a steering assist valve configured to selectively operate at least one said turn assist cylinder and thereby bias said corresponding caster wheel assembly during an operator commanded {TAIL ~ turn}, said {HEAD ~ steering assist valve} including an input gear; and 
a steering assist valve configured to selectively operate at least one said turn assist cylinder and thereby bias said corresponding caster wheel assembly during an operator commanded { TAIL ~ turn } , said { HEAD ~ steering assist valve } including an input gear ; and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH