. As far as the speed of the pto... I don't know. I will try to look at the pto tomorrow (as well as the end yokes and u joints to see what they are). But the truck has a Cat engine in it so I think that full rev is somewhere between 1900 and 2100 rpm (if that even helps with figuring the pto speed without knowing exactly what pto is on the truck. I did go to full rev to see how much more the new pump put out then the old one and that is when it failed. I appreciate all of the responses and if I missed a question, let me know.
Maybe the yoke had a stress riser at the keyway groove and it was just a strange occurrence. Maybe double check the water pump to make sure it turns many revolutions without jamming.
LMAO. Im going with this!