Patent ID: 7070019

Claim:
An all terrain vehicle comprising: a frame assembly, a pair of dirigible front wheels connected to said frame assembly, an engine disposed within a central portion of said frame assembly, a seat supported by said frame assembly and positioned generally above said engine; said engine selectively powering said front wheels through a front wheel drive assembly, said front wheel drive assembly comprising a lockable differential; a handle bar assembly positioned forward of said seat, said handle bar assembly comprising a pair of transversely spaced grips connected to a steering column, said steering column having a limited rotational range of less than about 270 degrees; a power steering cylinder comprising a cylinder body that is connected to said frame assembly, said cylinder body defining a pair of cylinder chambers separated by a piston, a piston rod extending from said cylinder body and being connected to said piston at one end and being operably connected to said steering column at another end; said steering column being fixed for rotation with an input shaft of a power steering valve, said power steering valve forming a portion of a closed loop power steering fluid system; said power steering valve comprising a spool and an output shaft, said input shaft and said output shaft being connected with a torsion bar, said output shaft being adapted for connection to said front wheels; said spool being connected to said output shaft such that rotation of said output shalt relative to said input shaft results in said power steering valve opening and flow in said closed loop being directed into or out of said cylinder chambers to effect movement of said piston rod; said closed loop power steering system further comprising a bypass passage that diverts flow from around said spool valve, a flow regulator being disposed within said bypass passage; and a controller being adapted to control said flow regulator depending upon a sensed vehicle operating speed and a sensed differential lock mode.