The upper end of the ratchet housing 92 and the lower end of the J slot sleeve 136 create {HEAD ~ a stop} which limits {TAIL ~ the upward motion} of the mandrel 22 relative to the drill string 32 
limits
The upper end of the ratchet housing 92 and the lower end of the J slot sleeve 136 create { HEAD ~ a stop } which limits { TAIL ~ the upward motion } of the mandrel 22 relative to the drill string 32
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 REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH