Need braking info...

[Rolex]

Don't ask why, but I'm wondering if it's possible to use a mechanical (servo driven) brake system with a brushless setup.
If it is, would I need a Y-splitter from the ESC throttle to the servo? There would not be a throttle linkage, only brake.

 

[Lessen]

Dont' ask why but I myself have often wondered the same thing. I think you're right about needing to split the signal. However, somehow you would need to disable the ESC braking.

1. Electronically - Would it be feasible to turn down the brake power as much as possible on the ESC. If your mechanical braking power was always stronger than your electronic braking power then the electronic braking is essentially null and no effect.. you think?

2. Mechanically - If you ran a one-way in the drivetrain before the mechanical brake, that only allowed forward motion and would make slowing via the motor null... you think?

*edit*
#1 does not work. Unless you could completely disable the electronic braking you would get a compound braking effect unless you incorporated #2. I think that's the way to go.

I suggested something like this years ago but was told it would harm the motor. To this day I cannot understand why.

 

[Rolex]

Okay, Josh, here's the story....
It's the huge Humm-Vee, and I'm running a brushless setup into a Revo Nitro 2 speed trans with reverse. Because of that, I've installed a shifting servo and linkage since the motor, in reverse, wouldn't reverse the drive in that type of transmission.
I've disabled any reverse and all braking and drag brake to the ESC so it will act the same as a nitro engine.

If it works out with the Y-splitter, any adjustment to the brakes would have to be mechanical, since any change to the EPA would have an effect on the ESC.
(Well, not sure of that since reverse is disabled in the programming)

I'm thinking any brake trigger would be ignored by the ESC, yet would still send the braking signal to the servo.

 

[Lessen]

If you can completely disable everything to the negative side at the ESC you should be golden. I wasn't sure if you could or not. At this point, if you've split the throttle/brake lead to the Rx then you'll get both positive and negative input to the servo. If what you say is actually "disabled" then changes to that side of EPA should not have an effect on the ESC. If it's simply turned all the way down that might be a different story.

 

[Rolex]

To the best of my knowledge, I had the choice to totally disable any drag brake along with braking and reverse. If that's the case, the motor should be in a stopped or neutral position during mechanical braking.
I've got absolutely EVERYTHING torn down right now since I just finished painting the brass chassis, so I can't test anything now.
I was hoping for some advance info so I could solder on the servo mount for the brakes.

When I had all the electrics set up and powered on, trigger gave me throttle and off. In the brake trigger position, I got nothing at all to the motor, so I'm guessing it should work if I run the splitter to the servo.
Since it's all been disabled through programming of the ESC, I think I might be able to set the end point for the brake servo with the radio.

 

[Lessen]

That sounds pretty safe Ralph. As long as the motor is neutral and not trying to stay at 0 RPM while you are braking, you should be in good shape, at least the way I see it.

I also think you're good to go with making brake EPA adjustments. If the ESC completely ignores all signal to that side of the channel there shouldn't be any change aside at the ESC, only at your braking servo.

 

[Rolex]

When I tested the drive, I could rotate the pinion in either direction while the radio was in brake position.
If your previous info related to mechanical braking with a motor that was also braking, that would be the reason it would get damaged.
Paint is almost dry, so once everything is reassembled I'll be testing it with a servo.
I THINK (?) it should work.

Now that I think about this a little more, it HAS to be set up this way since there is no way the electric brake would hold back through the nitro trans with one way bearings.

 

[hamz9561]

I believe you're on the right track, Rolex. From what I saw for the Tekno eRevo coversion, they use a splitter for the ESC and the now brake only servo.

 

[Rolex]

That's good to know, but I'm also pretty sure there's a different type of trans in the E. If there's a splitter, I'm pretty sure I can get it working.
I'll check the Tekno conversion and see what it looks like.
Got a link?

 

[beason]

the tekno conversion takes a nitro revo, and converts it to brushless. i would have a look at how they did it, and go from there. i think your on the right track though.

 

[Rolex]

Okay, so apparently they keep the nitro trans.
I think I can, I think I can, I think I can...

 

[Rolex]

There's the info on the Tekno conversion, so it would be a usable solution. I've already installed the brake and shift servos.

Uses stock Revo transmission, compatible with any ratio, center differential kit, rear brake kit, use the 2 speed or dial out 1st gear if you like (just loosen the shift point). Keep reverse if you want or take it out. We recommend using Robinson Racing steel transmission gears for ultimate durability. Uses stock mechanical brakes so you can tune front/rear brake bias if using the center differential kit. This results in much more predictable braking and less heat generation compared to using 'motor braking', not to mention it will save your transmission from unneeded stress.

 

[MotoGod]

Yup. It can be done for sure. Tekno does it in all theirs kits, but they also include their elektri-clutch setup to allow free-wheeling. It does require channel mixing on your radio as well.

 

[robmob]

My Ve8 has a mechanical braking setup.

2 ways you can do it.

As Josh mentions you can disable the braking function on the ESC and us a Y-Splitter. The ESC receives a braking signal, but ignores it since braking is disabled. The servo however, would actuate the brakes.

The other method is to use the channel mixing function on your transmitter assuming you are using your M11. You would still need to disable the braking function on the ESC.

Both work equally well. The Y-Splitter would essentially take the place of the mixing function. The only advantage to mixing is you have less wiring to tuck away.

 

[Rolex]

The ESC receives a braking signal, but ignores it since braking is disabled. The servo however, would actuate the brakes.

The other method is to use the channel mixing function on your transmitter assuming you are using your M11. You would still need to disable the braking function on the ESC.

Both work equally well. The Y-Splitter would essentially take the place of the mixing function. The only advantage to mixing is you have less wiring to tuck away.

The first paragraph is how I thought it would work.
Yes, using the M11, 3rd channel for the reverse shifter, and I never thought of using the fourth as the brake channel. In that case, I would set the mix to activate the brake servo from ch4 when the brake trigger is applied, but would NOT need the splitter from the throttle channel.
Wow, that's EXCELLENT advise.

 

[jw_petras]

Good luck!!!

 

[Rolex]

Thanks, but it's now working perfectly with channel 4 set to mix with the brake position on the trigger.
Great info, Rob.