U Joint angle limit

[Don_Sullivan]

I've had my BX1500 for about two months now and am very pleased with most everything. The MMM deck has just been put into hibernation and the snowblower is standing by for the first serious blast.

One loose end. The manual for the Quick Hitch Mid PTO kit, BX2712, has a warning not to raise or lower the snowblower while blowing snow. I asked one of the service techs at the dealer about this and he said the universal joints in the Quick Hitch drive line are not happy operating at angles over about 15 degrees. With a crude level protractor I found that at 15 degrees the SB shave plate is a little over 8 inches off the ground, compared with its maximum lift of about 10 inches (20 degrees).

Experience with my old (Cub Cadet) SB has demonstrated the value of maximum lift in coping with deep snow with frequent switches up and down. I guess I could cope with a 15 degree limit but does anyone out there have any info on such low angle limits for Ujoints? My only other info is a limit of 40 degrees on my Howard HR3 tiller.

This forum has been most helpful in my Kubota education. Thanks to all contributors.

Don Sullivan

 

[KubotaBling]

I was thinking more than 15% more like 30-45% somewhere in that range. 15% sounds awful low.

 

[RoyJackson]

"I guess I could cope with a 15 degree limit but does anyone out there have any info on such low angle limits for Ujoints?"

I can't say anything more then you have on PTO shafts, but automotive U-joints (for the drive shaft) have been held to a 15° limit as well. It is my understanding that angles > 15° will result in excessive wear on the U-Joints.

Limited usage on your snow blower might not be much of a problem...but then again you may have to replace your PTO shaft (or rebuild it) sooner then later.

 

[slowzuki]

Shaft and joint life start dropping off quickly after about 1 or 2 degree. by 15 degrees it is in the order of 1/25 of the life at 1 degree, at 45 deg it is like 1/1000 or something like that!

In practical sense, the life drops off when the angle is 0 due to lube getting driven out since the needles aren't rolling anymore.

So you would have to balance the increase in life due to reduce load vs decrease in life due to operating angle. Have fun!

 

[Don_Sullivan]

Thanks for the info. I wonder why the Howard HR3 tiller manual talks about a maximum angle of 40 degrees. Translation from Spanish?

As a practical matter most of the snowblowing is done near or at ground level anyway so if it's just a case of increased wear, rather than self-destruction, I should relax and enjoy it.

 

[sandyc]

Don:
If you look at the angle of the ujoint coming out of the middle pto drive and the angle of the ujoint where the shaft goes into the front quick mount I think you might get an idea of the angle that is used in the fixed drive train. Not too sure of the angle right now as I have't put the blower back on my 2200.

Last winter I ran the blower at full speed when moving snow and did not shut it off when I raied it to go after the heavy stuff by the street. In fact I would start on the snow piles with the blower fully raised and at full speed. After chewing up a foot of so I would back up, drop the blower to ground level and go after it again. I have a few stumps that I have to avoid by running the blower raised.
The ujoints seemed very tight after the season. No wobble or anything.
The important thing here is to keep the joints greased, the chain lubed with a good chain saw bar lube, and the front shafts lubed as well. The ujoints are no problem if you keep their angle pretty flat when greasing them. Don't forget that there is a zerk on the female end of the drive shaft coming
from the PTO.
You'll enjoy the blower, it will move anything and everything that gets in its way. Watch out for rocks!

 

[Don_Sullivan]

sandyc;
I don't even want to think about last winter - the snow was over the tops of the pasture posts. But I coped using the scheme you described and would like to do the same with the BX1500 when necessary. All lube locations found, checked and fixed where necessary.

Based on slowzuki's comment yestarday I asked Google about "universal joint angle life" and, as usual, got more than I ever want to know about the subject. Found references to a wide range of operating angles and can see that the mid-PTO's max speed of 2500 prm (if I can believe the manual) would be harder on ujoints than the rear-PTO's 540 rpm used by my tiller.

I took the BX outside yesterday and ran the SB (in low position, parked) at various speeds and thought it sounded pretty noisy. Will try to find a similar unit to listen to to make sure I don't have a problem.
Don

 

[jrlichina]

I'll just 2nd Roy's post, a complete and correct answer.

 

[slowzuki]

Yes, sorry not to mention speed, I was looking at car driveshaft universals. Obviously lower speed ones such as in a 4wd front truck axle can handle more angularity before extreme wear becomes an issue!

 

[sandyc]

Don:
My blower makes a bit of noise but when you figure that there are four ujoints, an auger and a blower as well as a gear box and a large chain ...well there is a lot of metal rockin and rollin on the front of the tractor. Once you get used to the noise it will sound normal especially when you see the snow being thrown fifty feet from where you are. Make sure you don't bury your wife's roses or you might have to redig the holes when you replace the roses in the spring.....take it from one who has been there. Watch the kids around the machine as well. The stones and ice thrown out of the shoot really travel.