4" vs. 6" + 8" Diameter Wheels

[vincentkee]

I've noticed a lot of the veteran teams used the 4" diameter wheels in their 6WD or 8WD drive systems.

Is there any significant advantage to using them over the larger 6" or 8" diameter wheels?

And is there any significant advantage to implementing a 8WD instead of a 6WD?

[Joe G.]

4" wheels allow you to create a longer wheelbase, since the smaller wheel allows the axles to be spaced apart further.

Additionally, 4" wheels reduce the reduction required from a CIM motor to achieve a reasonable speed. Smaller reductions mean less frictional loss.

They arguably produce faster acceleration, since the wheels have less rotational inertia.

[Vikesrock]

In addition to what Joe posted above they are also lighter and tend to result in a chassis with a slightly lower Center of Gravity.

[Hawiian Cadder]

i really like small wheels, but i like 5 or 6 inch wheels the best. they are large enough to raise the ground clearance above what a 4 inch wheel set would give.

[Vikesrock]

Originally Posted by Hawiian Cadder

i really like small wheels, but i like 5 or 6 inch wheels the best. they are large enough to raise the ground clearance above what a 4 inch wheel set would give.

What for? Is there any reason you needed more than ~5." of ground clearance this year?

[JackS]

Originally Posted by vincentkee

I've noticed a lot of the veteran teams used the 4" diameter wheels in their 6WD or 8WD drive systems.

Is there any significant advantage to using them over the larger 6" or 8" diameter wheels?

Check out this nearly identical thread. If you search around a bit on CD I'm sure you can find multiple threads with this information.

Originally Posted by Hawiian Cadder

i really like small wheels, but i like 5 or 6 inch wheels the best. they are large enough to raise the ground clearance above what a 4 inch wheel set would give.

If you are careful when designing your drive for 4" wheels, you shouldn't have a ground clearance problem.

[AdamHeard]

See this post I made in another thread for why we like small wheels.

http://www.chiefdelphi.com/forums/sh...6&postcount=74

Originally Posted by Hawiian Cadder

i really like small wheels, but i like 5 or 6 inch wheels the best. they are large enough to raise the ground clearance above what a 4 inch wheel set would give.

In 2010 we climbed the bump with 4" wheels.

[Hawiian Cadder]

i would prefer 5 inch wheels, but settle for 6 inch wheels for several reasons. most of the omni wheels from andymark smaller than 6 inches are very bumpy, also 4 inch mechanums don't exist for FRC. i think 6 inch wheels are the most versatile, and that the tiny benefit of going to 4 inch wheels is not worth the flexibility trade-off.

[Chris is me]

Originally Posted by Hawiian Cadder

i would prefer 5 inch wheels, but settle for 6 inch wheels for several reasons. most of the omni wheels from andymark smaller than 6 inches are very bumpy, also 4 inch mechanums don't exist for FRC. i think 6 inch wheels are the most versatile, and that the tiny benefit of going to 4 inch wheels is not worth the flexibility trade-off.

When do you ever design a drivetrain for both mecanum and regular wheels? There's flexibility, and then there's being a jack-of-all-trades, master of none.

[JackS]

Originally Posted by vincentkee

And is there any significant advantage to implementing a 8WD instead of a 6WD?

This thread is useful too.

[Akash Rastogi]

Originally Posted by Hawiian Cadder

i would prefer 5 inch wheels, but settle for 6 inch wheels for several reasons. most of the omni wheels from andymark smaller than 6 inches are very bumpy, also 4 inch mechanums don't exist for FRC. i think 6 inch wheels are the most versatile, and that the tiny benefit of going to 4 inch wheels is not worth the flexibility trade-off.

Even when two are paired together?

You can get a smooth ride with omnis...

[Hawiian Cadder]

Originally Posted by Chris is me

When do you ever design a drivetrain for both mecanum and regular wheels? There's flexibility, and then there's being a jack-of-all-trades, master of none.

one reason is nonadrive or octomanium or any other number of names for the same basic mechanical idea, the drives usually use 6 inch mechs and 6 inch traction wheels. i prefer to use a very standard, modular design strategy, with multiple options. there are many more options for 6 inch wheels than any other wheel set. closon, andymark, pneumatic, good omni wheels, mechanum. with 4 inch wheels many of these types of wheels must be custom made. the 6 inch wheel size is the most versatile. and while it is true that some sacrifice is made in order to gain this flexibility, it is such a small advantage that it doesn't really impact performance too much.

I already designed a frame that will accommodate any drive-train. one of the sacrifices of that frame, was giving up 4 inch wheels of any type.

[Vikesrock]

Originally Posted by Hawiian Cadder

i would prefer 5 inch wheels, but settle for 6 inch wheels for several reasons. most of the omni wheels from andymark smaller than 6 inches are very bumpy, also 4 inch mechanums don't exist for FRC. i think 6 inch wheels are the most versatile, and that the tiny benefit of going to 4 inch wheels is not worth the flexibility trade-off.

The 4" dualie omnis on 2175's robot this year gave a smoother ride than 6" omnis we have used in the past IMO. Admittedly they are a bit heavier and are more expensive than a single 6" omni, but the weight and cost both typically are gained back by knocking out a stage of reduction.

[Akash Rastogi]

Originally Posted by Hawiian Cadder

one reason is nonadrive or octomanium or any other number of names for the same basic mechanical idea, the drives usually use 6 inch mechs and 6 inch traction wheels. i prefer to use a very standard, modular design strategy, with multiple options. there are many more options for 6 inch wheels than any other wheel set. closon, andymark, pneumatic, good omni wheels, mechanum. with 4 inch wheels many of these types of wheels must be custom made. the 6 inch wheel size is the most versatile. and while it is true that some sacrifice is made in order to gain this flexibility, it is such a small advantage that it doesn't really impact performance too much.

I already designed a frame that will accommodate any drive-train. one of the sacrifices of that frame, was giving up 4 inch wheels of any type.

Smaller wheels in octocanums make desired reductions easier to produce.

[Ether]

Originally Posted by Joe G.

They arguably produce faster acceleration, since the wheels have less rotational inertia.

Does anybody have mass and moment of inertia data for comparable 4", 6", and 8" wheels?