Remote locking device

A number of pedestrians have been injured at railway crossings recently. The authorities have contracted Razman's Engineering Co to design a remote locking device that can be operated by the station attendant.

The gate is 100 m from the station and not always visible. The attendant needs to know if the gate is open or closed. A light globe must be used to indicate if the gate is open or closed. If the gate is closed the attendant presses a button which locks the gate. Releasing the button opens the gate. Once opened the gate should automatically swing shut.

As the chief engineer of Razman's engineering firm you are asked to draw and construct a model of the remote locking gate.

Below are a few hints on how to go about designing and constructing your model.

On the left is one possible design. Scan the image for hints.

An electromagnet is very handy because it can be turned on and off at the touch of a button. The electromagnet can be used to lift a bolt through a holding device to secure the gate.

Click to see a 120kb movie of how this can work.

Click to see another idea of a lock.

An electromagnet is a perfect device to use to activate the lock. Careful design will produce a very strong magnet at low current. The wire the current the hotter the wire becomes. Lots of looping wire ensures a powerful electromagnet.
Electromagnet Screw eye or loop of wire attached to the gate. An iron nail that is attracted through the screw eye and lock the gate. A holder to keep the nail in place. The gate post. The gate

The lock is designed using an iron nail, a screw eye or a loop of wire. The nail is held in place just under the screw eye. When the electromagnet is activated it is attracted up through the screw eye and locks the gate.

Click to see a 120kb movie of how the electromagnet attracts the nail through the loop of wire.

Extension activity. Every station attendant is issued with a security card that activates the lock. Construct a security card that is used to activate the lock. Click to see how a security card is constructed.
This is only a suggestion and you may have better ideas.
Draw a circuit diagram of the model.
Explain how an electromagnet works.
What is the advantage of using an electromagnet as opposed to a powerful permanent magnet?
When using only one battery as the power source, is it best to connect the lock and the light in a series or parallel circuit? Explain.

The elastic band provides the tension to automatically close the gate. Metal contacts that complete the circuit and cause the light to glow when the gate is shut The light indicating if the gate is open or closed An electromagnet that activates the lock The bolt that is lifted through a screw eye by the electromagnet The gate Click to see another version of this locking device.

Click to see how to make a bell.
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