A rail vehicle for movement along a track having a longitudinal axis, comprising: a frame; a carriage assembly operatively coupled to the frame; and at least one workhead coupled to the carriage assembly, the workhead having a jaw member for removing rail spikes; a mechanical detector coupled to the carriage assembly, the mechanical detector being operable to move from a first, disengaged position in which the mechanical detector is parallel or oblique to the longitudinal axis of the track as measured along a stem portion of the mechanical detector, to a second, engaged position in which the mechanical detector is substantially orthogonal to the longitudinal axis of the track as measured along the stem portion of the mechanical detector, wherein the mechanical detector is operable to detect a tie when in the second, engaged position; a hydraulic cylinder operably coupled to the mechanical detector through a coupling assembly and configured to rotate the mechanical detector between the first and second positions; and an onboard computing system operable to receive a signal when the tie is detected and cause the carriage assembly to lower into position adjacent a rail spike; a pair of guide rods coupled to the frame; and a subframe member including a plurality of connectors, wherein the carriage assembly is operatively coupled to the frame via the subframe member and the guide rods, and the plurality of connectors receive the guide rods in cavities defined by the connectors, wherein the subframe member is operable to move along the guide rods in a longitudinal direction for longitudinal displacement of the carriage assembly along and relative to the frame. a frame; a carriage assembly operatively coupled to the frame; and at least one workhead coupled to the carriage assembly, the workhead having a jaw member for removing rail spikes; a mechanical detector coupled to the carriage assembly, the mechanical detector being operable to move from a first, disengaged position in which the mechanical detector is parallel or oblique to the longitudinal axis of the track as measured along a stem portion of the mechanical detector, to a second, engaged position in which the mechanical detector is substantially orthogonal to the longitudinal axis of the track as measured along the stem portion of the mechanical detector, wherein the mechanical detector is operable to detect a tie when in the second, engaged position; a hydraulic cylinder operably coupled to the mechanical detector through a coupling assembly and configured to rotate the mechanical detector between the first and second positions; and an onboard computing system operable to receive a signal when the tie is detected and cause the carriage assembly to lower into position adjacent a rail spike; a pair of guide rods coupled to the frame; and a subframe member including a plurality of connectors, wherein the carriage assembly is operatively coupled to the frame via the subframe member and the guide rods, and the plurality of connectors receive the guide rods in cavities defined by the connectors, wherein the subframe member is operable to move along the guide rods in a longitudinal direction for longitudinal displacement of the carriage assembly along and relative to the frame.