Power windows are ones that use an electric system in order to raise of lower windows on a car. They have entirely replaced manual crank handle mechanisms on modern cars.
Before electric power windows, the Chrysler Corporation installed windows that could be operated without human effort in the 1930s. These systems were vacuum operated and produced by for Plymouth convertibles.
The first cars to be installed with power windows were Packard 180s in 1941. They used a hydro-electric system to operate.
In the same year, the Ford motor company installed their first power windows in the limousine and seven passenger sedan versions of the famous Lincoln Customs. At the time, their design must have felt like magic to drivers accustomed to crank handle systems.
Also, in 1941, Cadillacs were installed with power windows but only for the divider window between front and back. Here is where the typical scenes in Hollywood originate from; passengers in the back would raise the power window so that the driver could not hear what they were talking about. Obviously, at this time, it was only the rich and powerful that could afford such vehicles. In turn, such people found it very convenient that they could have private conversations in transit without the fear of an eavesdropping driver.
How do they work?
Power windows will only work when the ignition is on. In early models, power windows could operate even when the car was stationary, and the ignition was not engaged. However, this made them a lot easier to steal. In order to ensure that windows could only be operated by a car owner, they were disabled unless the ignition was engaged.
Power windows in modern cars:
In most modern cars, power windows can be used for a limited time after the car has been switched off. This is convenient because drivers often forget that the windows are open and have to re-engage the ignition in order to close them. Once the door is opened, this feature is also disabled.
Hydraulic drive system of early power windows:
The hydraulic drive systems of early power windows relied upon the release of pressure to lower the window. In order to raise the window, an electrical pump was needed to reintroduce the pressure at the point of the appropriate cylinder. Pressure lines to each cylinder, nestled inside the doors, were also needed. Coincidentally, the same hydraulic system could be used to raise and lower the roof of a convertible. These systems were replaced, however, because they were often unreliable due to their complexity. This meant fluid leaks were common.
Express down features in power windows:
In the 1980s, express-down features were added to power windows so that one press of a button could completely lower a window. No longer did the button need to be held down for the entire duration. In the 1990s luxury vehicles, particularly BMWs, Mercedes and Chryslers, introduced the express up feature as well. In most modern cars these features have become commonplace. Furthermore, controls are no longer confined to the driver. All passengers are able to operate their own power windows.
All latest cars have power windows now:
By 2009, all cars began being manufactured by power window systems. The last car to be manufactured with hand-crank windows was the Audi RS4 but they were only for the back-passenger windows.
Interestingly, younger drivers no longer understand the common hand signal inspired by the hand crank meaning that one should lower their windows to talk.
Safety features of power windows:
Power windows have caused many injuries in the past because their powerful hydraulic action can easily trap fingers, hands or even necks. For instance, a child may try to clamber up the door in order to get a better view out of the window and inadvertently push the button to raise the window. Unfortunately, there have been some fatal accidents as a result of this.
In reaction, most cars are now fitted with master controls on the driver door so that they can disable the buttons for passengers. These child locks make power windows much safer.
The newest safety features on power windows have sensors that notice when there is an obstruction and automatically reverse motion. Such advancements have been inspired reactionarily as a result of injury and, in many countries, have become regulatory law in the manufacture of cars.