A Text-book of Coal-mining: For the Use of Colliery Managers and OthersCharles Griffin & Company, 1904 - 563 Seiten |
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Ergebnisse 1-5 von 100
Seite 15
... employed . These are suspended from rods , which are raised up and dropped down , thereby chipping off small quantities of rock . The rods are rotated after every blow , so that the tool drops in a different place each time . The ...
... employed . These are suspended from rods , which are raised up and dropped down , thereby chipping off small quantities of rock . The rods are rotated after every blow , so that the tool drops in a different place each time . The ...
Seite 16
... employed . ( o ) Guides . To keep the hole vertical a guide - block is fixed at the surface . This generally consists of a block of wood ( a , Fig . 11 ) about 9 feet long , through the centre of which passes a hole of the same diameter ...
... employed . ( o ) Guides . To keep the hole vertical a guide - block is fixed at the surface . This generally consists of a block of wood ( a , Fig . 11 ) about 9 feet long , through the centre of which passes a hole of the same diameter ...
Seite 18
... employed to meet Difficulties of Deep Boring.— As the depth of holes increases a large number of difficulties arise , the greatest one being the weight of the rods themselves . Rods 1 inch square weigh about 1 ton for every 200 yards ...
... employed to meet Difficulties of Deep Boring.— As the depth of holes increases a large number of difficulties arise , the greatest one being the weight of the rods themselves . Rods 1 inch square weigh about 1 ton for every 200 yards ...
Seite 21
... employed , and the length of stroke can be varied by altering the position of the tappets . Before the valves can be opened , it is necessary that the piston - rod should move ; a small quantity of steam is therefore kept continually ...
... employed , and the length of stroke can be varied by altering the position of the tappets . Before the valves can be opened , it is necessary that the piston - rod should move ; a small quantity of steam is therefore kept continually ...
Seite 27
... employed at Villefranche ( Allier ) in 1876 , and Mr. Baure states that the success has been complete , as the greater portion of the cores were extracted in an unbroken condition . Not only did they obtain a complete section of the ...
... employed at Villefranche ( Allier ) in 1876 , and Mr. Baure states that the success has been complete , as the greater portion of the cores were extracted in an unbroken condition . Not only did they obtain a complete section of the ...
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Häufige Begriffe und Wortgruppen
alternating current amount angle Anthracite apparatus arrangement attached bars bolts boring bottom brake cage carbon carbonic acid carried cent centre chain coal coal-dust coils Colliery compressed connected consists cost cylinder depth distance drill driven drum employed engine explosion feet fire-damp fixed flange friction gear groove haulage hole inclined Inst iron lamp latter length lever lifted load longwall lower Lye Cross machine method mines motor obtained ordinary passes pieces pillars pipes piston placed plate plunger position pressure prevent props pulley pump quantity rails revolutions per minute roads rods roof rope round safety lamp screen screw seams Série shaft shown in Fig side sliding South Wales speed stall steam steel stroke surface timber tippler tool tube valve velocity ventilation vertical water gauge weight wheel winding winding engine wire yards