New Oberursel Ur2

[franzkait]

thank you Jan for your help , this is exact the way I did it . Rough cut 112 rpm , finish cut 140 rpm .
I had 5 original Oberursel Ur2 crankcases in my hands and did look for machining marks . I machine this one the same way the original was made , so it will look like an original . In a mill it is not possible, foto will come . And I do not like CNC made parts visible autosite . I think if a Oberursel looks CNC made , it looks like a joke .

[franzkait]

between cylinders , a 1/8 cutting bit , so no way to do it in a mill .
thread cutting with modern carbide bits need high speed .

[franzkait]

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[franzkait]

the magic con rod system

[j ferguson]

Does anyone know what advantage of this complicated design might have been?
Why not a hub with hinges (pins) like everyone else seemed to use. I think LeRhone developed this idea.

[tengew]

This was German engineering at its best
The broom handle was the same way the only screw on the pistol was used to hold the wood grips on the rest was keyed and fitted into each other part
Udo the ring that the rod ends fit into is that an oiled bronze or don’t they rotate inside the shell…….. This is amazing to watch it all fit together

[Taz]

j- The LeRhône system was far superior because each connecting rod had its own bearing race rather than concentrating all the forces on the bearing for the master rod. This master rod also had to absorb all the side forces of the other connecting rods at less than optimal angles while the LeRhône system let each rod oscillate to a small degree in its own race, while not affecting other rods.

Taz
Terry Phillips

[franzkait]

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[j ferguson]

Thanks much, Terry. It looks like axis of connecting rod always lined up with axis of crank pin.

john

[jumpinjan]

Originally Posted by j ferguson

Thanks much, Terry. It looks like axis of connecting rod always lined up with axis of crank pin.

That's right. Using the master rod/slave rods approach, the orbits of the slave crankpins are aberrated (they are not exactly like the master crankpin orbit). The result is their TDC (w.r.t. crankshaft angle) & deck heights are different to the master rod cylinder. These differences need to be compensated, and they are. Using the slipper rods approach, I think all that adverse geometry is pretty much eliminated.
Jan