MOTOR RESEARCH WORK

Shannon News, 14 September 1928, Page 4

MOTOR RESEARCH WORK

Extraordinary intricate &nd delicate pieces of apparatus, wonderful >recordors for verifying instruments and testing materials were open for inspection at thc ; annual visitation at the National Physical Laboratory, Teddington, in June, when oyer 160 guests were received by Sir Ernest Rutherford, president of the Royal Society, Sir Richard Glasebrook, F.R.S., and Sir Joseph Petavel, F.R.S., the director, and introduced to many marvels^ Tests on complete;laminated motorcar and motor-lorry springs have shown that the resistance of such springs to repeated deflections is considerably, lower than would be expected from a consideration of the strength of the material of which they are composed when the latter is tested as machined test pieces. In orttar to investigate this question a special machine has been designed and constructed in the engineering department for applying repeated deflections to single spring leaves. The machine gives 1500 repetitions of the deflection per minute, and the results obtained have shown'that the reduction in strength in the completed spring is due to a skin on the individual leaves.When this skin is removed the resistance to fatigue may be increased by more than 100 per cent. Efficiency tests of a gearbox have also been carried out. In testing, a.gearbox the actual loss of power, rather than the difference between the input' and the 'output'powers 1 is measured by supporting the gearbox in such a manner that the torque on the gear-box-frame is determined. This method of test enables an accuracy of one-fifth of one per cent., in the efficiency to be Obtained with ease.

Another extraordinary intricate piece of machinery was for the accurate measurement .of the different elements of gears and hubs, and this was carried out by means ol tooth-form records produced on smoked glass by a special form of pantograph, which reproduces the profiles with an'accuracy of .OOOlin. as regards shape and position. The records obtained are fullsize and measurements are made on a projected image at a magnification of 50 times. The method enables all the different elements, such as tooth spacing, profile and alignment, to be examined independently.