Here is an update covering what I've been up to.
A video of my first scratch built gearbox test under power. This is a braked differential type, planetary differential as the core.
The power is via centrifugal clutch. The engine is an O.S. Engines FS-20;.20 cid / 3,5ccm 4 cycle.
The clutch was machined from D2 type tool steel. The gearbox housing is made from .250" 7075 aluminum
plate; the ball bearings used and gears are all stainless steel. The remainder of the bearings are oilite type.The cover is
.250" acrylic fitted with a screw cap to add oil. The gearbox presently has better than .500" oil bath; I am using
Sta-Lube air tool oil. I will reduce the oil level after tests are complete.
As you can see this was truly an example of a "Jerry rigged" test setup; I wanted to test the gearbox but did not yet
want to commit to using this starter assembly; so no permanent mount was made.
http://www.youtube.com/watch?v=5_YHZLUItVI
At the end of the video you'll hear me exclaim as I burnt the middle finger of my left hand just after disconnecting the fuel line. The
exhaust stacks on model 4 cycle engines get quite hot!
All in all a very good test, even the clutch disengages when I want it to... I will take a break for a while then move on to the installation
into a model.
Since the video was made I've finalized the starter and most of the shift interface. I will begin on getting it mounted in the target model: a 1:10 Hetzer.
For the complete development story please refer to my website,
http://tanks.linite.com/ under the gearbox page. At the bottom of that page.
Jerry