Hello Tommy Cookers.
“my point was that cars have nil primary vibration - so their engine mounts don't need to be soft enough for primary isolation”
On the other hand, a car engine has to run at substantially lower revs as compared to a motorcycle engine; it idles at about half revs (say, 650rpm vs 1300rpm); it operates at lower revs; it accelerates strongly from lower revs (say, from 1,500rpm vs 3,000rpm, which makes the actual frequency of the secondary vibrations similar to the frequency of the primary vibrations of the motorcycle engine).
Besides, a car requires a better NVH (Noise – Vibrations – Harshness) than a motorcycle.
You also write:
“is it claimed that the PatVRA is a substitute for 'a pair of second-order counterbalance shafts ?”
The PatVRA rids the transmission from the inertia torque. Not the casing.
Typically only useful torque (power pulses torque) passes to the transmission and to the drive wheel(s).
The pair of second-order counterbalance shafts does a different job: on one hand it cancels out the second-order inertia force, on the other hand it cancels out the inertia torque (or moment about the crankshaft axis) on the engine casing. But the inertia torque (due to the motion of the four pistons that stop together and move near their maximum speed together) continues to pass to the transmission.
To put it differently, the two systems complete each other
A straight-four even-firing engine (say, a typical car engine) with “a pair of second-order counterbalance shafts” AND with the PatVRA on its flywheel, will be as smooth as the straight-six engines, as smooth as the typical V-8 engines, and as smooth as the Wankel Rotary engines (note: there will be a small difference due to the stronger power pulses – and the longer time interval between successive power pulses – of the four-in-line, but this may provide a better feeling).
You also write:
“nothing is transmitted when idling (I presume idle is used meaning the high rpm over-run case with manual transmission)”.
Suppose a car with manual gearbox (and conventional 4-cylinder engine) cruises on a level highway at 100mph (160Km/h) / 5,000rpm / 4th gear in the gearbox and 3/4 throttle.
If the driver releases the gas pedal (zero throttle) the engine “continues” to rev at 5,000rpm (with the revs of the engine and the speed of the car falling progressively due to aerodynamic, rolling etc resistance) sending the same inertia (idling) torque to the transmission, but no useful torque.
If the driver presses the clutch pedal (to disengage the engine from the transmission), keeping - with the gas pedal - the engine revving at the same 5,000rpm, then the transmission is released from the idling torque. The difference in vibrations / noise / feeling will be as if having the engine engaged with the transmission through the PatVRA.
If the engine was a typical V-8 (zero inertia torque to the transmission), the release of the gas cable leaves free from loads the transmission (no need to press the clutch).
I.e. what the PatVRA offers to a typical 4-cylinder car (or motorcycle) engine is that, from the transmission point of view, the engine is as smooth as a V-8 (or, say, a V-8 wherein the four cylinders are deactivated).
You also write:
“useful diagrams of those lever-type counterbalancers ....”
The various “balancers” invented to cancel out the vibration of some useful arrangements (single, twin etc) show the need for vibration reduction and the problems of the elastic mounts.
Here is the 635cc single crankshaft, single cylinder, opposed piston PatOP engine, standing free on a desk and running on Diesel fuel (17:1 compression ratio).
There are no balance webs, at all, not even on its crankshaft:
Imagine the “Commando” powered by the PatOP engine directly secured (without elastic mounts) on its frame.