an apparatus for adjusting the position of a seat comprises a rack and a clock nut that grips the rack . the rack comprises a threaded rod , while the clock nut comprises a short cylindrical body that is drilled and threaded along its diameter with internal threads corresponding to the thread diameter and pitch of the rack . circumferential reliefs are then formed in the threaded bore to enable the clock nut to be “ clocked ” from a position in which the threads of the clock nut engage the threads of the rack to a second position in which the threads of the clock nut disengage the threads of the rack . a pair of linkages are provided to rotate the clock nut between the engaged and disengaged positions and to transmit loads from the clock nut . because the clock nut engages multiple teeth of the rack simultaneously , the seat track locking mechanism of the present invention is capable of extremely fine position adjustment without sacrificing ruggedness and because of the design of the linkages , the seat track locking mechanism locks bi - directionally and with little or no backlash .