rdbruski

Do electric motors have need for 2 speed transmission? I know the e-maxx has 2 speed MANUAL transmission, but could electric motors benefit from an AUTOMATIC 2 speed transmission like the T-maxx 3.3 has?

I would think they would as you could then get a motor with less RPM and get the same top end speed effect. Also, there would be less heat generated on the motor.

annie_himself

I don't think so, I don't like 2-speed trannys anyway but I think they are more meant for nitros to get more acceleration and more top speed. Electrics don't have that issue because of the instant torque.

Access

The benefits aren't too great, especially with a good brushless motor that has pleanty of power. It doesn't really help in terms of acceleration or performance, but an additional gear might get you a little more top speed (when you use it) at the cost of runtime. You will end up using the low gear 90% or more of the time though.

Gecko

A two speed tranny is a good idea, however, a brushed 540 won't have that much power (Torque) to pull it much faster. I suggest to you a hot brushed or a hot brushless with "Accelerate forever" gearing.

hands without shadows

Any motor can benefit from a transmission.

Okta

Gears are meant for gas cars because they have specific torque curves and are designed to run in a certain RPM range (power band). Electric motor torque curves are much flatter and do not really benefit from 2 speeds.

AresROC

I guess I will put my two cents in...

Short answer - It depends...


Transmission is good for torque multiplication, even if you have a flat torque band; hence the low gear in the E-Maxx.
Locomotives benefit from NOT having a transmission because you would not have the drive train loss and maintenance to deal with.

An example: The Nissan Ultima sedan has a CVT, with infinite gearing ratios. It accelerates faster, runs the engine more efficiently, but does not save any gas, due to the power lost on operating the CVT...

RURC

In general a multi speed transmission is little to no help with an electric motor. But I have grown rather fond of listining to them. Also with the sensorless brushless motors it dose seem to allow more adjustability in driving. I have a GTRe by Schumacher, it has a 3 speed transmission. The thing accelerates like a rocket. You can hear the gears changing, it is really neat. I am running a Neu 1512 motor in it so power is not an issue. I dont think that multi speed transmissions would work well off road due to all the wheel spin you get. The majoritory of transmissions are dependent on rpm for shifting so all the off road slippage will not allow for smooth transitations between gears. Now I also have a converted Jato and it was a real handful with the 2 speed off road. I went and locked it into second gear and the car is just as fast as ever and just as quick but I dont get the "fish tail" when it shifts any longer. I think that depending where you are useing it there may be some benefit. I am still testing this out. I am going to get another GTRe and make it a single speed and do some time testing.

Here is a photo of the 3 speed in the GTRe transmission section.


Having built CVT transmissions (from Audi) they have no direct corelation to an electric motor. They cause the engine to see a rather constant load. All of the newer generation locomotives (I will guess from the 1960's on although the roots of electro-deisel go to the 1920's) have a deisel powered generator driving an electric motor. With the design of the rail system it is not dependent on varying speed too much. I think this is why they have no transmission, but weight could also be a small factor.

Vic Nyce

whoa that car is rad! any more photos or info on it??

jimroad471

So far, E maxx guys I know wanna lock out or remove the high gear. No need for it.

VintageMA

My 2c - I have a BL converted LST2 and I can not wait until I have the JBWeld to lock the 2nd gear to full-time. The first/second gear shift both in the up-shift and in the down-shift is nothing less than ruining the truck.

When accelerating, the instant torque of an electric motor comes into play. When the motor is spinning fast at the shift into second gear, instead of slowing down at the shift point, it just grabs a few more Amps of power from the battery and keeps spinning fast so the jump to second gear is so abrupt that if you are accelerating fast eneough you will put the truck backwards on it's lid at 20 mph.

When slowing down, the reaction is almost the same in reverse, at the downshift point the truck has the tnedency to lurch forward sometimes flipping it forward onto it's lid. I've sent to the LST2 into a 8 - 10 cartwheel roll just by trying to slow down.

The way I see it, the problem is due to the natural physics behind the two different power sources:

With a gas engine, you open a carb and a certain amount of gas is pushed into valve producing a certain amount of power. The motor will spin up to whatever speed that certain amount of power will let it go to.

With an electric motor, when you pull the throttle to 50% (and for those who are going to correct me, I already know the ESC applies 100% of the voltage for only 50% of the time - but this is for an example) the motor is sent a certain voltage. At this voltage (based on the speed rating rpm/volt) the motor will spin at a specific speed, and it will draw as many Amps as it can (with you battery being the only limitation) to rev to that speed.

So when the 1st to 2nd gear shift comes in a:
gas motor - will slow down to the load applied and the power supplied and then start revving up again.
electric motor - will simply draw more amps from the battery (if available) to maintain its current rpm, thus creating a much harsher shift point than the nitro motor would produce.

That being said, I am running a 6S MaxAmps 5000mAh LiPo hooked to a LMT 1950/7 motor, which being capable of a 50C burst could (in theory) put 5550 Watts through the motor.

That's more than 7hp moving through a 14lb vehicle - touch that nitro girls!!!!!!

RURC

Great information for this guy VintageMA but there is a problem with your math at the bottom. The 19xx series of motor is good to 1800 watts. I put a 2230 in a LST and that is a 3000 watt motor so you may be able to 5500 watts (that will also depend on your ESC capabilities) but the mortor will fry at that. You cannot make 7 hp with that system. On a 300 amp Schulze with a Neu Bam motor we are barely reaching that and those are 5000 watt motors.

Not to blast you, the rest of your lines are right on.