'Two substantially different approaches/solutions for the same problem' - ???manolis wrote: ↑Wed Dec 09, 2020 7:14 amHello MudFlap.
In the last posts there are three plots for the inertia and combustion torques; these plots were made based on the energy transfer between the cooperating parts of the engine.
The plots taken with the DOS balance program (older posts) were made based on the inertia forces, on the leaning of the connecting rods, on the resulting thrust forces onto the cylinder liners etc, etc.
Two substantially different approaches / solutions for the same problem.
I.e. when the driver of a racing motorcycle powered by a 4-cyl flat-crank engine closes the throttle to decelerate before a curve, the rear tire “tries” to get what is “going on” (zero useful power, yet increased idling / useless power).
With the same engine modified to “crossplane” (like the Yamaha R1) the throttle opening is directly proportional to the torque being applied (provided) to the transmission and to the rear tire.
Kawasaki GP 250/350 'tandem twin' 2T engine crankshafts were initially phased for 180 degree firing,Tommy Cookers wrote: ↑Tue Dec 29, 2020 12:23 pmthese inertia torques ........
(that could significantly pass to the load only if the transmission had hypothetical high frequency response)...
...inertia-related engine frictional moments on engine 'casing' ........
yes seem to be eliminated by 2 opposite-rotation crankshafts (ie coupled by direct gearing) .....
eg Ariel square 4s and c.1980 Kawasaki 250/350 WC winners and road replicas (also the Valveless 2 stroke car ?)
(thus according to MZ the piston side load helps exhaust port action)
though yes frictional moments aren't eliminated in typical GP V4s eg RG500s ie same-rotation crankshafts
btw/NOTE TO SELF .....
'Mr Jetpack' Bentley was on TV advocating jetpack racing - over lakes (UK-style 1 metre deep 'gravel pits' presumably)
what I had in mind was the reaction moments (at the gearbox mounts) due to the inertia torque moments in transmissionmanolis wrote: ↑Sun Jan 03, 2021 5:53 amYou write:
- “these inertia torques . . . would they pass to the load (hypothetical transmission as above) if said transmission was of ....
the 1924 Mercedes (4 cylinder Targa Florio) functionality ?
ie gearbox driving a differential having 2 concentric output shafts each driving its own crownwheel and pinion ....
one pinion driving on its left its crown wheel - the other pinion driving on its right the other crown wheel ....”
the Benz is totally different to the Mercedes (they were rival companies at that time)manolis wrote: ↑Thu Jan 07, 2021 6:44 amHello Tommy Cookers.You write:
- what I had in mind was the reaction moments (at the gearbox mounts) due to the inertia torque moments in transmission
for 2 reasons .....
1. claimed benefit of PatVRA as reduction in vibration from alternating torques around the eg engine/gearbox mounts
2. famous benefit of 'TF' Mercedes axle - no loss of traction due to 'torque effect' (before invention of limited slip diff)
so doesn't 'TF' cancelling at gearbox mounts transmission torque around gearbox shaft cancel torque vibration as in 1
....Regarding the unbalanced inertia torque on the engine casing:
With the gearbox / differential directly secured to the engine casing, and with the semi-shafts (of the rear wheels) arranged perpendicular to the crankshaft rotation axis, the inertia torque about the gearbox shaft is cancelled out; however another inertia torque is created, and this torque tries to vibrate the engine / gearbox / differential assembly about the rear wheels axis two times per crankshaft rotation.
And it doesn’t matter how many pinions and ring gearwheels are used in the differential.
This is so because the two rear wheels (i.e. the load) turn at the same direction.
The extreme variation of the kinetic energy of the set of the four pistons of the 4-cylinder engine (Mercedels Targa Florio, 1924) is translated into an extreme variation of the push of the drive wheels/tires to the road (and into an equally extreme variation of the push of the road to the vehicle).
Regarding the inertia torque, things are worse becasue the differential is away from the engine, so it cannot be secured to the engine casing.