. Railway mechanical engineer . ,Salem, Ohio. The base of this machine is strongly ribbedboth lengthwise and crosswise, and the T-slots are accu-rately planed, ample allowance of metal being left to preventspringing. The column is of semi-steel, ground to size, theinner column or post being reinforced by heavy ribs runningnearly the entire length. The outer column telescopes thepost and rests on a Ijall thrust bearing, making the swingingof the arm e.\tremely easy and also taking the thrust arm, which is of pipe section design, has a wide bearingon the column and is heavily ribbed to
. Railway mechanical engineer . ,Salem, Ohio. The base of this machine is strongly ribbedboth lengthwise and crosswise, and the T-slots are accu-rately planed, ample allowance of metal being left to preventspringing. The column is of semi-steel, ground to size, theinner column or post being reinforced by heavy ribs runningnearly the entire length. The outer column telescopes thepost and rests on a Ijall thrust bearing, making the swingingof the arm e.\tremely easy and also taking the thrust arm, which is of pipe section design, has a wide bearingon the column and is heavily ribbed to resist torsional andliending strains. It is raised and lowered by power and isprovided with an automatic knock out at both limits oftravel. Tlie arm is firmly clamped to the column by two conven-iently located levers, the bolts of which serve a three-foldpurpose. As shown in Fig. 1, these bolts act as limit screwsto prevent sagging and also as binders. In addition to this,when the levers are placed in the clamping position they. Fig 1—Silver Radical Drilling Maciiine tighten the split hub through which the elevating controllershaft runs, which prevents the elevating screw from being setin motion while the arm is clamped to the column. Thisavoids an\- danger of wrecking the machine. Another feature is the safety nut shown in Fig. 2. Thepurpose of this nut is to prevent the arm from dropping whenthe threads become worn in the elevating nut. The safetynut runs idle with >^-in. clearance between it and the arm,and when the threads wear out in the elevating nut, the loadis transferred to the safety nut, which brings it flush withthe arm, thus warning the operator in ample time to makereplacement and avoid serious accident. The safety nut alsoprovides for continuous use of the machine while the elevat-ing nut is Ijeing replaced. The head is arranged for rapid travel along the arm andcontains a two-speed back gearing that may l)e shifted whilerunning. The spindle is accurately gr
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectrailroadengineering
