Following the lead of Ricardo's engine for Triumph, Rudge had adopted the 4 valve layout for its motorcycle engines in 1924, using it to win racers and set speed records. For 1930 it was decided to apply the 4 valve design to a hemispherical head, arranging the valves in a radial fashion. Despite the complicated valve mechanism, in its first time out, Rudge won the 500 and 350 IOM TT races. A 250 version won its class in 1931.
At the same time the company scaled down the components to suit a 125 cylinder in order to create a 250 V twin which was tested in 1931. The blueprint above shows the basic layout. Only one prototype engine was built, it is now in the National Motorcycle Museum.
The drawing below shows the convolutions required to make 4 valves work in a radial format. A cam raises the pushrod which activates a rocker which depresses a second rocker which depresses one valve. The other end of that rocker raises and causes the third rocker to depress the other valve.
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| Stratford Rudge |
4 comments:
'Complex' doesn't begin to describe that valve gear, does it? Compare it to the BSA MC1:
https://classiccentre.net/wp-content/uploads/2020/02/image-2.png
From here:
https://classiccentre.net/bsa-mc1-the-racer-that-never-was/
The MC1 was an interesting design in a bunch of ways. For instance, the triple clamp/steering head was reversed. The 'steering head' was part of the fork assembly:
http://www.eurospares.com/graphics/BSAunitsingle/BSAMC1-1.jpg
Leading link forks, just to add to the quirkiness.
rdguy
I really like the aspect of using the "other end" of the rocker. Clever. The BSA radial, simpler but not in the machining setups... Also the Honda RFVC system did it simpler and with DOHC! https://thumpertalk.com/forums/topic/776574-thought-dohc-rfvcs-didnt-exist-well-they-do/
'then there's desmodromic for elegance.
.
Or for complication, I was looking for a picture of the combustion chamber of the Ferrari Type 035-5 a 3.5L 65deg. V12 5 valves per... and desmo. I can't find anything that says it was a radial valve setup, but with 5 valves it almost has to be? The mind boggles.
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