From the Iron Horse forum:

It looks like the current 2nd generation configuration of dw-Links such as the Mojo has are included in the patent drawings.

Congratulations Dave! We hope you gain many more business partners with this patent.

- ray

2. Thanks Ray, its been a long time coming!

7128329, my new favorite number... LOL

Dave

3. Dave, nice bedtime story! Now I can’t sleep again trying to find holes in the assumptions presented about anti-squat.

My basic perspective sees the fulcrum points leveraged mass transfer (or load shifting) occurs in response to acceleration around the wheel axles, not the tire patches, and the sprung Center of Mass.

I guess I need a clear reason of why to use the ground patch as a force vector fulcrum other than it’s traditionally used as an assumption in vehicle dynamics?

Example: Consider a suspended bike’s (or any vehicle’s) wheels somehow were hung rigidly with drive belts or chains (or drive-shafts) from an overhead cable or track so that the drive from the wheels accelerated a traction point at the overhead “ground” surface. Then the motor or rider acceleration input would still produce the same suspension squat tensions between the frame and axles. How would the optimizing “Anti-Squat Curve 17” be measured and plotted to such an overhead traction vehicle? Or for another example, how would a belt driven vehicle, such as a high performance military tank, “17” curve be calculated?

- ray

4. Originally Posted by derby
Dave, nice bedtime story! Now I can’t sleep again trying to find holes in the assumptions presented about anti-squat.

My basic perspective sees the fulcrum points leveraged mass transfer (or load shifting) occurs in response to acceleration around the wheel axles, not the tire patches, and the sprung Center of Mass.

I guess I need a clear reason of why to use the ground patch as a force vector fulcrum other than it’s traditionally used as an assumption in vehicle dynamics?

Example: Consider a suspended bike’s (or any vehicle’s) wheels somehow were hung rigidly with drive belts or chains (or drive-shafts) from an overhead cable or track so that the drive from the wheels accelerated a traction point at the overhead “ground” surface. Then the motor or rider acceleration input would still produce the same suspension squat tensions between the frame and axles. How would the optimizing “Anti-Squat Curve 17” be measured and plotted to such an overhead traction vehicle? Or for another example, how would a belt driven vehicle, such as a high performance military tank, “17” curve be calculated?

- ray
Just draw it out as a free body diagram, makes a lot more sense then. Your wheel is part of the linkage system used to find the force vector, which in turn describes the anti squat curve (or vise versa).

For a tank, every DRIVEN suspended wheel will have its own squat curve, defined by the wheel's position in relation to the center of mass and the suspension geometry. Non driven wheels do not have squat curves, as there is no force output, so you cannot use anti squat to offset resistance to suspension compression.

Dave

5. Originally Posted by _dw
Just draw it out as a free body diagram, makes a lot more sense then. Your wheel is part of the linkage system used to find the force vector, which in turn describes the anti squat curve (or vise versa).

For a tank, every DRIVEN suspended wheel will have its own squat curve, defined by the wheel's position in relation to the center of mass and the suspension geometry. Non driven wheels do not have squat curves, as there is no force output, so you cannot use anti squat to offset resistance to suspension compression.

Dave
That’s beginning to make sense. My hanging belt (or shaft) driven trolley or ground tank examples would redirect net force tangents from to all wheels driven by the final dive belt (or series of shaft drives) in context with the wheels’ swing lines, and a net-net-vector_force line could be derived.

Another question: Is the “Squat-Curve 17” the invention claimed by the patent no matter how it is executed? What is claimed as the exact curve’s dimensions seems vague. There have been previous designs with curves of similar progression; even a low monopivot suspension has this shape of a curve, but not nearly as acute in rate. What is claimed seems vague. (But I’ve only read the patent once, perhaps what is claimed is clear and I missed it.)

And another: How did you derive “Squat-Curve 17”? (Why not more rapid digression of anti-squat during shallow travel, or less rapid? Was it found by trial and error?)

Sorry, enquiring minds want to know!

6. Originally Posted by derby
That’s beginning to make sense. My hanging belt (or shaft) driven trolley or ground tank examples would redirect net force tangents from to all wheels driven by the final dive belt (or series of shaft drives) in context with the wheels’ swing lines, and a net-net-vector_force line could be derived.

Another question: Is the “Squat-Curve 17” the invention claimed by the patent no matter how it is executed? What is claimed as the exact curve’s dimensions seems vague. There have been previous designs with curves of similar progression; even a low monopivot suspension has this shape of a curve, but not nearly as acute in rate. What is claimed seems vague. (But I’ve only read the patent once, perhaps what is claimed is clear and I missed it.)

And another: How did you derive “Squat-Curve 17”? (Why not more rapid digression of anti-squat during shallow travel, or less rapid? Was it found by trial and error?)

Sorry, enquiring minds want to know!
Its all in the patent Ray, read through it a few more times.

For the tank, think of the wheels as idlers. They cannot exhibit any kind of squat performance. The idlers are not driving the tank forward, the track is. If the wheel that was driving the track was also in contact with the ground, then you could have some sort of squat response.

Any single pivot suspension will have a linear squat curve. It is not possible to have anything other than a linear squat curve with a single pivot suspension. I did "define" what a squat curve is, but it is something that exists in physics and vehicle dynamics, I just was the first person to document its existence. Then I developed a squat curve to meet the requirements of human powered vehicles like a bicycle. This became the basis for dw-link. The next and more difficult part was developing linkage layouts that allowed the leverage rates and braking performance that I desired. The patent claims surround the dw-link 3 stage squat curve, and various mechanical methods to achieve them. This patent that awarded on the 31st is not the last in the dw-link line.

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