Fecha de publicación: 06/11/1913 Fuente: WIPO "pollen" 7383. Pollen, A. H., and Isherwood, H. March 24. Order and order-type apparatus.-Electric step-by-step apparatus for copying reversible movements, applicable particularly for operating charting-tables in connexion with rangefinders, comprises a transmitter arm P rotatable over three fixed contacts A, B, C, which are wired to brushes A, B, C spaced around a rotatable commutator drum at the receiver. The commutator has two conducting segments 6, 7, which are connected by means of slip rings to the windings of oppositely-rotating clutches 1, 2, which co-operate with an armature 3 on a shaft 4, which is geared to the commutator. When the apparatus is at rest, the insulating space 8 between the segments 6, 7 is under the brush to which the battery is at the moment connected by the transmitter arm P. If the arm P is moved in either direction, so as to energize a different brush at the receiver, current passes through one of the clutches and the commutator is turned in the same direction as the transmitter until the insulating-space 8 is again brought under the energized brush. Instead of the clutches 1, 2, a motor with reversible field excitation may be employed.1>1>1>