Adjustable Way of Dropping the Center Wheel
 

Well, every drivetrain created in FIRST is unique and different. I thought of a way to adjust the amount of drop in the center wheel.



The first drawing is the part of the frame, the second part is the adjustable part. The drop is an increment of 1/16". 1-16 to 1/4. :D

Re: Adjustable Way of Dropping the Center Wheel
 

I really like your thought process here, and it is defiantly an interesting solution. The question I have is how often do you think you will have to change your center wheel displacement? Probably not very often during a competition but if this was for a development platform or practice bot I could see this coming in handy. Nice job.

Re: Adjustable Way of Dropping the Center Wheel
 

That's certainly one way to do it. I like it.

In 2007, 294's center wheel sat in a block on each side that was sitting in a slot. The bottom of each block was tapped, a bolt came up from the bottom of the frame into it. Tightening the bolt would pull the wheel farther down. Similar to how 294/968 tensioned their outer two wheels in 2006, but rotated 90 degrees. However, we quickly realized during the season that it wasn't very useful.

Re: Adjustable Way of Dropping the Center Wheel
 

We used a pnueumatic center wheel. When we wanted to raise it, we put more pressure in; lower it, drop the pressure.

Re: Adjustable Way of Dropping the Center Wheel
 

I really like the idea, but I will echo what the others have said, as you probably won't have to adjust it much during the season. However I could see the idea being applied to different areas where adjustment is needed.

Re: Adjustable Way of Dropping the Center Wheel
 

That's 330's strategy, except that the wheel is already dropped.

Re: Adjustable Way of Dropping the Center Wheel
 

The reason for this is that we dropped our wheel last year at 1/8", but this year it needed more but we were stuck with an 1/8 because of the way we did it. So in postseason i tried this and we lowered it to 3/16" and the frame turned like a champ.

Re: Adjustable Way of Dropping the Center Wheel
 

Well one situation when a pneumatic actuated center wheel is nice is if the game requires alot of pushing power then you can make it so all 6 of your wheels are on the ground at once. That obviously would make it very hard to turn especially if your wheels are wider than an inch. Then when you wanted to turn you could increase pressure and push the center wheel down farther and spin around very nicely.

However if your not going for that as others said you probably wont move them much once you find a nice offset that works for your robot.

Re: Adjustable Way of Dropping the Center Wheel
 

Uh... not pneumatic actuated, pneumatic. There is a difference. Pneumatic actuated is a cylinder attached to the wheel; pneumatic is like a car or bike tire; i.e. air-filled. You can't change the pressure mid-match, though a nail on the field might change it for you.:ahh:

Re: Adjustable Way of Dropping the Center Wheel
 

Yea, I forgot to mention that. Our's is already dropped as well. Of course this year we went with AM Performance wheels, so no more pneumatic. Saved us a lot of weight. We were like 105lbs this year.

Re: Adjustable Way of Dropping the Center Wheel
 

Cool. One thing to be careful of when testing a chassis during the build season is to have proper weight and surface (i.e. carpet). We have built many chassis that seemed crazy manueverable on concrete, and then added mechanisms and put it on carpet and voila, it turned like a 10 ton dump truck.

You can also change the "drop" by lifting the front or rear wheels. These are often easier as this will only effect tension on the chain loop to them as changing middle wheel drop often includes messing with multiple chain loop tensions.

Re: Adjustable Way of Dropping the Center Wheel
 

We found this out the hard way, we could turn on the concrete with the arm, so we didn't drop the center wheel enough. Competition time comes and boom, we can't turn unless in low gear.

Re: Adjustable Way of Dropping the Center Wheel
 

{kinda off topic} because we usually only had to turn right 1557 used a two wheel drive in the front with two skyway wheels side by side to each other in the back left and a caster in the back right that was raised about an 1/8th inch so when we turned the robot would lean to the right and make turning a breeze.

Re: Adjustable Way of Dropping the Center Wheel
 

I remember hearing that Truck Town had a pneumatic actuated center drop in '06. From what I heard they would have all 6 wheels on the ground when pushing, and could 'pop' their center wheels down with pneumatics when needed for turning.

Re: Adjustable Way of Dropping the Center Wheel
 

How much stroke on that piston???