krokodyl

I tried the throttle trim many times, it works aslong as i don't use brakes. I NEED BRAKES!!!!!!!!!!!!!!!!!!!!! this wont work. I need a way to stop my engine when it's to far away for me to pinch the fuel line. Is there any other options apart from the kill switch? Any help would be appreciated. Thank you.

loopdeeloop

My Feedback: (4)

If every time you apply the brake it kills the engine then this is a really dumb car/radio setup. Even relatively inexpensive radios today are programmable giving you some adjustability. Let's tackle this from another perspective. If brake application and force is adjustable, why can't you back out the idle stop screw and set up the engine idle speed using the throttle trim and then set up the brake for full on at engine idle. Maximum braking occurs with the engine idling. Again, you kill the engine by reducing trim. Our gasser airplane engines have throttle stop screws also. Some folks use them to adjust idle and others (including me) do not. It is far to simple to do it on the radio.

loopdeeloop

My Feedback: (4)

If you are implying that you are using the dead engine to help with braking, then we are wasting time. If braking application and force is not adjustable mechanically or via radio programming in your setup then I'm wasting my time. In your current setup, if you are worried about killing the engine for whatever reason, why not apply the brakes. Isn't that what your current setup does? If you are worried about a runaway due to radio glitch or loss of signal, then nothing you do short of programming "fail safe" will help you.

krokodyl

my current setup does this but i can simply change it in a second by opening the idle screw and putting the trim back to normal. I guess your right about the fail safe, I'm going to buy a kill switch instead of a fail safe, it's more expensive but a fail safe doesn't help in a mechanical problem whitch causes a runaway. Thanks anyway.

Big Alice

I give up. You need to look at how cars are set up.

dalolyn

My Feedback: (7)

Cars are set up at idle with the set screw. They also have a pretty strong spring pulling it back. push the trigger forward and the brakes are applied and the engine throttle rests against the set
screw at idle. Otherwise the engine would die every time you hit the brakes.

Airplanes or mine anyway are set up at fast idle with trim tap all the up, good low Idle at half trim, and kills the engine all the way back.

Barracuz

Maybe if OP posted some info on his truck we could pinpoint a solution.


Also kill switches won't work on a nitro. Or any other vehicle to be honest. Once the engine is killed the car will still roll to death.

loopdeeloop

My Feedback: (4)

So you have a runaway due to a radio glitch. Just how is this kill switch going to be activated. The radio is not working -- hence neither will the kill switch. And just so you know, nothing kills a nitro engine except lack of fuel and/or air. That can only be achieved by closing the throttle barrel completely or by some other means you shut off the fuel supply. I suspect you've had some runaway issues in the past and that points to the need for some new radio gear or at least an attempt to determine what's going wrong.

loopdeeloop

My Feedback: (4)

Airplane gasser engines also have a factory return spring on the throttle. Again, some folks use them as a safety device and others do not relying on a kill switch to kill the ignition. That spring is being worked against by a fairly strong servo in your car is it not? That spring is there for safety purposes only and has nothing to do with braking. It's sole purpose is to return the throttle should the linkage come undone. With that in mind, Since the job of the throttle servo is to modulate the throttle, it doesn't matter if that spring is working or not, nor does it matter if the throttle stop screw is made inactive -- provided you set the idle speed with trim rather than that stop screw. The throttle servo will stop its travel wherever the throttle trigger is or wherever the trim is set. That stop screw is strictly a mechanical limit. You can accomplish the same thing with trim and kill the engine with trim as well. Try this -- start the engine and place it on a test box of fixture. Advance the trim to anything above what the normal idle is. Now back out the idle stop screw and run the trim back down to what the idle speed the idle stop screw provided. . Now back off the trim fully. Engine stops doesn't it. Rev the engine and then chop the throttle applying the brakes. When you push the trigger to apply the brakes does not the servo go back to idle? Unless you changed the trim setting the engine should not die. How the centrifugal clutch reacts to sudden braking can have an effect on how the engine reacts and that would have to be played with but if it's not a problem otherwise it should not be a problem here. Nothing is really changed except how idle is determined.

As was suggested, the OP needs to tell us what transmitter he has, what car, and what engine and what the actual setup is.. There are as many setups as there are fleas on a dog. We may be chasing our tails here trying to fix a non-problem
I'm done with this unless the OP gets a little more involved.

dalolyn

My Feedback: (7)

That was a good one . Fleas on a dog. So true

SyCo_VeNoM

Nope won't do a damn thing to the motor my Savage X has a kill button(HPI option part) which pushes a piece of plastic into the flywheel, It does absolutely 0 damage to the motor.
I also usually carry a small piece of plastic when running my nitro buggy that I push into the fly wheel to stop it.

But yes as I said a fairly beefy servo would be needed probably as high of torque as made.

Also why I said for him to get a throttle return spring, and be done with it as its the only real practical solution.
Basically what he is asking for is not practical.

SyCo_VeNoM

yea some flyboys really need to get their head out of the clouds, and look at what they comment on.

Big Alice

To the op. That bumble bee fuel thingy says it's triggered by radio glitch, loss of power, loss of signal, or you can just turn your radio off. Any of those will turn your fuel off. I know some pretty smart people who swear by them so they must work as advertised. It's just another layer of security for your peace of mind. If you think you need it, put it on there. If you don't, don't. I just have a return spring on my nitros. some people want more.

1QwkSport2.5r

Here is what I consider a "normal" throttle/brake linkage on a RC truck. This is one of my LST2's. Servo pulls throttle and brake linkage goes slack; when servo pulls brake linkage, throttle is spring loaded against the throttle stop. Using throttle trim and inactivating the idle stop will kill the engine with this setup.

krokodyl

As far as i know, the kill switch is the only way to stop a car runaway that happened due to a mechanical problem in the engine, like in my first runaway. Also another question, It might be stupid but what does engine rev mean? nobody ever told me and the manual is garbage

1QwkSport2.5r

Engine revving is just that. Throttling up which causes the engine to rev up.

Anthoop

What an entertaining thread.

For a car I use a failsafe and a throttle return spring that will overcome a powerless servo...so if the car loses signal or if it loses electrical power then the engine will return to idle speed (by way of the failsafe brakes are applied also).
If the throttle/brake servo should seize/lock then I still can control the steering...

I check the operation of the failsafe before starting the engine and ensure that my batteries are charged and connections are good...and use the idle screw to control the minimum throttle gap.

Barracuz

Ok first a kill switch is meant to interrupt power to an electrical circuit. YOU CAN NOT KILL A GLOW ENGINE USING A KILL SWITCH! So no more talk about this kill switch you want to use. Glow engines work using glow ignition. Basically a heated wire that stays heated by the chemical reaction it has with the fuel. The only ways to kill or stop a glow engine are blocking the carb intake, pinching the fuel lines, plugging the exhaust, pulling the glow plug, Syco's idea of jamming jamming something in the flywheel like how HPI does and grabbing a 5lb mallet and whacking the engine with it.

So a kill switch will prove useless on the engine. But it could be used on a servo. But take note that when you kill power to a servo the servo will stay in its last position when it last had current. If you kill power to a servo while it's in a wide open throttle position then it will stay in the wide open throttle position.

Now you want to stop a vehicle if and whenever an engine malfunction occurs right? Well if the engine dies, you're radio will not be affected by it. In other words all you have to do stop it is hit the brakes. Also even if you purposely killed you're engine while the car is in motion, you're car will continue to roll away till it loses momentum or you hit the brakes.

That's all I can think of. I don't see how an engine malfunction would make you're car runaway. Unless you're carb jams up in the WOT position, either way you could always hit the brakes and with the engine still connected to the drive train that could kill it.

You must have a radio problem. Use a failsafe. If you get a radio glitch or low voltage to the circuit it's connected to, the failsafe will instantly put the servo in a set position you program. Which in most cases is the brake/throttle servo set to brake and closed throttle

You need to gives us details. I have no idea what you're trying to accomplish, what led to you runaway issue, and what your car is. I need the beans man, now spill em.

p51Dpony

lots of good ideas, some of mine are:
the throttle servo is also the brake servo, typical set ups have a "servo-saver" which is spring that allows overdrive of the function/allows pushrod to go past the controls endpoint without 'bottoming out' the servo. endpoints are adjustable. you can set up "full reverse" throttle trigger position on transmitter to give full brakes and good idle, and engine will kill if you also add full down/idle trim. many persons have alluded to this, it is all in the fine adjustments of the throttle trim and the servo savers (they are adjustable!)
this aforementioned scenario allows any simple non-programmable radio to accomplish what we are asking.

fuel line pinch is not good, too long a lag for engine to stop.... the runaway car has plenty of time to hit the curb 40 yds away and tear the front end off....

ramming parts into the flywheel, not always consistent, if your operating in cold weather plastic parts will break and/or become projectiles in bystander's eyes, which is frowned upon.

closing the carb all the way doesn't neccesarily shut off your engine, many/most engines have the airbleed screw that adjust idle air for carb full-closed position, but this is adjustable when present.

I had an airplane once that needed 'instant off' and this acclomplished by a servo operated pushrod that had clevis the grabbed the fuel line and pulled it off engine nipple if activated, worked good and consistent after some tweaking. alas.... required a dedicated servo so no good here

A neat technological advance, that doesn't exist but neat to consider, would be neat if engine was made w a "decompression switch/valve" so when activated compression was lost and engine would shut off. I have a chainsaw that has a decompression switch that is used to lower compression so you can pull the pull start to get it going(is a bigger engine), once pressure builts switch quickly pops back closed so engine runs. .... but a variation would be a switch like this to activate and decompress engine to shut it off... evolve this idea fellow engine enthusiasts.

the best all around fix though that is the most commonly used is you radio fail safe, that's what its for, AND most runaways are probably radio signal issues (forgot to put transmitter ant up.... car antenna was cut and too short or wasn't stretched out but instead was all coiled up, oh, and lets don't forget WEAK OR DEAD BATTERIES!. So attention to these little things is critical.

p51Dpony

and one more radio malfunction area: water shorting out wires, cars get way more water exposure than planes, almost as much as boats, and maybe a little less than subs.... but water will definitely cause issues serious enough that radio failsafe may not even work once a servo short out from water...

SyCo_VeNoM

Don't think that was necessary as if you don't believe it here look at this http://www.hpiracing.com/en/part/85068 its a hookup for the Savage that pushes a piece of plastic into the flywheel to stop the engine. No mallets or whacking needed. So its not really according to me what I said was make a version of that for remote throw via servo if he REALLY REALLY wanted it remotely done I never said how practical it would be either.




Well that is actually solvable dip the RX, and failsafe in plastidip(or some other sealant) to seal them , and get a waterproof servo

On2_n_On4

really? dude., please search and read before posting.

http://www.killerrc.com/product/bumb...o-kill-switch/
https://www.youtube.com/watch?v=jvDl0feOA2I
https://www.youtube.com/watch?v=E-BeyR6Tk3Y

ProductDescription

The Killer RC Bumble Bee Nitro Killswitch™ will automatically stop the fuel flow to your nitro engine during: radio glitch/signal loss, low battery, cut wires, or total battery power loss. You can also kill the engine any time you want by pressing the Aux button on your transmitter, or turning off the transmitter power button. No more plugging the exhaust, jamming up the flywheel, or pinching the fuel hose.

Barracuz

Sorry man. Didn't mean to offend or test your credibility. I have reworded that sentence.


You see when I think of a kill switch I automatically think of an electrical shut off. Never heard of that and it's very interesting but seems overpriced for what it does. And it won't do squat to stop a runaway car once it's head on into a curb or any other static object.


OP said he suffered an engine problem and car ran away. An engine kill switch once stop the car. It will stop forward movement but that 10lb block will still travel for a while down the road or wherever.

If OP had an engine runaway which then caused him to crash. Then he must have a carb or servo issue or a radio issue. He can buy a new carb and failsafe and a servo for less than that overpriced "fuel stopper", depending on the car of course.

And even if having that kill switch help stop a runaway engine he would then need to adress the carb, servo, and or radio.

On2_n_On4

It won't do squat to stop it? Did you read the product description??
What else do you need to stop it? If a servo goes dead just kill the engine from your radio.... as we all do on our 1/5 scale gas cars.

On2_n_On4

By the way., I rather pay 60 than paying someone else's property or hospital bills.... nothing is cheap in RC.