Running-in Practice Discussed
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A T an informal meeting held in PA London on Monday and organized by the lubrication group of the Institution of Mechanical Engineers, running-in practice for internal-combustion engines was discussed.
As an -introduction to the subject, the first speaker referred to running-in practice as applied to engine manufacture. He said that the determination of the completion of the running-in of piston rings and cylinder bores was when full power could be applied without scuffing, or when oil consumption stabilized at an acceptable 1eve1-0.5 per cent, of the fuel-consumption rate was suggested. Influences on running-in time were referred to, the point being made that crankshaft and bearing improvements had resulted in relatively rapid acceptance of high loadings for these parts.
One of the speakers who followed said that part of the problem was the beddingin of piston rings to cylinder bores which were not truly round. To do this quickly he advocated coating the top compressibn ring with an abrasive compound to a depth of 0.001 in. Such piston rings were currently being marketed in Great Britain.
Other speakers suggested that substances such as aluminium oxide could be added at the rate of about 0.5 per cent. to the fuel oil or petrol, in which they were soluble. The oxide formed an abrasive when burned, and helped the rapid running-in of rings and bores. It was said that the use of such additives caused no damage to fuel-injection systems because of their complete solubility in fuel, and none to bearings because of the small quantity used.
A time of two hours, compared with five or six using no additives, was said to have been found sufficient on some engines for complete running in when using these fuel additives, with no adverse effect on wear characteristics.
FRAMELESS TIPPING SEMITRAILER DEMONSTRATED DEMONSTRATIONS of the Villiers frameless trailer were held this week in London. The Marketing of this tipping semi-trailer was reported and the unit fully described in The Commercial Motor of November 11, 1960.
Design of the unit differs from that of a 'conventional tipping semitrailer in that it does not have the usual heavy frame. The hydraulic ram engages with the front end of the body, and is mounted on a special plate above the fifth-wheel coupling. The main hydraulic cylinders are imported from the Anthony Co., Streator, Illinois. U.S.A., and a Dowty hydraulic pump and Crane fifth-wheel equip
ment, springs and axles are used. The semi-trailer demonstrated had a 10-cu.-yd. all-steel body, built by H.B.R. Metal Industries, Ltd., Sunbury. Light-alloy bodies are to be built by G. E. Neville and Co., Ltd., Mansfield. Two production tippers will go into service shortly.