Patent GB-822442-A (GB)
Title: Hydraulic control apparatus for wire printers or the like
IPC: H04L17/28
Filed: 1955-12-23
Abstract: 822,442. Selective printing. INTERNATIONAL BUSINESS MACHINES CORPORATION. Dec. 23, 1955 [Dec. 31, 1954], No. 36984/55. Class 100(4) [Also in Group XXIX] Hydraulic set-up means is provided for selectively rotating and/or axially shifting a code rod of a wire printer to one of a predetermined number of positions. A code rod. 48 of a wire printer, Fig. 1, is positioned axially by piston 41 disposed in a cylinder 38 and rotationally by a piston 39 in a cylinder 37. A pump 22 supplies liquid to a cam-operated valve 31 through which liquid is supplied, in the position shown, through a duct 87 and past poppet valves 83 of control means 42, 43 into the lower ends of control chambers 74-76 to hold control pistons 71-73 against adjustable stops 79. When valve 31 is moved to the left, duct 87 is opened to exhaust and liquid is supplied through a duct 36 to the upper ends of the cylinders 37, 38. The lower ends of the cylinders 37, 38 are connected by ducts 77, 78 to the upper ends of the control chambers 74- 76. Operation of any one (or any combination of) magnets 80-82 open the associated poppet valve or valves 83 and the associated control chamber or chambers are opened to exhaust. Control piston 41 is thus displaced from its "home" position determined by a stop 44 a distance of one increment if chamber 74 is open to exhaust, two increments if chamber 75 is open to exhaust and four increments if chamber 76 is open to exhaust and correspondingly for a combination of the chambers being open to exhaust. Piston 39 is similarly displaced according to the operation of the valves 83 of the control means 42. All the pistons 39, 41 and 71- 73 are returned to their "home" positions when valve 31 is moved to its right-hand position. A valve 90 is cam actuated to supply make-up liquid to the ducts 77, 78 when the pistons are held in their "home" positions so as to maintain a constant volume of liquid between each piston 39 or 41 and its associated control pistons. In a modification, Fig. 4b, the control for piston 39 is again similar to that for piston 41. The left-hand end of the cylinder containing piston 41 is connected through a duct 113 to the left-hand end of control chambers containing control pistons 96; the right-hand end of the cylinder is connected by a duct 108 to the righthand end of control chambers containing control pistons 97. Control valves 98-100 are associated with pairs of control pistons 96, 97. In the position shown, liquid from an inlet 24 is supplied to the left-hand chambers of the pistons 97 to hold them in their "home" position, the liquid in duct 108 holding piston 41 in its "home" position against a stop 44, and the liquid in duct 113 in turn ensuring that pistons 96 are held against slide bars 112. Actuation of the associated valve opens the left-hand chamber of the piston 97 to exhaust and directs liquid to act on the right-hand side of the piston 96, driving it to the left. Piston 41 is thus moved a corresponding distance, and piston 97 in turn is moved to the left. On the return of the valve to its initial position the pistons are returned to their "home" positions. Make-up liquid is then supplied to ducts 113, 108 through valves 116, 117. Each valve 98-100 is actuated by a continuously reciprocating bail 120. Movement of the bail slightly to the left of the' position shown moves the valve to relieve the thrust of a latching armature 84. Energization of the associated magnet retracts the armature clear of the edge of the control valve, which is spring urged to follow the bail as it moves to the right. At the end of its rightward movement the bail engages a projection 121, knocking off the armature which is then spring biased to its latching position so that the valve is again latched after the bail has returned it to its initial position. In a modification of the arrangement of Fig. 1, the poppet valves are replaced by spool valves actuated in the same way as the control valves of Fig. 4b; also the distributing valve 31 is dispensed with and an accumulator permanently supplies pressure liquid to the ends of the pistons 39, 41 remote from the control chambers. In another modification, Fig. 6, the lefthand side of the piston 41 communicates through a duct .154 with chambers 146 of control pistons 144 and the right-hand side of piston 41 through a duct 156 with chambers 147 of control pistons 145. Each pair of control pistons is reciprocated by a cam 155 and have a cam-operated valve 141. A latch 148 holds the valve 141 in the position shown in which chambers 146, 147 intercommunicate and reciprocation of the control pistons results in an idle transfer of liquid from one chamber to the other. Actuation of the associated magnet releases latch 148 and valve 141 is spring urged to follow its cam and closes the intercommunication between the control chambers; movement of the control piston 144 to the left then displaces piston 41 a corresponding amount. The subsequent rightward movement of control piston 145 returns the piston 41 to its "home" position and valve 141 is again held by its latch. Make-up liquid is then supplied to ducts 154, 156 through cam-operated valves 158. Specifications 815,813 and 818,544 are referred to.