4WD, Tank treads and gear ratios.

[Pipisongo]

Hey all. I posted these three posts on the VEX forum but since you guys have so much experince building robots (of which I have none), I'm posting them here also.

One:
--------------------------------------------------------------------------
I'm familiar with gear theory (torque and speed). But what happens if you connect the wheels directly to the motor? (i.e. the same driveshaft from the motor is the one inserted in the wheel) Does this give good torque? Speed? I don't have any gear ratio involved so I don't know. Is it advisable to always use gears or sprockets, and not to connect the wheels directly to the motors?
---------------------------------------------------------------------------

Two:
---------------------------------------------------------------------------
What happens when I use four motors to make a "4WD robot". This is suggested in the VEX Inventor's Guide. That is, two motors on each side spinning in the same direction. One motor per wheel. I don't like the idea because I expect that the two motors driving one side of the robot will not be completely syncronized.

Is it necessary for the motors on the same side of the robot to be completly in synch. Or is the factory difference in speeds good enough for this arrangement?

Also what is the benefit of this arrangement, since the speed is "the same" on both motors on each side. I suppose I can expect a torque increase but not a speed increase. Is this correct?

Finally, can I expect greater torque (and traction) with four motors when using the VEX tank treads?
---------------------------------------------------------------------------

Three:
---------------------------------------------------------------------------
I purchased the VEX tank treads and have so far been dissapointed. Although I have not been able to build a suitable drive train for them yet, I suspect that they are a waste of money. I say this for 2 reasons.

1. They are made of plastic, and therefore they cannot get a good grip on most surfaces.

2. They don't "roll" that easily, so they require considerably more torque than a wheel of the same "diameter".

So my question is: Do any of you have experience with the VEX tank treads? Am I missing something here?
---------------------------------------------------------------------------

Thanks in advance for your help.