1. Design Of Sno–Bike Propulsion System Joe Fitzpatrick & Jeremy Lindeman Advisor: Prof. Eben C. Cobb Mechanical Engineering Department Design Concepts: Bikes have been used on snow before. The most common method for converting them for snow conditions, was to stud the tires. Another method of snow travel is track systems, these are available for ATV’s and is used for snowmobiles. Material Selection: One of the concerns with building a bolt on system is the extra wait and strain on the engine. It was important to keep the overall weight of the vehicle similar to that of the original. Without being able to adapt the engine or modify the bike in way. Materials that were considered for the cylinders were, PVC and rubber for the cutting fin. The problem with these materials was they did not satisfy the strength demands needed for the system. Aluminum was chosen for its light weight and strength. Gear Train: The gear train from the engine output to the screws had some design problems: 1. The axis of spin for the screws had to be perpendicular from the output shaft on the engine.. Solution: 2.The power had to be transferred from the perpendicular shafts down to the screw shafts. Solution: All Terrain Possibilities: Using the screw propulsion system over alternative propulsion systems has its benefits: a. Ability to travel through: 1. Snow 2. Sand 3. Water b. Swamp and mud Buggy's c. Boats and Submarines d. Lunar travel With the possibilities to have a system that will allow movement from; side to side and in place rotation, makes it very agile. With independent control over each screw it could produce a vehicle capable of handling changing terrain conditions. Building the Screw: Abstract: The goal of this MQP was to design a bolt on snow propulsion system to a Yamaha YZ 125 dirt bike. This system will allow the dirt bike to be used in snow and dirt conditions, where the typical wheel design would fail. The design solution was a system made up of two horizontal cylinders parallel to each other mounted to the rear swing arm of the dirt bike. These cylinders are attached by a frame that bolts on to the rear swing arm of the dirt bike. Each cylinder has a helical sweep cut running the length of the cylinder. From the cut is a protruded fin, making the cylinder look like a screw lying on its side. The two cylinders will spin in opposite directions of each other to create a forward thrust. Analysis: This design concept has endless potential. Due to the dirt bike constraints we were limited in what we could accomplish. Although there is potential for a bolt on system that would be universal to any dirt bike or other ATV’s. Weight was one of the major concerns for this system. By not having the ability to access certain materials and manufacturing processes, the system had to be constructed out of common materials and simple manufacturing techniques. Some CNC machining was used for construction of a hub for the rear sprocket and inner screw wheels. Other parts bought or reused from the bike. Final Product: 1.Construction of the cylinder. The cylinder is made from wrapping aluminum sheet metal around four aluminum wheels equally spaced on a shaft. 2. Attaching the fin in a helical sweep pattern to the cylinder. The pattern for the screw path was laid out on the cylinder, then small pieces of aluminum angle iron where bent and twisted to match the helical sweep path. Recommendations: It would have been a better design to have fewer spinning shafts. Using a spinning hub over for the rear axis shaft would have eliminated one spinning shaft, and would have allowed for a better frame attachment. It also would have been ideal to have the two screws cast out aluminum or some other material. This would provide a smoother fin and would save weight. Instead of attaching this type of propulsion to an existing vehicle, it would be best to center the vehicle on the screws. Also using two independent electronic motors for each screw would increase the directions of travel.