[qwerty12]

Well topic is abouth a small 2 wheels tractor and its 2 wheel trailor
Such one I have and its trailor must be rebuild from new. Althought small and abouth 13hp tractor those little things can carry really much weight(good gear ratio) and they are ideal foor woods and bad roads. They can go annywhere because they are small and yet have 4x4 drive. Dont know how to explain it to you...tractor has 2 wheels on drive and when you attach a trailor to him he has that axle wich you connect to trailor wich has a differential and so the thailor has a full sinchronized drive with the tractor.


The main problem on those little things is that joint on the end od trailor wich you connect to the tractor itself. It has to be able to move in 2 directions. Left and right(looking froom above) to allow you to turn tractor with it handles...and also up and down kinda rotation movement because trailor must have that abilliti to tread...exhample trailor is on straight road and tractor goes over the rock with one wheel...so the tractor must be able to incline on that angle while the trailor still remains straight.

Here is a little image:



The factory that made those tractors and trailors had it own sollutions with a 2 side moving shaft wich holds on the tractor with a wedge buth that solution is bad...over the years moving parths of that joint become spacey due the friction and than you have werry poor ability to manuver the tractor itself...




So the question is If you where to build such trailor what joint type you would use.

Anny ideas, comments and paint drawings are welcome and latter I will provide you a few pictures so you can see how factory made that joint.

[Fat Bob]

What about using a single joint Universal Joint? There are hundreds of styles to choose from. Google "Universal Joint" and you'll see what I mean.

These are a few used on automotive steering shafts.

[qwerty12]

Cant use that joint type because it moves in wrong directions. It would allow tractor to steer left and right but also when loaded trailor would push that joint down and then tractor and trailor would not be in a straight line...under that joint is an axle that goes from tractor to the differential(that axle uses universal joint) and that axle would broke from that kind of bending. Let me try to explain with paint, my english is bad...


Picture one
Tractor must be able to turn left or right:



Pucture two upper parth: Tractor must be able to stay in line when trailor goes on rock and mowes under angle(or trailor must stay straight when tractor goes in line)
Picture two lower parth...under no circumstances tractor or trailor must not bend. When going straight or when turning or when one unit is on straight line and other on angle...always tractor and trailor should stay in straight line wheen looking from side vew

[Otto Nobedder]

You need a "drive shaft", with "universal joints" at each end, and a "slip joint" at one end.

This is the same thing you have on a rear-wheel drive car or truck. One set of joints (at each end) transfer rotation.

http://en.wikipedia.org/wiki/Universal_joint

The other allows the drive shaft to grow or shrink as needed, as the angle between tractor and trailor changes the distance between tractor axle and trailor axle.

Take a look at this Wiki, which explains both...

http://en.wikipedia.org/wiki/Drive_shaft

Steve S

[qwerty12]

Again we mistunderstood ourselfs


Welll...the thing is...that trailor is attached to the tractor so it can turn left right up and down.

under that connection there is a shaft that transfers power from tractor to trailor wheels. and that shaft has those universal joints. BUth I am not asking on that...how to make that drive shaft.

I am asking you how would you effectivly make joint or connection between tractor and trailor so it can go left right and up down as shown on pictures

[Otto Nobedder]

As long as the front U-joint is in the same plane as the up/down right/left axes of the trailer...

That's the key. The joints, whether at the tractor or trailor end, must line up with where each moves relative to the other.

[noddybrian]

@ Otto.

I think there has been a translation issue - I believe what Querty is asking is nothing to do with the shaft & joints driving the rear wheels - it's a structural joint - if you've worked on earth moving equipment imagine an off highway / rock dumptruck such as the Volvo A25 or 30 or 40 - they articulate in the center & also swivel ( to the point you can roll the rear body upsidedown with the cab still upright - hopefully ! ) put simply there is a tube fixed to the cab chassis through which the drive shaft to the rear pair of axles passes - bushed around this is a small frame with a swivel joint top and bottom which allows it to steer via a hydraulic ram each side - I have pictures of them stripped down but in 35mm film - I stopped taking pictures long before digital - if I can find a digital version I'll upload it.
Most likely the thing he has looks like a large rotavator with just 2wheels - you can add a trailer to them and steer it manually by it's handlebars while sitting on the rear part - their common in spain / portugal though I've not seen his version with the rear drive facility - knowing what the 2WD versions pull I imagine they are quite good units - it's the joint joining the 2 halves structurally in question here - not a driveshaft.

[noddybrian]

1 Quick thought
- I've seen this done using the end of a front axle - the cut off axle tube being welded to one half & the other half bolted by a flange to where the wheel would usually go - a while ago one of the trucks on 4wheelers top truck challenge used this method - maybe someone on the forum could find a picture of that for qwerty .

[qwerty12]

Noddy...yes finaly someone understood my bad english Its simple thing "how to connect trailor and tractor thing" that I can not solve.

On the other hand connection with rear axle so rear wheel also have power that is no problem for this tractor it uses 2 of those universal joints(one near tractor, other near rear axle) and that drive never goes bad...

only this connection joint goes ofthen bad because fabric that makes those tractors made that realy badly(will picture that...its realy not bad solution buth because of constant use and heavy weight it goes bad) and I am looking for some new solution to that vork...

[WerkSpace]

In North America, companies such as Gravely and Grillo make two wheel drive tractors.
I believe that you are researching how to drive the trailer with the PTO. (power take-off)
https://www.youtube.com/watch?v=VnvdoPfYZZ8
http://www.youtube.com/watch?v=BENeGBksRo8

[noddybrian]

@WerkSpace.

Good call on the video - it's the structural mounting between the 2 halves he's trying to re-engineer - probably on a slightly bigger / heavier version - not the rotating shaft - if my photos did'nt pre-date digital I was going to find a picture of a similar set-up from when I had a 25ton Volvo dump-truck split in half - it's not obvious looking at the second video if that model does but Qwerty wants the trailer part to swivel as well as steer - obviously with access to machine shop facilities it would not be hard - but I'm guessing they are somewhat hard to find where he lives - if scrap vehicles are available I reckon a front axle kingpin / hub assembly is the closest off the shelf option for him.

[WerkSpace]

The two wheel drive tractors can carry very heavy loads with a PTO driven trailer.
The following video shows the 4WD capability. https://www.youtube.com/watch?v=vuKyrgwIFQI

[qwerty12]

Yes they can drive tons
They look smal buth that pto unit gives it ability to carry annything and annywhere.

Mine is 1986 year built and all those years we only change gear and engine oil and put some diesel inside. Its lombardini 450ccm engine 4 stroke diesel. Newa had a single falliure, and its working almost every day (Yes I lye once it had a minor faliure, a clutch cable broke...buth what to espect afther so much service )

Spo the only proiblem with this tractor is that connection joint between trailor and tractor. It holds good cant brake it...buth its just 2 bolts and they become bad afther years so while sitting you can move handler up down and thats bad for pto shaft joints and turning ability and lott of other... so I must rearange it somehof diferent that a factory made it. That clipp with grillo is nice...it has a different mounting than my tractor...buth cant see it clearly how its made...

[weldin mike 27]

If you look very closely at the last pic, you can see the it is connected with Large U bolts. The trailer arm rests on a bit of the tractor and the bolts hold every thing plumb and square.

[qwerty12]

Man...I simply feel so bad for not beeing able in 2 page topic to explain what do I need. Good damn running away from english classes.

So ms paint will be my tool

Here is a picture HOW THAT CONNECTION IS DONE on fabric trailor:


The main prooblem with that solution is that over time those moving parts of that joint become loosen. What I meen is that those holes become bigger and that bolt becomes smaller. And that pipe wich is welded on chasis becomes biger in inside diameter and that rudder becomes smaller. Its just mater of friction. 2 peaces of mettal constantly scratch each other and due the big forces from weight and bad roads that thing becomes to loose to drive.

I made those moving parts few times from metal just like factory does it...and no matter how thick and how strong metal you use it becomes loose due constantly use.





So the god damn thing I am asking in this foggy incomprehensible and point evading topic is... IS THERE anny other way that this particular joint could be made...al from new. And Is there anny solution to make that mechanical connection between trailer and tractor good enought so it wont become loose over time.


Thank you very much. I am out

[weldin mike 27]

Is it possible to leave everything as is and simply build up the worn areas with some special weld metal? The down side is that these rods are very expensive.

[noddybrian]

On a larger scale version of this the place where the bolt goes through has a double jaw with a spherical bearing in the center part & the pipe inside a pipe has a flanged bronze bush both ends - I don't know how to make a drawing on a computer to illustrate this - the spherical bearings are easily sourced from any bearing supplier or even Ebay - the pipe bushings really need to be made on a lathe although I've seen guys use plastic pipe for this - so long as it's kept greased it works OK - still think recycling a front axle hub would work well & if you what the donor vehicle is then spare bearings could be ordered if needed.

[AnvilJack]

I don't think qwerty12 should be "afraid" to renew (replace the existing linkage with a newly engineered identical linkage) the current linkage design. Everything has a life, and the question becomes, "how often does the part have to be replaced?" Ten years daily use up and down tough terrain with loads like that would be quite acceptable.

So, get a shop to replicate the manufacturers original design, using the best material they can acquire.

[Otto Nobedder]

qwerty12 is in a position where he must do with what he can do in his own shop, with the limited tools and materials he has at hand.

He's looking for (for want of a better term for his circumstance) a "redneck" solution.

Steve S

[Bill Beauregard]

Would a hinge joint serve the purpose? Two identical plates laid face to face, a hole in center sized for O.D. of Drawn Over Mandrel Tubing. Place two short pieces of DOM on a hard bolt, insert through holes in plates and weld. DOM may deform when welded. Fit can be refined with valve grinding compound. One of these plates needs a round hole, the other a kidney shaped hole for the drive shaft to pass. A pivot now accomplished You need a hinge to steer A similar process with one more plate, and 6 plate triangles. For welding purposes use a pipe cut square as a spacer, and a long bolt. Make two sandwiches from triangles with holes through one corner each sandwich having two of its layers to the rear, one to the front. Separate with the tube and bolt. Place these between the aforementioned plates. After welding, remove the bolt, and spacer tube. Replace the long bolt with two shorter bolts. All pivot points to be reinforced with weld in bushings made of D.O.M. tubing. Bolts could be double nutted and drilled to insert a pin in each nut. For easy flexing drill, tap, and insert grease fittings.

In the post WWII years an aftermarket manufacturer identified a problem in the Dodge Power Wagon. The frame was too stiff. Four wheel drive with open differentials when one wheel rode up on something, weight was removed from other wheels causing all available torque to go to unweighted wheels. To maintain traction a driver needed momentum. Slow moving beasts, the Power Wagon wasn't well suited to going fast enough to prevent being stuck,sometimes on dry land. They used a similar system to resolve the problem.

This would be easy to draw. I'm not sure I know how to send it.

[Bill Beauregard]

Where is your drive shaft? Is it inside the tongue of your trailer?

[qwerty12]

Bill thanks for such detailed description. The problem is m english is realy bad...especialy in technic vocabulary, and google translate does not helps much, so I understood very little from your post. If it is not a problem to you just make some scheme in ms paint and than you just save that on desktop, go to www.postimage.org and upload that picture there, and post a link here...

Talking abouth that drive shaft...its bellow the trailer connection point. Its not in same axle as on that grilo tractors. will post pictures soon

[Bill Beauregard]

From You Tube videos I see that your drive shaft is far enough out of the way to not be a big factor. For a swivel that allows tractor to be right high, trailer left high four wheeler people call articulation, some would accomplish with a pivoting rear axle. I think an easier solution is to cut your tongue and insert a swivel. I would use 2 discs of plate steel 2-3 cm thick X 30-40 cm in diameter. The easiest way to assemble is to drill 25 mm holes in each at center. Pass a 25 MM hardened bolt of the finest thread available, through these holes Run the nut down snug, drill a hole through one plate, and thread it for a grease fitting. As you have cut your tongue in half place this new assembly between the cut sections of your tongue with the bolt at center point of hollow tongue, and weld in place.

If this is all you do, it will be prone to quick wear. I would cut slots lengthwise in the bottom of your tongue just large enough to replace the bolt when worn. If this weakens the tongue too much, it can be reinforced with triangular gussets cut from plate matching the wall thickness of the hollow tongue.

I sometimes fabricate weld in bushings from DOM tubing, a product made with accurate dimension both inside and outside. Typically, the wall thickness is quite heavy. I expect you will find it in metric sizes 3/8' or 1 cm wall thickness 1" or 25mm inside diameter. Cut it to length somewhat longer than the thickness of your plates. Because it may not be perfectly square cut to length I would insert a washer between two short pieces of this tubing slide them over a bolt of the same diameter. Snug the nut, insert in the center holes in your two sandwiched discs. from the outside, weld each to it's respective disc. This provides a renewable swivel point and adds durability to the joint. The pivot bolt will need two nuts tightened against each other, and drilled, and pinned.

Whenever you weld, the softened metal in the heat affected area will conform to the space available constrained by the inflexible cool steel surrounding it. As it cools, it shrinks. The bolt hole through the center will become tight restricting free swivel movement. Often valve grinding compound, (an abrasive paste) will allow you to ream out the hole to once again fit the pin. If the bolt won't come out, heat it using care to not heat your bushings as hot. Dull red should do it. This softens the bolt, restrained by cooler metal surrounding it it can't expand, it is crushed to the diameter of the hole. When it cools, it will shrink,freeing it. You may ruin the bolt, don't pound it out pull it using a prying action.

With your swivel provided, I can't see in the You Tube Video how it presently hinges to steer. I will study to find it's mechanism. perhaps it can be modified to work better than my other hinge idea.

[WerkSpace]

From the image below,
it looks like a vertical tube is welded to a horizontal tube.
The vertical tube is being used as the steering axis.

The horizontal tube appears to be fit inside a second horizontal tube.
With some vertical slots cut into the outside horizontal tube,
so that the inside tube could twist independent of the outside tube.

The PTO driveshaft is located below the steering mechanism.

[AnvilJack]

So, what happened?

This was an extremely interesting thread.