How a washing machine door interlock with time delay works. (not a wax motor)

Like most of the components used in home washing machines the door locking mechanism is ultra cost optimised and refined for cheap and easy manufacture. Yet it performs three separate functions. Locking the door, enabling the machine when the door is fully locked and unlocking the door after a time delay to allow a spinning drum to come to a halt before it can be opened.

This particular lock is used in many European machines including Hotpoint and Indesit.

On the basis that these assemblies are mass produced I suppose it makes it viable to use them in other applications where you need the same interlock and time delay feature. The use of a PTC heater probably means that the mechanism can accommodate a wide voltage range.

Failure of these door locks is fairly common, especially if an attempt has been made to force a door open prematurely. They're fairly straightforward to change if you're technically inclined. Some may just require removal of the top of the machine, but some may require removal of the front too, sometimes including the sealing ring which is often held in place by a spring tensioned wire.

If attempting to replace a lock then make sure you get the exact replacement for your machine's brand and model number. Also make VERY sure the machine is unplugged before attempting a repair. Traditionally washing machines were a significant cause of electrical accidents because they are an essential item in the home and can cost quite a lot to have repaired, which encouraged DIY attempts. The older machines had a lot of exposed live metal components in them due to greater mechanical complexity than modern units and cost-optimised nature of the design. Add the fact that you are reaching into a cramped metal case with wet hands and repairs posed a major electrocution risk to the unwary. Especially when the power was repeatedly turned on and off during testing and then accidentally left on.
Modern machines are much more sparse inside, but still pose a significant shock hazard due to the fact that you're reaching in amongst grounded metalwork in a wet environment.

Modern machines are very modular, so if you are technically inclined and use common sense then you can often repair them yourself with components easily sourced online.

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