I have a sliding gate installed on my compound wall. I want to control the gate opening/closing with a motor. I have the electronic circuitry to control motor start/stop. I m thinking about attaching rack on the gate and pinion on the motor to achieve this. But the gate should be able to open/close manually in case of a power failure and I don't think this is possible with a gear motor. I have been searching for some mechanism to achieve this and I found planetary gear system. Does this solve my issue or is there any other mechanism to achieve the same?
As long as you're able to lock one of the planetary elements while the motor is powered that solves your problem but that doesn't seem like the most efficient solution. I would try an electromagnetic clutch between the motor and the pinion. When you have power, the clutch is engaged and the motor can turn the pinion. When you lose power, the clutch disengages and you can manually turn the pinion with a crank or equivalent.