UNDERSTANDING AND PROTOTYPING
For our initial steering design, we decided to use a rack and pinion connected to a U-joint, which would connect to the steering wheel. To come up with the design, students visited a golf-cart services shop where they looked at the steering components on golf carts to get a better understanding of the most efficient way to steer a car. They looked at the horizontal rack and pinion design on golf carts and took videos to examine in slow motion how all the connected parts moved and fit together. The owner was kind enough to donate several parts off of broken down golf carts to help us prototype and experiment with.
Turning the wheel turns the first U-joint, which rotates the U-joint connected to the rack and pinion. This makes the rack and pinion move forward or backward. Our idea was to fix the other end of the rack and pinion to a triangular attachment underneath the hub that would be connected to the front wheel. Thus, by steering the wheel, the rack and pinion would push forward or backward and make the wheel turn right or left.
The parts we acquired from the golf cart services allowed us to do some hands – on learning to conceptually understand each of the moving parts and how to attach them. As you can see from the above photo compared to the photo on the left, our rack and pinion would only be attached at one point instead of two, and it has been shifted to be vertical rather than horizontal.
From this prototype, we learned that the steering column was way too long and would need to cut it down to fit within the chassis. Additionally, from playing around with the angle of the rack and pinion, we discovered the ideal angle for it to be so that the U-joints could turn in conjunction with each other rather than being at too tight of an angle, which would make them grind against each other. Although many components still need improvement, this initial prototype was very helpful in understanding how everything worked.
BACK TO THE DRAWING BOARD
After making the initial design for the steering, we went back to the drawing board to try to get more finite numbers and dimensions for our design. We experimented with a scaled- down version of our solar car truing on a scaled-down track to find the angle the steering wheel would need to be at in order to have the ability to turn within a given radius in the Grand Prix. We then measured that angle to find out how far out the rack and pinion would need to be attached to the wheel in order to get the car to turn. We decided to design several different lengths of the hub and rack and pinion attachment to experiment with and find the optimal length for most efficient turning.
Here, Ginny and Anna are working to cut pieces for the prototype. We will be using aluminium tubing to attach the wheel and make the frame for each of the wheels. The idea is to attach suspension to these angled metal tubes, and then eventually add the hub, triangle attachment, and rack and pinion to the top. We are excited to get the steering mechanisms put together! After building, we will work on testing the efficiency of steering and turning within the given parameters of the competition. We are looking forward to getting the whole car put together, testing it, and reiterating! Until the next update…..