How did you do your axles
 

I was wondering how everyone mounted their axles and how they dropped down low to decrease their center of gravity.

At first we cut out brackets using our new plasma cutter but we had to bend them to mount onto the chassis. The problem was they were not being bent at the same place on each one and the axles were going way crooked. So I made these axle brackets that bolted right onto the kit chassis. It dropped our ground clearance down to a fourth of an inch. I made the holes that the axles went through into slots for a chain tensioner. I drew it out on CAD then milled it out of 1/4 of an inch aluminum on our CNC Machine.

Here they are. They are just beautiful.

Re: How did you do your axles
 

We used two different pairs of wheels (front pair was regular, back pair was Skyway Pneumatic 8" Diameter), so our back two axles had to be smaller and the sprockets didn't fit with the new wheels. To solve this we had to cut 6 aluminum disks (3 for each wheel) that had holes for the Shraeder valve as well as the six screws. Hmmm, I've gotten off the topic of axles, but there you go...

P.S.- I'me new at this and am having trouble posting pics. HELP!!! :ahh:

Re: How did you do your axles
 

Our team used a friction fit in alu shaft with cotter pins and spacers to keep it in place. Alu shafts fit though the holes in our alu frame. Can anyone see the issue here? :D We found out pretty quick that this wasnet the best idea, they were hard to remove after use, and we had alot of problems with them binding in the holes and mushrooming when we were trying to remove them. one had to be hacksawed off and nearly drilled out! We are going to design something better next year.

Re: How did you do your axles
 

Well we save the trouble of making "axle brackets" by just ordering a pillbox is what I think it is called which is just a bearing and a brace that we can screw into our chassis.

Another way we mount our wheels is by drilling into the profile and putting in a bushing. If we need to drop the CoG we just drill it into a vertical piece.

Re: How did you do your axles
 

We have been using Bosch Profile extrusions for our frame for a couple of years now so we came up with a small block that is keyed to the frame. We then grind flats on each end of the shaft and hold it in place with set screws.

The wheels that we use are machined aluminum, so we started pressing in needle bearings in the hubs for reduced friction and we use thrust bearings between the hubs and the shaft brackets.

The shaft itself is made out of case hardened shaft.

When all put together we have a very low friction setup for our tires that prevent binding and reduces power loss from the transmission system.

Re: How did you do your axles
 

can everyone show a picture of how they did it?

Re: How did you do your axles
 

OK well the way we did it was the way that we have did it since 2003.... we have to aluminum plates... and we put axles in that span both plates. the gears and sprockets and wheels go on those axles. i will try to get more pictures up soon but i have to find a way to get a camera into that very highly and very well secured gm powertrain :D . ill try to get some though. its really really simple.

Re: How did you do your axles
 

We (team 573) used gr 5 3/8in bolts the length we needed then through the wheels

Re: How did you do your axles
 

This year we used 1/2" keyed steel shaft. You can see the overall configuration in this picture. We used 1.5x2x1/8" wall box aluminum box tubing for the frame. We could have gotten away with 1x2x1/8. The wheels go on the outside of the tube and the sprockets go inside. Before it was welded we milled out a pockets (rectangular holes) on each side of the box tube. The pillow blocks fit in these pockets and can slide sideways to tension the chain. We have a small stationary block with a screw that is on the frame and the screw pushes against the pillow block to move it. It works really well. Extremely easy precision adjustment. Four 10-24 bolts clamp the pillow blocks to the box tube and keep it from moving. The pillow block on the outside has thru holes while the one on the inside has tapped holes so they pull together against the tube when tightened. Each end of the axle is tapped 10-24 and a bolt with a fender washer it used to "capture" the assembly.

The cutouts in the frame tube were made centerline. The bearing hole in the pillow block was made 3/64" off centerline so we flip the end two blocks up and the middle one down for a total difference of 3/16 lower for the center wheel.

You can see a picture of the pillow blocks here.
Picture showing sprockets
Good clean picture with tensioner screws
Up Close double sprocket with chain and tensioners

Re: How did you do your axles
 

we mounted them right under the chassis and used the same wheels from last year, we probably had the highest ground clearance in the competition, but we never flipped.

Re: How did you do your axles
 

Much like Sanddrag, our team used keyed shaft on our competition robot, though we did use 5/8th shaft instead of the lighter 1/2, it wasn't a strength issue, we just had the extra weight and had 5/8th keyed on hand when we built the chassis, so the robot got a little heavier drivetrain. On our practice robot (which is a 30 by 36 in square of 1x1 (1/8 in thick) aluminum angle. For those axles, sice we were just messing around with it, we bought sprockets, drilled them out, and bolted them to some skyway wheels. for the actual axle, we used some scrap barstock (I mean scrap...it was anywhere from 1/4 to 5/8 diam. because it was in a former life a practice piece for lathework), and we just drilled little 1x1in blocks of extruded alum. to act as pillow blocks (yes that bound up often, I don't advise it, it was just make-shift). In previous years, certain (not the drivetrain, but other axle-d items) parts have used brass bushings instead of bearings and pillow blocks, but we generally stay with pillowblocks on the robot.

Re: How did you do your axles
 

we just machine our own pillow blocks. An aluminum block with a slot and a couple screws for tension.