In addition, reference numerals and in FIG 4 designate a pair of air sealing plates which are mounted in a vertically movable manner to the bottom end portions of the left and right side walls and by means of {TAIL ~ a spacer} and a plurality of bolts , and these air sealing plates and are slidably held in contact with the canvas belt , so that the gaps between {HEAD ~ the left and right side walls} , and the canvas belt can be air tightly sealed 
In addition , reference numerals and in FIG 4 designate a pair of air sealing plates which are mounted in a vertically movable manner to the bottom end portions of the left and right side walls and by means of { TAIL ~ a spacer } and a plurality of bolts , and these air sealing plates and are slidably held in contact with the canvas belt , so that the gaps between { HEAD ~ the left and right side walls } , and the canvas belt can be air tightly sealed
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