Commando Crankshaft Porn

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Er , the One Piece Crank ( sans flywheel ) was introduced for the Triumph ' Big Twins ' in 59 . Definately refered to as ' Forged ' . Grain alignment etc said to be inherent in the Triples 'Forged in line ( Crank Pins )
then twisted . Seems Triumphs plant & equipment ( and Volumes ) gave the more options in manufactureing methods .

CENTRAL FLYWHEEL . Stated somewhere to Enhance Cornering aptitude , Vs " The inline four cylinder crankshaft assemblys mass inhibits alteration of course as the gyroscopic force along its lengths / extremeties
resists alteration in placement laterally / banking ".
Also at times the mass of the flywheel is discernable as per the wheels flywheel effect , (at 110 mph plus the magnitude becomes discernable )
Therefore , a Central flywheel becomes advantageous for enhanced manouvreability , in the veign of polar moments of inirtia / centraliseation of mass .

Also therefore the increased seperation of the mainshafts ( Grank / Gearbox ) Enhace Stability in our ' obsolete ' non unitary drivetrains . Dont tell the Japs. Theyll all want one and copy it . :?
 
Dances with Shrapnel said:
I will try to be kind here. If I understand your post above:/quote]

You did not understand what I was trying to say.

I did not blame the fall of the British Motorcycle industry on crankshaft design. That was just one part of how they kept 1930's designs and engineering in the face of the competition from Japanese big-four. Norton threw away the featherbed frame right when everyone else kept that chassis technology and used it to surround new engines with two-stroke and OHC technology etc..AMC threw out the best part of the bike and kept the worst, typical of the British Bike industry.

The 500cc World Championship of 1954 was won by Ray Amm on a Norton Manx with the flywheel located between the drive side bearing and output sprocket of the engine. the crankshaft itself was as small and light as they could make it.

That Norton is the only British Marque of the "big three" with crankshaft breakage is not the issue, all the British parallel twins vibrated to the point where they looked worse and worse as time went by, once again trying to squeeze more dollars out of 1930's designs forty years after the fact in the face of Jap and italian and German bikes that were far superior.

Maney''s cranks don't break simply because he did what Triumph did fifty years ago, made the crank and cases stronger. But Maney's cranks are not any improvement on the original design as if you put one of his cranks in a stock set of Norton cases it will still break them.

If you put a ten foot steel pole across two concrete blocks with a 200 pound weight in the middle and jump up and down on it that weight in the center will absorb your energy and start to move and it will tend to stay in motion even after you jump off. But if you slide the weight right over next to one of the concrete blocks and jump on the pole again and jump off, although the entire pole-weight assembly weighs the same as before, it will behave far differently, it might bend as much initially when you jump on it, but when you are off because it weighs less where it is bending the most it will vibrate(move) at a much higher frequency and those vibrations will be of smaller amplitude(distance). A crankshaft will behave the same way, and if it moves around less for a shorter period of time, then it will make any set of crankcases it is put into last longer.

There is no difference in the design in the crankshaft of a single cylinder or a 360 degree twin, the twin is just far worse off because the crankshaft is longer with the flywheel mass in the center where it can do the most damage, where in a Manx or other single, the flywheels are right next to the main bearings where they can not move around as much.

So make the crank whatever weight that you need, but put that weight next to the drive side support. Yes the crank will still twist and bend the same amount initially from the force of the power strokes etc., but those power strokes that are jumping up and down on the crank will not have the help of a center flywheel to make them larger in amplitude and duration.
Click to expand...
 
I did understand you but I was making a little fun of the drama.

I feel you are mixing a whole lot of emotional and technical issues and things are getting garbled up. You have compared a single cylinder Manx to a Norton Twin and then in my opinion made a leap of logic that there is little difference between the two types of crankshafts. Yes it is common knowledge and I understand the similarities of a single and 360 degree twin with respect to engine balance but that is about where all similarities end.

To the casual observer, a single cylinder crankshaft loads and stresses are significantly different from those of a vertical parallel twin (regardless of flywheel position); unfortunately I do not have the time to enumerate the ways.

Your analogy of a pole and mass is interesting but you assume that all conditions lead to a harmonic which leads to an amplitude node yet take your same analogy and bounce exteremely fast on unloaded flimsy pole and then bounce fast again with a large central mass on that same flimsy pole and you will see that there will be nowhere near the amplitude of deflection (thus reduced stress). Yes you can target a natural frequency (harmonic) but that is not how crankshafts are properly designed. Why in the world do they put bar weights in the ends of clip ons as opposed to up close to the fixing point of the clip on? Same scenario, to dampen vibration. You really need to factor in frequency with your analogy.

In your scenario of placing the flywheel on the end of a 360 vertical parallel twin crankshaft, that would be a disaster. Think about the horrible rocking couple you would introduce where the flywheel mass does not want to jump forward and aft, up and down yet the throw weights of both cylinders are trying to make just that motion. You have two separate unbalanced rotating masses at the end of a stick as well as unequally timed engine pulses. It seems logical to me to put a mass dead center between the two masses/reactions to dampen out the vibration. To me, this concept is so important in understanding what exactly the mass does in the center of the crankshaft, it is more than just rotational inertia.

Accepting the fact that there is no center main bearing, Triumph, BSA and Norton got this one correct. Again, why would the motorcycle industry world wide not all adopt this type of flywheel on the side. For the British bike industry it seems to me that it would have certainly simplified manufacture of the crankshafts.

As for the overall demise of the British motorcycle industry, I do agree that they were attempting to extend existing designs (for whatever reason but probably costs) and did not see the competitive nature and changing market conditions at the time.

Agree about Maney's cranks, they are not an improvement of design but of materials of construction. I recall there are some enhancements in the design but minor when compared to the overall design.
 
Is there detectable advantage rpm help for racers to run w/o the alternator rotor on end of DS? Other than the -1/3 hp drag on full charging load. I've seen one slung off center so stator insides turned to ceramic melt mix. But other end of crank also moved like a finger cleaning fudge out a bowl, at least half as much as DS. The all too plain evidence was by far the highest jerk loads on the crank occurs from TDC jerk down on intake stroke so crank ends strike their surrounds most in 5 to 7 o'clock arc around 10,000 rpm and 4 to 8 o'clock over 11, 000 inside Combat cases.

Likely there's some crank jump rope rpm harmonic that rebounds up at same time but wrong way as piston jerk pulls up - to magnify beyond just pure interial distortion. My sense of it is there's a gradual bow-ing within tolerance then suddenly more serious nonlinear deflection, sorta like umbrella flipping over center.

Will dream about new nano matrix graphpene ceramic miracle material tonight with replusive magnetic domains in flywheel to charge and stifle the jump roping.
 
Dances with Shrapnel said:
Why in the world do they put bar weights in the ends of clip ons as opposed to up close to the fixing point of the clip on? Same scenario, to dampen vibration. You really need to factor in frequency with your analogy.
Click to expand...
Right, it changes the frequency of the handlebar from high to a lower frequency. A weight in the center of a crankshaft, a beam or a guitar string will do the same thing, the crank will vibrate at a lower frequency(less movements but they are larger), a crank with a lighter flywheel will vibrate at a higher frequency(more movements but they are smaller).

Dances with Shrapnel said:
In your scenario of placing the flywheel on the end of a 360 vertical parallel twin crankshaft, that would be a disaster. Think about the horrible rocking couple you would introduce where the flywheel mass does not want to jump forward and aft, up and down yet the throw weights of both cylinders are trying to make just that motion.
Click to expand...

You are assuming things again. You can have a 360 cranshaft with no flywheel at all that can be balanced exactly the same as a stock Norton crankshaft. the counterweights balance the crank throws, the big end of the rod, and a percentage of the reciprocating assembly. Adding a flywheel to the crankshaft has nothing to do with balancing it unless you use part of the flywheel for that purpose. A flywheel and a counterweight are not the same thing.......

Dances with Shrapnel said:
From what I see, a center flywheel mass is essential to mitigate the bending moments
Click to expand...

Well you throw a lot of fancy words around but do you know what they mean? With the flywheel in the center of the crankshaft, or a weight in the center of any beam, just like the weights in the ends of clip-ons you brought up, the frequency of the crankshaft will be lowered, that is it's vibration will be one of less cycles per second but one of larger amplitude or distance, it will bend MORE. And this will increase the "bending moment". Because the crankshaft is bending more, it is putting more loads on the bearings in a direction they are not designed to work in, and it is putting more stress on the crankcase and cracking it sooner. So not only are you missing major points, the one that you did make, was a reinforcement for what I have said. Thank you.

Dances with Shrapnel said:
Accepting the fact that there is no center main bearing, Triumph, BSA and Norton got this one correct. Again, why would the motorcycle industry world wide not all adopt this type of flywheel on the side. For the British bike industry it seems to me that it would have certainly simplified manufacture of the crankshafts.
Click to expand...

Uh, no one besides the British put the fortune of their entire industry on a 360 degree twin with a center flywheel, and all those that did not are still around. Almost every modern automobile engine has it's flywheel where? That's right, on the end of the crankshaft right next to where the power is drawn from the engine, so actually my proposal has thousands of successful applications in history, your champion has three unsuccessful ones, named BSA, Triumph and Norton.

Besides that overwhelming common sense, some very great tuners and engineers have in the past done everything in their power to move as much weight as possible from the center of the crankshafts of British 360 degree parallel twin racing engines, C.R Axtell and Heinz Kegler to name two. Axtell found that moving as much weight as he could from the center of the crank to outboard towards the main bearings dramatically improved the life of Triumph twin racing engines.

Edward Turner's design of the 1930's for his 500cc motorbikes did it's job at the time. When someone argues incessantly that his work was the last word and that anything done to improve this seventy year old design is a waste of time and wrong, to me they seem small minded, closed-minded, ignorant and unintelligent.
 
Uh, no one besides the British put the fortune of their entire industry on a 360 degree twin with a center flywheel, and all those that did not are still around. Almost every modern automobile engine has it's flywheel where? That's right, on the end of the crankshaft right next to where the power is drawn from the engine, so actually my proposal has thousands of successful applications in history,
Click to expand...

OK, I understand what you are saying, but I think there's another perspective to the above core of your arguement - Yes, car engines have the flywheel on the end of the crankshaft as that's also the clutch / transmission interface, just a logical engineering thing to do. But, on the other end they also have a harmonic balancer. Torsional vibration on say a 6 cylinder in-line engine gets pretty wild when one end is loaded and the other relatively free. With regular passenger cars, the power output is normally well within these limits, but when you hot rod them, all sorts of ugly vibrational forces can happen. Cranks snap, if not blocks crack.

However, back to British m/c twins. The vast majority of these makes and models were made for a general purpose market, get to work, tour, some sport. Race set up of these types of engines was risky. Something Edward Turner of Triumph detested and tried to avoid as he knew design was not ideal for that sort of stress. Read John Nelson's book Bonnie and you get an insiders view of how hotting up Triumph twins was covert business until Turner saw sales related sucess. But in those days, it was pretty much the same type of bikes racing each other, there was no standout production model that challenged the prevailing designs of the time. Moral of the story is - The typical twin was a good bike for what the market purpose it was made for. Costed for production engineering, relying on proven tooling, common parts and trade skills.

Mick
 
beng said:
Dances with Shrapnel said:
Why in the world do they put bar weights in the ends of clip ons as opposed to up close to the fixing point of the clip on? Same scenario, to dampen vibration. You really need to factor in frequency with your analogy.
Click to expand...
Right, it changes the frequency of the handlebar from high to a lower frequency. A weight in the center of a crankshaft, a beam or a guitar string will do the same thing, the crank will vibrate at a lower frequency(less movements but they are larger), a crank with a lighter flywheel will vibrate at a higher frequency(more movements but they are smaller).

Dances with Shrapnel said:
In your scenario of placing the flywheel on the end of a 360 vertical parallel twin crankshaft, that would be a disaster. Think about the horrible rocking couple you would introduce where the flywheel mass does not want to jump forward and aft, up and down yet the throw weights of both cylinders are trying to make just that motion.
Click to expand...

You are assuming things again. You can have a 360 cranshaft with no flywheel at all that can be balanced exactly the same as a stock Norton crankshaft. the counterweights balance the crank throws, the big end of the rod, and a percentage of the reciprocating assembly. Adding a flywheel to the crankshaft has nothing to do with balancing it unless you use part of the flywheel for that purpose. A flywheel and a counterweight are not the same thing.......

Dances with Shrapnel said:
From what I see, a center flywheel mass is essential to mitigate the bending moments
Click to expand...

Well you throw a lot of fancy words around but do you know what they mean? With the flywheel in the center of the crankshaft, or a weight in the center of any beam, just like the weights in the ends of clip-ons you brought up, the frequency of the crankshaft will be lowered, that is it's vibration will be one of less cycles per second but one of larger amplitude or distance, it will bend MORE. And this will increase the "bending moment". Because the crankshaft is bending more, it is putting more loads on the bearings in a direction they are not designed to work in, and it is putting more stress on the crankcase and cracking it sooner. So not only are you missing major points, the one that you did make, was a reinforcement for what I have said. Thank you.

Dances with Shrapnel said:
Accepting the fact that there is no center main bearing, Triumph, BSA and Norton got this one correct. Again, why would the motorcycle industry world wide not all adopt this type of flywheel on the side. For the British bike industry it seems to me that it would have certainly simplified manufacture of the crankshafts.
Click to expand...

Uh, no one besides the British put the fortune of their entire industry on a 360 degree twin with a center flywheel, and all those that did not are still around. Almost every modern automobile engine has it's flywheel where? That's right, on the end of the crankshaft right next to where the power is drawn from the engine, so actually my proposal has thousands of successful applications in history, your champion has three unsuccessful ones, named BSA, Triumph and Norton.

Besides that overwhelming common sense, some very great tuners and engineers have in the past done everything in their power to move as much weight as possible from the center of the crankshafts of British 360 degree parallel twin racing engines, C.R Axtell and Heinz Kegler to name two. Axtell found that moving as much weight as he could from the center of the crank to outboard towards the main bearings dramatically improved the life of Triumph twin racing engines.

Edward Turner's design of the 1930's for his 500cc motorbikes did it's job at the time. When someone argues incessantly that his work was the last word and that anything done to improve this seventy year old design is a waste of time and wrong, to me they seem small minded, closed-minded, ignorant and unintelligent.
Click to expand...


You spout:
"Edward Turner's design of the 1930's for his 500cc motorbikes did it's job at the time. When someone argues incessantly that his work was the last word and that anything done to improve this seventy year old design is a waste of time and wrong, to me they seem small minded, closed-minded, ignorant and unintelligent"

Hmmm, very telling; maybe some projection going on here.

We were talking about a Norton Twin and everything including the kitchen sink is being thrown into this thread. What does a modern automobile engine have to do with a Norton twin (360 crank w/o a central bearing). This is like comparing oranges to claw hammers.

Motorcycle engineering firms of the time all got it right. We have spun Norton designed cranks (with modern materials) wayyyy beyond anything they dreamed of when they were designed. I can assure you that other constriants raise their ugly head (like mean piston speed). I cannot think of a siginificant twin (360) with no central bearing AND no mass in the center. They all had them; how could they have all missed this - incredible.

Axtel and Heinz were respected and moving some balance mass from the center to the sides is beneficial when considering the bending moments at speed; note that they did not try to move the mass to one side only - and they were respected.

I am talking translation motion here. You stated that a body in motion tends to remain in motion well the benefit of a central mass is: a body at rest tends to stay at rest.

Believe what you may but you cannot argue with the laws of motion, dynamics and kinematics.

As for fancy words, spare us the drama and just please point them out for me or ask what they mean. :)
 
Kitchen Sink . :shock: Just to prove 1930s tecnology was state of the art . ( not this modern cost effective stuff :lol: )Except THIS was a decade or two earlier . :D

Commando Crankshaft Porn


Commando Crankshaft Porn


The U-16 model designed by Bugatti was , if not accepted by his own country (France), accepted by the Americans though. This is the best-known of the License-Bugattis. At the end of 1917 Friderich went to New Jersey, where at the Duesenberg works the King-Bugatti should be build. Charles B. King made some considerable changes, after the U-16 Friderich had taken with him (he brought some 8C's to the US as well) showed "structural weaknesses": A test was stopped because of strange noises, and various parts were found to be broken.
Improvements were made affecting the valves, propellor reduction gears, water pump, oiling system etc. The ignition was changed to Splitdorf and Simms, with distributors mounted on the ends of the camshafts. Output was rated at 420HP, dry weight was 1248lb (550kg). The drawings below wil clearify some of the construction details, also for the Bugatti engines, which were not so very different.

The crankshafts are made up of two halves, as in the Bugatti. Each half forms a four-cylinder shaft with the throws all in one plane. The two halves are assembled at right angles. In assembilng the completed crankshafts in the crankcase they are placed in such relation that if No.8 crank left is on top dead centre, No.8 crank right will be 45 degree past bottom dead centre!
All bearings, including the connecting rod bearings are undercut, and thereby shorten the over-all length of the engine by about 5 in. (25cm)

Commando Crankshaft Porn


Commando Crankshaft Porn


Commando Crankshaft Porn


http://home.uni-one.nl/bugatti/revue3/rev3-3.htm
 
Matt Spencer said:
Kitchen Sink . :shock: Just to prove 1930s tecnology was state of the art .
Click to expand...

Ohhhhh, now you went and did. You are going to see the wrath of the chruch - the world is flat damit! :lol:

I did not see any flywheel on either end of the motor. Heresy I say, heresy! :roll:
 
Dances with Shrapnel said:
beng said:
Dances with Shrapnel said:
Why in the world do they put bar weights in the ends of clip ons as opposed to up close to the fixing point of the clip on? Same scenario, to dampen vibration. You really need to factor in frequency with your analogy.
Click to expand...
Click to expand...
Click to expand...
Right, it changes the frequency of the handlebar from high to a lower frequency. A weight in the center of a crankshaft, a beam or a guitar string will do the same thing, the crank will vibrate at a lower frequency(less movements but they are larger), a crank with a lighter flywheel will vibrate at a higher frequency(more movements but they are smaller).[/qoute]

Not so according to the bar weight manufacturers. The crankshaft frequency we are talking about is a direct function of rpm, no more, no less. Remember, a mass at rest tends to stay at rest so your frequency remains the same but the amplitude goes down - dampened.
 
Dances with Shrapnel said:
In your scenario of placing the flywheel on the end of a 360 vertical parallel twin crankshaft, that would be a disaster. Think about the horrible rocking couple you would introduce where the flywheel mass does not want to jump forward and aft, up and down yet the throw weights of both cylinders are trying to make just that motion.
Click to expand...
beng said:
You are assuming things again. You can have a 360 cranshaft with no flywheel at all that can be balanced exactly the same as a stock Norton crankshaft. the counterweights balance the crank throws, the big end of the rod, and a percentage of the reciprocating assembly. Adding a flywheel to the crankshaft has nothing to do with balancing it unless you use part of the flywheel for that purpose. A flywheel and a counterweight are not the same thing.......
Click to expand...

I've assumed nothing here, you have clearly missed the point and the concept. I agree that a flywheel is not necessary for balance but the resultant centripetal and reactive forces fore and aft, up and down are about a point of symmetry at the center of the crankshaft; exactly where the design calls for the mass which also provides flywheel effect. This bizzare idea of a flywheel mass on the end of the crankshaft would look like a hyper kinetic top in precession. Where did you come up with such a bizzare concept? No, the mass is appropriately located, no matter how much it may burn you personally that this was thought out correctly decades before.
 
HERE : :oops:

Commando Crankshaft Porn


Thisisa 54 , Id thought a 61 500 had the external flywheel . :? :oops:

Itsa bouta likea da this .( blankety Guzzis again . )
Commando Crankshaft Porn

EXternal ! :|
Commando Crankshaft Porn

Internal ! 8) :lol: :?

And then , :wink:
Commando Crankshaft Porn
Steve McQueens squirrel .
Couldnt find a picture of the Two Bearing ' overhung ' :shock: Scott Crank . :? . Pull the cover there and youre looking at the big end .
 
Matt Spencer said:
HERE : :oops:

Thisisa 54 , Id thought a 61 500 had the external flywheel .

Itsa bouta likea da this .( blankety Guzzis again . )

EXternal !

Internal !

And then ,
Steve McQueens squirrel .
Couldnt find a picture of the Two Bearing ' overhung ' Scott Crank . . Pull the cover there and youre looking at the big end .
Click to expand...


Oops, all appear to be singles, not parallel 360 twins w/o center bearing. :oops: :oops:

Little off topic :oops: but pretty pictures :lol: :lol:
 
hobot said:
Likely main reason for center flywheel is so it didn't show on outside.
Click to expand...

It is always interesting to speculate on why something came about. Had a few interesting PM's with a respected member of the list about Nitriding crankshafts. Was it used as a surface wear enhancement but also recognized as enhancing flexural durability or was it the other way around or both.

I doubt the center flywheel on the Norton twin and apparently all the major 360 twins w/o center bearing that used them was oly a convenience (out of site, out of mind because it functions to dampen translational movement in the crank.

There may be a pattern here where the centerally located mass is a proxy for a center bearing on this configuration of motor.

Can anyone think of a parallel 360 twin w/o a center bearing that does not include a center mass or flywheel?
 
hobot said:
This bickering bantering led me to a term called "shaft critical speed". Many things influence this.

Moderately complex article allowed me to keep reading attention on.
http://www.deviantmethods.com/bigmoose/ ... ration.htm
Click to expand...

Interesting article with a focus on torsional occilation, torsional harmonics and torisional dampening.

What is not covered here is translational dampening which probably is not needed considering the likely test engines configuration, crankshaft layout, main bearing locations and number of cylinders
 
Dances with Shrapnel said:
hobot said:
Can anyone think of a parallel 360 twin w/o a center bearing that does not include a center mass or flywheel?
Click to expand...
Click to expand...

Not quite the same deal, but into the 70's plenty of 4 cylinder car engines had three bearing cranks with two throws between bearings and all the flywheel mass on the end of the crank. Going back a bit further; in-line four's with only two main bearings and the flywheel on the end of the crank were not uncommon.

Fours may be in primary balance, but there is still the considerable thump of combustion pressure tending to displace the crank laterally every time a cylinder fires.

Gary
 
ggryder said:
Dances with Shrapnel said:
hobot said:
Can anyone think of a parallel 360 twin w/o a center bearing that does not include a center mass or flywheel?
Click to expand...
Click to expand...

Not quite the same deal, but into the 70's plenty of 4 cylinder car engines had three bearing cranks with two throws between bearings and all the flywheel mass on the end of the crank. Going back a bit further; in-line four's with only two main bearings and the flywheel on the end of the crank were not uncommon.

Fours may be in primary balance, but there is still the considerable thump of combustion pressure tending to displace the crank laterally every time a cylinder fires.

Gary
Click to expand...

No doubt plenty of examples of inline motors but I have never seen an in line with two adjacent cylinders phased at 360 w/o a bearing between them; usually 180 or 90. So it is a bird of a different color.
 
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