Thursday, June 23, 2011

Kodiak Yard Trike project - a new Atomic Zombie adventure

[FIGURE - K1] - The E-style BMX works hard to get me up a steep grassy hill

Now that we are living in much more rugged country terrain, I find that my needs for a fun and useful electric vehicle have drastically changed.  Our property is a 120 acre mountain top setting, with a windy paved highway on one side and an endless loose gravel road on the other. We will eventually cut trails through the land as well, which will traverse everything from rock ridges to steep hills.  Currently, I have the E-Style Electric BMX for riding around, but find that it can’t deal with the loose gravel up hills, nor can it cope with the extremely steep hills full of tall grass on our land. Going to the store 5 miles away down the paved highway has been great, though, but I see that I will be back at the drawing board to make an electric vehicle more suited to our new terrain.

[FIGURE - K2] - Loose gravel requires careful choice of traction and suspension

With endless gravel roads to travel down, I want an electric vehicle that can handle the terrain, as well as run for extended periods of time on a single battery charge. A 2 hour run time would be perfect, with a top speed of around 25 miles per hour - a trade between speed and hill climbing ability. I had a project called the “Kodiak Electric Scooter” on my drawing board for a few years, and now it seems like the name may fit my current needs. The original plan was a midsized electric scooter with balloon tires and a beefy motor to carry two people over any type of terrain possible, and that seemed like a good plan. Of course lately, I have been traveling with yard tools and sometimes find the need to move things around the yard (which can be a 20 minute trip if walking), so something a little larger than a scooter seems more logical, and having cargo space would be a bonus.

[FIGURE - K3] - Look what the junk-yard gods left for me to find!

As I was wandering through the back 40 (literally), I stumbled upon a few old 1900’s farming machines and this rotted out home built trailer. The trailer was completely rotten, but under the wood was this 1970s large car or pickup truck rear differential. I have not yet identified the make, but I think it may be from a Chevy half-ton of some kind. Right away, I took my bow saw and cut the differential away from the rotted trailer frame and then pulled it out of the bush by a pair of ropes tied to my belt. An hour later, I was looking over the new find thinking, “Hey, this might be the perfect transmission for my new electric vehicle.”
Huh??! - A truck differential you say??

Well, why not?? Anyone can find one for a few dollars at a scrap yard and you get an indestructible transmission system with a 3:1 or 4:1 built in gearbox, easy to use and powerful brakes on each wheel, and a steel foundation to mount all of your heavy parts such as motor, battery, and controller. Instead of dropping $500 on wheels, brakes, chains, and sprockets, I could just bolt a sprocket to the differential and run a chain right to a small sprocket on the electric motor. The only issue was the width, which was currently 65 inches from tire edge to tire edge, and I planned to cut 4 foot wide trails through the bush. Hey, I am a garage hacker, so I’ll narrow this differential to 40 inches using only an angle grinder and a basic AC welder!

[FIGURE - K4] - Tossing around some design ideas for the Kodiak Yard Trike

With the differential thrown in the plan, the Kodiak Electric Scooter was renamed the Kodiak Yard Trike, and I made several sketches. After a few pages of drawings, I decided that the best configuration for everyone would be a delta trike layout, with a cargo bed at the back, and a small motorcycle front end as this would allow many configurations to be adapted to the plan. With this layout, the Kodiak could be a yard cart capable of moving 1000 pounds or more, a fun ATV for bush use or hunting, a golf style cart for moving guests around the yard, or just an all around fun electric vehicle.

Finding a scrap motorcycle front (wheel and fork) should not be difficult and anything from a 250cc to 750cc scrapped motorcycle could be used. Add in a few lengths of 2 inch square tubing, and the vehicle will be ready for the motor. Ok, narrowing the differential may be a bit of work, but since the resulting motor will only be capable of around 15 HP (depending on your needs), I think a cut and re-welded axle would be fine as long as it was done properly. This cutting and rejoining of the inner axle will mean that no machining or re-splining of the axles will be necessary and that anyone with a hand held grinder could do it.

Stay tuned for more progress!

Since we are in the middle of a move and I have no garage to work in, I will probably get started on narrowing the differential, and hope to post photos of the operation in the next month or two. I think this project is going to be an extremely fun build, and I am looking forward to getting started on it. If you have any suggestions or ideas, then please drop by our forum and join the discussions!