Abstract: An automatic door opener (10) for opening or closing a door (28) includes a motor (14) driving a drive shaft (50) and an opener arm (18) connected to the door (28) and being responsive to rotation of the drive shaft (50) for moving the door (28) to an open or closed position. A clutch (46) operable to disengage the drive shaft (50) from the opener arm (18) is provided in the event of the door (28) engaging an obstacle, electric power being unavailable, or the door being fully open or fully closed. The door opener (10) may also include a brake (48) for selectively preventing movement of the door (28). Various embodiments of the invention are provided, including an electromagnet (80) and an electromagnetic brake (114).

Abstract: An automatic door opener (10) for opening or closing a door (28) includes a motor (14) driving a drive shaft (50) and an opener arm (18) connected to the door (28) and being responsive to rotation of the drive shaft (50) for moving the door (28) to an open or closed position. A clutch (46) operable to disengage the drive shaft (50) from the opener arm (18) is provided in the event of the door (28) engaging an obstacle, electric power being unavailable, or the door being fully open or fully closed. The door opener (10) may also include a brake (48) for selectively preventing movement of the door (28). Various embodiments of the invention are provided, including an electromagnetic clutch (80) and an electromagnetic brake (114).

Abstract: In an automatic wire cutting machine a stepper motor driven knurled roller is positioned between two wire guide channels to drive a wire toward a cutting station. The length of wire to be cut is set in a length counter. Drive cycles, during which the wire is driven a predetermined distance, are counted in the length counter. Then, the stepping motor is disabled and cutting blade is energized. This system prevents operation of the cutting blade solenoid at less than an acceptable duty cycle with short lengths of wire. Due to the particular displacement of the wire with each step of the stepping motor, the system is readily converted from English to metric units.