Four wheel drive question

[JVN]

Originally Posted by haverfordfords

Hi all,

For those of you that are creating robots with four wheel drive, how are you accomplishing this? The included gear box only supports two wheel drive and in order to get it to work four wheel drive you need two of part # FRC-2005-112-009.

Innovation First claims that they, "do not sell the transmission gears or sprockets individually. The gear you are looking for is included in the transmission kit. We only sell transmission kits in complete sets."

A complete set would be ridiculously expensive. My question therefore is how do you go around this technicallity to support four wheel drive, OR how did you order the two parts for four wheel drive without buying the whole set, OR does anyone have any extra of these parts?

If anyone could help out this rookie team, we would greatly appreciate it.

Thank you all,
Jason, Team Leader 1656

Jason,
Innovation First DOES sell sprockets individually, but not gears.
Please refer to this page: http://www.ifirobotics.com/kitbot.shtml

Note: you do not need any additional GEARS to make a 4WD system, only sprockets. You can buy 1 sprocket kit "ROBOT-SPROCKETS-2005" and along with the 2 extra wheels and wheel hubs included in the kit be 4-wheelin' before you know it.

The gearbox is easily convertable to a 4WD configuration. In fact, it was originally designed with 4WD in mind. If you simply buy the extra sprockets, you will be up and ready to go in no time.

If you have more problems, do not hesitate to ask,
John

[haverfordfords]

Originally Posted by JVN

Jason,
Innovation First DOES sell sprockets individually, but not gears.
Please refer to this page: http://www.ifirobotics.com/kitbot.shtml

Note: you do not need any additional GEARS to make a 4WD system, only sprockets. You can buy 1 sprocket kit "ROBOT-SPROCKETS-2005" and along with the 2 extra wheels and wheel hubs included in the kit be 4-wheelin' before you know it.

The gearbox is easily convertable to a 4WD configuration. In fact, it was originally designed with 4WD in mind. If you simply buy the extra sprockets, you will be up and ready to go in no time.

If you have more problems, do not hesitate to ask,
John

Thank you everyone for your great suggestions!!! So if I read this correctly, all we need is ROBOT-SPROCKETS-2005 and that has the parts we need? AWESOME! Please just confirm this and we will order that right away. Thanks again!

[JVN]

Originally Posted by haverfordfords

Thank you everyone for your great suggestions!!! So if I read this correctly, all we need is ROBOT-SPROCKETS-2005 and that has the parts we need? AWESOME! Please just confirm this and we will order that right away. Thanks again!

That's affirmative.
With the "ROBOT-SPROCKETS-2005" Kit ($80 + shipping) you can construct the 4WD configuration I show on the right in my above post.

Isn't that awesome?
Less than $100 for a fully working 4-motor, 4WD base.
It's a brave new world.

JV

[Andy Brockway]

Originally Posted by JVN

That's affirmative.
With the "ROBOT-SPROCKETS-2005" Kit ($80 + shipping) you can construct the 4WD configuration I show on the right in my above post.

Isn't that awesome?
Less than $100 for a fully working 4-motor, 4WD base.
It's a brave new world.

JV

You will also need the wheel adapters or make your own. IFI is currently out of stock. I was planning on making four plates and using only one wheel adapter per wheel. The plate would go on the opposite side from the sprocket. There are drawings for wheel adapters on the FIRST CAD library.

[haverfordfords]

I saw this FAQ on the IFIrobotics.com Site...

So, we also need the sold out hubs? Does this mean we also need an additional chain OTHER than the one included. Also, the sprockets listed below - those are IN ADDITION to the ones already in the kit (all four of them?), correct?

Sorry if this is a stupid question...

Thanks,
Jason

"What do we need and how do we make a four wheel drive system out of what we have in the kit?

Please check section 3 in the "2005 FIRST Robotics Competition Kit Transmission Manual -RevA" document located at http://www.ifirobotics.com/kitbot.shtml.

You do not need the custom PVC spacer used in the 2 wheel drive configuration and you need to use the 40mm key provided in the kit instead of the 20mm key. You also need additional parts to make the 4 wheel drive configuration. The additional parts you need are:

1. 21 tooth sprocket - Quantity 2. Available from ifirobotics.com
2. 28 tooth sprocket - Quantity 2. Available from ifirobotics.com
3. Skyway wheel hubs - Quantity 2 sets.
4. 10' of chain. Available from ifirobotics.com"

[elknise]

Kit Bot Parts

I just found out yesterday that IFI now sells individual sprockets of both kinds for 19.99$

[haverfordfords]

Originally Posted by elknise

Kit Bot Parts

I just found out yesterday that IFI now sells individual sprockets of both kinds for 19.99$

Yes, but according to that FAQ it seems that we need 2 of BOTH anyway? Is that true?

[MattB703]

Originally Posted by haverfordfords

Yes, but according to that FAQ it seems that we need 2 of BOTH anyway? Is that true?

Well, you should need a total of 4 big sprockets, one for each wheel, and a total of 4 small sprockets, 2 on each geabox output. Then you will put 4 separate chains, one to each wheel. You could run with only 1 sprocket on each output and use one longer chain to turn both wheels on that side but I'd advise against it. You would need to make a semi elaborate idler system to get an adequate (more that 150°) of chain wrap on the drive sprocket.

[Paul Copioli]

Quote:
Originally Posted by haverfordfords
Yes, but according to that FAQ it seems that we need 2 of BOTH anyway? Is that true?



Well, you should need a total of 4 big sprockets, one for each wheel, and a total of 4 small sprockets, 2 on each geabox output. Then you will put 4 separate chains, one to each wheel. You could run with only 1 sprocket on each output and use one longer chain to turn both wheels on that side but I'd advise against it. You would need to make a semi elaborate idler system to get an adequate (more that 150°) of chain wrap on the drive sprocket.

In either case, you need more than just the wheel sprockets. For the 4 chain option (two per transmission) as documented in the kit you need four output sprockets (two per transmission). For the two chain option (one per transmission), you will need at least one idler per side.

Bottom line, for four wheel drive you need more hardware than just two more wheel sprockets. That is why IFI packaged the sprockets together.

-Paul

[BlazinFire47]

well.... you can forsay create your own 4-wheel drive system you know.... but it does involve lots of build time and 3 weeks have passed now.... to keep it sweet and simple.... 4-wheel drive will not a big issue this year.... i forsee that most teams will be using 2 wheel drive or swerve.... so if it is easier right now use 2- wheel drive for the timeframe we have right now...

[csquared05]

last year we used 4 wheel drive, but it was extremely jumpy on the carpet last year when we were turning with the supplied wheels. We improved our control by using zip ties, but they weren't 100% effective. How have other teams overcome this jerkiness?

[Alan Anderson]

Originally Posted by csquared05

last year we used 4 wheel drive, but it was extremely jumpy on the carpet last year when we were turning with the supplied wheels. We improved our control by using zip ties, but they weren't 100% effective. How have other teams overcome this jerkiness?

A TechnoKat robot from a few years ago used a pneumatic "puck" that lifted the front end of the robot when the joysticks were calling for a turn. This was on a tank-tread drivebase rather than a four-wheel drive, but the idea works either way.

If you aren't dead set on the supplied wheels, you have many options, including omniwheels. The 2004 KatsKlaw just used extremely grippy rear tires and enough motor power to make the front wheels slip without too much skipping.