Linear Actuator- Help/Legality

Our team is thinking of ordering up this linear actuator and want to ask… Is it a legal part? We have looked at the rule book and still have questions so we thought we would ask the best resource we know of.

Is it legal for competition?
We are looking for FAST actuators. Also does anyone have a source or type they recommend for Fast actuators up to 12".


Thanks and good luck to all teams.

Out of the box this would not be legal as it is using a motor not on the list of allowed motors. However that motor appears to be very similar in size/shape to a CIM. If you could find a way to modify to accept a CIM instead, I would think this is legal.

Edit: Also note that this model has built in limit switches which appear to be directly connected to the motor leads. This as well is not legal and would need to be modified so as the only thing controlling the motor is the speed controller it is attached to.

AndyMark sells the DART actuators, and armabot sells one too. I would be hesitant with this actuator because the motor that drives it is probably not one of the FRC legal motors. Both the DARTS and the Armabots designed around already legal motors.

Dart Linear Actuators:

Also before this Thread blows up like every other point on the topic… My team is thinking of using this strategy as-well but in the Manual it is still too vague with R24 and the bumperzone with lifting your self up the Q/A will solve this topic once and for all

One compliant I have about DARTs is that we had major reliability issues with them in 2016. This was greatly our fault due to having a heavy arm and not having a lot of room to position the actuators in a good spot, but it seemed to be every match or 2 we would have to pull the actuators apart, regrease, clean, new bearings and more. At STL, we replaced the bearings on the bottom with massive bearings (And new plates to fit them) and iirc, never touched those actuators once that event.

If you use DARTs, plan to modify them imho.

WE have the Dart and like it for other uses but for what we want it is WAY too slow for what we want to do with this game.

We are looking for some linear actuators that have legal motors if at all possible or maybe a way to increase a Dart’s speed.

Thanks for your time and suggestions

There are different gear ratios that you can use
2:1 Ratio is 163.4 lbf in 6.67in per/sec theoretically
1:1 Ratio is 81.7 lbf at 13.3 in/s theoretically

Worth noting that while this actuator is not legal out of the box, if you were able to find a different actuator that is designed for automotive use (IE, MiniVan automatic trunk door actuators), that likely would be legal under the “Automotive Motors” category of the allowed motor list (providing the rules are followed regarding internal limit switches, as mentioned above).

Does anyone know if we can use the andymark linear actuator attached to the servo?
It is just more in the price range for my team. Or will it be really slow anyways. Also I was confused about the use of linear actuators because of the rule “Electrical solenoid actuators, no greater than 1 in. (nominal) stroke and rated electrical input power no greater than 10 watts (W) continuous duty at 12 volts (VDC)” but I guess these aren’t solenoids so the motor just has to be legal?

No, it is not legal as it is. The problem is the motor - it’s not on the approved list. It’s possible you could pull the motor off and replace it with a BAG or RS550, but I can’t guarantee that will work without first doing it myself.

Please note that this thread was from 2018, where the motor rules were slightly different - the legal automotive motors part of the rule was fairly broad and vague, and led to some issues, particularly around teams finding linear actuators they thought qualified as automotive motors, but did not. That’s why the rule was updated this year to a specific list of part numbers, none of which are part of a linear actuator.

Your best bet is to use one of the linear servo’s or DART actuators from AndyMark, depending on your exact needs.

Actually, I’m certain that the item linked by @nikkiregimbal1 is legal for 2019 - as it is an example of an item further down table 10-1:

PWM COTS servos with a retail cost < $75.

Wow, I would have sworn that was linked out to an Amazon item.

The Andymark servo is legal.

1 Like