Singer OHV Watercooled 4 Valve Racer, 1912
The new Singer racer with four overhead valves and water-cooled head.
Design of water-cooled head and valve actuating mechanism.
Singer 1912 4 Valve Watercooled Engine
En abril de 1912 las principales revistas de motociclismo de Gran Bretaña: “The Motor Cycle” y “Motor Cycling” describían un nuevo modelo para competencias presentado por Singer y con grandes expectativas puestas en las carreras del Senior TT y en Brooklands.
Diseñado por Louis Coatalen, de la Sumbeam Co. el motor era un 500 cc de 85 x 88 mm. de alta compresión con cuatro válvulas a la cabeza y tapa de cilindro refrigerada por agua. El árbol de levas inusualmente estaba ubicado en la parte delantera del motor y era comandado por cadena, mientras que el magneto Bosch también era comandado por otra cadena expuesta ubicada en el otro extremo del árbol de levas. La tapa de cilindros estaba abulonada al cilindro (que era refrigerado por aire) mediante unas bridas estrechas y contenía cuatro válvulas, siendo cada par (de admisión y de escape) comandados por una única varilla.
Dos pequeños radiadores, que contenían 11 litros de agua y estaban colocados tipo alforjas en el frente del tanque, refrigeraban la tapa de cilindros actuando por el sistema de termosifón. Otras innovaciones fuera de lo común era el control de la bomba de aceite mediante un pedal montado en el apoyapié derecho que se accionaba con el taco. El tanque de combustible era de gran capacidad y el silenciador algo inusual.
Los ingenieros de Singer esperaban lograr velocidades de 130 a 145 Km/h, pero problemas en las válvulas y sopladuras de la junta de tapa de cilindro hicieron que en las pruebas iniciales el prototipo no superara los 100 Km/h. A pesar de rastrear publicaciones posteriores no pude encontrar ninguna noticia de este modelo, por lo que supongo que terminó siendo archivado en el olvido, como tantos otros diseños demasiado arriesgados para la época.
The Singer Co. have evolved a very novel engine for racing purposes with which they expect to do great things at Brooklands. The power unit was designed by Mr. Louis Coatalen,. of the Sunbeam Co. The bore and stroke remain 85 x 88 mm. respectively, so that the machine is eligible to compete in the 500 c.c. class. The head is water- cooled, and in it
are placed four large valves, two being for the exhaust gases and two
for the inlet.
The ports are cast in the head. A roller chain-driven camshaft in front of the engine operates stout push rods, opening the valves by a neat overhead rocker system, which can be clearly
seen in the accompanying illustrations. The exhaust valves can be depressed by the usual hand lever through a neat cam gear bolted on to the lower top tube. Two small water radiators are carried pannier fashion, attached to the down tube, circulation being carried out on the thermo-syphon system. The magneto (an enclosed Bosch) is driven by a separate exposed chain off the end of the camshaft. The water-cooled head is bolted down to an air-cooled cylinder with tapering flanges.
Other Departures from Standard.
Besides the engine there are several unusual points on the machine, noticeably the webbed lug to take the rear ends of the top tubes, also the neat method of controlling the oil pump by a pedal mounted on the foot-rest. All that is necessary to inject a charge of oil is to depress by the heel a pedal fitted on the right footrest. This raises the pump handle by means of a Bowden wire, the plunger being afterwards depressed by means of an, internal spring. It is quite reliable, having received a prolonged testing at Brooklands.
The tank comes to the level of the top of the frame on one side, so as to give a greater capacity. The silencer also is unusual, but as its construction will be clear from the photograph a description is unnecessary. It is hoped that the machine will accomplish the speed of eighty to ninety miles per hour, and its performances will be watched with interest by followers of the racing game.
Sources:
Sergio Scalerandi & Howard Burrows, and Boston City Library.
Reproduced with acknowledgement to Mortons Motorcycle Media, holders of the copyright for "The MotorCycle" and "Motorcycling".
