Patent GB-258294-A (GB)
Title: Stepped grate
IPC: F23H7/06
Filed: 1926-09-13
Abstract: 258,294. Lomshakoff, A. S. Sept. 12, 1925, [Convention date]. Addition to 257,960. Grates.-Step grates having the grate bars arranged in two groups, alternate bars being members of the same group, and in which the bars make oscillatory movements longitudinally of the grate as described in the parent Specification, are actuated directly by a steam or other fluid-pressure engine, the valve gear of which is operated so that the frames which carry the grate bars make oscillations which are divided up into smaller successive partial oscillations. The length and frequency of the partial oscillations and the points at which they take place can be varied. The frames 4 of the grate bars are connected by extensions 3 and cross-heads 2 to pistons 1 controlled by slide-valves 5 so that they move in opposite directions. A rod 7 attached to one of the grate frames rocks a lever 8 pivoted at a point 12 the position of which is automatically shifted, the lever 8 being guided in a fork 13 to prevent lateral movement. A roller 9 at the end of the lever 8 contacts with one of two jaws 10 which are pivoted together and to nuts on a rod 15, Fig. 5, with right- and left-handed threads, turned by a hand-wheel 14 to adjust the distance between the jaws. The rod 15 is carried by a bolt 16 pivoted in the forked end 18 of the valve rod 11 so that the roller 9 moves the valverod to shift auxiliary valves 6 and admit pressure fluid to the main valve 5 and move it to reverse the motion of the piston. A lever 35 pivoted at 36 transmits the movement of the rod 11 to the valve rod of the other cylinder so that the piston of the other grate-frame is simultaneously reversed. Pivoted to the valve rod 11 and to the framing at 24<1> is a lever connected by a rod 25 to a ratchet-wheel 26, Fig. 8, mounted on the shaft of a worm 27 driving a worm-wheel 29 rotatably mounted in a fixed casing 28 and provided with a variable crank 32, 30 connected by a rod 31 with the pivot 12 of the lever 8. Each movement of the valve rod 11 in one direction thus turns the worm wheel to adjust the position of the point 12 i.e. alter the point at which the next partial oscillation takes place. The amount of movement of the worm-wheel for each movement of the valve rod can be adjusted by a rotatable cover plate 34 adapted to cover a number of the teeth of the ratchet wheel 26. A hand-wheel 33 adjusts the length of the crank of the worm-wheel by turning a screwed rod 32 on which runs a nut carrying the crank-pin 30, In a modification the lever 8 is pivoted at its upper end to a slide which reciprocates on a fixed pin and has a projection adapted to engage at the ends of the partial oscillations with nuts on a sleeve having right- and left-handed threads rotatably mounted on the valve rod 11 and turned by a hand-wheel to vary the distance between the nuts, which are prevented from rotating bv a plate on the slide. The work is equalized between the two cylinders by having on each frame 4 a rack, and a gear-wheel gearing with both racks carried by a link from a fixed part of the framing. One steam cylinder may drive both frames, one being driven direct and the other through a lever so that the oscillations of the frames are always in opposite directions.