. Transactions of the Institution of Mining Engineers . -iron, grey cast-iron, malleable cast-iron, high-carbon cast-steel, and non-ferrous castings such as aluminium, bronze, etc. The conditions enumerated above are successfully fulfilled by meansof a special flat compound low-voltage generator, which feeds thecircuit through a constant-current controller in the form of a solenoid-operated resistance. This solenoid is in series with the arc, the currentthrough the arc being controlled by automatic variation of a variableresistance in response to the pull of the solenoid, which compresses orre
. Transactions of the Institution of Mining Engineers . -iron, grey cast-iron, malleable cast-iron, high-carbon cast-steel, and non-ferrous castings such as aluminium, bronze, etc. The conditions enumerated above are successfully fulfilled by meansof a special flat compound low-voltage generator, which feeds thecircuit through a constant-current controller in the form of a solenoid-operated resistance. This solenoid is in series with the arc, the currentthrough the arc being controlled by automatic variation of a variableresistance in response to the pull of the solenoid, which compresses orrelaxes a series of copper and carbon plates. The ordinary carbonresistance can be used, but is not successful, since the plates becomevery dirty, thereby causing excessive heating. There is, in addition, a pilot motor, which is operated by a switchat the welding-tool handle, by which a further adjustment in resistancecan be made, so regulating the amperage that the operator can changethe arc current without leaving his work. This is very essential when. Fig. 1.—RoBEY Compound Set and Flywheel in Gutted Six Cracks can just be discerned on the Face of the Wheel,AS indicated by the Arrows. building up a large patch, as the heat increases with the deposition ofthe metal, owing to the path of the current lying through the deposit;and as it is essential, in order to ensure a successful patch, that thetemperature of the deposit should be kept as low as possible compatiblewith complete fusion, a gradual reduction of arc current is is known as the Wilson system, or constant-potential type, in whichan open-circuit voltage, not exceeding 35 volts, is used. Inasmuch asthe current control is automatic, it differs in this respect from— (1) The drooping characteristic type, with a voltage of from 60 to75 and a current varying in inverse ratio to the voltage; and (2) The constant-potential type, with a voltage also of from 60 to75, but with the current control
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Keywords: ., bo, bookcentury1800, bookdecade1890, booksubjectmineralindustries
