rail head after the wheel of the rail car moves from the skid the skid rails on the rail head and falls automatically on the road bed at one side of the rail for this purpose the skid embodies a continuation that brings about an unbalanced net force due to gravity application_number US 90803486 A description shown in the schematic of fig1 is a system frequently used for loading mine rail cars a series of mine rail cars 6 attached by connecting means 8 are positioned on a rail spur 10 of a loading area a loading hopper 12 containing a partially opened bottom 14 is positioned above the rail spur 10 a conveyor means not shown conveys the mined mineral into the loading hopper 12 the partially opened bottom 14 of the loading hopper 12 allows the mineral to fall into the mine rail car 6 accurate positioning of the mine rail car 6 beneath the loading hopper 12 is required to prevent spillage of the mineral once one mine rail car 6 has been filled with the mineral a subsequent mine rail car 6 must be positioned underneath the loading hopper 12 to allow the loading process to continue the rail spur 10 of the loading area is frequently constructed on a level or sloping grade car spotters 15 which are positioned by hydraulic actuator arms 16 are located between the rails of the spur 10 actuation of an arm 16 causes the car spotter 15 to push against the mine rail car frame to thereby push the mine rail cars 6 the car spotters 15 are positioned such that once the actuator arm 16 of a first spotter 15 has been fully actuated an actuator arm 16 of.