Patent GB-636734-A (GB)
Title: Improvements in or relating to silo unloaders and control mechanism therefor
IPC: B65G65/38
Filed: 1946-11-28
Abstract: 636,734. Pneumatic silo unloader. LEACH CO. Nov. 28, 1946, No. 35301. Convention date, Sept. 5, 1945. [Class 78 (i)] A silo unloader, for installation in a silo above the surface of the silage, comprises a vertically movable frame 26, means 67 for lowering the frame in the silo, a cutter 38 journalled in the frame at the centre of the silo for rotation relative to the frame in a substantially horizontal plane, blades 42 on the cutter for loosening the silage at the upper surface of the latter and for working the loosened silage in toward the centre of the silo, and air duct 35 adjacent the centre of the silo, and suction means for discharging the cut silage from the silo. Fig 1. Forage 17 contained in the silo 19 is cut by blades 42 which are supported on extensible beam 38 which is caused to rotate with duct 35 by motor 45 situated on the non-rotating frame 26. The blades feed the forage towards the centre where agitators 53 (also driven from motor 45) introduce the forage to the rotating duct 35 which feeds it to the stationary suction tube 62 whence it is discharged by fan 60 to the outlet 66. The frame 26 has extensible parts 27 which run in vertical guides 32 so that winch 72 elevates the frame and cutters through the medium of ropes 67. Alternatively, the frame 26 may be a three-armed spider supported by a rope at each extremity. Cutters (Figs. 3, 4, 5). Motor 45 drives fan 61 through belting 46, and the suction sucks up the forage into duct 35 and discharges it at 66. The motor also drives the large gear 52 via belting 46, gears 47 and 48, shaft 49 and gear 50, and chain 51 ; the large gear 52 is fixed to duct 35 which is fixed to cutter carrying beam 38 so that the cutters rotate together with the beam and the duct. The agitators 53 are joumalled in gear 52 and therefore gyrate with the gear. Also, the two gears 57 fixed in the ends of the spindles of the agitator engage a stationary chain 58 which is wrapped round stationary gear 59 and the slow gyration of the agitators therefore causes fast rotation of the agitators. Winch drum (Figs. 9, 10). The supporting cables 67 are combined to form cable 73 wound on drum 72. The latter has fixed thereto ratchet teeth 78 which engage with two pawls, lifting pawl 79 and locking pawl 85. Lifting pawl 79 is pivoted on handle 84 which itself pivots on the drum trunnion 74 and the movement of the handle (and therefore of pawl 79) is controlled by the movement of piston 90 within oil cylinder 89, lug 88 on the base of the cylinder being pivotally connected to an abutment 82 of the handle. The interior of circular ratchet teeth 78 is a rotatable disc 98 which is provided with a cam 99, the function of which is to force locking pawl 85 out from contact with the ratchet teeth at the appropriate moment. The disc 98 is moved by handle 84 ; in one direction by the coupling spring 100 and in the other direction by the contact of the side of the handle with lug 102 fixed on the disc. Valve 94 permits a flow of oil in one direction to allow the pawl to be moved easily counterclockwise and prevents flow of oil in the other direction, the oil therefore passing back along pipe 96 and through 97 slowly and with difficulty. Operation. Pawl 79 is freed by lever 108, from ratchet teeth 78 and moved forward by the handle 84 and dropped again on to the teeth. This counterclockwise movement of the handle drags disc 98 together with cam 99 towards pawl 85 and, the force applied by the handle to the teeth having released the drum from the pull of rope 73 which supports the unloader, the cam 99 slips under pawl 85 and thus disengages it. The drum is now free to allow the unloader to descend under its own weight, the handle being forced slowly clockwise by the tension of cable 73 under. contact of cylinder 89. As the handle rotates it connects with abutment 102 on disc 98 and when the handle has regained its former position, cam 99 on disc 98 is forced to slip from under pawl 85 and to allow this pawl to jam the ratchet wheel and bring the descent of the unloader to a halt. Automatic switching-in of the cutter motor (Fig. 10). The circuit of the cutter motor 45 includes switch 104 which is time-controlled by lever 105, such that when lever 105 is raised by hand the motor is switched in and the cutters rotate and such that the motor continues as the lever drops under gravity and is switched off as the lever reaches its lowermost position. Lever 105 is operated by locking pawl 85 by means of the abutment 107 on the pawl which contacts abutment 106 on lever 105. Firstly, lever 105 is raised to its uppermost position so as to switch on the cutter motor. Then lever 84 is rotated anticlockwise as described above. Pawl 85 is freed by the movement of cam 99 and, when the pawl is in the non-locking position, its abutment 107 catches and retains abutment 106. The cutter motor therefore continues until handle 84 has been forced back to its initial position and has then ejected cam 99 from underneath pawl 85 and back to its original position so that abutment 107 moves out of contact with the lever 105. The descent of the. unloader now ceases but the cutters continue to rotate (to clear up the remaining forage) until the lever 105 of switch 104 has reached its lowermost position.