The following text may have been generated by Optical Character Recognition, with varying degrees of accuracy. Reader beware!

340 holes for the coupling bolts are now Crilled and reamed by means of a jig. The coupling bolts are steel, fin- ished all over and furnished with nuts and split pins. The air pump is of the Edwards type, driven from the low-pressure crosshead through the medium of a walking beam. The pump casing is cast iron, lined with composition metal and is attached to facings on the engine hed plate. The pump rod, or piston rod, is steel covered with brass. The buckets are cast iron with composition followers. The pump casing is bored on a vertical boring mill, after which the necessary flat surfaces are finished on the planer. The holes for locat- ing it in place and those for the cover are drilled by jigs on the ra- dial drill. The pump rod is turned in the lathe, cased with brass and then carefully finished. It is ob- vious that it must be both round and parallel to insure the pump function- ing without leakage. The pump pis- ton is cast:iron. This 'unit is ma- chined on the vertical boring mill by methods familiar to every mechanic. The air-pump crosshead is a steel - forging, finished all over.. This mem- ber drives the bilge pumps also, these being located at the sides of the air The crosshead pump. is first cen- FIG. 17--SEVE >} - | 7 RAL REVERSE-SHAFT BRACKETS LOCATED ON THE PLANER FOR MACHINING AT ONE OPERATION THE MARINE REVIEW tered and the round portions finished in the lathe. Flat portions are next finished on the planer after which the holes for the air pump and bilge pump pistons, or plungers, are ma- chined. °Thi¢ 'work is done on a horizontal boring mill. The holes are first roughed, drilled and then bored to size with boring bars. Care is exercised to make sure that the holes are correctly spaced the required dis- tance apart, otherwise the unit would not align properly in. the assembling operation. * Machines 40 Pieces Simultaneously In ordinary marine-shop practicé, it is customary to machine parts one at a time, due to the fact that manu- facturing operations for a given period are confined to but one engine. In building marine engines in lots, how- ever, the work is expedited materially through machining a large number of parts at one operation. This saves a large amount of time, due to the fact that it takes approximately as long to set up a machine tool for a given small operation as it does to machine the work after it is set up. An excellent illustration of how time is saved at the Hamilton plant in machining units in quantities is shown in Fig. 20. The parts shown are air-pump shaft boxes. This oper- ation, which is the first machining op- milling the flat sur- faces. The work is done on a large horizontal milling machine. Forty box halves are strapped to the platen at one set- ting." A large 'in- serted-tooth cutter eration, consists of. July, 1919 is utilized for milling. After the pieces are milled; they are held together im; pairs: and .- bored.' to receive the. shaft. This work is gen. erally done on the vertical boring mill as this tool, owing to the fact that its platen, or face plate, is hori. zontal, readily lends itself to opera- tions of this kind. Under ordinary working conditions, a pair of these boxes will last for many years with- out: attention, provided, of course, they are properly lubricated. Wiss wear develops, it is a simple matter to file away a slight amount from, the flat surfaces that are in -contact when the boxes are assembled, and scrape the box to a good fit again, The walking beam that> drives the air and bilge pumps is a double, unit made of steel plate. The first opera- tion in machining these parts is rough- ly to cut them into the desired shape, after which they are surfaced on the planer. Several are held on the platen at one setting by means of pinch dogs and clamping posts. For further finishing operations, several plates are fastened together for machining. The outside is fin- ished on the planer and shaper after which the holes are drilled and bored. Fig. 18 shows eight plates fastened together in position under a radial drill. Here the hole is finished in one end and an arbor inserted for holding the plates in correct loca- tion during subsequent operations. This arbor furnishes a simple means to the desired result. After the holes ,are machined, the plates are taken apart and finished smooth by drawfiling. As previously indicated, the walking beam consists of two plates, which are spaced the required distance apart to accommodate the link that drives the unit from the crosshead. Thus, while the distance between the holes need not be held