I'm looking here for suggestions.

I have a HS-805BB with Torque (Kg-cm/Oz-in): 24.7/343 @ 6.0 V to rotate a robot body up and down from one side. It seems to me that this servo is always running at its maximum torque which is not good for its life span and battery consumption, so I thought of two solutions:

  1. Install a second servo on the other side and have both servos working parallel.
  2. Build a gear box to increase the Torque limits.

What are you suggestions as to which option is most preferable?


Installing a second servo for moving the same axis might be problematic from a controls point ofview. Since (I assume) your servos are position controlled (and not torque controlled) delays in commanding them and mechanical toleraces of the assembly may lead to sitations where the two servos act agains each other at the beginning or at the end of motions (maybe even during). E.g. fits servo recieves a command to pull, starts pulling, the other one recieves the same signal a few ms later, until then the first one is actingagainst the second one.

If you have rpm reserves, installing a gearbox would be a good solution.

You can also install some kind of ballancing (e.g. preload with a spring) or counterweight mechanism is your application allows this (e.g. elevator have counterweights, robots have springs sometime in the lowes joint agting against gravity).

  • $\begingroup$ Using springs as mechanical energy suppliers was an idea I had previously but fitting it on my actual design was a bit of challenge to me with my lack of experience in robotic design. My concern with the gearbox option is that it will limit the max rotation the robot will have. $\endgroup$
    – Iron Fist
    Mar 26 '18 at 8:12
  • 1
    $\begingroup$ When considering springs, don't forget about torsional springs. They can be mounted right on the axis of rotation, and finding the space for them can often be a lot easier than for linear springs. $\endgroup$
    – SteveO
    Mar 26 '18 at 13:37

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