front of the door jamb can be occupied by a filler block and additional bolts extended through the flange 18 and this filler block and into the jamb 12 the operation of the device is very simple a gentle push on the button 16 will energize the motor 31 which will proceed to rotate the shaft 36 and the radius arm 37 this action will apply force to the door through the roller 42 which will roll across the surface of the door as the door swings open as shown in fig2 regulations require that the door open slowly enough so that it will not produce a danger of collision with objects on the opposite side of the door or with people who may be approaching it it is commonly accepted that a rate of door opening must be such that at least 3 seconds is required for the door to swing to the fully open position this time can be adjusted by the control mechanism if an object or a person is encountered during this movement the motor 31 will stop until the obstruction is removed if a person tries to shut the door and overpower the opener this will let the door close and the arm.