need help on reversing cam mech

[aonemarine]

A long time ago I saw a YouTube video of a model steam engine that had a gear set up on the front of it that could be swung around to reverse the cam which would reverse the engine rotation. I'm trying to find this video again or maybe a picture of the gear arrangement so I can incorporate it into my engine design. Pretty sure the video was foreign and was a model of an actual engine. Any one remember seeing it???

 

[GailInNM]

Was is similar to this one?
Gail in NM

 

[aonemarine]

Thanks gail, yes very much like the green engine you have there...

 

[aonemarine]

Does this arrangement have a name???

 

[GailInNM]

The linkage is a known by various names. Flat differential, spur gear differential and parallel shaft differential are the most common. Some times known as phase shifter.The engine pictures was made by Cheddar in the UK. They have been out of business for a some years now.

This type of differential was used on very early Cadillac motor cars and other manufacturers. A good description used to show up using Google looking for Cadillac differential or spur gear differential.

In the photo attached there are 4 gears associated with the reversing. One of them can barely be seen is attached to the crankshaft. That gear and the one on the "cam" shaft need to have the same number of teeth and the two idlers do also.

In operation the lever is moved through 90 degrees and this shifts the phase of the valve shaft by 180 degrees. You can not "notch up", that is reduce the steam admission duration, as can be done with most valve gear, but that is not much of a problem for most of us.

Gail in NM

 

[aonemarine]

What I'm working on is a 4 cylinder inline uniflow, with poppet valves, didn't plan on making it reversing at first but now I'm thinking about it. Cam profile could be interesting....