Passing Comments
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Finishing Holes With Steel Balls
AMODERN method of sizing and finishing holes is known as ballizing. It is effected by pressing precision-finished metal balls of suitable size through the holes. The result is a high degree of accuracy and uniformity with a greatly improved finish—much better than that obtained by ordinary machining.
Although not entirely new the technique has recently been applied to arbor and power presses and airor hydraulic-powered machines for automatic production. The main feature is that the process does not remove metal, but, by a burnishing action, it improves the surface structure, leaving a layer of dense metal.
In carrying out the process a hole is machined under size and an oversize ball is forced through it, resulting in an expansion substantially equal to the interference fit. Part of the total expansion is a function of the elasticity of the material, consequently, the wall springs back by that amount after the ball has passed, but a portion of the deflection is permanent.
13allizing has been used successfully for holes of 0.02-in. to 5-in. diameter. However, it is not suitable for castings in which there may be hard spots or where the holes are partially interrupted or have undercuts within them. The speed of production is high and maintenance is limited to ball replacement. Tungsten-carbide balls can finish some 10,000 holes before replacement.
As a practical example, the holes in certain distributor gears are being finished at the rate of 800 per hour, with a tolerance of 0.005-in. The power press employed carries A28 a fixture containing 25 chromium-alloy balls. After each stroke a ball is sent automatically to the starting position for the next stroke, and 100,000 parts can be finished before it is necessary to replace the set.
Prophecies From the States
AT a November meeting of the Society of Automotive Engineers held at Oklahoma, a representative of the Cummins Engine Co. said that vehicle makers, highwayresearch officials and vehicle operators had been making some interesting predictions as to the future of road haulage. They believe that within a reasonable time tractors will haul loads of up to 43 tons at high speeds.
This assumption is based on certain factors. Amongst these are fewer restrictions on legal weights, more States allowing the use of twin axles on tractors, and a trend towards bigger trailers, 40 ft. long and 13i ft. high, which will demand more powerful tractors, partly because of their greater weight and the higher air resistance. Also, whilst the national average of speed limits in 1953 was less than 45 m.p.h., those permitted on the new limited-access highways and toll roads vary between 55 and 60 m.p.h.
It seems, therefore, that for the next 10 years engines in the 500 b.h.p. range will be needed, and will most likely be operating on oil, for units of this type give lower fuel and maintenance costs per mile or per hour.
Whilst it is generally understood that the oil engine has its greatest scope in long-distance and inter-city transport, it has been forecast that, by 1961, 15 per cent. of all lorries used in local delivery work will be running on oil.
The Police Were Too Nosey
TT is a common human habit to identify various things 1 by their smell. In this connection, and not long ago, two policemen observed liquid leaking from a drum on a stationary lorry. It was colourless, and the officers concerned, using the aforesaid method to ascertain what it was, were rapidly overcome and had to be sent off duty for a time.
It appears that the liquid was dimethyl-sulphate, the effects of which could, if splashed onto a person's body or clothes, be fatal if the person concerned did not quickly Strip and wash thoroughly. Incidentally, in this case, the driver was fined for carrying an " insecure " load.
Give More to M.LR.A.
AT the recent luncheon of the Motor Industry Research Association, the president, Sir Henry Spurrier, was unavoidably absent and at short notice the chair was taken by Mr, R. F, Newman, the Thornycroft director who is in charge of the company's big commercial-vehicle factory at Basingstoke. He substituted most ably, an opinion which was expressed by many present. His main theme was that M.I.R.A. did not receive from the industry as much support as its great value merited. He considered that, with the industry now so prosperous, it could afford to give more consideration to the future, With the development of new roads it was particularly essential to design and produce vehicles to use on them—vehicles on which gear changing would hardly be required. One point he made was that in America there was a cautionary note and they were not rushing too quickly into pneumatic suspension..
Incidentally, the U.S.A. was paying amazing attention to research. He had just visited that country and had found that Fords had 10,400 workers on research alone. American research had discovered a new noise which was called rumble." This was found in i.e. engines in which the compression pressure had been raised too high.
M.I.R.A. had had a successful year and had improved facilities, particularly for basic research and in connection with its proving ground, but it was important to remember that the Government helped it in a certain relation to how the members helped themselves.
Land-Rovers in African Rally
EARLY this month will see the start of the 8,500-mile
long Algiers-to-Cape rally, and of the 30 entries two British-driven Land-Rovers will be competing, a third Land-Rover having been entered • from France. One of the British vehicles is driven by Peter Riviere and Gyde Horrocks, the vehicle which they are using being that which recently completed a 25,000-mile South African journey and which has received very little attention since then. The other British Land-Rover is in the hands of Bill Wauchope and Erich Lessing, this vehicle having been used on Mr. Wauchope's farm and entered in several Land-Rover Owners' Club trials in Britain.
The rally will last for six weeks and will take the competitors across the Sahara through Nigeria. French Equatorial Africa, the Belgian Congo, the Rhodesias and into South Africa. The Land-Rovers are entered in the utility class and another entrant in this class is a large Berliet all-wheel-drive lorry. The two British Land-Rovers left for the Continent by Silver City Airways on Saturday. December 27,