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How Propeller is Reclaimed by Bronze- Welding SOUTHERN shipyard was faced with the problem of a propeller shaft-way which had been bored over- size in the hub of a four-bladed steel propeller. In ordinary practice, the whole casting would have been con- demned by the shipwright, which would have necessitated the expense Shaft Hole of Propeller Built Up of ordering a new casting and delay- ing the work for a_ considerable length of time. The welding department decided to build up the shaft hole by bronze- welding. The interior circumference of the shaft-hole was built up and _then machined to fit. The illustra- tion shows the propeller after bronze- welding had built up the shaft-way. Cutter Blades Preserved by Hard-Facing Edges COMPANY in Maryland main- tains a fleet of dredges that are constantly engaged in harbor im- provement work. The bottom of the bay is mainly sand, and considerable difficulty results from the wearing away of the steel cutter blades due to abrasive action. These rotary cutters consist of a steel casting having six spiral blades, extending from an annular base and terminating in a central point which is attached to the drive shaft. <A heavy frame, known as the ladder, supports the drive shaft and the cut- ter. One end of the ladder is attached to the deck of the dredge and op- Blades of Cutter with Stellited Edges erates in the manner of a hinge so that the cutter can be raised or low- ered by a hoisting boom. On the un- derside of the ladder is the suction pipe. The sand is loosened by the rotary cutter and drawn through the pipe by a centrifugal pump and forced out at the point of disposal. The six cutter blades are about 12 inches wide, one inch thick and taper to %-inch at the cutting edge. In an effort to lengthen the life of these blades the company applied Haynes Stellite to some parts of the cutting edges of the blades of one of the cut- ters aS an experiment. At the end of one year the sand cutter was removed from service and inspected. The hard faced parts were only slightly worn while the uncoated metal of the cut- ter was worn away to such an extent that an early replacement was nec- essary. As a result of this test, the dredg- ing company now hard faces with Haynes Stellite all blades as shown in the accompanying illustration. Sec- tions of the blades about 4 inches wide and 25 inches long were hard faced along the edges as shown. This procedure increases the life of these cutters many times and has effected a savings in both time and money for this dredging company. Propeller Type Blower Will Exhaust Gases HIS unusual looking piece of equipment is a Westinghouse pro- peller-type blower of special design Welded Propeller Type Blower which is to be installed on a gasoline tanker to exhaust the gases from the pump room to the atmosphere. The blower is turbine driven and is rated at 6000 cubic feet per minute at 4- inch static pressure. : The entire unit is of welded steel construction and of extremely simple design. The propeller is three-bladed and is driven by a single-wheel tur- bine having inside buckets milled in the wheel, through a steel shaft sup- ported in grease-lubricated bearings. This is another application of the Westinghouse blower, which is an in- vention of H. F. Schmidt, consulting engineer, and is built at the South Philadelphia works of the Westing- house Electric & Mfg. Co. MARINE REVIEwW—January, 1931 New Electric Air Oscillator Has Double Horns MORE powerful electric fog signal to increase the safety of navigation has been installed by the lighthouse department on each of three new lightvessels which are to go into commission shortly. This New Electric Air Oscillator in Place new signal is a powerful type of elec- tric air oscillator. The three new lightships will replace the three older ships which have given many years of excellent service at Nantucket Shoals, Fenwick Island Shoal, and Frying Pan Shoals. The electric air oscillator is sim- ilar to those which have been in op- eration at a number of shore sta- tions and lighthouses. A smaller and less powerful type of electric air fog signal, known as the ‘‘nautophone,” has been in operation at several sta- tions. ‘The installation of these electric air oscillators upon lightships and at shore stations marks another ad- vance in the use of electricity for navigating purposes. The accom- panying illustration gives a good idea of the construction used in mounting the fog signal on the new Nantucket Shoals lightship. The use of double horns pointed in opposite directions. allows for a more uniform distribution of sound throughout the horizon than can be obtained with a fog horn having but a single horn. The pitch of the sound signals emitted by this latest type of fog signal is musical. It differs from the harsh raucous signals which are characteristic of many fog horns op- erated by steam or compressed air. The maximum intensity and uniform pitch of the signals are maintained throughout the duration of the blasts and for the time desired. 53