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I would like to control the locking of a gear, using a solenoid. My original idea was to simply activate the solenoid to pull back the lock (a tooth that sticks into the gear), but that means that I'd need to keep applying current to the solenoid as long as I want the gear unlocked.

Now, I'm thinking it would be better to have a mechanism between the solenoid and the gear, so that a pulse to the solenoid would unlock the gear, and another pulse would lock it. Kind of like the mechanism in a click type pen. What would be a good choice of mechanism to accomplish this, considering how solenoids have a very short stroke distance?

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  • $\begingroup$ What exactly is the purpose locking the gear? $\endgroup$ – GisMofx Jan 8 '16 at 14:59
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    $\begingroup$ I want to hold a load without continually powering a stepper motor. I'd stop the motor (with power), apply the break to the non-moving gear, then turn off power to the motor, so calling this a "break" might be misleading. I realize that I could simply use a solenoid, and depending on whether I plan to have the motor moving more of the time or holding more of the time, the I'd either be activating the solenoid to brake or using the solenoid's spring to brake. Either way, I don't want to need to activate a solenoid for long periods of time, which is why I'm looking for this type of solution. $\endgroup$ – uncaged Jan 8 '16 at 15:28
  • $\begingroup$ do not use gears for such purpose. gear teeth will likely be sheared off. $\endgroup$ – Fennekin Jan 9 '16 at 15:03
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    $\begingroup$ Stepper motors typically hold position when depowered due to the existence of permanent pole pieces. Will that suffice? $\endgroup$ – Carl Witthoft Jan 11 '16 at 13:42
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    $\begingroup$ Unfortunately, the non-powered holding strength won't suffice, but thank you for mentioning it. $\endgroup$ – uncaged Jan 12 '16 at 15:51
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I wouldn't suggest putting objects into gear teeth if the object engages the teeth while a motor is powering the gear, the gear will likely be damaged. If there is compressed air available, I would suggest a solenoid valve operated air cylinder pushing a brake pad against a rotating shaft. Also, electric brakes are available: http://www.mcmaster.com/#brakes/=10l6j16

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    $\begingroup$ I should have made it clear that the "break" wouldn't stop motion, but will only be applied to hold the load after the stepper motor stops, so that after the break is applied, power can be removed from the stepper motor. $\endgroup$ – uncaged Jan 8 '16 at 15:33
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Your toggle design has the disadvantage that the same input from the controller both locks and unlocks the gear. This can be problematic if the state of the lock is not what the controller thinks it is.

Instead using an actuator that remains in position you can move it forward to lock and backwards to unlock. Whether the locking mechanism is a brake pad or a pawl that meshes with the gear is irrelevant to this.

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    $\begingroup$ The controller will remember. That isn't a problem. I've thought of using a linear actuator (screw type), but I'd like it to work faster. The solenoid would accomplish this, but I don't want to need to keep powering a solenoid for such a long time. $\endgroup$ – uncaged Jan 8 '16 at 15:31

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