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Impressive Demonstration —contd.
Page 70
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adhesion. and the only answer here was anti-skid devices. The very complex problems posed by these were now being investigated by Clayton Dewandre, Mr. Ballard said.
The film portrayed tests in a series whose results were used to compile the graphs accompanying this article. These illustrate quite clearly the effectiveness of the G-Matic valve. The most interesting aspect is the way in which braking characteristics almost identical to those of the laden outfit were obtained with the light/laden valve in part-laden and unladen tests and when the tractive unit alone was braked. The most important point, however, is that a far greater rate of retardation was reached with the valve in use before skidding—and loss of control—occurred.
LIVE TESTS The same advantages were demonstrated on the actual road tests, when two outfits were used—one a Shell tandemaxle tanker, the other the single-axle semi-trailer and AEC tractive unit used in the filmed tests. Both were run halfladen at first, the tanker with its front compartments filled and the single-axle outfit with the load on the rear half of the platform. When the light/laden valve was disconnected heavy braking locked the driving wheels and, when braked on the turn, there was an obvious tendency to jack-knife with 'both Outfits. When the valve was linked into the system. however, the only wheels that locked on both outfits were the fronts, and when braked on the straight the outfits ended up perfectly straight, whilst on turns there was never a sign of a jackknife.
The Clayton Dewandre test vehicle was afterwards put through the same exercises, first with the tractive unit only, then with the semi-trailer unladen. In both cases the same improvements when using the 0-Made valve were demonstrated.
When given the opportunity of driving the test vehicle 1 found the stability— and the stopping performance—greatly improved when the light/laden valve was in operation. Instead of the need to " correct " on the steering when running without the valve, the vehicle pulled up perfectly straight with the valve in use Because the pedal effort was not overlight with the valve in use, much more control of braking was possible; and although kicking the front wheels meant that the front end went off course when braking on a curve, this was only with maximum-pressure application, and control could be regained by reducing the effort.
Altogether, the tests were most convincing and it is certain that a driver used to an attic outfit fitted with the light/laden valves would feel much more confident about braking in an emergency when driving empty. This is confirmed by the news that a tanker operator who had tested the equipment on one outfit very soon put in a request for 400 more sets! I can see a great demand for the G-Matic, and wise operators will get their orders in quickly. Birfield Acquires Auto Transmissions: The share capital of Auto Transmissions Ltd. of Coventry and of its associated company, Axel Wickman Ltd., has been acquired by Birfield Ltd. The present managing director of Auto Transmissions. Mr. A. S. Lamburn, will join the new board of directors.