Dedicated Throttle & Brake Servos (?)

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Yes you just let off the trigger and hit the button for the rear brake. It’s all good but I’m telling you guys it can be done.
Dude, first of all the wall of words gets my goat.

You’re also talking out of your blow hole. Who the fcuk has a handbrake on their RC??? An E-brake as you call it only operates the rear wheels.

A drift machine will be either rear wheel or all wheel drive. When would you only want to operate the rear brakes only? This is an RC, not Ken Blocks Hoonigan.

A petrol, gas, benzine powered RC car does not need this and they are nothing like an ARRMA electric car. You are confusing the situation because Erik will definitely have mechanical linkages to all systems.
I guess you really done read a wall of words huh? Lol. The poster literally said he wants to lock up the rear axle. Maybe that’s why your arguing that it’s wrong because we are taking about two different things. I’m actually answering HIS question 2B72B74A-5EA3-4983-A47C-9A7017D894CC.jpeg
 
I believe he was using the term "hand throttle" to get his point across. Yes it can be done, but tbh with how gas responds to input, you'll have better timing using the trigger for the process, and not having a separate function to command full brake.
 
Yes you just let off the trigger and hit the button for the rear brake. It’s all good but I’m telling you guys it can be done.

I guess you really done read a wall of words huh? Lol. The poster literally said he wants to lock up the rear axle. Maybe that’s why your arguing that it’s wrong because we are taking about two different things. I’m actually answering HIS question View attachment 70485
My bad, I hold my hands up.

Don’t listen to me Erik get an ESC and you’ll be cool. A Dawg clearly knows what he’s on about. I get what you’re trying to achieve.
 
I agree both of you may have the better way. That’s fine. Other people have info that may be useful to the original poster even if it’s not to you.

Milo again maybe you have the better way but come on you didn’t even read what he was asking for and you were not answering the question correctly then. At least give me that. I mean it’s pretty funny
 
I said I hold my hands up but I was referencing what he needs not what he was asking for. That’s my fault.

If Erik wants a hand brake in his petrol powered rig then I wish him luck. Same as I wish others luck.

Your comparison is not the same but hey it’s just a hobby. Your attention to detail is good but your comparison to an ESC is not.

Erik has mechanical linkages and that was what I was focusing on. It’s not a competition on who has the most knowledge, if it is that’s not me.

Hey ho anyway, show us what you’ve got then?
 
Hi All,

So I think you all have given some answers for what I'm hoping to accomplish. I still have more research I need to do, for sure. Also keep in mind Im not a super RC master, so some of my ideas may be ridiculous, and I'm hoping you guys can call me out on it if so.

The ultimate goal is to use the trigger for throttle, but also use it for brake. Ideally, there is a single servo for the throttle, and a second servo that will activate the rear disk brake. As silly as it may sound, I currently only have designed the rear disk brake on the live axle, and I plan on using that as the "hand brake". Its got the be powerful enough to lock up the rear tires. My current design doesn't include front brakes. My thought is that I can use the rear brake smoothly, for regular deceleration, but then jam the trigger hard to fully apply and lock them up. Alot like 80cc shifter carts (rear brake only).

I plan on running just a single servo for steering for now, until I find out that it may not be enough. So in total, 3 servos.

I don't like the idea of having a on/off type switch for the 3rd channel (hand brake).


I've looked into the Futaba 4 channel radio, I think it is the 4PM, but unfortunately it is out of my budget for now. There's got to be a 4 channel radio out there for less? I understand I wont be king of the hill in terms of radio, but thats fine. Unless you guys are saying there literally is no other option for what I want to do. Also, reading the specs just confuses the snot out of me! Lol.


Regards,

Erik
Also, and highly important, is that when I make references such as "I plan on", and "ultimate goal" really just means "in my head this is what I'm thinking". It doesn't mean that is set in stone.

Thats why I'm here, to pick the brains of you all, and learn on some ideas that can help me in my design. I really appreciate all the feedback so far.

Regards,

Erik
 
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Ok, first you can accomplish what you want to do with 1, 1/5 scale servo. There is really no need for 2 since your running just rear brakes. I'm assuming your not at all familiar with how 1/5 scale brakes are set up, and it's really not hard to do via the linkage. I'll get some pictures up as examples tomorrow.

Second, there are other options, but range and longevity will be issues. Sanwa may be an option few guys have them with decent results, they would have to chime in though. My philosophy has been buy once cry once. Futaba is a proven radio system that wont let you down, and I believe has the features you are looking for, if you decide to go with channel mixing for your set up.

Third, I cant express how much were in need of pictures to see what were dealing with. I have no reference as it's a 1 off so cant say what would work well or not from prior experience.

So home work for you. Take pictures. Then we can move forward.
 
You can do what you just mentioned using the 3pv with a 4 channel receiver. So slightly under $200 and you can sell the 3 channel receiver it comes with for $35
 
Your forgetting kill switch, needs it's own channel, so dedicated 4 channel set up. The 4th channel in a 3pv is for a certain function. I'd have to dig my manual out and see what it was for sure, but wouldnt work to control 3 servos and still have a functioning kill switch.
 
RC6GS
Digital 6-Channel Proportional RC System
low cost , decent range , 6 ch tx/rx , has all the functions of the super high end units , easy to start with while you figure out what you want to do , with many extra ch';s for all kinds of stuff as you figure out your setup.
 
I'm a sponge, so keep the knowledge flowing!

Here are some pictures of the chassis. The next major steps are the front steering and throttle, but I need to figure out my electronics situation and placements before I keep going.

Also, I took a photo with a large disk brake to show my intentions, albeit poorly. The one I have now is nearly identical, but is hub mounted to the rear axle and is only 2.25" in diameter. The hub is being machined now. So just picture a disc brake on the rear axle. Going cable operated or hydraulic hasn't been decided.

Regards,
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Erik
 

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Pretty basic set up, lots of room to mount whatever youd like. If you didnt have the engine laying in an odd position would have made a single servo a cinch, but theres always the cable option I suppose. No different then a weedwacker or saw. Hydraulic brakes if decent ones will give you the best results, again I'm going off buy once cry once. Mecatech is great stuff. Imo you pit the cart before the horse with the brake design, unless you'll be having your own calipers made as well.
 
Hi Seandonato,

Thanks for the brand suggestions, Ill look into them. Weight balance is a design factor here, and laying the engine down is also helping me keep a lower cog. Not to mention body fitment when it's all said and done. Sometime I feel like I always put the cart before the horse with a design- as- I- build process, lol!

Regards,

Erik
 
Hi Seandonato,

Thanks for the brand suggestions, Ill look into them. Weight balance is a design factor here, and laying the engine down is also helping me keep a lower cog. Not to mention body fitment when it's all said and done. Sometime I feel like I always put the cart before the horse with a design- as- I- build process, lol!

Regards,

Erik
Cheers, I can understand. Just makes linkage a bit more difficult for your set up.
 
I've gone through each message with a finer tooth comb to extract as much as I could out of it.
This is what I feel like I've learned- correct me if I'm wrong- and what I still feel like I'm missing.

Steering - 1 channel, 1 servo
Throttle - 1 channel, 1 servo
Rear brake - 1 Channel, 1 servo
and I like the idea of a kill switch, so 1 channel, and....?
4 channel minimum. 3 servos.


I looked at the Sawya transmitter that was mentioned, but it wasn't much less than the others mentioend, so no luck for me there.
I looked into Futaba 3PV, which is higher than my budget, but...not out of realm..
The Futaba is a 3 channel, but has an option to be purchased with a 4 channel receiver. That, I don't understand. They call it a 3(+1). 4WS/BRK MIXING (SMX): is what I'm looking for, right?
The Radiolink would pain me to buy because it just seems cheap, but I have to be real to myself at some point and realize that's where my budget is putting me. It's 6 channels, but I don't understand its capabilities, so I don't know if it would work my potential setup.

But, from what I've gathered, this is how I would physially do it?:
  • Channel 1, feed the steering servo. Pluged into CH1 on receiver. Mechanical linkage (What if I wanted/need to add a second servo in the future? Would that change any of my channel needs?)
  • Channel 2, feed a throttle servo. Plugged into CH2 on receiver. Mechanical linkage.
  • Channel 3, feed the rear brake servo. Plugged into...CH3? Mechanical linkage to either a cable, or to hydraulic master.
  • Channel 4 - Killswitch
  • Then, to accomplish my throttle/brake trigger dilemma, I would channel mix 2 & 3? Trigger back is throttle, forward is rear brake.
If that's the case, what makes the Futaba 3PV unit not applicable, when purchased with the 4 channel receiver?

Regards,

Erik
 
I have a 3pv tried it with its 4 channel mix on my rack crawler, it leaves much to be desired. Ie I could have 4 wheel steer but no crab, no front steer or rear steer only. That was a hard pass for a rock crawler. It should* work for this application with brake and throttle mixing, but the mix programming is pretty basic in it. Let me dig the manual out tonight when I get home and I'll put up the mix section of it for you to read over.

You shouldnt even dream of running something this big without a kill switch. Period. 30lbs(if the weight stops there) @40mph will break a leg, or much worse.

What saw did you rob the engine out of? I have an idea for a cable throttle and single servo to work the brakes and throttle but need to know if there was a cable bracket available for the carb on it. It would require a bit of fabrication on your part to work, but I think it would be pretty trick and simple, and would weed out one more thing to go wrong.

Edit:
Had another thought. Figure out if your going cabel brake or hydro. I would give the nod to hydro, but it may be a bugger to find something existing that works with your scale. Cable would be easy, but cant say many here seem to be in love with it.
 
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Hi Seandonato,

The engine came from a McCulloch 710. I got a couple of good saw engines, a 610 and 710, and chose the bigger one for this build. I'm using some of the components from the 610. I like to collect and build things out of small engines, primarily two strokes.

As for the brakes, my current thought and design process is for the rear disk brake. I got my inspiration from bicycles/gopeds, and the parts are readily available and often times much cheaper than RC specific stuff. For some reason I feel like RC parts are just anodized and slapped with a huge markup! I haven't chosen either cable or hydraulic yet, because it partly will depend on what I can source for a decent price. I'm not cheap, but I've got my hands dipped into tons of project so if I were to just bug out on everything, I'd be broke. If that makes sense.

As for the throttle servo, I really need to mount it first and then work on the linkage, sort of playing with the design as I go. I'm not too worried about it though, I expect it will be a simple aspect. I already have a 25kg small case servo dedicated for this. Actually, I've got a couple of those servos on hand, I wonder if a 25kg one would be brute enough for the brake system too....

I'd love to hear your idea though for a single servo setup. Ideally, fabrication is preferred, rather than buying parts. The more this is custom, the cooler I'll feel.

Regards,

Erik
 
Hi Seandonato,

The engine came from a McCulloch 710. I got a couple of good saw engines, a 610 and 710, and chose the bigger one for this build. I'm using some of the components from the 610. I like to collect and build things out of small engines, primarily two strokes.

As for the brakes, my current thought and design process is for the rear disk brake. I got my inspiration from bicycles/gopeds, and the parts are readily available and often times much cheaper than RC specific stuff. For some reason I feel like RC parts are just anodized and slapped with a huge markup! I haven't chosen either cable or hydraulic yet, because it partly will depend on what I can source for a decent price. I'm not cheap, but I've got my hands dipped into tons of project so if I were to just bug out on everything, I'd be broke. If that makes sense.

As for the throttle servo, I really need to mount it first and then work on the linkage, sort of playing with the design as I go. I'm not too worried about it though, I expect it will be a simple aspect. I already have a 25kg small case servo dedicated for this. Actually, I've got a couple of those servos on hand, I wonder if a 25kg one would be brute enough for the brake system too....

I'd love to hear your idea though for a single servo setup. Ideally, fabrication is preferred, rather than buying parts. The more this is custom, the cooler I'll feel.

Regards,

Erik
Cheers, my name is sean btw. No need to spell out my entire name.
Heres the mix page of the instructions for the 3pv. It's very very basic and featureless imo, as you have to use channel 2 and 4 under the brake mix, the 4ws is useless in this application as it will only mirror the other servo.
16147160337132427489878677514999.jpg

You need to remember channel 4 is only a slave channel and not programmable to do much, hence why I suggested a 4pv or 7px. Then you have normal servo mix capabilities.
Second I think your 25kg servos are going to be woefully inadequate for your braking needs, 25kg roughs out to 350oz in. Where as most of us run a d845wp hitec which is 50kg as brake and throttle servo, your rig is going to be pig heavy, of this I assure you. It will need all the help it can to stop effectively.
Any examples of what bicycle specific parts your looking at? And yes rc stuff is expensive, kinda the name of the game. Take for instance imported your pm710 is a 70.5cc engine netting around 5.6hp, a modded zenoah g340 will get you up closer to 9hp and weigh half as much, it will also set you back $600.00 give or take. I'm not knocking the want to build and use your own stuff, just let you know where the cost comes from. Light weight power dense engines, and parts specifically made to keep up with that power. A 70cc rc max engine is more along the lines of 15 ish hp. I'm a big saw nerd and that's just not obtainable from an old 710. Anyway. Some more for you to think about.
Back to the single servo set up. I would advise a hilatronics 8000, 1000+ oz in of torque, will stop that beast with ease. The key to using it as a single servo is getting your linkage set up properly I would advise a push pull system, that way you can have a double slider with easy adjustments like a normal rc. I would set it up exactly like this.
16147171049963060282849348413411.jpg

When the throttle is applied the brakes simply relax
16147171738224265733337036108554.jpg

When the brakes are applied the throttle is returned to closed and the brakes are pulled on in this set up (for push just reverse the rod direction from what is shown if pushing a master cylinder. Brake movement doesn't matter as there is a small weak spring to keep the throttle pushed closed
1614717320619116801405458656206.jpg

In your application you have a ton of real estate to use. Situating the servo intron and off to the side you should easily be able to fabricate linkage to get to the carb, and have a master cylinder/ cable termination block next to the engine. Thus fully integrating the kiss method and eliminating the need for another servo in the mix. Then you can get away with a 3 channel radio. Throttle and brakes on 1 channel, steering on another, and kill switch on the third channel.
I can understand the multiple hobby thing and wanting to piss a bit of money on each of them, lord knows I have too many hobbies and projects. But i find I'm much happier when i finish one and then move on to the next project.
Cheers
 
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