Poka Yokes

An envelope

The bottom section of this proxy ballot has important instruction. The instructions are perforated for easy removal. The mistake proofing comes in when you try to fit the ballot in the envelope.

It does not fit. When you remove the perforated section, final instructions are in your hands. Your attention has been managed through design.

Faucets When pipes are likely to freeze, the

common practice is to open faucets slightly and let them drip. If you’re not home or just forget to leave the faucets dripping, you can cause significant damage to pipes and property.

This device automatically opens a valve that discharges just enough water to avoid pipes freezing. Actuation is accomplished without using an external power source. When pipes are likely to freeze, the common practice is to open faucets slightly and let them drip. If you’re not home or just forget to leave the faucets dripping, you can cause significant damage to pipes and property.

This device automatically opens a valve that discharges just enough water to avoid pipes freezing. Actuation is accomplished without using an external power source.

3.5 inch diskette

3.5 inch diskette cannot be inserted unless diskette is oriented correctly. This is as far as a disk can be inserted upside-down.

The beveled corner of the diskette pushes a stop in the disk drive out of the way allowing the diskette to be inserted. This feature, along with the fact that the diskette is not square, prohibit incorrect orientation.

Automobile

Automobile controls have a mistake-proofing device to insure that the key is in the on position before allowing the driver to shift out of park. The keys cannot be removed until the car is in park.

Electronic door locks

Electronic door locks can have three mistake-proofing devices:

insures that no door is left unlocked.

doors automatically lock when the car exceeds 18 miles an hour.

lock won't operate when door is open and the engine is running.

Bathroom sinks

Even bathroom sinks have a mistake-proofing device. It is the little hole near the top of the sink that helps prevent overflows.

An iron

This iron turns off automatically when it is left unattended or when it is returned to its holder.

The dryer

The dryer stops operating when the door is opened, which prevents injuries.

Parking garages

Parking garages have low clearance. To insure that cars entering the garage will fit, garages are fitted with a go/no-go gauge at the entrance. Hitting the swinging sign or pipe will not damage the vehicle as much as driving into a concrete beam

Deep water submarine

The bathyscaph is a deep water submarine used to explore the very lowest parts of the ocean. It is electrically powered. Once at the bottom, if the batteries or electrical system fail the best outcome would be for the sub to return to the surface. The designers made this outcome occur by holding the ballast in place with electromagnets. When power is lost, the ballast drops off automatically and the sub starts its ascent.