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366 THE MARINE DRIFT BOLT DRIVER FOR SHIPYARDS which he. will use as headquarters. Mr. Root handles the marine castings busi- ness of the Central Foundry Co. Centrifugal Pumps A pamphlet is being circulated by the De Laval Steam Turbine Co., Trenton, N. J., illustrating and describing a com- bined steam turbine and_ centrifugal boiler feed pump. On this machine the steam turbine rotor and the pump im- pellers are mounted upon the same shaft and are enclosed in the same housing. The pumps are made in _ capacities from 2000 to 10,000 boiler horsepower. Drift Bolt Driver The drift bolt driver shown in the accompanying illustration has been de- veloped by the Denver Rock Drill Mfg. Co., Denver and New York. The machine is 22 inches overall, weighs 68 pounds and can be handled by two men. It is so arranged that the lower handles can be placed in the same plane as the upper ones for driving TWO-MEMBER LOCK NUTS FOR MARINE WORK REVIEW August, 1918 horizontal bolts in narrow places, - or across the upper handles for up or down bolts. While the hammer is _ powerfy] enough to drive the largest drifts jp wooden ships rapidly, its comparatively slight recoil allows it to be used on the staging around the ship, and for up bolts and treenails on the bottom or sides of the vessel. Different snaps for the large drifts, treenails, and headed bolts are provided. A trigger in the handle controls the in- let of air at the will of the operator. When desired, it can be fitted with an air feed for driving horizontal bolts or those pointing up. Lock Nut of New Type While many kinds of lock nuts have been brought out from time to time, none has embodied principles similar to the device shown in the accompanying illustration. This check nut is a product of the Drake Lock Nut Co. of Ohio, Cleveland. As the 'illustration clearly shows, the device consists of two sections, a lower member which seats itself firmly on the casting or other part through which the bolt or stud projects and a_ supple- mentary nut which is screwed down to meet the lower member. The lower member is provided with a pilot that fits a counterbored depression in the lock nut. This pilot has at its top a 25-degree angle which, in opera- tion, engages an angle of the same de- gree at the base of the countersunk depression in the upper member. The pilot is slotted in four places. Thus, after the lower nut is firmly seated, the action of the upper nut compresses the pilot, causing it to freeze firmly to the threads of the bolt. By referring to the sectional view, it is seen that the device is so constructed that there is ample space between the two members after the upper nut has been screwed home. This principle applies to the space be- tween the top of the pilot and the root of the countersinking as well as to the space between the hexagon nuts. Owing to the fact that the move- ment of the slotted member is not cir- cumferential, no wear is brought on the threads as the device is locked. Thus, the nuts are designed to be used a num- ber of times without injury to the bolt threads. It is said that these nuts have given satisfaction under the most exacting re- quirements, among them being an in- stallation on 3-inch piston air drills as used in shipyards. An interesting test was also made in marine engine-room service. In this case double 1-inch nuts were used but, owing to the excessive vibration, they had to be watched care- fully and tightened daily. The lock nut under discussion was installed and is