Apparatus for separating a letter stack

Claim 1

In apparatus for the separate discharge of letters and similar flat items from a stack of such items, which apparatus includes a movable support for supporting the stack of items, a withdrawal mechanism mounted to engage the foremost item in the stack and withdraw that item from the stack, means defining a supporting wall manually movable into an initial position for supporting the trailing end of the stack, and drive means connected to drive the supporting wall toward the withdrawal mechanism under control of the state of a switch actuated in dependence upon the force being exerted by the stack on the withdrawal mechanism, the improvement wherein: said apparatus further comprises resilient force equalizing means between said drive means and said supporting wall in drive transmitting relation therebetween, said equalizing means being constructed and mounted for permitting advancing movement of said supporting wall to lag behind that corresponding to the sum of the drive movements produced by said drive means whenever the pressing force between said supporting wall and the stack exceeds a given value, and a guide bar extending parallel to the direction in which said supporting wall is driven; said drive means comprise: a guide sleeve rigidly connected to said supporting wall and mounted on said bar for displacement therealong; a motor; a motion transmission member connected to the output of said motor to be driven thereby; a releasable connecting member connecting said motion transmission member in driving relationship with said sleeve; and a second sleeve carrying said releasable connecting member and mounted on said bar for displacement therealong and relative to said first-recited sleeve; and said resilient force equalizing means comprise spring means mounted between said sleeves for producing a force urging said first-recited sleeve relative to said second sleeve in the direction toward said withdrawal mechanism, and abutment means arranged between said sleeves for delimiting the distance established therebetween by the force produced by said spring means.