[MOC] Hay rake for Claas Xerion

[ozacek]

Following my previous post asking for opinions about the design of a hay rake's rake arms, I finally completed the whole design.

It uses the Xerion's power output axle in order to drive some of its functions, and It has a few particular features:

1) the wings can be raised & lowered with a switch (linked to a changeover catch).

This was a major design challenge, considering the weight of the wings and the fact that we're limited by the power of the Xerion M-motor & clutch-gear. In the end, the biggest issue came from what might be a design flaw in the 'Gear-16 with clutch' part. While most gear are just a tiny bit narrower than 1L, these ones are exactly 1L. Because of that, when bound by two liftarms, friction is inevitable (like happens in 42055's gearbox). And to make things worse, in a design like mine where the gearbox is in-between the two wings, the weight of the wings pushes on those bounding liftarms and friction goes through the roof. To solve that, firstly I attached the pulling part of the wings to the upper & lower liftarms of the frame, so that the weight would work towards releasing pressure instead of creating it. Secondly, I redirected the pushing part of the wings to a support frame underneath the whole structure, bypassing the structure's liftarms altogether.

The wings lifting brings another subtle problem, which I only noticed at the end of the first draft: you can't actually use two universal joints, because then both wings will go up & down in opposite directions! Therefore one side as to use 3 gears to invert the rotation. However gears take up much more space than U-joints, which complicates further the design of the wings' attachment to the body, already a difficult & critical part.

 

2)  the rakes' rotation can be started/stopped with a switch (linked to a changeover catch)

Both functionalities make use of the same driving gears. 

3) the tractor's steering is transmitted to the rear wheels through steering arms, as the head rotates with the tractor

Based of mentalspagat's hey rake for 8284. A clever design, I like it (although tough to implement without using a studded 'Technic Plate 1x5 with center axle hole' part - I don't build with studded parts).

4) a pair of levers allows to simultaneously either raise the support legs + engage the coupling to the Xerion, or lower the support legs + release the coupling.

This was the other difficult thing. I really like the support legs mechanism from the Xerion's A-model tool, and also the coupling mechanism from the B-model tool. I though it would really be nice to have a single lever that achieves both at the same time. Which is also very convenient: as soon as you detach from the tractor, the support legs are also lowered so that it stands by itself right away. To achieve that, it requires the use of a part that has an axle hole (so that we can rotate an axle with a lever), but also lets that axle sliding loose, otherwise preventing any rotation of the head. Luckily, there exists a single part that meets those requirements: a changeover catch!

5) the follower-wheels under the wings have a small, limited turning radius in order to be able to follow in curves

The tricky thing here was to give some freedom of movement without giving too much. An engine crankshaft part is stuck in-between axle connector parts, which have a recess making them a bit less than 1L-width, allowing for some leeway.

____________________________________________________________________________________________________

Instructions available on Rebrickable.

 

Edited May 8, 2019 by ozacek

[Carsten Svendsen]

Nice, I like seeing equipment being constructed. I would probably like it more if the rakes went up to the full 90°

[ozacek]

4 hours ago, Carsten Svendsen said:

Nice, I like seeing equipment being constructed. I would probably like it more if the rakes went up to the full 90°

Right, but the small linear actuators do not have enough range for that. The big ones would need to be used, which is basically a complete redesign of the wings..

[Carsten Svendsen]

22 hours ago, ozacek said:

Right, but the small linear actuators do not have enough range for that. The big ones would need to be used, which is basically a complete redesign of the wings..

The small ones do have enough range, it's just about finding the right pivot point 

[LEGO Train 12 Volts]

Very nice ...the whole tractor with trailer is huge!

[doug72]

On 5/9/2019 at 10:58 AM, Carsten Svendsen said:

The small ones do have enough range, it's just about finding the right pivot point 

Agree - it can be achieved.
It took me  a lot of trial & error before I got my Fowler Gyro Tiller MOC to raise and lower the frame for the rotating cutters correct between ploughing & travel positions.

Edited May 11, 2019 by Doug72

[ozacek]

On 5/11/2019 at 3:20 AM, Doug72 said:

Agree - it can be achieved.
It took me  a lot of trial & error before I got my Fowler Gyro Tiller MOC to raise and lower the frame for the rotating cutters correct between ploughing & travel positions.

I wonder about that... maybe it could have been achieved if I could move the actuators up, but they had to be there because of the dense gearbox. In any case, I tried many pivot approches and that's the best I could find.

[Jeroen Ottens]

Very cool design. A lot of clever building techniques in a deceptively simple machine. I like the colourscheme, the neatness of the design and the overall finished feel. I especially like the rear wheel steering mechanism. I am not sure what your adversity is to the 1x5 plate with axlehole though. It is a standard part that is used up to today in official LEGO Technic sets (or did you mean the old one with the extra holes in the end?)

[ozacek]

6 hours ago, Jeroen Ottens said:

Very cool design. A lot of clever building techniques in a deceptively simple machine. I like the colourscheme, the neatness of the design and the overall finished feel. I especially like the rear wheel steering mechanism. I am not sure what your adversity is to the 1x5 plate with axlehole though. It is a standard part that is used up to today in official LEGO Technic sets (or did you mean the old one with the extra holes in the end?)

Thank you, I appreciate :)

About the 32124 1x5 plate, it's just because it has studs and I prefer to build completely studless. Lego indeed still uses that part, but they also use regular lego parts in technic sets, which I don't (in fact, whenever I build other people's MOC's, I always do without all the regular parts).

Speaking of other people's MOC's, the next on my list is your 675LT Spider. I don't particularity want to build a McLaren Spider, but I really want to see that roof mechanism in action! :)

[eric trax]

The model is impressive but you made a very big mistake. Why are the rakes move the hay to the sides and not to the center?

[ozacek]

Someone actually pointed that mistake on Rebrickable, but it's very easy to fix, you just have to move the switch lock under the frame to the other side.

[eric trax]

On 5/21/2019 at 11:41 PM, ozacek said:

Someone actually pointed that mistake on Rebrickable, but it's very easy to fix, you just have to move the switch lock under the frame to the other side.

I realize that fixing this problem is very simple. However, the fact that you committed it in the basic mechanism is a problem.

I note that the model itself is very nice except this one and I like it very much.

Edited May 27, 2019 by eric trax

[ozacek]

9 hours ago, eric trax said:

However, the fact that you committed it in the basic mechanism is a problem.

I'm not sure what you mean..? It's not at all committed, the switch that starts the rotation can go both ways (and so trigger clockwise or counter-clockwise rotation), but the rake arms are inclined towards the ground in one way, so that it wouldn't make sense to rotate the other way. To prevent that, I just put a pin that blocks one of the two positions of the switch (which I chose at random when making the instructions, since at the time I didn't know it made a difference). All that has to be done is to put the blocker pin the other side in order to block the other switch position instead - i.e. it's not linked to the base mechanism at all.

Anyway thanks for your praise :)

Edited May 28, 2019 by ozacek