On 08/01/2020 17:05, Dave Plowman (News) wrote:
In article ,
Fredxx wrote:
cheap chinese motors used in e.g. car window winders are deliberately
pants to that they can be stalled without burning out wires or fuses.

Car window winders are an especially bad example. They use load sensors
to ensure nothing is trapped, such as a child's arm, in the window.

Interesting. Never come across that. How do they work? And why fit a motor
so powerful it could do an arm damage? Most are easily stopped by hand.

An arm is not a problem, a neck is. It takes very little pressure to
stop either breathing or cut off blood to the brain. Children have died
that way, which is why load sensors were added.

A reasonably powerful motor is required, because otherwise you could be
unable to open it (or worse, close it) as the car ages and the mechanism
stiffens or when there is ice on the doors. A 90's Cavalier used to have
an override button on the centre console to temporarily disable the load
sensors for this. These days repressing the button a few times does the
same for some vehicles.

It is likely that the reason that you can easily stop a window, is
because it is sensing too much load and stopping - some actually reverse
a short distance as well.

SteveW