Warning: preg_replace(): The /e modifier is deprecated, use preg_replace_callback instead in ..../includes/class_bbcode.php on line 2968
Length of servo horn
Results 1 to 8 of 8

Thread: Length of servo horn

  1. #1
    President JSLICK's Avatar
    Join Date
    Apr 2010
    Location
    Stowe, Pa
    Posts
    3,624
    Post Thanks / Like
    Rep Power
    10

    Length of servo horn

    Just got the rcbros ota steeting and I was wondering if i should go with a long horn or a short one? the pic on the site shows a shorter horn. If I use a longer horn won't I get more throw from the servo?
    EPARCCrawlers President

    2010 1.9 Inaugural Champion
    2011 Class 2 Scale Season Champion
    2012 Club Champion 1.9, 2.2, Class 1, Class 2
    2013 Class 2 Scale Season Champion
    2014 East Coast G6 1.9 Driver of the Day


    TEAM DRIVER
    LOCKED UP RC
    - SCALE PERFORMANCE PARTS -

    TEAM DRIVER
    OTTSIX

    TEAM DRIVER
    Purpmart Specialist

    TEAM DRIVER
    CREATIONFAB Web Wheeler


  2. #2
    Administrator brazwewn's Avatar
    Join Date
    Apr 2010
    Location
    Alburtis, PA
    Posts
    3,240
    Post Thanks / Like
    Rep Power
    10

    Re: Length of servo horn

    More throw and more force, due to a longer lever arm. The question is, do you have enough room to use a longer one.

    Wes

    Quote Originally Posted by jslick
    Just got the rcbros ota steeting and I was wondering if i should go with a long horn or a short one? the pic on the site shows a shorter horn. If I use a longer horn won't I get more throw from the servo?

  3. #3
    Paid Website Supporter Gimp's Avatar
    Join Date
    Apr 2010
    Location
    Lansdale (Home) & Harrisburg (School)
    Posts
    767
    Post Thanks / Like
    Rep Power
    12

    Re: Length of servo horn

    Quote Originally Posted by brazwewn
    More throw and more force, due to a longer lever arm. The question is, do you have enough room to use a longer one.

    Wes

    Quote Originally Posted by jslick
    Just got the rcbros ota steeting and I was wondering if i should go with a long horn or a short one? the pic on the site shows a shorter horn. If I use a longer horn won't I get more throw from the servo?
    Actually, this is something alot of people don't understand. You want a short servo arm with a longer knuckle arm.

    Think about it this way, your rig is almost vertical and leaning one way. That long servo arm make it easier for the weight of the truck to rotate your servo (without you doing anything).

    This has been covered over on RCCrawler quite a few times. I'm also going to school for Mechanical Engineering, and after taking statics courses and doing alot of free-body-diagrams on forces, it all makes perfect sense. But if you just think about it carefully, you'll understand.

    Wes has the right idea, just backwards. The longer arm will allow more torque to be applied to the SERVO, not the servo to the knuckle "moment arm"

  4. #4
    Paid Website Supporter Gimp's Avatar
    Join Date
    Apr 2010
    Location
    Lansdale (Home) & Harrisburg (School)
    Posts
    767
    Post Thanks / Like
    Rep Power
    12

    Re: Length of servo horn

    Found the article. Explains it a little clearer than me lol
    http://www.rccrawler.com/strongsteering.html

  5. #5
    President JSLICK's Avatar
    Join Date
    Apr 2010
    Location
    Stowe, Pa
    Posts
    3,624
    Post Thanks / Like
    Rep Power
    10

    Re: Length of servo horn

    Thanks Gimp, I guess the next thing is to get better knuckles on the LCC.
    EPARCCrawlers President

    2010 1.9 Inaugural Champion
    2011 Class 2 Scale Season Champion
    2012 Club Champion 1.9, 2.2, Class 1, Class 2
    2013 Class 2 Scale Season Champion
    2014 East Coast G6 1.9 Driver of the Day


    TEAM DRIVER
    LOCKED UP RC
    - SCALE PERFORMANCE PARTS -

    TEAM DRIVER
    OTTSIX

    TEAM DRIVER
    Purpmart Specialist

    TEAM DRIVER
    CREATIONFAB Web Wheeler


  6. #6
    Administrator brazwewn's Avatar
    Join Date
    Apr 2010
    Location
    Alburtis, PA
    Posts
    3,240
    Post Thanks / Like
    Rep Power
    10

    Re: Length of servo horn

    Makes sense when you take more than a second to think it through. I guess it has been way to long since my Statics class.

    Wes

  7. #7
    Administrator brazwewn's Avatar
    Join Date
    Apr 2010
    Location
    Alburtis, PA
    Posts
    3,240
    Post Thanks / Like
    Rep Power
    10

    Re: Length of servo horn

    Always up for learning and trying new things. So, I dug thru my tool kit and found an old servo horn with the hole drilled closer to the mounting screw, for my Jeep. It is not by much, but I think this is as short I can get with still having full travel on my steering. I already have the Vanquish knuckles on both rigs.

    After I made sure it would work, I started to realize that if the knuckle arm being longer allows for more torque, which I get. The inverse should hold true for the servo horn. In other words by shortening the servo horn you reduce the amount of force the tires can transmit back into the servo. If my assumption is correct (this would be where the resident engineer in training steps in) than it is a win win.

    Shorter servo horn increases the force the servo can exert to turning the tires. It also reduces the amount of force the tires can exert on the servo "breaking the servo". Longer knuckle increases the moment arm and allows for more force on the tires from the servo. It also reduces the amount the tires can force on the servo, same concept of before.

    I am not sure if I was just wishing a difference, but it felt a little harder to turn the servo with the tires after I shortened the horn mount. One more cool thing to add to the old brain bucket.

    Wes

  8. #8
    Paid Website Supporter Gimp's Avatar
    Join Date
    Apr 2010
    Location
    Lansdale (Home) & Harrisburg (School)
    Posts
    767
    Post Thanks / Like
    Rep Power
    12

    Re: Length of servo horn

    Quote Originally Posted by brazwewn
    Always up for learning and trying new things. So, I dug thru my tool kit and found an old servo horn with the hole drilled closer to the mounting screw, for my Jeep. It is not by much, but I think this is as short I can get with still having full travel on my steering. I already have the Vanquish knuckles on both rigs.

    After I made sure it would work, I started to realize that if the knuckle arm being longer allows for more torque, which I get. The inverse should hold true for the servo horn. In other words by shortening the servo horn you reduce the amount of force the tires can transmit back into the servo. If my assumption is correct (this would be where the resident engineer in training steps in) than it is a win win.

    Shorter servo horn increases the force the servo can exert to turning the tires. It also reduces the amount of force the tires can exert on the servo "breaking the servo". Longer knuckle increases the moment arm and allows for more force on the tires from the servo. It also reduces the amount the tires can force on the servo, same concept of before.

    I am not sure if I was just wishing a difference, but it felt a little harder to turn the servo with the tires after I shortened the horn mount. One more cool thing to add to the old brain bucket.

    Wes
    Wes, you have it 100% correct. Very nice/simple explanation too. I think everyone needs to read that article because so many people have the right idea about moment arms, but backwards because it's the servo doing the turning, not the wheels.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •