Santa’s Sleigh
Santa’s sleigh pulled by four motorized reindeer. Features drive and steering.
Datasheet:
Completion date: 23/12/2016
Power: electric (Power Functions)
Dimensions: length 62 studs / width 17 studs / height 12 studs
Weight: 0.73 kg
Suspension: none
Propulsion: 2 x PF L motor geared 1:4.8
Motors: 2 x PF L, 1 x PF Servo
This creation was a quick built put together in two days because I was asked to build something special for Christmas. It was propelled by two coupled PF L motors, which drove a shaft connecting the sleigh to the reindeer. The shaft then drove a connecting shaft to each single reindeer, which moved a reindeer’s four legs, head and tail. The main shaft had an u-joint behind the last pair of the reindeer, and could bend left or right. Bending was controlled by two links connected to a big gear wheel at the bottom of the sleigh, turned left and right by a PF Servo motor located horizontally inside the sleigh. This provided steering, by changing the angle between the sleigh and the reindeer.
The build was pretty straightforward, the only issues I had to solve were the traction of reindeer’s feet and sleigh’s stability. The reindeer, with their 16 legs total, were unable to move the sleigh until I’ve added rubber axle joiners to their feet, and even then they struggle because of the small contact area between the legs and the floor. The whole vehicle was actually designed for riding on snow, where the sleigh could be pulled on skids and the reindeer’s feet could push against snow. Since there was no snow, I had to adapt it for operating on the floor – and in addition to rubber axle joiners on the feet, this required adding wheels to the sleigh. The wheels could be taken off easily and I’ve gone through several different setups to find the best one. Initially the sleigh had 2 fixed wheels in front and a pivoting one in the back to make steering easier, but it turned out that the rear wheel has plenty of weight on it and generated significant friction. Then I’ve tried using just 2 fixed wheels at the back of the sleigh, and this kept steering smooth but put a lot of stress on the links and driveshaft which effectively had to support the sleigh’s front. In the end I went with 4 fixed wheels which were installed close together near sleigh’s middle, which kept the sleigh stable without impairing the steering too much. This solution made the sleigh move and steer very well, there was very little friction and the reindeer had no problem pulling the sleigh.
The actual sleigh was kept simple and almost entirely filled with mechanisms and electric parts. I’ve decided to cover it with a piece of canvas, as this didn’t add much weight and made the sleigh look like it was completely filled with gifts. An extra bonus was the fact that the IR signal could penetrate the canvas, so I could cover the PF IR receiver and still control if from above. I could even turn the battery on and off, I just needed to locate its button.
The entire model was an interesting kind of creation – it was technically a walking mechanism powered and driven from a trailer. It also shown that even a simple walking mechanism can work very efficiently and move a lot of weight if traction and stability are taken care of. My only regret is not having any snow to test it on.
Edit: the model was tested in snow over 2 weeks later, video included below.
