California Drive

[LondonBoy29]

In a California or West Coast drive system, how much lower should the middle two wheels be relative to the two in the front and the two in the back? What are the pros and cons of using California vs. Tank?

[Chris is me]

Never heard it called "California Drive" but considering your non-US location, it certainly makes sense as a name.

The "drop" part of a West Coast style drivetrain is actually common to most high traction tank drives, six or eight wheel. The center wheel or pair of wheels is lowered a small amount (between 3/32" and 3/16") to aid in turning while maintaining high traction.

[thefro526]

Just to add onto what Chris said, drop center 6WD's and 8WD's don't always have to be 'West Coast Drives' but the numbers stay true. Drop center six and eight wheel drives are extremely common - and very effective - using about any build method.

If you do a search on West Coast Drives or drop center drive trains you'll find all the info you could ever want and then some.

[LondonBoy29]

Thanks a lot. I have been reading about it, and I am wondering what is a live axle and what is a dead axle?

[EricH]

Originally Posted by LondonBoy29

Thanks a lot. I have been reading about it, and I am wondering what is a live axle and what is a dead axle?

A live axle has the axle rotating and used to drive the wheel. A dead axle is where any rotation of the axle is inadvertent; it's your standard chain-sprocket-wheel setup.

[Trent B]

Originally Posted by EricH

A live axle has the axle rotating and used to drive the wheel. A dead axle is where any rotation of the axle is inadvertent; it's your standard chain-sprocket-wheel setup.

To elaborate.

Live axle is where the axle is suspended in bearings and the sprocket and wheel are rigidly attached to it (direct drive is also a live axle design using the gearbox shaft as an axle)

Dead axle is where the axle is any rod (in some cases just a standard bolt from a hardware store) and the wheel is on bearings with a sprocket bolted to it.

Another note, 6WD is often much better than 4WD especially in a drop center configuration because it takes an incredible amount of torque to rotate a 4WD system due to the long wheel base, whereas 6WD with a drop center configuration has an effectively shorter wheelbase.

[Ether]

Originally Posted by eagle33199

Using standard tank drive, where all wheels are the same height, leads to trouble turning.... As the robot turns, you'll realize that the wheels have to move sideways (called scrub). This motion is high friction, and reduces your ability to turn quickly or sharply.

Originally Posted by Trent B

it takes an incredible amount of torque to rotate a 4WD system due to the long wheel base

A force calculator (and, for those interested in the physics, a complete explanation with the equations) can be found here.

Just by seeing the name of this thread, I want to create a parody of Katy Perry's California Girls. Just imagine it: Cal-i-fornia drive, it's so incredible! No outer frame, live axel setup.

DSK, if you're listening, and have a female vocalist, PLEASE make this song!

[Akash Rastogi]

Originally Posted by SuperNerd256

Just by seeing the name of this thread, I want to create a parody of Katy Perry's California Girls. Just imagine it: Cal-i-fornia drive, it's so incredible! No outer frame, live axel setup.

DSK, if you're listening, and have a female vocalist, PLEASE make this song!

I'd rather have it go along to Tupac's *California Love....



*-(real music)

[MagiChau]

Originally Posted by SuperNerd256

Just by seeing the name of this thread, I want to create a parody of Katy Perry's California Girls. Just imagine it: Cal-i-fornia drive, it's so incredible! No outer frame, live axel setup.

DSK, if you're listening, and have a female vocalist, PLEASE make this song!

I will never be able to view West Coast Drive the same way ever again.

[Jim Wilks]

Originally Posted by Ether

A force calculator (and, for those interested in the physics, a complete explanation with the equations) can be found here.

Nicely done!

[Xifilzer]

Currently my team builds robots with a 6 wheel drivetrain (pneumatic or AM rubber wheels + omnis), and we just completed our 3rd season. This past season we built our own chassis (as opposed to a kitbot) and housed the wheels in 1" x 3" tubing on one side, and 1/8"plate on the other, and drove 8" pneumatic wheels using sprockets and chain. But, with our side plates taken off, our robot was stanced, and all the wheels were angled. We have accurately drill pressed all our holes, and house the shafts of the wheels through both faces of the tube. Is there a different means to go about constructing a West Coast Drive? How would you prevent your wheels from angling under load?

Thanks in advance,
Xifilzer

[Mike Marandola]

Originally Posted by Xifilzer

Currently my team builds robots with a 6 wheel drivetrain (pneumatic or AM rubber wheels + omnis), and we just completed our 3rd season. This past season we built our own chassis (as opposed to a kitbot) and housed the wheels in 1" x 3" tubing on one side, and 1/8"plate on the other, and drove 8" pneumatic wheels using sprockets and chain. But, with our side plates taken off, our robot was stanced, and all the wheels were angled. We have accurately drill pressed all our holes, and house the shafts of the wheels through both faces of the tube. Is there a different means to go about constructing a West Coast Drive? How would you prevent your wheels from angling under load?

Thanks in advance,
Xifilzer

Might be a dumb question, but are there bearings in BOTH faces of the box tubing? How much space is between the outside of the the box tubing and the wheel?

[indieFan]

Originally Posted by Xifilzer

, and all the wheels were angled. We have accurately drill pressed all our holes,

How did you drill the holes? A drill press does not have the same ability to drill straight like a mill. I would suggest drilling the first wall, then use a transfer punch to get the second wall in the same location. For anything over 1/4" diameter, start with the hole in the first wall being the largest size transfer punch available, transfer it, then drill the larger hole.

[Xifilzer]

Originally Posted by indieFan

How did you drill the holes? A drill press does not have the same ability to drill straight like a mill. I would suggest drilling the first wall, then use a transfer punch to get the second wall in the same location. For anything over 1/4" diameter, start with the hole in the first wall being the largest size transfer punch available, transfer it, then drill the larger hole.

Originally Posted by Mike Marandola

Might be a dumb question, but are there bearings in BOTH faces of the box tubing? How much space is between the outside of the the box tubing and the wheel?

Sorry a correction to my original post, we used pillow blocks mounted to the underside of 1x3 tubing instead of running the shaft through the tube.

http://www.mcmaster.com/#5913k61/=1285fnp


Looking from an aerial perspective, going from the outer side of the robot inward, this was our setup:

shaft collar, flange bearing in a 1/8"side plate, two 1/8" thrust washers, 8"pneumatic wheel bolted to a keyhub, a sprocket for 25 chain, two thrust washers, pillow block, shaft collar (for spacing), a sprocket for 35 chain, shaft collar.

This sums up to around 3.25" between the pillow block and sideplate, and 1.5" from the pillow block to the tip of the shaft on the inside. I'll try and take a picture tomorrow.

Thinking about it more, i think the pillow block may have been the source of our problems, since it allowed the shaft to pivot, instead of binding in place had we simply gone straight through the tube (with bearings XD).