| 摘要 |
722,335. Door-operating apparatus. SCOTT, L. W. Feb. 27, 1953 [Feb. 27, 1952], No. 6191/52. Class 66(1). [Also in Group XXVIII] Double hinged doors for mines in which the air pressure is greater on one side of the doors than on the other are opened simultaneously against the air pressure by power-ram means, the pressure of the ram being automatically reduced after the initial resistance of the airpressure has been overcome, and the pressure on the ram being relieved to allow the doors to be closed simultaneously by weight means. In the arrangement shown in plan, arms 17 fixed to the hinge spindles 3 of the doors 1 are connected by links 15 to a crosshead 11 secured to the piston-rod 9 of a compressed-air ram 8. Links 100 connect the arms 17 with the doors 1 to relieve the strain on the hinge spindles. Air is admitted to the front end of the cylinder 8 through a valve 7 controlled by a handle 47. A by-pass 85, which may have an adjustable valve 86, reduces the effective pressure on the piston after it has covered a part of its stroke, and a release valve 87 determines the cushioning pressure at the end of the stroke ; a cushioning spring may be used. When the valve 7 is restored, to release air from the cylinder, the doors are closed by a weight 53 connected to them by a cord 60 ; the exhaust from the cylinder may be regulated by a valve. The parts of the mechanism projecting beyond the doors are accommodated in a recess over the doors with an end wall 62. In a modification, the ram opens the doors by a pushing action; in this case the cylinder 8 may pass through the wall 62. The cylinder is preferably formed of a steel tube with separate end-caps formed with square flanges and held together by tension rods 66, which also secure the ram to its fixing means 68, 69, the caps thus being readily interchanged to reverse the ram; each cap has a hole to receive the inlet pipe or the release valve which are thus also interchangeable to reverse the direction of action of the engine. According to the Provisional Specification, instead of using a by-pass passage a reducing valve is placed in the main inlet pipe and is operated to restrict the air flow by air from a port in the cylinder which is uncovered by the piston during its stroke ; several such ports may be provided, the pipe to the reducing valve being connected to the selected one while the others are closed by plugs, or the pipe being fixed and all the ports connected to it, those not required being shut off by plugs. A separate closing weight may be provided for each door. |
