grader blade offset

[Renze]

i still didnt start my 3pt road grader project as i'm spending all my 2 weeks of vacation dismantling sow cages, welding on the dirt buggy, and welding on the tandem hay trailer i'm building.

Anyways, during the tedious tasks it's good to think about the next project:
I was looking at a Komatsu grader, which had the blade offset taken care off by a single hydraulic cylinder, that pushed the blade along a slide rail.
I like the idea for simplicity: otherwise i'd need a double articulating blade carrier beam, which i want to avoid because i want strong gauge wheels, and mount everything to 1 single inline frame tube, gauge wheels, cylinders and main blade pivot.

The question i have, is: what's the best and easiest way to build a slide rail for the blade offset: Because its mounted on the blade, its close to the dirt and dirt doesnt slide...

Would a big round tube with 2 slide pieces work good, where these slide pieces can also work as a pivot for the blade tilt function ?

I'm looking for ideas...

 

[3RRL]

Yeah, that would work but you'd have a heck of a time keeping from rotating back against pressure without support behind it. Perhaps a dual square tube set up like the round? But I'd like to see a sketch of all you want it to do first.

 

[Renze]

i've been thinking about it and got a different idea:

The main reason i'd like a linear offset is that i was afraid getting into trouble with the blade rotating cylinder, if i swing the offset arm to outer postition, like fully right, while the blade is rotated fully left.
The cylinder mounting points vs. the blade rotating pivot would be allmost aligned, e.g. its on a dead piont where the blade could put enormous forces on the cylinder.

Your worm gear turret solves this problem totally, but i dont have friends with the mills, skills and time to do it that way.

But what i thought of, was using 2 double acting cylinders, where the cylinder pivots and the main blade pivots are not mounted in a line, but in a 90° angle.
This way, when one cylinder reaches its dead point, the other cylinder is in its strongest position and vice versa. I could achieve a lot more rotative force with simple pins and bushings.

I hope you get what i'm talking about, its about the same idea as why crankshafts have all cylinders timed differently, to balance the torque output on the crankshaft.