Screaming Falcon500 motors

Our team just built the transmissions for our coder bot. We were trying to test our drivetrain code to see if the wheels would spin in the correct direction, but when we tested the drive code, the falcons made a high-pitched beep/scream noise for as long as the motors were set with voltage.

Does anyone know what this could mean, or what makes falcon motors scream?

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That is the sound of the falcons stalling.
You should check if the motors in each gearbox are set to the same direction. Them fighting each other might be what causes the noise


The right side motors are set inverted while the left side motors are not.

Here is the code we have for the drivetrain subsystem

public class Drivetrain extends SubsystemBase {

private MotorController leftFront;

private MotorController leftBack;

private MotorController rightFront;

private MotorController rightBack;

private MotorControllerGroup left;

private MotorControllerGroup right;

private DifferentialDrive drive;

public Drivetrain() {

leftFront = new WPI_TalonFX(1);


leftBack = new WPI_TalonFX(2);


rightFront = new WPI_TalonFX(3);


rightBack = new WPI_TalonFX(4);


left = new MotorControllerGroup(leftFront, leftBack);

right = new MotorControllerGroup(rightFront, rightBack);

drive = new DifferentialDrive(left, right);


public void joystickDrive(XboxController controller, double speed) {

double xSpeed = (controller.getRightTriggerAxis()-controller.getLeftTriggerAxis())*speed;

double zRotation = controller.getRawAxis(Constants.XBOX_LEFT_X_AXIS)*-speed;

drive.arcadeDrive(xSpeed, zRotation);


If it’s not a coding error then it must be a mechanical error.

Check wiring maybe? Make sure the entire robot is red to red and black to black.


You should take a look at the current for all of the motors. Motors fighting each other will show up as high current…

You may have mapped motors wrong; each gearbox has a right and left motor in it, for example. We, um, might have done that Monday… If its sorta easy to pull the bull gear or motors you might want to. That will allow you to see each of the output shafts and confirm rotation and which one is which.

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Also verify that the IDs are correct, you may have one left and one right talon on each gearbox,
In general, following this is helpful, because it ensures each motor individually works before diving into system verification


We actually just tried to spin the wheels manually and they wouldn’t budge at all, so it’s an issue with the construction of the gearbox.

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In the future, please wrap your code blocks in triple backticks (```) for proper formatting.


Thanks for the tip


So I always try to get the team to check out the chassis based on the below procedures. May help for future checkouts

  1. visual check of all wirings
  2. If can, check all can ids of all CAN components
  3. Put chassis on blocks so wheels can turn
  4. manually move all wheels, enough so that each chain link engages all of the sprockets, look for and listen anything out of the ordinary, should have smooth motion throughout, no binding or high resistance
  5. if multiple motors on each side, unhook all but one on each side.
  6. turn on power, make sure all of your speed controllers (and falcon) are lighting up (minus the ones you disconnected)
  7. enable the robot, drive right side forward, make sure right side is moving forward, do the same for the left side (make sure to check this one side at a time), now do backwards, one side at a time
  8. turn off, switch to second set of drive motors, repeat 7, and then the third set if you have 3 motor drive
  9. if all motors check out, then go ahead and connect all motors on drive to verify
  10. take robot off blocks
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check that your screws mounting the falcons are not so long that they go all the way through the housing and bind against the internals of the falcon. most likely your issue if it will not turn by hand


This caused the same issue for us. Switched to 1/2" screws to mount to the gearbox and the problem was solved.


Second this. Sounds like the culprit if you cant turn it by hand.

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This is likely the issue. I’ll check tomorrow.

Thanks as usual Christopher!

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