On Tuesday, 5 March 2019 17:54:27 UTC, Marland wrote:
tabbypurr wrote:
On Tuesday, 5 March 2019 08:16:53 UTC, Andy Bennet wrote:
On 03/03/2019 20:41, Max Demian wrote:
On 03/03/2019 17:06, harry wrote:
https://www.youtube.com/watch?v=C3p55J-VA5k
Not very easy to see how it worked, what with the time to get going and
the steam obscuring the view. Did the patent on the crank necessitate
the odd ratchet mechanism to turn reciprocal to rotary motion? (Probably
not as I don't suppose the Frogs would care about English patent law.)
I think the piston is omnidirectional as far as the power goes, with a
spring return at the end of the stroke. If thats the case then the
ratchet mechanism is actually quite efficient as you are getting fairly
smooth torque at the wheel for the whole wheel rev. I guess the piston
on the other side might concievably be at mid power stroke when the
other side returns.
I think reverse gear selection could be improved though!
AIUI...
Piston power output is unidirectional, it powers upwards.
One power stroke only moves the roadwheel part of a revolution.
There is only one piston. The engine can only continue driving the wheel
when the dray coasts far enough to re-engage the ratchet mechanism.
Uphill or with low steam pressure that fails to occur.
The ratchet mechanism makes gearing from piston to wheel consistent, but
of course the piston steam pressure falls greatly during the stroke.
I don't know for certain but piston return is most likely by gravity.
Top speed IIRC was 2.5mph. And yes, that was a speed record 
NT
The original is in a museum in Paris and has two cylinders one each side of
the driven wheel.
https://goo.gl/images/f9RgL9
This video on you tube shows how it worked.
https://youtu.be/L4A5ZNjisRM
The ratchet looks like it may have been inspired by clock mechanisms.
No engine braking so perhaps best it was slow.
GH
Flip the driving levers puts the engine in reverse, that's the brake system. And at that speed you can always poke a stick through the spokes to stop one of the wheels. Nevertheless it lost control & crashed on its first outing.
MPG must have been horrendous with such low pressure steam.
NT