Bristol Hercules radial engine gear train - photos

**Altair** · Apr 28, 2021, 03:42 PM

WWII-era Bristol Hercules radial engine gear train.

Previously:

Bristol Hercules double-row radial engine cutaway - photo
Wright 18-cylinder radial engine - video
Aircraft radial engine cutaway - GIF
Radial engine cutaway - GIF
Double row radial engine - GIF
18-cylinder radial airplane engine cutaway - photo

**chainsawd** · Apr 29, 2021, 10:26 PM

Amazing engineering

**Paul Alciatore** · Apr 30, 2021, 02:09 AM

Oh My Gosh!

**IntheGroove** · Apr 30, 2021, 04:11 AM

One chipped tooth and it's all over...

**hemmjo** · Apr 30, 2021, 04:21 AM

It is indeed amazing. Designed in someones head, on a board, with pencils and instruments, no CAD or computer simulation for assistance. Then built by real machinists, with no CNC, who were under tremendous pressure. Assembled by hand with each gear messed properly with its bothers and sisters.

Having never seen one before, I was having trouble finding the valve train. All I could see were ports open into the side of the cylinders. It had me thinking surely it cannot be 2 cycle.

Discovered this explanation for that extensive gear train.

**2SSRedline** · Apr 30, 2021, 05:19 AM

Here is an attempt at a scale model of this engine.
https://agelessengines.com/sleeve.htm

**hemmjo** · Apr 30, 2021, 05:35 AM

That is impressive. That guy is a little bit crazy.... in a good way.

**IntheGroove** · Apr 30, 2021, 07:40 AM

Knight sleeve valve engine...

**Hans Pearson** · Apr 30, 2021, 09:16 AM

An extremly intricate valve system for virtually no gain in power but a slightly lower engine weight of 1925 lb (strangly enough). The Hercules power output was 1375 hp from a 2360 cu in engine. The closest I could find readily was the Curtis Wright R-2600 which put out about 1500 hp at a weight of 2054 lb. The valve timing on a sleeve valve engine was more involved than assembling an old Swiss watch although the poppet valve engine had timing gears and a set of cam rings with lobes to lift the cam followers. I think that the close proximity of the Hercules spark plugs was one reason for the reduced power output of this type, even though the port openings on a sleeve valve engine was bigger than on an equivalent poppet valve engine.

**Rangi** · Apr 30, 2021, 07:13 PM

Many Thanks for posting. Brought back many memories. Complicated, British of course, but reliable. Drank a lot of oil compared with a Pratt or Wright engine.
Rangi.