My Lego Technic tractor with tedding machine. It features a pneumatic control system, IR controlled. Please read the article for the details.
Tedding is used to dry the grass, before harvesting it.
About this creation
This is my Lego Technic tractor. I have chosen for MF (Massey Ferguson) , because that brand interests me. The tractor has 4WD: I used two old style differentials between the front and back axles, because it was not possible for me to a calculated gear ratio with special chosen gears for that. It performed really good, so maybe I will use it in future tractors too. The tractor performes really good: it has a good traction. The tractor contains an electric-pneumatic system (later more on that). So the tractor is fully remotely controlled, also the pneumatic functions.
The tedder is a Lely Lotus 770 . It has 6 turntables rotated by one race buggy motor, geared down 8x. It consumed most of the battery box' power during tests and the video.
When the tedder is unfolded, you can see its very large dimensions. While driving, I had to turn a lot to prevent the tedder hitting something. To unfold it, firstly the pneumatic cilinder above the frame extends, pushing the whole thing in upside direction. Then the two other pneumatic cilinders at the back will extend and the tedder is unfolded. Watch the video for the best details.
The tedder folds up to a light, stable vehicle, easy to pull. Of course, there comes wiring out of the front: the tedder contains two double acting pneumatic systems, each requiring two pneumatic hoses. So when the tedder is being connected, 4 pneumatic hoses have to be put onto 4 pneumatic nozzles. Also the electric wire needs to be connected to let the tedder work. See the image below.
The nozzles are divided in sets of two: The one above regulates the extending, the one underneath the retracting.
How does this work? Below the tractors seat, you can find two small pneumatic cilinders. Together they have a very important function: this is the compressor of the tractor. It is driven by one of the three PF M-motors under the seat. The air is directed to two pneumatic switches (you only see one on the photo above). The other two PF M-motors regulate the switches by one 24t/worm gear reduction. In this way, the switches are kept on their position. The hoses, coming out of the switches, go to the pneumatic hoses at the back. (The routing of those hoses was a lot of work)
At the photo on the left side, you can see the motor for steering.
The four pneumatic hoses were cut out of some spare parts. I usually hate cutting parts, because it isn't real LEGOŽ any more, but now I decided to do it because the 8110's nozzles were'nt present at that time.
Off course, when your model has to contain a lot of IR functions, you also have to keep space free for IR Recievers. My tractor had 3 of them, 1 on the left, 2 on the right.
One additional photo of the combination.
The tractor has frontlights, shining through one stud of transparant Lego plates. This was necessary in order to shape the front of the tracor.
And there comes the question: where did you get the idea to build it? Well, by having controlled this nice combination by myself in real life, and after taking some nice pictures of it..
Driving (PF XL)
Steering (PF M)
Activating compressor (PF M)
Switch/nozzle 1 (put tedder up/down) (PF M)
Switch/nozzle 2 (put elements up/down) (PF M)
Electric PTO (rakes turn 129 RPM (!) (Race Buggy Motor)