Are linear tracking arms better than pivoted arms?

I think the difference in the stress on a cantilever caused by a straight line arm vs a pivoted arm has to do with inertia, primarily. Lets assume there is zero friction. The cantilever is therefore bearing only the inertia (in the horizontal plane) of either a pivoted arm or a straight line arm. Inertia is related to mass and is the property of a static object to stay static and of a moving object to continue to move in the same direction and at the same speed (in the absence of friction). In the case of a pivoted arm, because it is rotating with respect to the pivot, which does not move at all, the net inertial mass is lower than for an air-bearing straight line arm, where all parts of the arm from front to rear have to be moved equally by the force on the cantilever alone. Many air-bearing arms have very low mass arm wands to compensate for this issue. Then in the real world there also IS a force on the cantilever necessary to overcome friction, to add to the problem. The cantilever has a huge mechanical advantage in overcoming friction at the pivot, but no such mechanical advantage in overcoming friction at the air bearing. Obviously, all these forces are tiny, else the cantilever would not last more than a few mm of travel. I am not about to argue that these things nullify the potential goodness of linear tracking.

Lewm, Exactly!

About ten years ago I did initial sketches on a tone arm that used a mechanical track that had zero bearing slop. The are was otherwise conventional in that it used a pivot like a radial tracking arm, and a servo that was light-beam activated. Of course I never built it, instead I handed it off to a tone arm manufacturer, but it seems like its not likely to see the light of day anytime soon if it ever does. But it is a design that solves this problem.

I own an LP cutting lathe, and every time I look at the lead screws and do the setup on the cutterhead itself, I think about doing a linear tracking arm. Right now its more important to run the lathe than make a tone arm...

I have used the airbearing arm on three maplenoll tables and have never had a cantilever issue as has been reported in this thread concerning air bearing arms. My experience with the maplenoll is only 5 years but i have been very impressed with the performance. as for hours of use, I spin anywhere from 5 to 15 albums a week so i have racked up quite a few hours on these arms. As i have stated before, i have never owned one of the premier pivot arms so my comparison of the linear arm is to either stock arms on dual and denon tables or a rega rb300 on a gyrodec. But the ability to track tough passages has never been an issue with the maplenoll arms. As for as tracking warped records, my basic ariadne out performed the gyrodec with a rb300 easily. The apollo table with the vacuum hold system has been spectacular. I have modified the original tonearms to move from Aluminum or brass wands to carbon fiber wand along with replacing the headshell and vta adjustment to include an on the fly zlift vta adjustment on my two earlier ariadne tables. These mods had a significant improvement to the performance which i attributed to the increased stiffness of the assembly. These tonearm assemblies are pretty light mass especially since i use the zyx line of cartridges which are pretty light anyway. Having said this, part of the setup is the level adjustment. When properly adjusted, a very slight pressure will move the assembly with ease. When compared to my rega RB300 on my gyrodec, the movement of the airbearing arm is so much smoother. as for the bearing slop, i do not understand the comment completely so I can not comment on it. Sut the arm is very stable. I do dampen my arm slightly. I do not have the breath of experience on all of the tonearms and tables as compared to some of the other guys so please take my comments accordingly. That being said, i do like the maplenoll arms compared to my previous experience with the rega arm

In general ( terrible term in itself.... ) the horizontal moving mass of all tangential ( linear ) tonearms is much higher than with any pivot tonearm.
The armpipe of the linear tonearm first needs to be deviated from the zero error line to move. then the whole assembly with the bearing/housing moves. It does so by the lever of the armpipe ( reason for short pipes with Versa Dynamics and Souther - but they have other problems, due to this super short armpipe). All this force - the force needed to move the whole tonearm - is applied at the stylus/cantilever/suspension of the cartridge.
The passive linear tracking tonearm needs kind of negative feedback loop to move forward.
The lever only acts when there is an error first.
I think anyone can illustrate the situation in a minute on a sheet of paper with the force vectors - it really nice clarifies the point.
The movement of the linear tonearm is a chain of error-correction-error-correction. The force takes action at the stylus first and declines the cantilever - then the armpipe follows with the bearing/housing behind.
Not a healthy situation for any cartridge.
I love the principle of linear tracking due to its theoretical advantage of zero tracking error. Its just that in the experience working with the various designs offered to the audiophile in the past 4 decades since the Rabco saw the light of day, none could overcome the inherent mechanical problems which ultimately nulls and voids the theoretical advantages in the long term.
A problematic situation for the cartridge (a working situation it was not designed for...). A problematic situation for the energy transfer abilities of the tonearm due to anything, but a tight, rigid bearing ( in real world ).
I would love to see a linear tonearm fulfilling the promises of the theoretical basic concept.
But zero tracking error is not everything in tonearm design.
Once minimized, there are several other aspects which too do have strong influence to the sonic quality of the performance.

Dear Pryso - as a more direct answer to your question 02-22-10 directed to me - the "stress" on the cantilever mounted in a pivot tonearm (if we leave skating-force aside for a moment and address the force vector only, which promotes the movement of the tonearm.. ) is very different from the one applied by guiding a linear tracker.
The derivation force in the linear tracker adds a force to the stylus which is about 90 degrees off - i.e. in the linear line - towards the "normal" (read: in pivot tonearm) force which does (normally...) point towards the pivot point of the tonearm.
The cartridge and its cantilever ( every cartridge - even DECCA/London and IKEDA with their "string" holding the "vertical" cantilever or arc in position) are designed to address that ("normal") force only and thats why that "linear derivation force" in a linear tracker puts indeed - no matter how careful set-up, leveled etc. - an additional stress on the cantilever/suspension system.
And it does so in a way the cartridge was not designed for to withstand for long.
A short sketch on white paper will immediately illustrate the forces and the dilemma.