The twin Metric, which is made in four sizes.
30-2, Mortimer Street, London
Motores Metric OHC
Finalizada la Gran Guerra los diseños aeronáuticos comenzaron a influenciar en el diseño de los motores de motocicletas. Es así que a fines de 1919 la recientemente creada firma Metric Co. de Londres presenta una gama de ocho motores con árbol de levas a la cabeza y otras características de avanzada.
El diseño de Mr Bacher, quien había estado antes involucrado con motores JAP, era limpio y moderno. La tapa de cilindro de aluminio era desmontable y la lubricación por bomba centrífuga.
El árbol de levas se encontraba totalmente encerrado en una tapa de válvulas y era comandado por un eje con engranajes oblicuos, siendo el primero en utilizar esta configuración.
El cigüeñal estaba montado sobre rodamientos a rodillos, mientras que el eje del árbol de levas lo hacía sobre dos rodamientos a bolillas.
El rango presentado comprendía cuatro monocilindricos de 255 a 500 cc y cuatro bicilíindricos en V de 510 a 1000 cc. En estos últimos, los cilindros eran iguales a los de los modelos monocilíndricos y además compartían varios componentes importantes. También había un modelo para carreras que tenía doble válvula de escape.
A pesar que sus fabricantes pensaban empezarlos a entregar a partir de Febrero de 1920, pienso que cuestiones de confiabilidad o de precio, hicieron que nunca fueran vistos colocados en una cuadro de moto. No obstante se veía como un diseño avanzado para la época, no?
After the Great War, aeronautical designs began to influence the design of motorcycle engines. In late 1919 the newly created Metric Co. London featured a range of eight engines with overhead camshafts and other advanced features.
The design of Mr Bacher, who had previously been involved with JAP engines, was clean and modern. The aluminum cylinder cap was removable and the centrifugal pump lubrication.
The camshaft was completely locked in a valve lid and was commanded by an axle with oblique gears, being the first to use this configuration.
The crankshaft was mounted on roller bearings, while the camshaft made it on two ball bearings.
The range presented included four singles from 255 to 500cc, and four V-twins from 510cc. The cylinders of the twins were the same as those of the single cylinder models and also shared several important components. There was also a competition model which had two exhaust valves.
Even though the manufacturers thought to start delivering them from February 1920, due to questions of reliability or price they do not appear to have been fitted to any production motorcycle.
Skew gears are used to drive the vertical shaft of the valve mechanism. The gear wheel above drives the magneto.
The oil pump shown in part section and in diagrammatic form. The rotating member, driven from the camshaft skew gear, throws oil by centrifugal force into an annular chamber and thence through a pipe to the crankshaft, and to the overhead valve gear on each cylinder head.
Section of the Metric engine cylinder head. The. valves are operated by rockers, and an overhead camshaft contained in a casing cast in one with the cylinder head.
Plan view of cylinder head of the racing model. showing location of the twin exhaust valves, inlet pocket, and sparking plug hole.
Cross section of the single-cylinder engine, showing the overhead camshaft.
Sources: Sergio Scalerandi, Graces Guide
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