My Senior design project - a "Swamp Thing" tracked vehicle clone

[aczlan]

I don't disagree with that. I just wonder if getting into the diff would be worth the effort. I have a factory manual here - I will look into it. Thanks for the comment.

If you wont, it will eventually fail spectacularly... Its up you.

Since you are only a hop, skip & jump from me, may be you could help me?

I am happy to help on here, but I have enough projects of my own that preclude me driving 2 hours (one way) to work on someone else's project.

Aaron Z

 

[texasranger556]

I would HIGHLY recommend that you weld up the differential rather than bolting one side to the frame.
The spiders gears in the differential are not intended to have one side spinning and the other side not moving the time. Affixing one side to the frame and leaving the other side to spin will cause the spinning side to spin at double the "normal" speed for a given gear and engine RPM.

Aaron Z

+1 on this. Years ago my brother grenaded the diff in his neon doing one wheel burnouts. They aren't meant to spin full time or even 1% of the time. And as Aaron mentioned you'll get a 2:1 speed increase locking one of the output shafts.

 

[Renze]

I thought it may be possible to detune it by disabling a cylinder or pulling a NASCAR trick of adding an intake restrictor plate. Anyone else have a better idea?

What is wrong with you ? Ones ought to push it to the max, e.g. increase turbo wastegate setting, bigger exhaust, till it breaks and then improve reliability.

 

[Dave M7040]

Hello all, I am a retired mechanical engineer having stopped looking for a regular job for about three years now. I have been looking to keep my gray matter busy other than working on the regular upkeep jobs around the house. I like to tinker, design and build things; I have a fairly complete machine and fabrication shop at home and am well versed in the use of various computer programs including 2D and 3D CAD. Some time ago, I came across the Youtube video of a tracked vehicle called "Swamp Thing" which was built by an individual named Tom Zervas in Saginaw, MN sometime around 2011. Here's a photo of it and you can see his video here:

Another old engineer here. You are building my dream machine. For ideas, it is amazing how many different styles of commercial machines that are being made to provide mobility to war vets. From wheel chairs with tracks to much more elaborate machines.
Extreme Offroad Tracked Wheelchair the Original Ripchair 2. - YouTube
Part of my work life was an automotive engineer for Transport Canada. My comments have to do with your choice of engine and transmission. My experience is that automotive differentials do not like the high and sudden loads they experience when you make steering inputs by braking one axle.

At one time for autocross type competitions we would have two brake levers, each controlling a rear brake on a rear drive car. The idea was to force a quicker turn around the pylons. The differentials failed often, the other axle suddenly having to accelerate to 2x rpms when one axle stopped.

I also did some public safety demonstrations for Transport Canada where rear tires were exploding. This was in the day of big block rear wheel drive vehicles. If you were stuck in some snow and one wheel was spinning, often in frustration, the driver would push the gas to the floor

The rotating tire was spinning close to 200 mph and would shatter: the bead cables failing. Half the rear fender was destroyed. The public safety concern was for the people who might be pushing the car and be close to the rear fenders.

Kubota was making a tracked tractor for snowmobile trail grooming. Other forum members have said that differentials could not last in these L series tractors.

Having one hydraulic pump driven by an engine and supplying to hydraulic motors for each track would give you a better design.

Here is some info I have collected:

My first idea was to modify this hauler to haul me.

Please provide updates on your very interesting project.

Dave M7040

 

[Garauld]

Dave, I have had a Bobcat and now have a mini excavator. Yes, having hydraulics would work and those are what I believe, the original Swamp Thing is using. I wanted to design and build something a bit different so a FWD engine & automatic transmission was selected. I think (and hope) it will run well.

 

[Garauld]

Status update: over the last couple weeks, I have refined some of my part models on the computer and have also been working on the Toyota Echo engine. The 1.5L engine came from a car that was flipped upside down after the driver lost control on an icy road. Luckily, the driver was not hurt. The wrecker driver tried to start it but to no avail. Over a year later when I went to see/buy it, it ran but had a fairly loud tink noise. Long story short, it has a pair of bent connecting rods that need to be replaced. I pulled the cams today and will, hopefully, get the head and lower housing off tomorrow so I can get access to the conn rod bolt nuts. Once I get it back together, I plan to mock up a full sized cabin from 2x3s and cheap paneling. I ordered some conveyor belting for the tracks and bid out the steel sheet I will use for the tub (or frame, if you will).

 

[Groo]

I suspect that it isn't just con rods.
Use it as is to mock up and prove the concept, then mess with the engine or replace it when everything else is working right.

 

[Garauld]

Today I finally got around to splitting off the lower oil cover from the Echo block to gain access to the conn rod ends. As suspected, I had a couple of noodly rods:



I found a couple of used rods on Ebay which I ordered along with a new gasket set, head bolts and a rubber Chevy auto transmission mounting block that will be repurposed as a front engine mount. The pistons, bores and crank in the Echo engine all looked fine so there are no plans to futz with them unless I have an issue with installing the replacement rods. I also ordered 316 lb of steel sheet for the frame or what I call the tub. Next up is to order some trailer wheels to run on the tracks. I'll be able to roll the body around once those are mounted. I previously ordered some 5/16" 2-ply conveyor belt that will need to be cut into 5" wide strips for the 14" tracks - that should be here soon too. Stay tuned...

 

[Al 2]

Just for added interest , check out the Sherp / offroad vehicle videos. Quite amazing.
Look here: sherp atv videos - YouTube. Among other things you can vary the air pressure in the tires by using air from the exhaust or even store fuel in them for that long ride. Almost forgot. It's powered by a Kubota engine.
Al

 

[airbiscuit]