tractor grader construction

[rdbrumfield]

To me the simplest way to offset would be to us an axle you can steer. By turning the wheels left or right it would take it out quite a ways, would be great for slopes or ditching. Go take a look at a motorgrader and take a look at the front end. They are double jointed so you can steer and lay the tires over so they can grip better in soft ground. You could accomplish this by using a large universal joint, say off a large truck, welding one side to a spindle, the other to an axle tube and use two tierods. One for steering, one for tilt. Fact is one side is already fixed up if you use the driveshaft for an axle. Put a hyd cyl on the steering and backing would be a breeze.

 

[Renze]

To me the simplest way to offset would be to us an axle you can steer.

The biggest problem i run into, when using a conventional steered axle, is that the axle swings outward when offsetting the grader. When i tilt the blade as well, to cut a roadside onto the crown, the wheels would run way outside the cutting width of the blade.
When cutting a watering ditch, the wheels wont run in the ditch so ditch cutting depth is very restricted.

Because i have a 3 meter blade (dont want to go wider, its a pain when doing 5 meter wide roads) i already have this problem even with an articulation joint behind the grader blade.
I must change my idea and make the articulation joint in the drawbar, even though its less favourable because its in the line of power, from blade to tractor drawbar.

The idea of using the U joint, i dont think any welds will hold on the (cast iron ??) crosspiece, to weld the steering arms to it.... ???

 

[rdbrumfield]

Those are of cast steel, big difference, after all, the shaft is welded to it. One thing, the tierod and canting rod will have to be double jointed at the ends. If you are putting the articulating joint in front, just mount the axle rotated 90 degrees, that way it will lay over but not steer.

You are most likely right about putting the articulating joint in front of the blade as you are pulling it instead of pushing.
I am a finished blade hand with a road grader, so I understand the need to sometimes get the tires in the ditch following the blade with the steering up on the shoulder.
Depending on how much offset you need, or want, you could also suspend the blade table from a couple of ears that are a few feet above so the table and blade can swing out to the side and be locked by a slide tube with holes along it for a pin to drop in. This could also be done for the drop tubes to give you more drop or hieght beside the drawbar, especially for ditching it might come in handy.

 

[Renze]

Those are of cast steel, big difference, after all, the shaft is welded to it. One thing, the tierod and canting rod will have to be double jointed at the ends. If you are putting the articulating joint in front, just mount the axle rotated 90 degrees, that way it will lay over but not steer.

I have a rigid axle which has cost me 10 Euro... I am not going to buy a steered axle, i'd rather invest the, lets say 150 euro, to get a relative lathe me some bushes for the articulation joint.

I am a finished blade hand with a road grader, so I understand the need to sometimes get the tires in the ditch following the blade with the steering up on the shoulder.

With a tractor drawn grader i would do this the other way around: i'll have the tractor up on the shoulder, and the grader wheels will get lateral support by the ditch side.

Depending on how much offset you need, or want, you could also suspend the blade table from a couple of ears that are a few feet above so the table and blade can swing out to the side and be locked by a slide tube with holes along it for a pin to drop in. This could also be done for the drop tubes to give you more drop or hieght beside the drawbar, especially for ditching it might come in handy.

With an articulation joint in front of the blade, i can get about 3 foot of offset, that should be enough to cut ditches, and to swing it under the horse fence to pull back the first ploughing furrow from the edge, when grading after ploughing a paddock.
Thats the most important reason i want the articulated frame: a conventional grader with A frame and slew ring, will allways require depth correction when swinging the blade under the fence row.. We have posts every 4 meter so its a lot of work...

About ditching, with about 4 ton pulling, and an 18" blade, i dont think i am going to cut huge ditches in one pass. Running the grader wheels in the ditch will double the max cutting depth as well as the tilt angle in the second pass.

 

[Renze]

a design update: i sketched a mid articulation joint, and after doing some strength calculation, simplifying the design of my drawbar. I think i'll weld the two 5 inch pipes onto each other like a figure 8 and then close the sides with plate, to create a big rigid oval tube, which will be filled with concrete for ballast.

This setup will give me about 60cm of offset (2ft) at 20 degrees articulation.

I am happy with the design from drawbar to the articulation joint... From there onwards, i need to think it over a bit, and think which design is best doable with the steel in my scrapbin...

 

[rdbrumfield]

That looks pretty good what you have going on there. I do think I would have the blade a bit back of the articulation point as you might want to have some sort of table to be able to swing the blade a bit for casting. I can see where you will want the offset to be away from the tractor too as it won't want to turn one way as you will be able to be square the other.
I have to laugh, I have built a lot of things and I always want it to do it all. Never achieve total success, but it does the work.
good luck with it, looks like it is going to be a well thought out project.