Compression drivers have used a variety of "precision metal spring" surrounds for as long as metal diaphragms have been used, though excursion for those drivers is generally less than +/-.5mm, a tiny fraction of the excursion expected of a low frequency driver.
I have seen examples of woofers using a metal spring spider that looked something like a 45 record adapter (example below) though can't remember the manufacturer.
Metal spiders and surrounds likely have not caught on in high excursion use for a variety of reasons- weight, tooling cost, metal fatigue, and comparatively less vibration damping than the usual materials are the first that come to mind.
Attachments
I didn't know him, you're right, he looks too bulky and heavy .....🙁
A simple search shed enough light on my doubts, but I still don't know what use ferrofluid has in all this .....
Racing car shock absorbers are manufactured with much stronger retention effects than ordinary vehicles, using heavier liquid and / or adding check valves.
It was always funny to me that the owners of private cars adapt (tune here) the series vehicles to make them "competitive", without taking into account basic engineering criteria. The engineers think about it before producing the car, then comes the "wizard" and decides that a simple modification makes the vehicle more apt to "bend better", "better stability" for example.
How when wider wheels are placed, so that they have a greater surface of support against the ground and in turn greater distance between wheels in a transverse direction.
Consequence of this? the angle of support of the wheel is modified, and then the load forces act diagonally on the rule instead of horizontally.
The result is obvious, the bearings are broken and you have to change them repeatedly (not easy task) or reuse the original tires.
Sketch in next post.
active suspension systems in cars - Google Search
Sorry for the off topic.
They should read "vertival force" instead of "horizontal force"
I hope you understand the idea .....😉
The rules of the ruleman are damaged because the balls work forced sideways!
Well, the drawing is not very neat, I know ... but what matters is the intention, I guess ! 😀
Sorry super off topic
Attachments
Last edited:
See attached photos. These are of the piston assembly in a standard road car damper. The piston has a series of holes drilled in it. The metal discs are shims which are stacked up and cover half the holes on each side of the piston. The piston is on the end of a shaft which is fixed to the chassis of the car. The piston rides in a cylinder which is attached to the suspension. The cylinder is filled with oil on both sides of the piston.
When the suspension in the car or chassis moves up and down the oil has to flow through the holes in the piston to get to the other side. To do this, in each direction it must bend the stack of discs to uncover half of the holes. The higher viscosity the oil, the smaller the holes or the thicker the shim stack, the greater the damping forces. In a damper with ferrofluid instead of standard oil, there is a coil of wire used to put the ferrofluid in a magnetic field. By varying the strength of the magnetic field, the viscosity of the fluid is changed and therefore the damping forces.
With respect to wheel widths on road cars. When the suspension is designed, the wheel is optimized for a particular offset. This is the distance from the geometric center of the wheel to the mounting plane machined into it. This offset is designed to minimize the torque or overturning moment on the wheel bearing pair. This is close to the diagonal force line in your sketch.
When installing wider wheels on the car, if you keep the offset of the wheel the same, the overturning moment on the bearing pair isn't increased. However, if you use the increased available grip from the wider wheel and/or tire, the magnitude of the vertical force is increased, so the bearing can wear out faster. From the outside of the car, it is impossible to determine if the wheel has the stock offset or it has been changed.
If you wanna play, you gotta pay. In any case, wheel bearings are dirt cheap compared to performance tires.
When the suspension in the car or chassis moves up and down the oil has to flow through the holes in the piston to get to the other side. To do this, in each direction it must bend the stack of discs to uncover half of the holes. The higher viscosity the oil, the smaller the holes or the thicker the shim stack, the greater the damping forces. In a damper with ferrofluid instead of standard oil, there is a coil of wire used to put the ferrofluid in a magnetic field. By varying the strength of the magnetic field, the viscosity of the fluid is changed and therefore the damping forces.
With respect to wheel widths on road cars. When the suspension is designed, the wheel is optimized for a particular offset. This is the distance from the geometric center of the wheel to the mounting plane machined into it. This offset is designed to minimize the torque or overturning moment on the wheel bearing pair. This is close to the diagonal force line in your sketch.
When installing wider wheels on the car, if you keep the offset of the wheel the same, the overturning moment on the bearing pair isn't increased. However, if you use the increased available grip from the wider wheel and/or tire, the magnitude of the vertical force is increased, so the bearing can wear out faster. From the outside of the car, it is impossible to determine if the wheel has the stock offset or it has been changed.
If you wanna play, you gotta pay. In any case, wheel bearings are dirt cheap compared to performance tires.
Attachments
Accordingly, the point is that street cars are for driving on the street and a "sports preparation" without considering the risks can result in fatal accidents.
" I don't know if you've read the link, but look at this part:
Berta skidded on board the new test car, fell by a bench almost 200 meters and saved her life as a miracle. "The ceiling was at the height of the doors, but I left without any scratches," the Magician recalled in his book. The reason for such an accident? One of the wheels had broken."
El dia que el Torino argentino puso de rodillas a los autos mas importantes del mundo - Infobae
Why did it split? Look at the photos of the link, the magnesium alloy wheels! A steel rim does not split, it deforms, but it keeps spinning in place, even with the tire collapsed after a strong impact.
I had this car when young, Fiat 128, the phrase here was "doubles as a Scalextric", and I attest that it was true. I had already bought it refurbished.
But traveling with my wife and children on the road the vehicle had a very strong blow when the wheel fell into a well.
I decided to inspect the two tires on the impact side.
The left front had cracked! I put the help (metal) and when I returned from those vacations I decided to place the original wheels and also never had to replace the wheel bearings. I had already done it twice in the end of a year, and they were SKF!
Thanks for the explanation about ferrofluid in modern shock absorbers! I didn't know them.
PS:
The magician told Oreste Berta, he completely reformed the classic "Tornado Jet" engine that was incorporated into the Torino (the original engine was from the USA)
between them :
Step 5 to 7 benches (the engine vibrates a lot at idle)
Fully reformed the cylinder head and the camshaft (the original rocker arms and valve guides, the original engine consumed industrial quantities of oil)
He modified the clutch command system, going from hydraulic to mechanical (this seems like an implication, but the pistons (2) were housed inside the clutch housing and the high temperatures spoiled the rubber bowlers, to replace them ... ..have to disassemble the box set - ZF- gimbal!)
Oreste Berta - Wikipedia, la enciclopedia libre
So when my countrymen talk to me about Torino, I close my mouth, I don't want to hurt more sensibilities (my father-in-law had a Torino) 😀
Attachments
Last edited:
Here you can see the standard design of a conventional shock absorber (monotube) and a special one (bitube) with extension and compression valves. Hydraulic both.
A shock absorber discharged had two typical failures, loss of liquid or malfunction of the valves. And you can also see the operation of gas shock absorbers. They were not used in "series" vehicles in these parts. It is not necessary to understand the Spanish language, just by looking you can understand.
Sorry off topic
YouTube
I'm struggling to gather lessons from car and motorcycle suspensions for speakers. I've spent quite a lot of time sorting out suspensions and steering geometry in bikes (and a swell Lotus, some decades ago) and fooling with those little disks in Jack's illustration... not to mention spring rates and anti-sway bars.
For a car, we have an input in terms of road irregularities and contours varying in frequency and acceleration. The suspension has to isolate (with a low pass filter) that from the passenger/rider (in a sprung compartment of known weight) while maintaining an adequate uninterrupted tire contact patch on the pavement. By "isolate", I mean the passenger/rider is stationary in the vertical direction above a certain frequency (like .5 Hz).
Also, movement and resonance of the system has to be damped to perceptually acceptable levels.
That challenge is staggering, esp on bikes. A smart ferro-fluid element clearly can be very beneficial. Makes the challenge of making an audio driver seem simple.
Noticed that the audio set-up is actually the opposite of what I've described above? You have a cabinet that remains stationary and a cone that moves at various frequencies and accelerations.
B.
For a car, we have an input in terms of road irregularities and contours varying in frequency and acceleration. The suspension has to isolate (with a low pass filter) that from the passenger/rider (in a sprung compartment of known weight) while maintaining an adequate uninterrupted tire contact patch on the pavement. By "isolate", I mean the passenger/rider is stationary in the vertical direction above a certain frequency (like .5 Hz).
Also, movement and resonance of the system has to be damped to perceptually acceptable levels.
That challenge is staggering, esp on bikes. A smart ferro-fluid element clearly can be very beneficial. Makes the challenge of making an audio driver seem simple.
Noticed that the audio set-up is actually the opposite of what I've described above? You have a cabinet that remains stationary and a cone that moves at various frequencies and accelerations.
B.
Last edited: