. Electric railway review . operate. The door is constructed of a curtain proper composed ofwood slats strung on phosphor bronze ribbons and running invertical guides of wood. The curtain is suspended from androlls upon a barrel consisting of a tube of sufficient diameterto afford absolute stiffness which contains within it the helicalsprings necessary to counterbalance the weight of the whole is supported on brackets of heavy cast iron attachedto the upper rear corner of the bracket on the outside by meansof heavy pivot pins—and also to the lower outer corner—are twoheavy cast iro
. Electric railway review . operate. The door is constructed of a curtain proper composed ofwood slats strung on phosphor bronze ribbons and running invertical guides of wood. The curtain is suspended from androlls upon a barrel consisting of a tube of sufficient diameterto afford absolute stiffness which contains within it the helicalsprings necessary to counterbalance the weight of the whole is supported on brackets of heavy cast iron attachedto the upper rear corner of the bracket on the outside by meansof heavy pivot pins—and also to the lower outer corner—are twoheavy cast iron arms, the upper one extending downward fromthe top and the lower one extending upward from the carry a heavy horizontal arm pivoted at their ends, in themiddle of which is a bearing carrying the curtain shaft. Thelength of this horizontal arm is equal to the horizontal distancebetween the upper and lower pivot pins of the vertical arms, andthus, through a horizontal slot in the bracket, the curtain shaft. Wood Rolling Door, Open. may be moved forward or backward a certain distance alwaysmoving in a straight horizontal line. On the tube barrel areplaced spiral cast iron rings to which the suspending ribbons areattached, so that after the first turn of the slats around the shaftthe roll is always circular. On the rear flange of the bracketsand behind the curtain proper is carried a pivoted cradle inwhich operate two rollers. On the bottom of the brackets aresuitable curved projections forming a throat which serves toguide the curtain properly down into the groove. It will be seen from this arrangement as illustrated that thecurtain hangs in a straight line from the spiral rings downthrough the throat of the bracket and into the groove. As thedoor unrolls the shaft moves backward, maintaining the verticalposition of the slats, which bear against the rollers on the backflange of the bracket. As the door is rolled up and the diameterof the roll increases, the whol
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectstreetr, bookyear1906
