ESE's works engine tuner

[wobbly]

The Aprilia had its balance shaft across the front gear driven on one side then a bevel drive on the other side.
This drove a small shaft up over the main bearing cavity below the transfer duct entry cutout , and into the back of the offset RV.

[husaberg]

How did Aprilia turn the rotary valve on their engine? The rotary valve that is replacing the normal reed inlet.

I have seen a picture of an engine which is driven by belts off the clutch but wasnt sure if it was an Aprilia or not

Have a look here. close to 600 pics
https://www.kiwibiker.co.nz/forums/a...p?albumid=4839

[jamathi]

How did Aprilia turn the rotary valve on their engine? The rotary valve that is replacing the normal reed inlet.

I have seen a picture of an engine which is driven by belts off the clutch but wasnt sure if it was an Aprilia or not

No belt, that was decided from the beginning!
Gear driven from the balancer shaft.

[Frits Overmars]

Gear driven from the balancer shaft.

[Frits Overmars]

each ball, although hardly moving geographically, will be rotating at twice the revs it would in a normal single-direction bearing arrangement with one race fixed and the other rotating.

They would, if inner and outer race both had the same diameter, which is physically impossible. As it is, the balls will be rotating at more than twice the revs they would make in a conventional crankshaft bearing.

The picture on the left shows the conventional situation: the yellow inner race, fitted on the crankshaft, rotates counter-clockwise, while the blue outer race is stationary.
The circumferential velocity Vi at point A of the inner race equals inner_rpm x radius CA.
Point B of the red ball is stationary, resting against the outer race. So the circumferential velocity at point A of the ball equals ball_rpm x ball diameter AB.
As there is no slip between inner race and ball, both these circumferential velocities must be equal:
inner_rpm x CA = ball_rpm x AB
ball_rpm = inner_rpm x CA / AB

The picture on the right shows a stationary yellow inner race with the blue outer race rotating clockwise around it.
The circumferential velocity Vo at point B of the outer race equals outer_rpm x radius CB.
Point A of the red ball is stationary, resting against the inner race. So the circumferential velocity at point B of the ball equals ball_rpm x ball diameter AB.
As there is no slip between outer race and ball, both these circumferential velocities must be equal:
outer_rpm x CB = ball_rpm x AB
ball_rpm = outer_rpm x CB / AB

Now we superimpose both situations. The inner race rotates CCW and the outer race rotates CW. Total ball_rpm becomes:
ball_rpm = [inner_rpm x CA / AB] + [outer_rpm x CB / AB]

inner_rpm and outer_rpm are opposite, but both are equal to engine rpm, so:

ball_rpm = engine_rpm x (CA + CB) / AB

I'd suspect that what kills them is lubrication failure - balls against cage.

I'm not sure, but you may have nailed it Grumph.

[Haufen]

No belt, that was decided from the beginning!
Gear driven from the balancer shaft.

Did you happen to measure the power consumption of the gear drive for the disc? For example by running the engine non-fired on the dyno with and without the shaft?

[Frits Overmars]

Did you happen to measure the power consumption of the gear drive for the disc? For example by running the engine non-fired on the dyno with and without the shaft?

What would that have told you Haufen? The friction of the disc mainly depends on the pressures working on its surfaces, and those are mainly influenced by gasdynamics. No firing engine = no gasdynamics. And the same goes for the friction losses in the bevel gears that are mainly dependent on the power being transmittted through them.

Calculations were performed on the disc drive, in order to determine the required diameter for the drive shaft. The outcome was the 8 mm shaft that has been the cause of a number of engine failures during races, because the calculated friction torque was not nearly as high as the neglected torque peaks, necessary to accelerate or decelerate the disc during gear changes.

[lodgernz]

They would, if inner and outer race both had the same diameter, which is physically impossible. As it is, the balls will be rotating at more than twice the revs they would make in a conventional crankshaft bearing.

The picture on the left shows the conventional situation: the yellow inner race, fitted on the crankshaft, rotates counter-clockwise, while the blue outer race is stationary.
The circumferential velocity Vi at point A of the inner race equals inner_rpm x radius CA.
Point B of the red ball is stationary, resting against the outer race. So the circumferential velocity at point A of the ball equals ball_rpm x ball diameter AB.
As there is no slip between inner race and ball, both these circumferential velocities must be equal:
inner_rpm x CA = ball_rpm x AB
ball_rpm = inner_rpm x CA / AB

The picture on the right shows a stationary yellow inner race with the blue outer race rotating clockwise around it.
The circumferential velocity Vo at point B of the outer race equals outer_rpm x radius CB.
Point A of the red ball is stationary, resting against the inner race. So the circumferential velocity at point B of the ball equals ball_rpm x ball diameter AB.
As there is no slip between outer race and ball, both these circumferential velocities must be equal:
outer_rpm x CB = ball_rpm x AB
ball_rpm = outer_rpm x CB / AB

Now we superimpose both situations. The inner race rotates CCW and the outer race rotates CW. Total ball_rpm becomes:
ball_rpm = [inner_rpm x CA / AB] + [outer_rpm x CB / AB]

inner_rpm and outer_rpm are opposite, but both are equal to engine rpm, so:

ball_rpm = engine_rpm x (CA + CB) / AB

Frits, thank you for this analysis, but I think there is an error.
You appear to have omitted the factor 2*PI in the calculation of the circumferential velocities of the inner and outer races, and the factor of 1*PI in the circumferential velocity of the balls. The PI cancels out of course, but because you have used the diameter of the ball rather than its radius, the factor of 2 is not cancelled.
If I'm right, the final equation is:

ball_rpm = engine_rpm x 2 x (CA + CB) / AB

Or maybe not...

[flyonly]

Is the a recommended volume calculation for a still air box for a given CC capacity or carb inlet size?


Sent from my iPhone using Tapatalk

[Michael Moore]

the calculated friction torque was not nearly as high as the neglected torque peaks, necessary to accelerate or decelerate the disc during gear changes.

An engineer at Tilton Engineering (clutches) told me that their first go at specifying a clutch for the Wittner Guzzi racer didn't work (too small) because they'd ignored the torque spikes seen a a large displacement twin cylinder race bike.

cheers,
Michael

[jamathi]

Did you happen to measure the power consumption of the gear drive for the disc? For example by running the engine non-fired on the dyno with and without the shaft?

No, never!

[jamathi]

What would that have told you Haufen? The friction of the disc mainly depends on the pressures working on its surfaces, and those are mainly influenced by gasdynamics. No firing engine = no gasdynamics. And the same goes for the friction losses in the bevel gears that are mainly dependent on the power being transmittted through them.

Calculations were performed on the disc drive, in order to determine the required diameter for the drive shaft. The outcome was the 8 mm shaft that has been the cause of a number of engine failures during races, because the calculated friction torque was not nearly as high as the neglected torque peaks, necessary to accelerate or decelerate the disc during gear changes.

The problem of breaking shafts was solved by fitting a shock absorber.
Something like old English bikes had....

[jonny quest]

A shock absorber to the hub of disk valve?

[husaberg]

A shock absorber to the hub of disk valve?

A shaft the correct dimensions and materials.
Old daigo and pommy ohc shitters often had waisted shafts but they only turned at half engine speed at half the revolutions.

I would muse that it allows them to act as a torsion spring rather than saving weights
Much like these ATV axles?

later...........

3) Design is another very effective method of increasing axle shaft durability. The two different designs are waisted and non-waisted. In most applications a waisted design is a superior design. What waisted means is having a section of the shaft that has a smaller diameter than the minor spline diameter. The objective of this is to give the axle a larger section that it can twist instead of concentrating this twisting on a very small section of the shaft. The ability to twist allows the shaft to absorb greater torque and shock loads. We have done a substantial amount of development using both computer modeling and destructive testing and have discovered that the design of the waisted portion of the axle shaft is critical to gaining the maximum benefit of from it. Factors such as the length, diameter and radiuses have a significant impact on the effectiveness.

later again Grump told be Colin Chapman once decided to use a real thin steering shaft, sure enough it turned out to be zstrong enough not to break, but added a whole extra revolution to the steering lock in twist.

[Frits Overmars]

Frits, thank you for this analysis, but I think there is an error. You appear to have omitted the factor 2*PI in the calculation of the circumferential velocities of the inner and outer races, and the factor of 1*PI in the circumferential velocity of the balls.

I only needed the relation between those circumferential velocities, so there was no need to calculate each of them in meters per second.

The PI cancels out of course, but because you have used the diameter of the ball rather than its radius, the factor of 2 is not cancelled.

The diameter AB of the ball is the radius with which point A circles around point B in the left picture and with which point B circles around point A in the right picture.