It could work, but the exact diameter might not for this purpose. Since the ring piston is very specifically sized to truck kingpins, the master would ideally be sized appropriately for the actuator strength with a safety margin in mind. Whoever has a lathe to turn the ring piston would also be easily able to make the master piston too, as it would be the same thing: rod with o-ring or Q ring, hollow cylinder with a fitting on the end.
Im not so sure about this, Only the inner diameter is fixed to the diameter of the kingpin.
you could fatten the ring as long as the hollow diameter remains the same
exactly that. Perhaps not a stepper/rack because that requires power to hold position.
Like a smaller version of this will work. No power is required until a change in pressure is needed. Otherwise system draws 0 power to hold a clamp pressure.
Yes, outer diameter can be fattened, but only to an extent before it could collide or interfere with the hanger. so not infinitely adjustable.
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trouble with all this is is a complete system bring up.
theres nothing quite like it on the master side.
The hydraulic systems of this size I know of are almost always hand operated.
Basically we are talking mountain bike brake sizes
Modifying a brake lever from a mountain bike seems reasonable and a more assured way to a proof of concept
I’ve taken those apart too and it is a simple rod with an O ring on it with holes in the cylinder to grab oil from a small reservoir. I can make more detailed cad files for these parts and make them easy to machine on a lathe if someone actually wants to try to make it.
Something like this attached to a bike brake lever?
Changed Link, its still not a great option due to the low strength
alternatively and much cheaper
I personally don’t like the idea of tightening kingpin to increase stability… bushings can only go so loose or so tight before bad things happen on either end of the spectrum. Plus, ime tight trucks do not always equal stability… and I’d rather not sacrafice manuverability for the illusion of stability with tighter trucks… better to use lower rebound bushings to begin with. Either way I’d love to see things experimented with, and I’m sure I won’t disuade anyone from trying new things just getting my thoughts out.
Worm gear on an adjustable baseplate would be cool, but it would be tough finding the right duro bushings to work well across the range of angles since the higher stability lower angles will feel so much softer with the same bushings.
IMO, the best course of action is an adjustable steering damper, something that can be adjusted on the fly by speed from the vesc. On the rear truck- for me, any dampers on the front made for a horrrrible ride.
The steering damper on the rear of this setup worked wonders to eliminate speed wobble, something like this that would adjust with speed would be my perfect solution- set your angles, bushing setup, and just have a stable ride at speed and all the agility and carving at low speed. Only thing this was lacking was that if I was to go real fast I’d crank it a few turns first.
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I value your input, but thats not really whats trying to be achieved here.
You raise valid points, and most of them have been discussed and explained
bushings: we’re using bushings specificly designed to work across many compression factrs
Steering dampener: does not provide the same effect (works on rate of change of lean angle, rather than proportional)
Rear/Front: the ring pistol solution can be applied to one (most likely both)
I totally get what your saying, but Im hoping were past arguing the merits of this, and just sorta going for a proof of concept.
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Kind of like that. I see those micro servos going upwards of 20 lbs, the full size servos may be way too big for our purpose. Although there is nothing bad from trading travel distance for pressure. 20 lbs at a 1-100 pressure ratio is still 2000 lbs.
For a comprehensive answer we first need to know what kind of pressure we aim to achieve at the kingpin. I honestly have no idea how much pressure we’re putting in when we crank down a kingpin nut. My guess is 1000 lbs of pressure at the kingpin will give enough “stiff” compression, need to clamp a bushing with a strain gauge to figure out what a stiff compression value is
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That’s were I keep failing as well.
I think we can calculate it based on the hardness rating of the bushing and the mm of deflection. At least to some ballpark value for now.
Going on from that:
here is an approximation, this isnt specific to skateboard bushings but gives us something to work with for now
Looking at the amount of threads that can show , i would get maxium deflection at no more thatn 10mm. based on this, and the 70 shore hardness, around 2 to 3 thousand pounds is not outside the realm of usability.
Now this is not even close to being something we can base our design on, but the methodology to calculate it would appropriate
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Yes here is another way of going about it if we simply do a torque measurement on the Bolt
T=KDPT=KDP
- TT = Torque (in-lb) 360 ( based on years of torque specs by feel, will measure later)
- KK = Constant to account for friction (0.15 - 0.2 for these units)
- DD = Bolt diameter (inches) 0.5
- PP = Clamping Force (lb) ??
I applied this to my problem
- T= 360 in-lb
- D= 0.5 in
- K=0.2
This gives P=T/KD=3600 lbs
Same order of magnitude so thats nice
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Seems like numbers in excess of 2000 lbs is not too hard to achieve. a 200mm servo at 60+ lbs can easily generate multiple tons of pressure with that much mechanical leverage
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I can help but you guys arent there yet
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Yeah not even close. But thanks for the info
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I agree, there is a huge difference with quality, high-rebound urethane. Also, a very small difference of compression will have an impact on wobbles at various speeds. It’s not like we are taking a bushing completely loose. It will always be under varying levels of compression. They take far more abuse during carving.
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At what point should we just be designing a ESK8 truck thats more like a DH Truck?
They dont seem to have problems with high speeds?
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I’d argue the applications are different so the truck design should be different
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- skilled riders
- they don’t do sharp turns, fuckers keep sliding constantly
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