Patent GB-568332-A (GB)
Title: Improvements in apparatus for drying tea and the like
IPC: F26B17/00
Filed: 1943-06-16
Abstract: 568,332. Drying tea &c. RIDLER. W. F. A., and MARSHALL'S TEA MACHINERY CO., Ltd. June 16. 1943, No. 9642, [Class 34 (ii)] [Also in Group XXIV] In tea and like drying apparatus with rows of trays which can be tilted to allow the material being dried to fall from one row on to the trays in the row below, the means for tilting each row of trays are actuated by mechanical means which are operated upon the engagement of a clutch, and cam means operated by driving means at any desired speed between two predetermined speeds cause engagement of the clutches intermittently in sequence. At regular intervals, all the rows of trays, starting at the bottom row, are tilted in rapid succession.. The trays in each row are pivoted at their ends and a crank on a pivot at one end engages in a hole in a tilting bar 2 connected by a rod 3 to a crank disc 4, rotation of which causes the bar 2 to move against the action of a spring and so tilt the trays. There is a separate tilting bar for each row of trays. A train of gears 5, loosely mounted on the shafts 4, is continuously driven. Associated with each gear is a clutch which is brought into operation at intervals by movement of a lever 7 actuated by a cam 10 which is rotated through one revolution at regular intervals. When the clutch is closed, the shaft 4 and crank disc rotate with the gear-wheel 5, and the bar 2 moves to tilt the trays. When the clutch opens, the bar returns to its original position. The clutch is formed by a conical recess on one side of the gear-wheel 5, and an inner conical member slidable longitudinally on and keyed to the shaft. It is normally held open against the action of a spring by the lever 7, the forked end of which engages with projections 43 on a ball-bearing associated with the inner clutch member. The other end of the lever, which is pivoted at 8, has a cam follower 9 which is pressed against the inner wall of a flanged cam 10. When the cam follower enters a recess in this inner wall, the clutch is closed.. The cams are mounted one above another on a shaft 12, and the recesses are displaced angularly at equal intervals from one cam to the next, so that the rows of trays are tilted and restored to their original positions at equal intervals in the rotation of the shaft 12. This shaft is driven from a power-driven pulley 13 through bevel gears 14, conical pulleys 15, 16, sprockets and chain 19, 20, 21, reduction gearing 22, which may be epicyclic, bevel gears 23, 24 and an internal spur gear 25 which engages either of the pinions 28, 29 mounted on a sleeve 30 splined on the shaft 12. The teeth on the bevel-wheel 23 are interrupted so that the bevelwheel 24 is rotated only intermittently. Interengaging locking platen 32, 33 ensure that the wheel 24 revolves only once for one revolution of the wheel 23. For this purpose, the circumference of each plate is interrupted in one part 55 or 56, Figs. 6 and 8. When the teeth on the bevel-wheel 23 engage those on the wheel 24, the gap 55 enables the plate 33 and wheel 24 to rotate. When one revolution of the wheel 24 has been completed, the flat edge 56 allows the plate 32 and wheel 23 to continue to rotate. The sleeve 30 is slidable vertically by operation of a rack and pinion, so that either the pinion 28 engages with the teeth 26 or the pinion 29 with the teeth 27. A plate 34, which passes through the slot 36 or the recess 35 when the pinions are in one of the engaging positions, is fixed to the sleeve 30. The numbers of teeth 26, 27 is the same as the numbers of those on the pinions 28, 29 respectively. The plate 34 is so shaped that it cooperates with the recess 35 or gap 36 to ensure that for each rotation of the wheel 23 there is one rotation of the shaft 12, with a consequent cycle of tilting. The period of the whole operation can be varied within a certain range by moving the belt 17 on the pulleys 15, 16, and a further range can be obtained by interchanging the sprockets 19, 21. For each such period, two speeds of tilting are obtainable according to which pinion 28, 29 is engaged. The shaft 12 may be hand-driven for initial charging.