The raw purpose of the ALX-2 was to simply model a brand new steering system that came to me like a vision. However, throughout the process of building it, I realized there were many other things I�d like to see in an RC car. In doing so, the AXL-2 possesses characteristics different to that of most RC cars, such as those seen in the drive train, suspension, chassis, and of course, steering. Also taken into consideration are the material speculations for each new part and the potential practical uses for each new idea.
At first glance, the drive train is your basic 4-wheel shaft drive setup. However, there are two major modifications, the first of which being the addition of a second motor adjacent to the original motor. During the testing phase of the ALX1, I found that having both motors spinning in the same direction at very high speeds developed a rotational inertia problem, causing the car to veer left. This brings us to the second modification, which is intended to fix this very problem. In order to counteract these inertial forces, I weighted the spur gear on the driveshaft. Another suggestion was to reverse one of the motors, and flip it around on the car. However, this would not work. Although one of the motors would be turning in a different direction relative to itself, it would still be turning the same direction to the car! Both motors in the ALX2 should output around 1,400 watts @ 20,000 RPM each, for a total of about 3.5 horsepower at the wheels.
The main objective of the ALX2 was to create a better steering system, and suspension certainly plays a critical role in handling. Because of the way the steering system is designed, it creates a massive reduction in unsprung weight when compared to conventional methods. The suspension system is very similar to that of an F1 car, except for the integrated chassis roll/anti-roll system that is found in the ALX2. All wheel base/length, toe in/out and caster/camber are infinitely adjustable via tie rods and yankee adjusters. With different thread follower shrouds, the attack angle and progressive rate can be changed to suit different suspension setups. This will also be the area that decides squat and anti-squat via adjustable bumpers on the rockers. Because of the steering design, the only unsprung weight, besides the wheels and tires, are the bearing hubs! This should cut the reaction times in half. Roll/anti-roll is adjusted by the spring tension and dampening of the shock located mid-front in the center of the car.
The chassis has some very unique features. The drive-shaft carrier is mounted flush with the bottom chassis plate until just forward of the steering servo. This will give the ALX-2 more rear traction and stability. The chassis plate is actually wider than the tires in some places, but is off set by their circumference. All areas that are not mechanically critical have been removed. There is also a great amount of flex in the chassis in all of the areas, except for the drive train where the drive-shaft carrier prevents twisting and flex. The differentials are held into place by blocks installed in the front and rear of the chassis.
Steering is accomplished by a completely new method. To provide the Ackerman-Effect, the ALX-2 employs a Pitch Degrading Thread (PDT). This could very possibly be a technological breakthrough! It�s lighter, more responsive and more efficient than most conventional methods. Also, in most cases, the PDT has a smaller footprint and much less "slop" than the conventional methods. PDT steering accomplishes this all at a comparable and competitive price. This system requires very little torque, while a standard servo can actuate the PDT. Adjusting the spring tension on the PDT worm gear-keepers allows you to adjust the bump-steer or completely eliminate it. Ackerman and Toe may be adjusted by different PDT worms and Follower Arm-to-belt placement. In the ALX-2 steering is accomplished by all 4 wheels, and still carries the Ackerman effect to the rear.
As far as materials speculation goes, I designed the ALX-2 with standard materials in mind with room for more mechanically advanced materials later. All keepers, pins, balls, CVDs, and clips were designed for various steels. Tie rods, wheel bearing hubs and screws are to be milled from Titanium - Grade 2 ASTM B-348. All injection-molded parts are designed for Delrin or glass filled Nylon at 30%. The PDT worms should be in some high performance plastic such as polyimide or Ryton. The chassis thickness and weight is calculated for 6061T6 Aluminum. All gears should be Kevlar reinforced Nylon, and belts should be a woven Aramid impregnated composite of some type. The driveshaft should be Carbon Fiber. All wheels and other plastic parts should be polyester.
I forecast that the PDT steering system could be used in many other industries as well, such as tractors and other construction equipment, where great forces are applied to the wheels yet minimal torque and space is available. Because of the PDT system�s weight, extreme efficiency, response time, and no "slop" mechanism, the racing industry might soon be very interested in this technology. There are many other deployable methods of the PDT system, such as both opposing threads being manufactured on the same rod, or the rods moving as opposed to the follower Arms. The ALX-2 is a very crude model for the potential of the PDT. Just by examining my diagram I�m sure you can come up with 1000 better ways of using this technology.
The first picture of the following table is the complete, rendered drawing of the ALX-2. Pictures 2 through 6 pertain to the Drivetrain. The suspension is depicted in pictures 7 through 12, while the chassis is depicted in pictures 13 through 16. Lastly, steering pictures are displayed in 17 through 24.
Roll your mouse over each number to see a preview of the drawing along with its caption
Click on the number to see a larger version of the drawing
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