Letter-box collection record marker - uses anvil with spring biassed punch and hammer which is guided to be perpendicular to punch

摘要

The appts. marks a card carried by an operative to ensure that all points on a route have been visited, and is partic. applicable to clearance of public post-boxes. The operative places a card in a slot provided, and the opening of the post- box door operates a hammer which marks the card. The record card marker uses a spring release method to make the hammer force independent of the vigour with which the door is opened. The marker assembly is fixed to the door of the post box and the hammer is fixed to an arm which is in contact with the end of a torsion spring tending to push it downwards. A longer arm engages the hammer arm and compresses the spring when the longer arm contact the fixed part of the post box. When the door is opened the arm is released and the hammer is driven onto the card by the spring.