Patent GB-721253-A (GB)
Title: Device for controlling the number of strokes performed in an intermittently working apparatus
IPC: G06M3/02
Filed: 1952-09-30
Abstract: 721,253. Ratchet gearing. LARSSON, O. E. Sept. 30, 1952. No. 24498/52. Class 80 (3). A device for controlling the number of strokes performed in an intermittently working apparatus, the operation of which is started and stopped by means of an impulse member having an operative position and a position of rest, said device including a ratchet wheel which is adapted to be turned one step for each stroke of the apparatus by means of a pawl actuated by the apparatus, comprises an abutment adjustable on said ratchet wheel in accordance with the desired number of strokes and a locking device for retaining the impulse member in its operative position, and is characterized in that said abutment is adapted directly to actuate the locking device to release the impulse member and disengage the pawl from the ratchet wheel when the abutment together with the ratchet wheel has been turned the predetermined number of steps. As shown, a driving shaft 51 carries a cam 79 to which is pivoted a rod 80 connected e.g. to a device, not shown, which upon each revolution of the shaft and cam intermittently moves a cardboard blank through a stapling apparatus, the shaft also carrying a dog 79<SP>1</SP> engaging an impulse member or rod 66 which it can push downwardly, from the position of rest shown, to an operative position. A bell-crank lever 84 is pivoted to the other end of the impulse member, which is connected through links 95, 96 to a pivoted pawl 90, spring urged into engagement with a ratchet wheel 91 and moved, through linkwork 89, 88 and a roll 56 engaging the cam 79, to rotate the ratchet wheel one step in the direction of the arrow 69 for each rotation of the shaft 51; the link 96 also co-operates with a holding pawl 97 actuated so as to prevent reverse shown) in the opposite direction. An adjustable rotation of the ratchet wheel by a spring (not abutment 93 can be rotated with respect to the ratchet wheel and fixed with respect thereto to control the number of staples introduced by the apparatus into the blank in each cycle, the wheel also carrying a fixed abutment 100; these two abutments co-operate, respectively, with an abutment 94 on a rod 85, connected through a pivoted lever 86 to the bellcrank lever 84, and with a fixed abutment 99. The abutment 93 having been adjusted so that the machine performs the required number of steps, operation commences when a cardboard blank is fed into the stapling apparatus and operates a switch through which current is fed to an electric motor rotating the shaft 51, so that the cam 79' pushes the impulse member 66 down and rotates the bellcrank 84 and links 95, 96, whereby the pawls 90, 97 engage with the ratchet wheel. Rotation of the bellcrank 84 also allows the lever 85 and the lever 86 connected thereto to be pulled downwardly by a spring, this movement of the lever 86 serving to lock the bellcrank 84 and impulse member 66 in their new positions. The pawls 90, 97 are engaged with the ratchet wheel and each rotation of the shaft 51 causes the pawl 90 to rotate the ratchet wheel through a distance corresponding to one step in the direction of the arrow 69. The process continues until the adjustable abutment 93 on the ratchet wheel engages the abutment 94 on the rod 85, which is thereby raised to disengage the locking device comprised by the bell-crank 84 and lever 86, and allow the impulse member 66 to be raised by means of a spring (not shown). This upward movement moves the links 95, 96 to withdraw the pawls from the ratchet wheel, which is then rotated by its spring in the reverse direction to that of the arrow 69, until its fixed abutment 100 engages with the fixed abutment 99, thus restoring the apparatus to its original condition. The cardboard blank leaving the stapling apparatus operates another switch which stops the motor and the rotation of shaft 51.