and secured with nuts not shown the guide roll 14 is fixedly secured and may be located in any desired eccentric position to allow adjustment of tension of the apron 4 the eccentric guide roll 14 may be enclosed by a freely rotatable cylinder so as to minimize resistance to the rotating movement of the apron 4 the stands 7 7 pivoted on front lower sections of the side frames 15 15 are respectively provided with screwed steps 7a of an adjustable height and pivots 7b received within holes 7c so that the stands 7 are inclined somewhat backward as shown in fig1 slits 22 22 are formed in front lower sections of the vertical walls of the opposite side walls 15 15 to hold a reciprocating lever 20 of a device for picking off the fly carried by the clearer as indicated in fig3 the apron 4 is stretched between the guide roll 14 and the apron driving roll 13 within the frame assembly 6 and driven by the latter roll 13 while the apron driving roll 13 is supported by the shaft 5 the shaft 5 is reciprocated but is operative to move the apron 4 in only.