Steering System
The steering system is a very important component of the recumbent trike. The goal is to design and build a steering system which will provide the rider a comfortable riding experience with easy maneuvering. After doing many researches about steering principles and designs, we came to know about two very popular kinds of trike steering mechanisms. The picture below shows how the difference between them.
Research has shown that both direct and indirect steering systems are comfortable and provide very good control to the rider. So, it is the rider's decision on which one to choose. We have chosen direct because of design simplicity and ease of manufacturing. The following picture shows how the direct system works.
Research
A lot of research was done before considering direct steering mechanism for our trike. We studied the very basic principles of front wheel steering. By doing so, we came to know about the following design parameters:
1. Ackermann Steering Geometry- Any vehicle with two wheel front steering needs to follow Ackerman Steering Principle. To follow this principle, the two front wheels need to turn at different angles while making either a left or a right turn. The picture below shows this geometry.
The angles circled red in the above picture show that the turning angles are different for the two wheels. In this picture, as the vehicle is turning to the left, the left wheel needs to turn at a higher angle than the right wheel in order to follow Ackerman’s Principle.
2. Camber Angle- Another important feature of a good tricycle steering is the camber angles. The following picture shows three different types of camber angles possible.
We decided to use negative camber where the two wheels are positioned at an angle toward each other.
It improves the cornering grip of the tires during cornering. So, it maximizes grip and provides better traction
A very important thing to remember about negative camber is that too much of it will increase the wear of the inside tire and this can result in handling imbalances, tire blistering and overheating.
3. Caster Angle- Caster angle is known as the angular displacement of the kingpin axis from the vertical axis. This angle can be adjusted to optimize a vehicle’s handling for particular driving situations. The following picture shows three different types of caster angles
Zero caster angle is not best suited for either acceleration or steering. Too much caster or positive caster will cause the vehicle to understeer or have a lack of responsiveness during turning into a corner. Whereas, too little caster or negative caster will make the vehicle oversteer or making its rear slip out, causing its front to turn too much. We have decided to use positive caster for our trikee design for better steering.