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Harley-Davidson Pushrod patent

More speed for the next V2

Harley-Davidson is working on the successor to the Milwaukee Eight. It is air-cooled again, but should be able to withstand significantly more speeds, as a now published patent shows.

HAs a traditional manufacturer, arley-Davidson will hold on to air-cooled V2 as long as possible, even if the Americans already have liquid-cooled DOHC units in the making. A successor to the current Milwaukee Eight is therefore already in development. A now published patent reveals the first details about the revised valve train in the new V2.

Valve bridge and more speed

The new engine also uses an OHV arrangement, four-valve technology and push rods. On the new engine, however, they are no go along both on one engine side, but are distributed on both sides of the cylinder. This means that fork rocker arms are no longer controlled, but only a single rocker arm on the inlet and outlet side. This in turn presses on a valve bridge, which then actuates both valves on the inlet and outlet side. The valve bridges are guided and secured against rotation on a central axis. This construction is not new and is also not considered to be very speed-resistant – with around 4,000 tours, valve actuations such as those found predominantly in truck and boat engines have so far reached the limit. Harley-Davidson, on the other hand, claims to be able to achieve 6,800 to 7,000 rpm. The current Milwaukee Eight currently has 5,500 laps. In the largest expansion stage with a displacement of 1.9 liters, 109 hp and 166 Nm of maximum torque are available.

And why the effort? Due to the smaller rocker arms, these can be stiffer and lighter, which in turn means less moving mass. In addition, tilting moments on the valve stems can presumably be reduced by the valve bridges. The patent specification itself also shows that easier maintenance is an advantage.

Unfortunately, the patent specification does not reveal any more about the new engine.

Conclusion

The fact that Harley-Davidson wants to stick to air-cooled engines is understandable given the conservative clientele. The fact that the Americans are betting on higher speeds is very surprising.

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