As the bars 24 rotate around {TAIL ~ a sprocket}, as shown in FIGS 4 and 5, the bars reverse {HEAD ~ direction}, going from pointing up to pointing down or vice versa 
As the bars 24 rotate around { TAIL ~ a sprocket } , as shown in FIGS 4 and 5 , the bars reverse { HEAD ~ direction } , going from pointing up to pointing down or vice versa
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH