Traction trouble

[Rickertsen2]

Originally Posted by maxlobovsky

If you are using skid-steer as in 2 wheels and 2 skids, your problem may be that you dont have enough weight on the drive wheels. If you can shift some weight over to them, you will get better traction.

I assure you most of our weight is over the drive wheels.

[Biff]

Originally Posted by Rickertsen2

I assure you most of our weight is over the drive wheels.

If you can go to a 14 inch Wheel, skyway has a tube and tire kit that fits on the 12 wheel hub, it is wider and has pretty aggressive tread. This will also make your bot faster, 12.5inch to 14 inch. They also were selling the whole thing filled and assembled. The part number for the whole tire and wheel is WHL1250 Sub 300-8 The part number for the tire only, you still have to get a inner tube, is Tire 2062 I don't have notes on the inner tube. Good luck BTW some of the pics in posted of this years bots have the 14 inch tires.

[Dick Linn]

What tire pressure are you using? Gearing? Be more specific and we'll see what we can advise.

[Rickertsen2]

Originally Posted by Dick Linn

What tire pressure are you using? Gearing? Be more specific and we'll see what we can advise.

Tire pressure. We tried deflating the tires. Gearing? Don't remember of the top of my head. We have the Chips and Drill combined on each side of the bot. I want to say somehing around 30:1 from the drills and the chips are matched at free speed to the drills.

[andy]

Lemme elaborate James,

We have roughly 130 ft/lbs of torque per wheel, we move at a top speed of about 8 ft/sec. We have plenty of power, but we cannot get the power to the ground, we are doing burnouts and skidding on carpet. We are looking into other wheel options, we are looking at things like gokart slicks and solid urathane skyways.

Thoughts?

-Andy

[Solace]

skyway sells a version of some of its pneumatic wheels where the air tube is replaced by a hard foam insert. they have excellent traction, but I'm not sure that you can get it with the big wheels (ours our only 6")

[ngreen]

Originally Posted by andy

Lemme elaborate James,

We have roughly 130 ft/lbs of torque per wheel, we move at a top speed of about 8 ft/sec. We have plenty of power, but we cannot get the power to the ground, we are doing burnouts and skidding on carpet. We are looking into other wheel options, we are looking at things like gokart slicks and solid urathane skyways.

Thoughts?

-Andy

My thoughts would be two front gokart slicks and then for the back have a wheel with lots of forwards traction but not much side to side traction so you can turn. We used 4 gokart slicks last year. See the picture. We ended up putting caster on cyclinders to drop down when we wanted to turn a lot. We were reseting breakers. So these would be great for the front but find a better way for them to slide in back with out giving up the traction forwards. Maybe fully inflating them would help some though.

[andy]

Hey all, thanks for the input!

We are using two drive wheels with two skids on the rear.
(we're using skids cuz we thought we wouldnt be able to skid stear-have had bad experiences in the past)
Today I came up with a new concept. Put another set of drive wheels just behind the others. That way we have the best of three worlds: we have great traction, turning ability (because the wheels are close together), and we can drive in straight lines easier. Also it is narrower then the gokart slicks so that we can still drive up the stairs and make it around the goal.

Try my poor ASCI drawings

where
() = wheel
v = skid
- = frame

*current side view*
()-------v

*proposed side wiew*
()-()----v

This option would be very easy to add to our robot and would add only about 10 pounds of weight and it just so happens we have weight to spare.

By the way, who is your supplier for the gokart slicks? I've had the hardest time finding them on the internet. Thanks!

Thoughts? Opinions?

Thanks
-Andy

[ngreen]

Its a local distributor but I am not sure where they get them from. It was all by accident last year too. We wanted knobby tires and after we ordered them we got the slicks back. But the worked great. I like your new idea a lot. We do have traction problems but we need the traction to get over the step. Good luck.