Power Window

Power windows or electric windows are automobile windows which can be raised and lowered by pressing a button or switch, as opposed to using a crank handle. Power windows have become so common that by 2008, some automakers eliminated hand crank windows from all their models.

Power windows have come under some scrutiny after several fatal accidents in which children's necks have become trapped, leading to suffocation. Some designs place the switch in a location on a hand rest where it can be accidentally triggered by a child climbing to place his or her head out of the window. To prevent this, many vehicles feature a driver-controlled lockout switch, preventing rear-seat passengers (usually smaller children) from accidentally triggering the switches. This also prevents children from playing with them and pets riding with their heads out windows from activating the power window switch.

Starting with the 2008 model year, U.S. government regulations required automakers to install safety mechanisms to improve child safety. However, the rules do not prevent all potential injuries to a hand, finger, or even a child's head, if someone deliberately holds the switch when the window is closing. In 2009, the U.S. auto safety administration tentatively decided against requiring all cars to have automatic reversing power windows if they sense an obstruction while closing. Proposed requirements concern automatic ("one-touch up") window systems, but most vehicles with this feature already have automatic-reversing. The federal government made a written contract that all automakers should make the lever switches (as opposed to the rocker and toggle switches) standard on all new vehicles by 1 October 2010.

Power windows are usually inoperable when the car is not running. This is primarily a security feature. It would be a simple thing to allow electric power windows to be operable when the ignition is turned off, however it would also make the car much easier to steal. Some systems offer the compromise of leaving power applied to the windows until a passenger door is opened at which time the window power is removed.

Hydraulic drive systems could lower the windows at rest, since pressure from the hydraulic system was merely released to lower the window. Raising the windows required an electrically operated pump to operate and introduce pressure at the appropriate cylinder. These systems also required pressure lines to each cylinder (in the doors, as well as on certain cars, to the power seat and a power operated convertible top). Because of the complexity, the system could also leak fluid.