HS-475HB Servo

The Rules allow for an “C. An unlimited number of FIRST Tech Challenge (FTC) servos (HITEC HS-475HB servos).”

On the website, Servocity offers a stock 90 degree rotation for the servos and also a 180 degree and continuous rotation option. I called them to see how this is accomplished, and they told me that resistors are added to change the available rotation.

My question is would these be legal under the rules? I’m afraid that this might count as “modification” or not be concurrent with the FTC servos intention.


You could also use <R51>B, which allows “An unlimited number of COTS servos with a maximum output torque of 55 oz-in and
maximum rotational speed of 100 rpm at 6 Vdc (e.g. HITEC model HS-322HD or HS-325HB servos, as provided in the Kit Of Parts),”

I am sure of this, however: if you use a servo with a different part number than the FTC ones in <R51>C, it had better meet the specs in <R51>B!

I’m not sure if having the rotation shortened is legal, but Q&A can tell you. It is a stock configuration, but still…

Haha, it seems you are looking at this in the same kind of way I am. They are both listed as “HS-475HB Servo” when I go to order from ServoCity, but they do have different product numbers. I don’t know if this is considered lawyering of the rules, but it seems that this is allowed. IMO spirit of the rules is to prevent teams from using something like this.

Just to be on the safe side, Q&A it. I would suspect it would be legal to use any of the three rotations, but you never know. (And, under which part of the rule, B or C.)

I’m also very interested in hearing the answer to this!

It’s a key element of our design, and I just started wondering if it would violate any of the rules about motor or signal mods. Ouch.

The question has already been asked.


So a standard servo that has a limited rotation (or not) is allowed provided that it doesn’t violate <R51-B>.

Ah! You don’t find that searching for “servo”, but you do searching for “servos”.

I’d still like to get a definitive answer on hacking the servo’s internal resistor (which is what the servocity kit does) since it is so integral to our design. Better do it now than in the pits. I’ll post a question in the morning after a night’s sleep.



I would say that if you do the mod yourself, you’re on questionable ground; <R53> bans modifications. However, this is available as a stock configuration. What I would do is go ahead and ask if you can do it yourself. If you can, go for it. If not, get a stock servo with the rotation you’re looking for.