GB569564A - Improvements in mechanical stokers - Google Patents

Abstract

569,564. Variable-speed ratchet gearing. DAY, C. C., CROMPTON, J., and MIRRLEES, BICKERTON, & DAY, Ltd. June 16, 1943, No. 9628. [Class 80 (ii)] [Also in Group XXX] A mechanical stoker of the screw conveyer type is driven at variable speeds by means comprising a lever 14 which has a pivot 12 adjustable while the driving means is in motion and is oscillated to impart to the conveyer screw 28 a step-by-stop rotary motion. In the construction shown the lever pivot 12 is carried by a block 4 slidable in a stationary guide 3 and adjusted by a screw 5 and hand wheel 11. The lever is continuously oscillated by a crank-pin 19 engaging a slot 15 and mounted on a beltdriven pulley 21 on a shaft 22, and its pivot 12 is adjustable so as to be either coaxial with a pin 23 engaging a slot 16 in the lever, or, as shown,'out of line therewith. The pin 23 is carried by an arm 25 which is pivoted at 26 to radius arms 27 loose on the conveyer shaft 28 and has a cam end 29 engaging the periphery of a disc 31 fixed to the shaft. A tension spring 32 controls the lower end of the arm 25, and a spring-loaded friction pawl 33 prevents backward rotation of the screw. When the pivot 12 and pin 23 are in line the arm 25 is not affected by the oscillating lever 14, but when they are not in line the arm is oscillated and gives a step-by-step rotation to the disc 31 at a rate depending on the distance between the centres of the pivot 12 and the pin 23. Toothed ratchet-and-pawl mechanism may be used instead of the friction ratchet shown.