Marcel Viratelle (1877 – 1954) fue un inventor frances que fabricó inusuales modelos de bicicletas a motor, motocicletas, sidecars y cyclecars entre 1906 y 1924 en París y Lyon-Villeurbanne.
En el Salón de París de 1906 presenta una bicicleta motorizada con soluciones de avanzada: motor cuatro tiempos de 178 cc (57 x 70 mm) con válvula de admisión por depresión y concéntrica con la de escape. Era refrigerado por agua con sistema por termosifón, radiador tipo “panal de abejas” y ventilador comandado por correa desde el eje del magneto. Tenías una caja de tres velocidades epíciclicas (formando una unidad con el motor) que se comandaba por medio de una palanca y un cable Bowden desde el manubrio, mientras que con otra palanca similar se comandaba el embrague. La ignición era por magneto, la horquilla delantera tenía una pequeña suspensión y la transmisión final era a cadena. Los posapiés podían ser desmontados y colocados a 90 grados para actuar como pedales en caso de falla del motor.
En 1916 Viratelle diseña un 350 cc válvulas laterales (73 x 82 mm) que es construido en cantidades muy limitadas entre 1918 y 1922, al que se le agregó un bicilindrico de 700 cc.
El motor era de aluminio y las válvulas estaban dispuestas en la parte trasera, mientras que la transmisión a cadena estaba completamente cubierta. Detrás del motor estaba integrada la caja de tres velocidades que se preseleccionaban desde una palanca en el manubrio pero que no se acoplaban hasta que se presionara el pedal del embrague.
En el caso del bicilíndrico, los cilindros estaban dispuestos uno al lado del otro y el cigüeñal era a 360°. En ambos modelos, los radiadores estaban colocados a los laterales del tanque de combustible y detrás de la horquilla, mientras que el ventilador ahora era comandado por correa desde el eje del motor. El arranque era por medio de una manivela desmontable que se guardaba colgada en los soportes del guardabarros trasero.
La horquilla tenía un interesante sistema de suspensión por hojas de elásticos que actuaban como resortes y como parte integrante de la horquilla misma. El cuadro atrás era rígido, pero el asiento y los posapiés estaban vinculados entre sí para mantener al conductor suspendido.
Las Virallete se destacaron especialmente en las grandes carreras de resistencia tan populares en ese momento.
Se conoce de la existencia de solo tres ejemplares sobrevivientes.
Address: 1907: Patent Office, Viratelle, 49 rue du Surmelin, Paris
Later at Society Electric, 17 rue Jean Goujon, Paris
Marcel Viratelle (1877-1954) was a French inventor who built unusual bicycles, motorcycles, sidecars and cyclecars in the years 1906 through 1924, in Paris and Lyon-Villeurbanne.
At the Paris Salon of 1906 Viratelle presented a motorized bicycle with advanced features: four-stroke engine 178cc (57 x 70 mm) with an overhead exhaust valve and an automatic inlet. The exhaust valve gives every impression of being desmodromic - that is, it is opened and closed mechanically, with a coil spring retaining the valve in place when fully closed. One writer goes so far as to suggest that the system was designed with valve overlap in mind, the inlet valve being sucked open during the final phase of the exhaust stroke prior to the piston reaching top dead centre. The same author writes:
It was water-cooled with a honeycomb radiator system somewhat similar to the Bradshaw, with a belt-driven fan from the magneto drive. The gearbox was three-speed in unit with the engine controlled by Bowden cable from the handlebars, with another similar lever controlling the clutch. The ignition was by magneto, the front fork had suspension and transmission was by chain. The footpegs could be dismantled and placed at 90 degrees for use as pedals in case of engine failure.
In 1916 Viratelle designed a 350 cc side-valve (73 x 82 mm) machine which was built in very limited numbers between 1918 and 1922, along with a 700cc V-Twin.
The engine was aluminum and the valves were laid out on the back, while the final drive was by chain in a fully-enclosed chain-case. Behind the engine was an integral three speed gearbox with preselection from a lever on the handlebars, and the gear was engaged by depressing the clutch pedal.
In the case of the V-twin, the cylinders were parallel with a 360° crankshaft. On both models the radiators were placed at the sides of the fuel tank and behind the forks, while the fan was driven by a belt from the crankshaft. The starting mechanism was by means of a detachable crank handle located on the the rear mudguard supports.
The front forks had an interesting suspension system consisting of steel blade springs integral with the fork assembly. The frame was rigid, but the seat and the footboards were sprung and linked together allowing the rider to maintain a steady position.
The Viratelle was often mentioned in the results for very popular endurance trials of the day, for instance the Tour de France.
Only three of these machines are known to have survived.
1. Alec Ulmann in The Bulb Horn.
See also The Motor Cycle, Feb 3rd 1921
A Water-cooled Lightweight
This is the Viratelle motor bicycle of 11/2 h.p., 57x70, water cooled, cooling being arranged on the thermo-syphon system, the honeycomb type radiator, with fan driven by belt from the engine-shaft, being fitted. In addition to the above, it has a three-speed epicyclic gear, incorporating a free-engine clutch, contained in an oiltight gear box behind engine. The change is effected by moving a lever attached to the right handle-bar, which is connected to the striking mechanism by means of a Bowden wire; a lever fixed to the left handle-bar controls the clutch.
The whole idea is very neatly carried out.
1907 Paris Salon
The Motor Cycle November 20th, 1907
At the same depot several models of the French-made Viratelle were to be seen. No one can accuse this machine of being out of date It is a machine which has been thoroughly thought out from stem to stern.
The single-cylinder has a bore and stroke of 73x82 mm. (350 c.c.). Both valves are enclosed, and are situated at the rear, while the whole of the transmission is entirely protected. Behind the engine is a three-speed epicyclic gear box. The gears are selected by a lever on the handle-bars, while the clutch is engaged either by the pedal provided or by the handle-bar lever. Water-cooling is arranged on the thermo-syphon principle, the radiator being carried behind the front forks. Between each portion of the radiator is a fan driven by means of a flexible shaft from the magneto drive. The forks are not without interest, as they are hinged at the fork crown, and are provided with laminated springs which act both as fork springs and as girders. Knock-out spindles Rare provided to each of the wheels, and a spring seat-pillar and sprung footrests form part of the equipment. Control wires pass through the handle-bar tubes, which are finished in black. A similar machine was also shown to us which was fitted with a two-cylinder engine with the cylinders arranged side by side.
Motor Cycles at the Paris Salon
The last machine in this group is the Viratelle, which was seen outside Olympia last November. It has a water-cooled side-by-side four-stroke twin engine, placed across the frame, with integral gear box, the final drive being by chain. Two circular radiators are located at the fore end of the tank. A single-cylinder model on similar lines is also exhibited.
The Motor Cycle. October 13th 1921. p447
Extensive article at https://sites.google.com/site/marcelviratelle/
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