1. A rail bearing for a warp stop motion action having electric contact rails and guide rails for the stop motion drop wires, comprising a base body having two spaced parallel legs, one of said legs having a plurality of recesses therein, an upright guide plate provided with spaced parallel slots for the guide rails dispoSed between said spaced parallel legs, an upright distance plate disposed on top of said upright guide plate, said distance plate having spaced parallel slots for accommodating the contact rails, a cover for clamping said distance plate and said guide plate to said base body, means for connecting said cover to said base body, said means comprising a cable one end of which is connected to the other leg of said base body, and a gripping member connected to the other end of said cable and connectible to one of a plurality of the recesses in said one leg of said base body.

2. A rail bearing for a stop motion action having electric contact rails and guide rails for the stop motion drop wires, comprising a base body having two spaced parallel legs, an upright guide plate provided with two series of parallel slots of different depths on opposite sides thereof for receiving said guide rails, said guide plate being adapted to be selectively inserted into said base body between said spaced parallel legs in two positions which are 180* apart, and an upright distance plate disposed on top of said upright guide plate, said distance plate having spaced parallel slots for accommodating the contact rails.

3. A rail bearing for a warp stop motion action having electric contact rails and guide rails for the stop motion drop wires, comprising a base body having two spaced parallel legs, an upright guide plate disposed between said spaced parallel legs, and having slots adapted to receive said guide rails selectively in two positions which are 180* apart, and an upright distance plate disposed on top of said upright guide plate, said distance plate having spaced parallel slots for accommodating the contact rails.