Crossbars 312 and 314 located slightly inboard of sprockets 304 and 310 serve as limit stops for slider 302 at {HEAD ~ opposite ends} of its path of {TAIL ~ travel} 
Crossbars 312 and 314 located slightly inboard of sprockets 304 and 310 serve as limit stops for slider 302 at { HEAD ~ opposite ends } of its path of { TAIL ~ travel }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL