Gear ratios and reduction

[Zuki Tyler]

In my build up, I'm making a custom trans., that has an overall ratio of 182:1 in conjunction with a motor that spins faster (less torque) than a lathe motor.

I'm going for gear reduction and the multiplication of torque, rather than using a motor that has more torque, due to a higher turn.

It's kind of like the guys with 200:1 Toyotas vs. a Chevy 350...they essentially do the same thing, but one is spinning at a higher speed.

What are the transmission gear ratios that some of you are using?

 

[customxprone1]

Pede electric tranny is 2.72:1

 

[Mad Scientist]

It seems that spinning a low turn motor at high RPMs through a lot of gear reduction would would drain the battery and heat the motor up faster than running a higher turn motor at moderate RPMs through less reduction. Just wondering why you are taking this approach.

 

[mike]

The crawl ratio for my comp crawler is around 40:1 with a 55t lathe.

 

[Zuki Tyler]

It seems that spinning a low turn motor at high RPMs through a lot of gear reduction would would drain the battery and heat the motor up faster than running a higher turn motor at moderate RPMs through less reduction. Just wondering why you are taking this approach.

Well, I had all the parts laying around, it's small, light weight, and they all are free.

The way it works out in my head, if the motor turns more, with constant level of torque, there is less strain on it, and it would be easier on the battery. But I'm also not an electrical engineer.

Seeing that mike uses a 40:1 ratio, I may just pull out a gear, and use an idler...going down to 47:1

I still want to see what some other ratios in use are, possible out of something other than a lathe (I know that's the norm though)

 

[ECAMERON87]

I used to use a 52.75:1 ratio in my tranny (not including the axles) With a Magnetic Meyham motor. And it was nice and slow. The motor hardly felt it. I still had nice and long run times. The thing I hated was how long it to just to get to the next obstacle, so I took out the middle gear and used an idler gear in there instead.
Since then I have redone the tranny a little bit. I now run a 26:1 ratio with a Lathe motor (axle gear not in the equation). It still crawls really slow with plenty of torque for my heavy vehicle. I also have some wheelspeed if needed.

 

[microgoat]

If you use enough gear reduction, you could get away with using something like a Speed 300 to save weight. However, to get it to spin fast enough, you'll need to give it more volts, which means more cells, so either put the weight back or use an 11.1 lipo.

Taking this approach might let you place the batteries on the axles, using 8 or 9 2/3A cells to pump the voltage up while keeping the chassis light. The downside is complexity. You'll have lots of gears, each one an opportunity for something to go pear-shaped.

I can't see any advantage to using a fast 540 motor at all :?

 

[Zuki Tyler]

are you talking 27 turn stock or 10 turn race motors that will be what affects your gear ratio , the less turns the more gear you need.

I'm talking stock here, I'm also assuming it is a 27 turn, but it's not a 540 size motor, and it's out of a radioshack truck (so are all the gears).

If you use enough gear reduction, you could get away with using something like a Speed 300 to save weight. However, to get it to spin fast enough, you'll need to give it more volts, which means more cells, so either put the weight back or use an 11.1 lipo.

Taking this approach might let you place the batteries on the axles, using 8 or 9 2/3A cells to pump the voltage up while keeping the chassis light. The downside is complexity. You'll have lots of gears, each one an opportunity for something to go pear-shaped.

I can't see any advantage to using a fast 540 motor at all :?

Like I mentioned before, it's not a 540. Also, I'm not 100% concerned with weight savings, as this truck will only be bounced over the trail in the backyard.

But you're right about the complexity, at 182:1, there are 6 gears involved. At 47:1 (with idler) that goes to 7. The complexity doesn't bother me a whole lot, all the parts are free if they strip. I also get a kick out of engineering my own stuff.

I've got experience with an undergeared, high torque truck- and a deeply geared, MUCH less powerful (try 60ft lbs) truck, and it's obvious to me which I prefer. Putting power to the ground, a Chevy 350 won't snap an axle at idle, but a 40hp geared Zuk will.

 

[ECAMERON87]

Excellent analogy with the geared Zuki. Now if only I could use a geared down Sammy case in my K5 blazer?!!

 

[Zuki Tyler]

Excellent analogy with the geared Zuki. Now if only I could use a geared down Sammy case in my K5 blazer?!!

The input shaft is the size of your little finger. It'd be a pain in the butt (literally) to pull the shards of the case out of your behind every time you put it in 4lo, and canned it.