Shortening a jackshaft

.
.Here is a little bit of light reading from old Mr Fuller.........

...............................Billy..................................

dno wrote:

Dave_64 wrote: Like This, gives two different MAX angles for two different lengths,
Is that measured between the two faces OR the MAXIMUM inclination (or slope)
of the shaft??

Dave

the last tail shaft shown here is ok even though have it marked as not ok
All PTO shafts on trailing farm implements have this arrangement when they turn a corner and last for ever and a day
As long as the angles are equale and the uni crosses are in line they work fine

People say the tail shaft cant be dead straight as the uni's wont lubricate I dunno how true this I think if they were dead straight they would never have a need to turn so it would be fine
However if it was only a poofteenth off I think thats when you would have a drama so its easier make them with a good angle so have plenty lubrication as they rotate around

Paul

OK, think I got it now. The two vertical faces of the opposing flanges have to be as close to parallel as possible, within one degree, especially on such a short shaft.Inclination of the short coupling obviously has to have a minimum of either 8 or 20 degrees going by that Spicer chart I posted earlier. Reckon I can work that into the equation, output from auxilliary flange to diff flange also to be parallel (no more than ONE degree), but a little more leeway allowed because the prop shaft will end up just under a meter.
Thanks Guys.
Dave

The Holden Commodore used a proper CV joint in the tailshaft to take care of odd angles.An old solution used by some US 4x4s is to put a double uni into one of the shaft joints,so that the front axle can have a lot of caster.I think Landcruisers also used a double uni.before the IFS version .I have found that with light shafts you can break the rules to some degree,but with 1600 and up,vibration will cause mounting bolts to undo.You used to see some pretty crazy angles in old trucks with joey boxes.I remember a Federal with a Perkins that had the joey box mounted in the diff space of the pusher axle,with the shaft going to the rear 2sp diff.He used to cart Ford cars Geelong to Brisbane in the 60s and 70s.

Flanges have to be parallel. (or as good as you can get) Any out of parallel makes the shaft come and go in the spline causing high frequency vibration and wear.
Think you'll find the max angle from the chart is more to do with clearance issues.
I had a very short shaft on my V drive setup. The yokes would almost bottom against it's mate due to the steep shaft angle.. In fact I made a mistake once when replacing the unis, and they fouled. Must have been a slight manufacturing difference one side of the yoke to the other and she wouldn't rotate smoothly.
Pulled her apart and refitted 180 out, all good.

On a superior rear engined VBUS model they have a real short shaft with the gearbox uni not aligned and leads the diff uni by 18 degrees. Had one shaft returned to Hardy Spicer several times, they didn't understand leading and trailing joints and wouldn't weld it back in the correct position. It didn't vibrate any more after i attached it to the scrap metal bin.

Mrsmackpaul wrote:

dno wrote:

Dave_64 wrote: Like This, gives two different MAX angles for two different lengths,
Is that measured between the two faces OR the MAXIMUM inclination (or slope)
of the shaft??

Dave

the last tail shaft shown here is ok even though have it marked as not ok
All PTO shafts on trailing farm implements have this arrangement when they turn a corner and last for ever and a day
As long as the angles are equale and the uni crosses are in line they work fine

People say the tail shaft cant be dead straight as the uni's wont lubricate I dunno how true this I think if they were dead straight they would never have a need to turn so it would be fine
However if it was only a poofteenth off I think thats when you would have a drama so its easier make them with a good angle so have plenty lubrication as they rotate around

Paul

Not quite right Paul, even on farm implements the shaft on the implement is best set horizontal to the ground. Check the angle on the bottom shaft in the last pic.
The second Pic from the top IMO best represents a farm implement scenario.

dno wrote:

Mrsmackpaul wrote:

dno wrote:

Dave_64 wrote: Like This, gives two different MAX angles for two different lengths,
Is that measured between the two faces OR the MAXIMUM inclination (or slope)
of the shaft??

Dave

the last tail shaft shown here is ok even though have it marked as not ok
All PTO shafts on trailing farm implements have this arrangement when they turn a corner and last for ever and a day
As long as the angles are equale and the uni crosses are in line they work fine

People say the tail shaft cant be dead straight as the uni's wont lubricate I dunno how true this I think if they were dead straight they would never have a need to turn so it would be fine
However if it was only a poofteenth off I think thats when you would have a drama so its easier make them with a good angle so have plenty lubrication as they rotate around

Paul

Not quite right Paul, even on farm implements the shaft on the implement is best set horizontal to the ground. Check the angle on the bottom shaft in the last pic.
The second Pic from the top IMO best represents a farm implement scenario.

If you look at the draw bar from the seat on the tractor as in a birds eye view its like the last picture when you turn
The draw bar pin is the same measurement on all implements to the uni and the same to the PTO shaft on the tractor I think its 14 1/2 inches but could check

Paul

Arrr, I see what you mean. I give up using the draw bar years ago as my PTO
would knock like all hell on the baler when turning hard, now I use the tool bar on the lifting arms. Very little to no knocking.