Lengthen a pto shaft

[gemini5362]

Ok I understand your viewpoints. And I am sure you are very correct. I would definetly reccomend that anyone reading this thread take the advice of the other posters because they have a wealth of experience to deal from. And I will freely admit I use my tractor as a very cool play toy. I will also admit that at this point in the discussion I am probably just being obstinate. I do however just for the sake of arguement and not as a reccomendation, Think that welding in a piece of tubeing is not a lot different than taking a new tube and welding on ends. People I have talked to that know a lot about welding have told me that if you prepare it properly and get good penetration that a piece that is welded is as strong or stronger than the original. ( These guys used to weld lift hooks on steel ladles that when full weighed about 100 tons ) The few driveshafts that I have been associated with the male portion of the telescoping tube was a lot shorter than the outer female tube. If you cut the tube at one end then the chances of the male part getting to a point where it would not slide should be fairly slender. But let me reemphasize that I agree with the other posters totally and 80.00 is not much to be safe. I am just making conversational arguements here.

 

[Soundguy]

Hmm.. Most driveshafts I see that telescope are equal lengths...both sides.

With a piece of tube welde dinto the yoke.. you have 1 failure area. With a piece welded int he middle, you have 3 failure areas. And while the weld itself may well be stronger than the parent metal.. Ill wager that when you put the hp and shok to it, the place it breaks will be just past the weld where the 'weaker' metal meets the stronger metal.

If you are patching a driveline.. do a whole side... the scab is just a nightmare waiting to happen in all but the most sever situations, or in extreme emergencies.. etc.

Soundguy

 

[Farmwithjunk]

Ok I understand your viewpoints. And I am sure you are very correct. I would definetly reccomend that anyone reading this thread take the advice of the other posters because they have a wealth of experience to deal from. And I will freely admit I use my tractor as a very cool play toy. I will also admit that at this point in the discussion I am probably just being obstinate. I do however just for the sake of arguement and not as a reccomendation, Think that welding in a piece of tubeing is not a lot different than taking a new tube and welding on ends. People I have talked to that know a lot about welding have told me that if you prepare it properly and get good penetration that a piece that is welded is as strong or stronger than the original. ( These guys used to weld lift hooks on steel ladles that when full weighed about 100 tons ) The few driveshafts that I have been associated with the male portion of the telescoping tube was a lot shorter than the outer female tube. If you cut the tube at one end then the chances of the male part getting to a point where it would not slide should be fairly slender. But let me reemphasize that I agree with the other posters totally and 80.00 is not much to be safe. I am just making conversational arguements here.

When it comes to being obstinate, I take a back seat to no one. I guess my pont is this. If you have all the equipment to do the job RIGHT, and have the ability to do it RIGHT, and STILL want to take the time, you can take a wild chance on a patched pto shaft ....or....spend maybe $100. You don't have the equipment and/or ability, you can spend a bunch to have a welding shop take a crack at it. Did I mention $100 already?

Not worth the hassle. Not worth the risk.

 

[Fredex]

I do however just for the sake of arguement and not as a reccomendation, Think that welding in a piece of tubeing is not a lot different than taking a new tube and welding on ends.

Hi again, Gemini. For the sake of further description and understanding. Replacing the tube at the yoke is not quite the same as extending the existing tube. When the old tube is extended you butt-weld 2 pieces of tubing together. That's a rather thin weld. If the inner portion of the drive shaft doesn't extend past the weld into the old section, then that thin weld must transmit the entire torque load. At the yoke the tube is inserted a short distance into a square hole in the yoke. When you replace the entire section at the yoke you cut the angle-weld at the yoke and pull out the entire old section including that short section inside the yoke. Then slide in the new, longer section and re-weld to the yoke. Most of the torque is transmitted through the square tube fitted into the square hole of the yoke; the weld mostly just holds it in place.
Fred

 

[bx23barry]

All I can say is I have welded up driveshafts with 2-3 batterys, jumper cables, some stick rods and a few pairs of sunglasses in the middle of nowhere on jeeps and never had one come apart before it got home. Having it out on the bench in the shop is a piece of cake.

 

[Slamfire]

Got an extension, and it works pretty good, although there's a bit of slack in the overrunnin' clutch and that's magnified at the end of the extension. I was thinkin' of weldin' somethin' on the end of the shaft where it connects to the gearbox. Say a piece of barstock between the universal and the gearbox. What do you think. Oh the telescopin' shaft is triangular in shape there's no way to lengthen that!

 

[gemini5362]

Hi again, Gemini. For the sake of further description and understanding. Replacing the tube at the yoke is not quite the same as extending the existing tube. When the old tube is extended you butt-weld 2 pieces of tubing together. That's a rather thin weld. If the inner portion of the drive shaft doesn't extend past the weld into the old section, then that thin weld must transmit the entire torque load. At the yoke the tube is inserted a short distance into a square hole in the yoke. When you replace the entire section at the yoke you cut the angle-weld at the yoke and pull out the entire old section including that short section inside the yoke. Then slide in the new, longer section and re-weld to the yoke. Most of the torque is transmitted through the square tube fitted into the square hole of the yoke; the weld mostly just holds it in place.
Fred

Oh my god you are talking about putting a tube on the right way. I am not use to people doing that. I was talking about just cutting the tube off of the yoke then butt welding it to the tube. If you are talking about doing it right I would have to agree that would be much stronger.

once again just for the sake of arguement since I dont want to sit in the back. If you take the time to grind all the ends at a 45degree angle. then weld them up using multiple passes if necessary to the point where the weld is flush with the rest of the tube. And if you have someone that knows how to weld and get good penetration etc. I think you will break the u- joint long before you break that weld. I know fredex knows what he is talking about. I have as I posted before seen guys butt weld stuff onto various metal objects at the steel mill I worked on and let me tell you they ground it down to a 45 degree angle and then filled back in and for strength ran other beads over that. this stuff held things in the tons or 100 plus tons. I never saw a weld fail.

I had to weld a new piece in a driveshaft for my 3 ph post hole digger. I did it the way I described unfortuneatly I did not get a thick enough piece of tubing and I bent the tubeing but the weld did not break.

 

[gemini5362]

Slamfire is the slack going to really make a difference once you get the blade spinning it will keep on spinning it will it not ?

 

[Slamfire]

I hope not, it's just a little wobbly, maybe it'll be ok.

 

[gemini5362]

Every once in a while in an effort to improve myself I watch discovery channel. I just saw an episode called SUPER TOOLS it was about the specialty tools Newport News shipyard uses to build a nuclear aircraft carrier.
One of the things i noticed was that they mentioned when the shipyard puts a ship together it BUTT welds the plates together they interviewed the safety inspector the inspects welds. He said that when something was properly BUTT welded then the weld became stronger than the metal and if something was going to break it would break somewhere other than the weld.

If it is good enough to put Nuclear Aircraft Carriers together then BUTT welds should be able to hold my PTO driveshaft for my mower.