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savage on/off switch question

Discussion in 'HPI Savage' started by bone, Aug 7, 2017.

  1. bone

    bone Member

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    i had a little mishap the other day,,i was jumping a little hill with the savage and i kinda had a bad landing and it clicked the switch to the off position on the truck.. and when that happened the throttle went to full throttle,,lucky it stripped the spur and it landed right by me so i blocked the pipe to kill the motor...i have a pretty strong throttle servo on it,,so I'm not sure if i loose power to the truck how to correct that from happening again...its just kinda strange that when i turn of the power to the truck only the servo still moves to open throttle
     
  2. Jam Racing 1

    Jam Racing 1 NPTB Monitor, Master of the known universe.... HPISF Staff

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    Put a throttle return spring on it, will close the throttle when you lost power....
     
  3. bone

    bone Member

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    isnt it strange that the servo would still move by itself with no power going to it
     
  4. bone

    bone Member

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    if i turn the radio off and leave the truck on,,,the servo puts on the brakes
     
  5. Jam Racing 1

    Jam Racing 1 NPTB Monitor, Master of the known universe.... HPISF Staff

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    most likely vibration causing it to do that
     
  6. bone

    bone Member

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    I'm testing it without the truck running
     
  7. bone

    bone Member

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    i put a return spring on the carb..i turned on the truck and then the radio...everything works fine..with the truck not running and i give it half throttle and turn the truck off like i lost power the servo stays at half throttle...the spring does nothing..you cant even move the servo...the only way the servo moves is if there is a command from the radio
     
  8. Jam Racing 1

    Jam Racing 1 NPTB Monitor, Master of the known universe.... HPISF Staff

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    This is where a failsafe comes into play, if my transmitter loses connection with my receiver it kicks in and applies full brake, in your case the radio must not have one or it is not setup properly, but in any case a return spring is also good insurance for those unwanted things that happen from time to time...

    and as you are doing your "test" you should turn off the switch in the truck and see if it closes your throttle, in both cases I recommend using both a failsafe and return spring on the throttle or else you leave yourself open to a runaway....
     
  9. bone

    bone Member

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    when both radio and truck are on and i turn the truck off like it lost power the servo stays in the position of the last command...it will not move even when i try to move it with my fingers...which i think is strange...but as soon as i turn the truck back on all is good...
     
  10. Jam Racing 1

    Jam Racing 1 NPTB Monitor, Master of the known universe.... HPISF Staff

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    You are right something strange is going on, if I turn off the receiver switch on any of mine it goes to closed position....
     
  11. bone

    bone Member

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    If i turn off the radio and keep the truck on it goes to full brake....i think i need to get rid of the on/off switch
     
  12. olds97_lss

    olds97_lss Well-Known Member

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    If you lose power, the fail safe (FS) won't help you, only the TRS (throttle return spring) will. When power to the receiver is lost, the FS won't be able to send your servos home.

    What servo are you using for t/b? Curious to know which one it is so I don't buy it.

    An electronic fail safe can do 2 things, depending on how it's made. It will go to a preset position when it loses signal from the transmitter and/or when the voltage of the receiver pack drops down to a dangerous level, it will go the previously set position.

    If your FS is built into the receiver, then it will typically go wherever the servos were when you bind the receiver to the transmitter. I set mine when the wheels are steering straight and the throttle is at idle. I never cared to set it to full brake, if it kicks in mid-flight, I wouldn't want the tires to lockup causing it to flip and sending it to it's death.

    If your FS is external, then they usually have a button or something on them that you press when you have your servos where you want them. Then that is where it will go when it loses signal or power power drops.

    I don't know of any built in receiver fail safe's that monitor voltage and engage when needed. I've only had spektrum, and all of those only help if signal is lost. The old micro ofna failsafes I used to use when I ran AM/FM radios would do both, monitor signal and voltage.

    It's strange that your servo locks when power is lost to the receiver. Some are hard to move off power and generally is a bad idea to try due to the strain you put on the gears. But when your vehicle is screaming away from you towards a lake or a person out of control, hurting a servo is the least of your concern.

    Remember though, I don't believe there is a fail safe in existence that will do it's job when power is lost to it or the receiver. It will only work when signal is lost or power is low.
     
  13. bone

    bone Member

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    Great write up...i appreciate it...and after reading about some servos are hard to move without power...thats just what mine does...i can get it to move without power i just have to use more force to get it to move...i just figured it would move easy....its gonna take a pretty strong spring to move this servo...so thanks everyone for your help
     
  14. Grey80

    Grey80 Member

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  15. Grey80

    Grey80 Member

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    Throttle spring . Nothing can help you when that happens . Never had that happen .
     
  16. Grey80

    Grey80 Member

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  17. Grey80

    Grey80 Member

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    You need a servo over 100oz 4 sterring , on eBay they have generic 120 ounce servos for 25 bucks . Guest put hpi savage servo it's black and red . Only 25 bucks not bad
     
  18. bone

    bone Member

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    a few years ago i was jumping hills with my nitro and it hit and turned off the on/off power switch and it was to far away to run to and it stayed on full throttle and blew the engine...this is the second time this happened,,,i just got lucky this time that it was close and it stripped the spur
     
  19. bone

    bone Member

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    Ok...this is the only way i can use a throttle spring with this servo and close the throttle all the way when i turn the truck off only....it works perfect
     

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  20. Jam Racing 1

    Jam Racing 1 NPTB Monitor, Master of the known universe.... HPISF Staff

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  21. bone

    bone Member

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  22. olds97_lss

    olds97_lss Well-Known Member

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    FYI, they connect directly to the carb. The small eyelet goes around the throttle arm on the carb, the large eyelet goes around the high speed needle assembly.

    This is the one on my savage-x:
    [​IMG]

    Then even if the ball end pops off the carb, your covered.
     
  23. bone

    bone Member

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    the spring i had would not work that way..until i get that spring this will work
     
  24. olds97_lss

    olds97_lss Well-Known Member

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    I did something similar on both my revos because the crappy throttle pivot setup that traxxas uses causes the carb to bind too much, so I have to have the TRS on the linkage instead and hope it never pops off.

    [​IMG]
    [​IMG]
     
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