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What is an Emergency Stop Button?

S. Gonzales
S. Gonzales

An emergency stop button is a button that is used only when the functions of a machine need to be halted immediately. These buttons can be pressed when anything regarding the machine's functions or the operator's surroundings pose a threat to production or safety. They put an end to a machine's current functions, so other machines related to the stopped one might also have to modified when the button is pressed.

As a safety measure, emergency stop buttons are a critical part of potentially dangerous machines that contain electrical circuits. They can be found on gas pumps, saws, mills, cutting devices, and other moving machinery used for industrial purposes, such as conveyor belts. The more complex the machine, the more likely that it will have an emergency stop button. These buttons typically work by cutting off power to the circuit that provides electricity to the machine.

Woman holding a disc
Woman holding a disc

The button is wired into the machine's main and normal circuitry. Once it is pressed, it breaks and opens the circuitry, which, in turn, cuts off the electrical supply and shuts down the machine. The electrical power supply is interrupted and causes the machine to halt its functions immediately.

A standard stop button shouldn't be confused with an emergency one. Stop buttons are usually located next to start buttons and are generally of comparable size to the start button. An emergency button is usually much larger and more obvious, and it's often red. It can be made of metal or plastic and can also come in different forms to suit a particular machine. For example, they can vary in position and release styles; some can require key, push-pull or twist releases. Depending on the size of machine, multiple emergency stop buttons could be found on a single machine.

Operators should be aware that using an emergency stop button can result in the complete shutdown of the machine. Should an operator decide to restart the machine's functions, he or she might have to reset the machine and the stop button manually. After this occurs, the electricity circuit that powers the machine can be closed and restored to full operation.

Discussion Comments

elizabeth23

@Malka- I have been looking into buying treadmills and some had emergency stop buttons like yours. Now that I know they work well, I think I will try out some more of those on my next trip looking at them.

I was told an emergency stop button was important and kind of didn't pay a lot of attention, but you make good points about them and how well yours works.

Malka

@Hawthorne - Your treadmill's emergency stop button is a push button, huh? Wow. No offense, but mine seems a bit more practical.

Rather than any button at all, my treadmill's emergency stop "button" is actually a piece of thin cord (rope type cord, not electrical cord) that attaches to a mechanism inside the treadmill. The other end has a little red plastic clip on it, and clips to my shirt.

If I ever fall or move away far enough to pull the cord, the treadmill comes to an immediate and full stop. I tested this when I first got the treadmill, and it works like a charm!

The cord is long enough to provide some slack, too, so I don't have to fuss about whether I will accidentally pull it all the time. It seems like the ideal way to make a treadmill emergency stop button.

Hawthorne

@liz1103 - In most situations, you're right, an emergency stop button guard is a good idea -- especially when you're dealing with a push button switch rather than a turnkey one or anything. However, there is at least one exception I can think of: emergency stop buttons on exercise equipment.

Take, for example, my treadmill. It has a big red emergency stop button right on the front of the handlebars, and it could easily be accidentally pressed, but I've never had trouble with it. If my treadmill was going too fast for me to handle, though, I sure would be glad it was so accessible.

Monika

@JessicaLynn - Although pulling an emergency stop switch when it isn't an emergency is funny in movies, it's not very funny in real life! In fact, I'm pretty sure there are probably legal penalties for doing such a thing. It's just like pulling a fire alarm when there isn't really a fire!

liz1103

When you are in a setting that uses emergency stop buttons, it can be important to have an emergency stop button guard for each of them. Unintentional or accidental use of the emergency stop buttons can be a problem, especially when complete shutdown of machinery is involved.

In some settings, the emergency stop buttons are installed at normal operator stations. This can make it even easier for these buttons to be accidentally set off.

You don’t want to use a guard that completely blocks the button. But, sometimes rings or something similar around the device can help prevent the button from accidental use. These types of guards can work without preventing the button from being used when it is needed.

Andras

I used to work at a gas station. This was my first exposure to a work environment that has one of those large red emergency stop pushbuttons. I was trained in the proper procedure of how to use the button and what type of situations would require an emergency stop.

Working at a gas station required a lot more attention to safety than I realized before working in one myself. I definitely felt safer knowing that I was able to stop the gas from flowing in case of an emergency.

It was a little nerve wracking to think about, but knowing the emergency procedure eventually became just another part of my role as a gas station clerk.

JessicaLynn

I believe emergency stop switches are also present on trains, or at least they used to be. I know in movies they are often used as a plot device during chase scenes or in comedy.

I actually just watched the Marilyn Monroe movie "Some Like it Hot" for the first time last week. There is a scene in that movie where the emergency stop switch is pulled as part of a comedic device. And it was very funny!

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