MOTORING NOTES
THE 1927 DAIMLER CAR
I dive just returned from a delightful week's tour in a Daimler car, and during this time approximately a thousand miles were covered. An excellent opportunity was thus afforded of judging its capabilities, and I have nothing but genuine praise and admiration for its remarkable silence, smooth running and flexibility ; its wonderful powers of acceleration ; the ease with which it surmounts the stiffest hills ; and its supreme comfort. It is not mere maximum speed that makes a fast touring car, but rather a combination of rapid accelera- tion, smooth acting brakes, comfortable springing and ease of control. Given these qualities, quick journeys are possible without racing, and it is in this respect that the new Daimler makes such an excellent performance. Particularly is this excellence apparent when long journeys have to be under- taken, and the silence of the Daimler becomes a factor of ever- increasing importance in minimizing fatigue.
The cost of the maintenance of a car is really of more im- portance to the owner than the initial cost. In this direction the 1927 Daimler scores greatly, for the simple reason that its design has eliminated so many features from which trouble is most likely to be experienced. By substituting a smooth and silent sliding motion for the damaging and noisy hammer-and- anvil action of the poppet valve, the sleeves remove at once both the chief source of wear and the principal cause of troublesome adjustment. The sleeve-valve never requires either grinding or any other form of attention. So far from wearing out, its large surfaces run themselves into a more intimate contact and a more perfect finish, which shows up In the vicinity of the ports as a brilliant but dark-hued gloss. One of the most important advantages of the sleeve-valve engine is the absence of the springs on which poppet valves :depend for one part of their movement. The sleeves are operated by connecting rods, and are thus as positive as the piston in their action in both directions. This not only eliminates the spring with its attendant liability to breakage and high-speed valve chattering, but also removes the delicate tappets which are a constant cause of troublesome adjustment and source of ever-increasing noise.
Reduction of wear and tear to the minimum is not the only advantage of the Daimler sleeve-valve engine, which has the further advantage of possessing an absolutely pocketless com- bustion chamber. As is well known, valve pockets not only decrease the efficiency of an engine by loss of heat through their extensive surfaces, but they are prone to cause detona- tion, and thereby to set up a form of knocking that is both unpleasant to the user and detrimental to the engine. In the sleeve-valve engine, perfect combustion of the mixture is assisted by the central position of the ignition plug from which the nucleus flames engendered by the spark are carried like burning torches quickly to all parts of the chamber. There is an ideal simplicity about the Daimler cylinder head with its central ignition plug, and the fact that the cylinder heads themselves are so easily detachable greatly facilitates the de- carbonization of the -surface on the rare occasions when this may become necessary.
An extremely interesting system of dual ignition is one of the features which specially appealed to me. The magneto or the battery can be brought into action as required by merely moving a switch. Hitherto, only the most expensive ears have been fitted with dual ignition, but it is so widely recog- nized as a desirable precaution that it has been incorporated on all the 1927 Daimlers. Both systems operate over the entire speed range and either can be used as preferred. There is no perceptible difference in their practical effect, but the battery ignition gives a full strength spark that is independent of engine speed and is, therefore, an absolute assurance of quick starting and perfect slosir-speed running.
Economy in fuel consumption appeals very strongly to every car-owner, and the 1927 Daimler is especially interesting
because the driver is provided with means whereby he can exercise ready control over the amount of petrol flow from the float chamber to the jets, and also over the temperature of the cooling water in the cylinder jackets. There is an intimate connexion between these two things, maximum economy oi fuel consumption being only possible when the engine is hot. When the engine is cold, a more liberal supply of petrol essential in order to compensate for thevieakening of the rax. ttire due to chndensation on the'surfaces of the induction pip( and to the possibly imperfect combustion of the petrol in the • mixture that enters the cylinders. The very necessary van. tion of supply is achieved by the movement of the ” eConomy lever" on the steering column, which thus enables the driver to adapt the carburetter instantly to suit the prevailing cond. tions ; the temperature of the cooling water being indicated to him by a thermometer upon the radiator. In order to insure easy starting, however cold the weather and however long the car has been standing idle, a small primer, connected with the economy lever, not only' primes the cylinder with a rich mixture, but also with oil, thus eliminating any trouble arising through dryness if the engine has been out of use for a long time.
The Daimler four-wheel brake system is one of the most important features of the 1927 car from the driver's point of view, their remarkably even grip, resulting from their per- fectly balanced action, giving a degree of safety that enablis better use to be made of the power of the engine and a higher average speed to be maintained without transgressing " Safety First" as the all-important rule of the road. One fact that will appeal specially to the owner-driver regarding this brake system is that the driver is relieved of the fatigue of applying high pressure to the brake pedal. An auxiliary mechanism that derives its power from the engine is employed in such a way as to increase the braking force by an amount proportional to the driver's own effort. - While the brake is very light in action' it retains the senSitii,eness of personal control which is so essential to safety and comfort.
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E. T. BROWN.
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