. Supplement to Spons dictionary of engineering, civil, mechanical, military, and naval. 906. coal the full depth of the screwed sleeve k, the nut j is formed in two halves, hinged together andsecured by the catch m, so that it can be opened, the screwed sleeve withdrawn, and the iDoring baradjusted without the neces^sity of screwing the sleeve k back again. The end of the boring bar isprovided with cutting head n, so that the coal is [removed in washers or ring. The breaking downapparatus is shown in Figs. 903 to 906; o are the expanding pieces, formed with taper grooves intheir interior; p i
. Supplement to Spons dictionary of engineering, civil, mechanical, military, and naval. 906. coal the full depth of the screwed sleeve k, the nut j is formed in two halves, hinged together andsecured by the catch m, so that it can be opened, the screwed sleeve withdrawn, and the iDoring baradjusted without the neces^sity of screwing the sleeve k back again. The end of the boring bar isprovided with cutting head n, so that the coal is [removed in washers or ring. The breaking downapparatus is shown in Figs. 903 to 906; o are the expanding pieces, formed with taper grooves intheir interior; p is the wedge ; Fig. 903 is a section through the expanding pieces, showing the wedgeinserted; Fig. 904 the wedge driven home and the block of coal breaking away from the faceby the expansion of the pieces o ; Figs. 905 and 906 are end views, before and after driving inthe wedge. 2 D 2 404 COAL MINING. Fig, 907 is Hurd and-Simpsons apparatus for breaking down the block of coal cut out by theheading machine, and for removing the thin layers of coal left by the machine between the roof a
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectenginee, bookyear1879
