Here’s an interesting formula (don’t get bored, it’s not what you think – it’s fun):
Do you know what it is and what it means?
Try this: it's a description of a minivan with automatic doors. Okay, it does look a bit strange, but it is short and to the point. Here’s the long version:
Automatic Rear Doors = ((rear track + rear wheels)+(chain drive+pawl+gears)*electronics package)
Admittedly, the shorter version is more fun to write up, but the longer version is a lot more descriptive as it shows how the automatic rear doors on a minivan work.
Normally, the hefty sliding back doors have tracks above and below the door. They also have a set of wheels that run on those tracks. To operate them, all you have to do is pull the handle and yank to door toward the rear.
How automatic minivan doors work
Automatic rear doors are far more convenient, especially for small drivers, as they eliminate the need to pull the massive doors that are often barely manageable if you are short. Instead, the driver just presses a dash-mounted activator button (there is one on each side) that sends signals to the minivan control module (computer) that determines whether you are opening the right or left door. The door or doors then begin moving toward the rear without further involvement by the driver.
Automatically, the doors, following the contours of the upper and lower tracks, move backward and somewhat outward from the body, until they seat at their full extent. For this to happen, the activation signal turns on a drive motor for the chain drive that is used to pull the doors open. A pawl on the drive chain grabs and locks on a gear (there is a row of gears unseen on the bottom of an automatic rear door). Once it is locked on, the drive chain and pawl pull the back doors open. The process works in reverse to close.