Switch mechanism for door operator

DETAILED DESCRIPTION FIGS.
1 and 2 illustrate therein a motor driven door operator 11 which may be manually or remotely controlled for opening and closing an upwardly acting door 12.
One such door, which is designed for covering an opening 13 defined above a floor 14, is comprised of several horizontally hinged sections having rollers 16 mounted thereon for engagement with side rails 17 for guiding the movement of the door between a substantially vertical closed position and a substantially horizontal open position.
However, the invention can be readily adapted to other types of doors and other patterns of door movement.
The operator 11 includes an elongated horizontal beam 18 defined by a pair of guide rails 19 and 21 between which a carriage 22 is supported for movement lengthwise thereof.
The carriage 22 is pivotally connected to the upper end of an arm 23, which arm at its lower end is connected to the door 12 by means of an intermediate spring box 24.
To permit movement of the carriage 22, the operator 11 includes a reversible electric motor 26 which is drivingly connected by an intermediate belt 27 to an intermediate shaft 28, which in turn is drivingly connected by a chain drive 29 to a main drive shaft 31.
The shaft 31 is rotatably supported by bearings 32 and 33 on a housing 34 which is fixed with respect to the stationary beam 18.
A driving sprocket 36 is fixed to the shaft 31 and is engaged with an elongated chain 37 which is connected at its opposite ends to the opposite ends of a cable 38, which cable extends around a pulley 39 rotatably supported upon the front end of the beam.
Two corresponding ends of the chain 37 and cable 38 are interconnected by mutual engagement with the shuttle 22, as shown in FIG.
2.
Accordingly, as the chain and cable are moved around the sprocket 36 and pulley 39, respectively, the carriage 22 is moved lengthwise of the guide rails 19 and 21, whereby the door 12 is moved in either an opening or closing direction.
The lengths of the chain 37 and cable 38 are selected so that the chain is always in engagement with the sprocket 36 and the cable is always in engagement with the pulley 39 throughout the full extent of linear movement of carriage 22