Help with Belt driven car!!

SimonTr · #1 01-31-2004, 06:57 PM

I turn my gear car into a belt car. pully from the motor to a pully that has a gear in the front for the drive train. I was wonder, how do you calculate the ratio from speed or acc? the reason i asked this is my bro has a 5 cell mod with SB motor, and i have a 4 cell with SB motor and i could keep up with him. does the rules applies for pully also? bigger pully on the motor more acc, smaller pully on the motor more speed?

aero528 · #2 01-31-2004, 07:08 PM

i think so , but dont qoute me on it, sorry

Exaran · #3 01-31-2004, 08:06 PM

Oddly, it IS the same as it is for gears, but the opposite of what you said:

Bigger pulley on the motor itself = more top speed/less acceleration

Smaller pulley on the motor itself = less top speed/more acceleration

That rocks that you made that work. Where did you find the pulleys and belts? Now you can go with HUGE motors and not worry about getting the gears to mesh

spitty12 · #4 01-31-2004, 08:19 PM

Very cool, what kind of belt did you use?

Schr-eng · #5 01-31-2004, 09:08 PM

You calculate the gear ratio the same way as if you were working with gears.

This can be done by comparing the radii of each of the pulleys.

That’s cool that you made it belt driven like that, given the flexibility of the system. If I were you I would try to get rid of the drive axle all together for a couple of reasons:

1) It’s not as efficient to have a belt to the drive axle as it would be to just have a belt to distribute the power. You’re dealing with a lot of mass being driven by an elastic force, anything you do to lighten that mass helps a lot.

2) Just as that band can ease with fitting larger sized motors, it can also be helpful in altering the length of the vehicle. This means you can tune the car even more, and get a little more performance if tweaked properly.

SimonTr · #6 02-01-2004, 12:18 AM

I went to radio labs, which is a Car/ Home audio store, which also has a small vcr repair in the back. i bought along the white drive gear and found a pully the same thickness and roundness as the bigger teeth area. then you cut the white gear to make it look like your 4wd red gear, or you could buy the 4wd and use that. then drill a hole big enough to fit that gear/ or half the gear in the pully and glue. Then i put everything together and bought it to my electronic store to buy tape player belts, tried out the smallest and then test the tension on the belt entil i was happy with the tension and flex on the belt. i have used bigger motor and all i have to do is go out and find the belt to fit. the only down side to the belt thingy is that when you go in full reverse, and then hit forward while on high, you can hear the belt slip, while the car is going in reverse. like if the engine is raving. and when it has enough tension, it just shot forward.

Schr-eng:
what do you mean by gettin rid of the drive axle?? i could adjust the tension with spacer under the motor mount.

Exaran · #7 02-01-2004, 12:03 PM

Thats pretty sweet. Good thinkin.

good diagrams too

neurokinetik · #8 02-01-2004, 02:31 PM

Good mod. Looks like a way around the pinion gear woes that we have been having, and also work well for the people who are trying to fit larger motors that can't get the gears to mesh.

Schr-eng · #9 02-01-2004, 05:17 PM

Quote:

Originally posted by SimonTr

Schr-eng:
what do you mean by gettin rid of the drive axle?? i could adjust the tension with spacer under the motor mount.

If you look at some other micro rc cars, most with 4wd don't have a drive axle. They use a belt to distribute power.

I can't think of any examples at the moment... maybe micro RS4?

I'm suggesting that you somehow find a way to drive the front wheels with just a belt and take the drive shaft out of the equation. I don't know exactly how you would go about doing this, it would take a couple of more pulleys to get the belt to spin on the correct axis.