THE NEW DAIMLER “DOUBLE-SIX.”
DETAILS OF A NOVEL TWELVE CYLINDER ENGINE BY A FAMOUS FIRM.
THOUGH primarily intended for use in fast travelling vehicles of the luxury class, the new Daimler “
Double-Six” is full of technical details that cannot fail to interest the student of design. The new engine has a capacity of just over seven litres and is rated at 49.4 h.p., the cylinder dimensions being 81.5 mm bore by 114 mm. stroke. The reason for adopting twelve cylinders in place of the already smooth running sixcylinder model is to provide a power unit, which in the words of the makers ” runs like a turbine,” and in the case of the Daitnler sleeve valve principle, the multiplicity of cylinders has been carried out without the usual complications to be found with a twelve cylinder power unit, where the ordinary forms of valve mechanism are used. Cast in blocks of three, the cylinders are arranged in banks of six and set at an angle of 60 degrees. Seven bearings are employed for the support of the crankshaft, upon the crank-pins of which the big-end bearings of the “
H” section connecting rods lie in pairs, those of the right hand bank of cylinders being forked, thus allowing the diagonal pairs of cylinders to lie in the same transverse plane.
The form of aluminium piston used is very interesting, the skirts being split to well above the gudgeon pins, springs being arranged internally near the bottom of the skirts to ensure a good working fit with a complete absence of piston slap. The usual eccentric shaft mechanism for operating the sleeves has, of course, been duplicated, and the drive from the crankshaft is carried out in a particularly neat
fashion. In order to ensure of full lubrication of the sleeves directly the engine is started up from cold, an extra supply of oil is controlled by the priming lever, admitting oil directly to the tops of the sleeves.
To ensure a correct distribution of gases to each set of cylinders, a multiple jet Daimler carburettor is arranged on each side of the engine, the outlets being fed to a cylindrical aluminium casting, through the centre of which passes the water pipe from the heads of the cylinders to the radiator, thus assisting in the vaporisation of the mixture. Furthermore, the arrangement of the carburettors includes the warming and cleaning of the air as it passes to the intakes.
At the front of the engine there are two transverse shafts, the one above the crankshaft driving the two magnetos, whilst a second shaft below the crankshaft operates the impellers of two centrifugal water pumps. A Lanchester torsional vibration damper is arranged, as in the case of the previous Daimler models, and as may be seen from the accompanying illustrations, the details of the engine have been worked out with every consideration for accessibility.
We hope to be able to give fuller details of this new model and impressions of a road test in an early issue.
SIMPLIFIED GEAR CHANGING.
The new gear box demonstrated by Messrs. Lea & Francis, Ltd., recently, has been designed to facilitate gear changing, the gears being of the constant mesh type, the engagement taking place by means of internal clutches, instead of by the sliding wheel method. Though many drivers have deep rooted prejudices against so-. called ” fool-proof ” devices, there is still a great deal to be said for improved gear engagement, especially where quick driving is concerned.