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ALEX DEN OUDEN |
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Oude techniek en werktuigbouw, industriële geschiedenis en archeologie |
Historical engineering and technology, industrial archaeology and history |
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| © AdO 1998 ... 2004 | ||
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The description and illustrations given here are taken from Spon's Dictionary of Engineering, Div. VI, pp.2237-2239, edited by Oliver Byrne and published in 1873 by E.& F.N. Spon in London.
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The crane is worked by a single oscillating cylinder I, shown enlarged here. It is supported by brackets on the bed-plate B. The joints for the steam and exhaust pipes at the trunnions are made tight by gun-metal cones J, fitted to the trunnions and held by studs in the brackets. When these have become polished by working, the wear upon them is very slight, and this construction has been found very suitable for the rough treatment to which cranes are usually subject.
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| On the crank-shaft K is a friction-wheel L, kept continually revolving by the engine. On the second shaft M is another friction-wheel N, which can be moved by the lever O into gear with the driving wheel L, or by an opposite motion of the lever, can be pressed against the brake P, or (when lowering the load) can be held between the two. The other end the shaft M carries pinions, gearing into the wheels on the shaft of the chain-barrel Q. | |
There are two pairs of wheels and pinions, R and S, for varying the speed according to the weight to be raised. The pinions are thrown in and out of gear by a sliding key. By this means the width between the frames that would be required for moving the ordinary clutch is saved. | |
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A principal difficulty experienced in steam-cranes for ship-purposes is in the arrangement of the turning gear, so that when the vessel leans over to one side, the crane shall be powerful enough to swing the weight and yet not cause a sudden start or shock to break the gear. In this crane, a coned friction-clutch is used, to allow a slip at first to start the weight gradually. The arrangement of the foundation plate C of the crane admits of a much larger spur-wheel than usual being employed to bring up the power. On the crank-shaft K is a worm T, working into a worm-wheel on the shaft of the bevel-wheel U, which gears into the two bevel-wheels above and below. As these are kept constantly revolving by the engine, the crane can be moved round either way by raising or lowering the coned clutch V by the lever and screw W. The lifting lever O and the screw W being close together, the two operations of lifting and turning the weight are easily managed by one man. |
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The valve motion of the oscillating cylinder I is designed to compensate for the oscillation of the cylinder without the use of sweeps and guides. A radius rod X is centred on the cylinder bracket and connected to the eccentric rod Y by a link Z, to which the valve-rod is attached by a pin. The link Z combines the vibrations of the eccentric rod Y and radius rod X, so that at the point where the valve-rod is attached the curve described by the radius rod compensates for that described by the eccentric rod in such a degree as to bring the valve-rod into the curve it would naturally be made to describe by the oscillation of the cylinder, as shown by the diagram in the final Figure. |
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