An electrical switch and leaver is provided which when operated energises the solenoid valve to allow the air to enter the pilot chamber. This changes the position of the spool, which allows the air pressure to enter the cylinder chamber either to open or to close the door. The switch may be near the driver, or near the doors, or at both places.

In order to avoid banging of the door cushioning is provided at both ends. The speed of closing & opening the door can be adjusted as desired so that a smooth operation of the door is achieved.