. Electric railway review . tool with all of thestrains in one straight line between the point of the drill and thepoint of the feed screw. The drill spindle has a ball thrust bearinglocated at the base of the gear case casting. Provision is made for the application of grease to the gearswhich are all hardened by special process. The gears when run-ning at their normal peripheral speed of about 475 feet per minuteare absolutely noiseless and on a drill capable of drilling 114-inchholes in iron or steel, the energy required to drive them up to thisspeed empty Is about IS watts or 1-40 of a mech
. Electric railway review . tool with all of thestrains in one straight line between the point of the drill and thepoint of the feed screw. The drill spindle has a ball thrust bearinglocated at the base of the gear case casting. Provision is made for the application of grease to the gearswhich are all hardened by special process. The gears when run-ning at their normal peripheral speed of about 475 feet per minuteare absolutely noiseless and on a drill capable of drilling 114-inchholes in iron or steel, the energy required to drive them up to thisspeed empty Is about IS watts or 1-40 of a mechanical total energy required by this drill running empty at full speedIs 83 watts or 1-9 horsepower, including all mechanical and elec-trical losses. The temperature rise of the drill after 10 hours fullload service will not exceed 35 degrees C, or 63 degrees F. abovethe surrounding air. This is accomplished by the excellent elec- Duntley Portable Drills Duntley Portable Elect Ms—Section of Two-Motor Drill,. Field Plan—Two-Motor as the single-motor. 3-motor and ■2-motor drills, respectively. Thesingle-motor drill which the manufacturers consider adapted to allclasses of general work for drilling in iron and steel up to 1%inches in diameter is as its name would signify, provided with onerevolving electrical element or armature. The single-motor drillsrange in size from %-inch capacity for the breast drill up to IV*inches capacity. The magnetic field casing is a steel casting ofhigh permeability to which are bolted drop-forged pole pieces. Thearmature is of the slotted t.\pe. with hand-wound coils of doublesilk covered magnet wire secured in place by means of wedges, nobinding wire being used. The commutator is built up of hard-<irawn copper bars, insulated with the best grade of amber mica, trical design in connection with a special ventilating system whichkeeps a stream of cold air pouring through the windings at aUtimes. A fan is provided on the armatur
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectstreetr, bookyear1906
