Metal Rectifiers for Welding
Page 67
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WHILST alternating current is satisfactory for most arc welding, •direct current sometimes permits easier and more effective working. In a number of applications it is essential, as in the welding of aluminium, copper, nickel and their alloys, corrosion-resisting steels, and the -lighter gauges of mild steel.
Traditionally, D.C. for welding has been supplied by motor-generator out fits, but Quasi-Arc, Ltd., Bilston, Staffs,
has done much to popularize the metal rectifier. Typical of a new range of
Quasi-Arc rectifiers is the MCR.375 • single-operator welding set. It consists of a step-down transformer, a variable reactor and a selenium metal rectifier enclosed in a sheet-metal mobile cabinet measuring 32 in. by 33 in by 51 in. The equipment weighs 81 cwt. and is designed for three-phase operation.
A three-phase moving-core reactor gives stepless regulation of output over the full current range from 30 to 375 amp. and adjustments can be made on load. Full rectification is provided by the three-phase rectifier, which is bridgeconnected, whilst the components are cooled by a fan fitted with a centrifugal switch to prevent their use if the fan fails.
A power saving of over 40 per cent. is claimed for average working condi tions, and the absence of any con tinuously moving parts, except for the fan, reduces maintenance costs. It is also stated that the rectifier gives superior arc stability, a smoother weld and greater ease of striking.
A New Spray Gun A GRAVITY-FEED spray gun of .1-3. entirely new design has been developed by the Aerograph Co., Ltd., 47 Holborn Viaduct, London, E.C.1. Known as the Type GFG, it gives particularly fine atomization and greater speed than normal. All the vital body threads are hardened to resist wear.
Lucas Self -aligning Mirror THE Lucas self-aligning device has now been introduced on model 406 and 407 wing mirrors by Joseph Lucas, Ltd., Great King Street, Birmingham, 19. It gives a good swing-hack action to absorb accidental bumps and obviate damage to the mirror.
Incorporating the new device, the 406 mirror with convex glass costs 5s., whilst the flat-glass 407 may be obtained for El 3s. 6d.
New Type Treadplate SO far available in two patterns only, heavy and light, the P-G-P aluminium treadplate produced by the British Aluminium Co., Ltd., Norfolk House, St. James's Square, London. S.W.1, can now be supplied also in
small pattern. The design has been devised specially for such items as kicking-plates, bulkheads and flooring on buses and coaches, and for other applications where a • lighter, small pattern is more suitable.
Self-curing Body Filler
L'EATURES of a self-curing paste I body filler known as Car-Pak, produced by Cago, Ltd., 38 Lakey Lane, Birmingham, 28, are that no heat is required for its application, it can be used for filling to any depth in one operation, it does not shrink and dries metal-hard in 30 minutes.
Further claims for the preparation are its ability to adhere to all metals and its resistance to oil, grease, petrol and so on. It is also said to provide an excellent painting surface.
Mixing and spreading apparatus is supplied. There are two sizes of trade Pak weighing 3 lb. and 10 lb. A trialsize kit may be obtained for 7s. 6d.
Sand for Skid Correction AN electric road sander similar to those used in North America is now available in this country. It is manufactured by the York Trailer Co., Ltd., Summit Works, Burnley, Lancs.
Its object is to ensure that a driver always has the means at his disposal for correcting a skid and overcoming wheelspin. One filling of the containers is considered to be sufficient for a 300mile journey.
The equipment consists of two pressed-steel containers, each with flexible rubber nozzles, which are mounted on the chassis frame immediately ahead of the driving wheels. The containers have a capacity of approximately 261 quarts. The material used is dry seaside gravel.
Sand is distributed by means of impellers operated through electric magnets which are controlled by a switch on the dashboard.
New Tool Kit P-1 A NEW tool kit No. 4 is now avail able from J. Stead and Co.. Ltd., Manor Works, Cricket Inn Road, Sheffield, 2, and consists of a plastics wallet containing 6-in, combination pliers, a cabinet-handle screwmaster, a Phillips-type screwmaster, an amber plug tester and a four-in-one screwmaster. The kit costs El 3s.