4:1 vs 5:1 gears

[Afrikakorps]

Hi everyone,
this may sound a little silly but has anyone tried both taigen 4:1 and 5:1 gearboxes?
I have both and find the 4:1 to have much more torque.
I have heard that the 5:1 is a 2 speed gearbox but i don't understand this. Can anyone explain.
The only advantage of he 5:1 is that it is much lower in height than the 4:1 or 3:1 gearboxes.
Is there an alternative low height gearbox ?
Any comments welcome.
thanks
Afrikakorps

[Max-U52]

Hi, AK. Yes, I've tried both, and it's a complicated subject. First, they're called dual ratio or 2 speed because you can remove the gear from the axle, turn it around, and you effectively bypass the last step of gear reduction. Or, you can do as I have done and mill flats on the axle shafts that allow you to simply loosen the set screws, slide the gear over and tighten the set screws back up. The big problem with that whole concept is the motors. Not enough oomph, if you can dig it. That's the main reason they've been so slow to carry the new steel ones at Imex. You see, when they were using brass they not only had a much quieter gearbox, it also operated with lower torque requirements from the motor. Steel gears are harder to turn than brass gears. Why, I don't know, but that's the problem. Ever since they went to steel gears in the dual ratio (or low/low) gearboxes they haven't been able to find a brushed motor with the cojones to do the job.

So that's why I grab up brass gear sets any time I can, and why I have a set of steel dual ratio boxes on the desk instead of in a tank. Oh yeah, they'r also MUCH louder than the old brass style and that's another thing I don't like about them. I really wish they'd bring back the brass dual ratio boxes, at least long enough for me to stock up on a couple dozen sets.

[Max-U52]

Here's a video that explains the two speed concept pretty well.

[Rad_Schuhart]

Max, What do you think about this ones?

http://g01.s.alicdn.com/kf/HTB1FHm1HXXX ... XFXXXp.jpg

They have plenty of room for bigger motors.

[tomhugill]

Hi, AK. Yes, I've tried both, and it's a complicated subject. First, they're called dual ratio or 2 speed because you can remove the gear from the axle, turn it around, and you effectively bypass the last step of gear reduction. Or, you can do as I have done and mill flats on the axle shafts that allow you to simply loosen the set screws, slide the gear over and tighten the set screws back up. The big problem with that whole concept is the motors. Not enough oomph, if you can dig it. That's the main reason they've been so slow to carry the new steel ones at Imex. You see, when they were using brass they not only had a much quieter gearbox, it also operated with lower torque requirements from the motor. Steel gears are harder to turn than brass gears. Why, I don't know, but that's the problem. Ever since they went to steel gears in the dual ratio (or low/low) gearboxes they haven't been able to find a brushed motor with the cojones to do the job.

So that's why I grab up brass gear sets any time I can, and why I have a set of steel dual ratio boxes on the desk instead of in a tank. Oh yeah, they'r also MUCH louder than the old brass style and that's another thing I don't like about them. I really wish they'd bring back the brass dual ratio boxes, at least long enough for me to stock up on a couple dozen sets.

Having steel gears doesn't make the gearboxes harder to turn, if anything a softer material such as brass absorbs energy when its minutely deformed which would make it less efficient than steel, sort of like running on sand. However this is all negligible compared to losses in the running gear and the torque required to overcome resistance from the surface it's running on. I had the old brass and the news steel side by side recently and the brass where slightly easier to turn but I put that down to the new motors having slightly stronger magnets.

[Max-U52]

You're right that it shouldn't make a difference if the gears are brass or steel, but it's one of those freak things. Take a set of motors from the brass gear set and put it in the steel and it won't run as well. Why this is I don't know, but I have found it to be true. Lack of a proper motor is the main reason Imex still doesn't have the steel dual ratio gears in stock. They ran fine with the 360 motors when the gears were brass, but those motors just won't do for the steel gears. Weird but true.

[Afrikakorps]

Thanks to everyone for your imput, and especially Max-U52 for your explanation and video clip.

I have the steel 5:1dual ratio (or low/low) gearboxes in my Taigen KV-2 because i can't fit the hi/low 4:1 into it.They are just a bit to high (4mm) for the top to close properly. They just fit in a friends Heng Long, but this may be because it doesn't have torsion bare suspension.? Maybe someone else has had a similar problem.?

Max-U52, if the final drive gear is moved closer to the outside gear (nearer the tracks) is this the position for more torque ?
Also Max, if the US and Australia weren't so far away i would take you up on that offer to mill the drive shafts.

Rad, I have seen those mato gears in brass in aa all metal Sherman ,but have not had a chance to measure their height. ( a fit problem in my KV-2 )

Once again, thanks Guys

AK