GB906887A - Braking control for door closers - Google Patents

Abstract

906,887. Door closers. BARDFELD, W. Jan. 25, 1960 [Jan. 29, 1959], No. 2592/60. Class 65 (1). A door closer comprises a rotatable closing shaft 1 urged by a spring 38 in the door-closing direction and a brake for braking the closing movement, the brake being actuated by a control cam 18 (Fig. 4) which can be set in various angular positions about an axis 19 spaced from the axis (of the shaft 1) about which the cam is rotated when the shaft is rotated in order that the braking torque may vary in dependence on the angular position of the shaft. The brake comprises a pair of brake shoes 3 (Figs. 1, 9, 10) pivoted on a pin 7 (Fig. 6) carried by a plate 11 fixed in the closer casing 9 and adapted to be pressed apart into contact with the inner wall of a brake drum 2 by a second cam 12 located between the opposed ends 14 of the shoes and turned by a follower arm 15 carrying a roller 16 for contact with the face 17 of the control cam 18. The brake drum is connected to the shaft 1 by a pawl 33 and ratchet-wheel 31 so as to be rotated only during door closing movement and the brake shoes are held resiliently in their inoperative position by circlips 6 located in grooves 5 in the shoes. The control cam is pivoted at 19 to a distance-piece 22 which is rotatable on the shaft 1 and can be clamped thereto in any angular position by means of a clamping-screw 25 (Fig. 1) engaging a ball 26 which co-operates with a groove 26<SP>1</SP> in the shaft. During door closing movement the direction of rotation of the shaft is anticlockwise as seen in Fig. 4. For adjustment, the door is first opened until it is in the position at which, during closing movement the braking action is to cease and fast final closing movement is to begin, and the distancepiece 22 is then clamped to the shaft so that the end 18<SP>1</SP> of the control cam is opposite the roller 16. The cam is then adjusted on its spindle 19 to pre-set the variation in the braking torque, which can be made to increase, decrease, or remain constant as the door closes according as the end 18<SP>1</SP> of the cam is at a greater, a lesser, or the same distance from the shaft 1 than is the end 18<SP>11</SP>, and for this purpose two set-screws 20, 21 in engagement with oblique surfaces 24 on the cam are provided in the distance-piece. The follower arm consists of two parts 15<SP>1</SP>, 15<SP>11</SP> pivotally connected at 27 and adapted to be set at various angular positions thereby to vary the magnitude of the braking torque. In order to set the parts a screw 28 is provided in the part 15<SP>1</SP> and engages an oblique surface 29 on the part 15<SP>11</SP>.