Patent GB-719781-A (GB)
Title: Improvements in wire-tying mechanism for automatic hay balers
IPC: A01F15/14
Filed: 1951-07-17
Abstract: 719,781. Baling-presses. SPERRY CORPORATION. July 17, 1951, [Sept. 6, 1950.] No. 16923/5. Class 94 (1). [Also in Group XXII] In a wire-tying mechanism for an automatic hay baler in which a needle delivers a loop of wire around the end of a bale to a wire carrier which moves past a twister to lay one strand of the loop in the twister in overlapping relation to a free end of wire extending from the loop which has previously been laid therein, the twister is moved to a projected position to receive the wire and subsequently returned to a retracted position after completion of the twisting operation. Rearward movement of compressed hay in the baling chamber causes rotation of metering wheel 70, Fig. 1, carrying a cam which after one complete revolution, corresponding to the formation of a bale of the desired length, actuates a trip mechanism to cause rearward movement of a push-rod whereby a toggle linkage is operated to engage a one-revolution clutch in the drive to the wire-tying mechanism and move a latch into position to hold the compressing-plunger in its retracted position while the bale is tied. The wire-tying mechanism comprises a pivoted needle yoke 155, Fig. 1, oscillated by a link 154 and crank 153 on shaft 152 and carrying a pair of arcuate needles 156 with bifurcated ends; a pivoted wire carrier 162, Fig. 16, oscillated by an eccentric driven by the shaft 152 and provided with upper and lower wire-retaining devices 163; fixed upper and lower wire guides 170 and wire-twisting mechanism comprising upper and lower slotted pinions 194, Fig. 18, carried by a housing 190 mounted in guides for lateral reciprocation under the action of a crank 201 and connecting rod 202 driven by a shaft 116. The initial position of.the parts is shown in Figs. 16 and 33, the wires having their free ends disposed in slotted members 146 carried by the guides 170 and passing around pulleys 177, Fig. 13, forming part of the retaining devices 163, and then back through the members 146 and around the rear end of the bale in formation to the supply. As the bale is formed, the wire is drawn from the supply so that it extends around three sides of the bale as shown in Fig. 27. The clutch is then engaged by the trip mechanism to couple a segment gear 104, Fig. 10, to a drive gear 103, whereby a pinion 117 is rotated to drive a shaft 118 coupled by chain and sprocket gearing to the shaft 152. The needle yoke 155 and wire carrier 162 are thus moved as shown in Fig. 28 to carry the wires from the supply across the front end of the bale and to carry the free ends of the wires forwardly across the twisting mechanism. The gear 104 also rotates a pinion 112 which drives the shaft 116, whereby the housing 190 is projected to position the twisting pinions for the reception of the wires. After the pinion 112 has been rotated 180 degrees it ceases to mesh with the gear 104 and an arc 120 integral therewith engages an arc 121 on the gear 104 to hold the housing in its projected position. As the carrier 162 moves forwardly the wires slide through slots in the guides 170 and the free ends are carried up over horn-shaped guides 147, Fig. 13. The wires are thus directed into the slots of the twisting pinions, and towards the end of the forward stroke of the carrier their free ends are forced between springs 171 and serrated members 172 carried by the guides 170. The retaining devices then pass between the forks of the needles, see Fig. 29, and the loops carried thereon ride over sloping surfaces 175, Fig. 13, As the carrier commences its rearward stroke, the loops move downwardly past latches 176 into engagement with the pulleys 17 so that further wire is drawn from the supply on the rearward stroke, To ensure that only the inner strands of the loops are directed into the twisting pinions, the strands are separated by pins 181, Figs. 7 and 16 which are projected vertically from a housing 180 supported between the guides 170. The pins are coupled by links 182 to a sprung-urged rotary plate 183, but are retained on their retracted portion by a latch 'until the latter is tripped by an abutment 185 on the carrier 162 as it moves rearwardly. As soon as the inner strands of the loops have been positioned in the twisting pinions parallel to the free ends of the wires as shown in Fig. 30, the gear 104 engages a pinion 140 to effect rotation of a universally-jointed shaft 144 which is geared to the twisting pinions. After four twists have been made, knives 196, Fig. ig, slidably mounted on either side of the pinions, are actuated by a cam 198 on the shaft 144 to sever the ties from the supply and the gear 104 re-engages the pinion to rotate the shaft 116 another 180 degrees, whereby the housing igo is retracted and the wires stripped from the pinions by fixed cams 203, Fig. 18. To ensure that the slots in the twisting pinions are positioned correctly after each cycle of operations, a fork 210 integral with the shaft 144 engages a roller 211 as the housing is retracted and a spring-pressed ball engages a centreing hole formed in the side of the central gear which meshes with the pinions. The wire is supplied from cans 151, Fig. 23, over guide wheels 213, and to ensure that the baler does not continue to operate when the wire supply is exhausted, the wires pass through guides arranged to prevent closure of switches controlling a warning buzzer or the ignition circuit of the engine. To damp vibrations and take up backlash, the needle yoke 155 is engaged by a brake 217 at the commencement of its stroke.