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  1. BrianPetersen

    LandRover Death wobble

    The common feature between Jeep Wranglers and Land-rovers of the type mentioned in the original post (along with a few others known for similar behaviour) is the solid front axle. A disruption on one side affects the other side. Sloppiness in anything affects both sides. I'm not aware of decent...
  2. BrianPetersen

    Tesla Cybertruck fire and alleged design flaw. . .

    Any sort of time delay beyond milliseconds requires an assumption that the vehicle's electrical and control systems remain sufficiently integral through the crash to allow the timer to count down and the action to be taken. What actually happens is that once the various crash sensors and the...
  3. BrianPetersen

    Tesla Cybertruck fire and alleged design flaw. . .

    One would hope that battery / electrical system failure / compromise as a result of a collision impact is considered. Normally the point at which the airbags and seat-belt pretensioners fire, is before there is significant compromise of the bodyshell, and one would think that the signal to fire...
  4. BrianPetersen

    Tesla Cybertruck fire and alleged design flaw. . .

    Most of the rules were written before there was such a thing as electronic controls. All risk assessment procedures, FMEA included, are subject to some degree of subjective evaluation. To what extent do you address combination failures? How do you estimate the probability of an event occurring...
  5. BrianPetersen

    Tesla Cybertruck fire and alleged design flaw. . .

    You're assuming that a certain manufacturer actually does FMEAs, as opposed to "yes, boss, we'll make that work".
  6. BrianPetersen

    Tesla Cybertruck fire and alleged design flaw. . .

    Tesla doors have an inside mechanical release, but it's in a different location from the way users normally open the doors, so they wouldn't necessarily know about it. (Bad.) The cybertruck has an additional problem in that there is no outside mechanical door handle at all. (Very bad.) Tesla...
  7. BrianPetersen

    LandRover Death wobble

    On Jeep Wranglers it's usually the front axle track-bar to body attachment - either the bushing is shot, or the bolt has loosened and allowed the hole in the bracket to be ovalled out. But, loose connections anywhere in the steering or suspension arms can cause this, and you're supposed to...
  8. BrianPetersen

    Race clutch intermediate steel plates

    "Race car" covers a lot of ground. For that matter, "clutch" covers a lot of ground. Cast iron, and high-carbon steel, are the usual choices. They may be chrome-plated. Don't see any reason for using special alloys. The steel plates in motorcycle and automatic-transmission multi-plate clutches...
  9. BrianPetersen

    Designing a cam

    Seat-to-seat timing, it's possible. (Open 35 BTDC, close 65 ABDC, for example, would get you there.) Give us the corresponding event timings at 1mm lift. With proper ramping-up of acceleration to keep "jerk" finite, it'll take a fair number of crank degrees to get from the seat to 1mm lift...
  10. BrianPetersen

    Designing a cam

    Hmmm. I spin my Yamaha R3 roadrace bike to 13 000 rpm pretty regularly. (DOHC 4-valve-per cylinder, 2-cylinder 321cc, nothing particularly high-tech, valvetrain uses direct-actuated buckets, with shims between each valve stem and bucket for setting clearances.) I'd estimate valve lift to be...
  11. BrianPetersen

    balance question

    If all you're considering is the first-order vibration, a 90-degree V-twin with the right crank counterweights can achieve it. It follows that they can be stacked end-to-end while maintaining each "V-twin" balanced. (A conventional V8 is, conceptually, four 90-degree V-twins stacked end to end.)...
  12. BrianPetersen

    Designing a cam

    200 degrees seat-to-seat duration sounds shy. Intake valve opening will probably be 10 or 15 degrees BTDC and intake valve closing will probably be at least 30 degrees ABDC and probably more, unless there's something going on that the rest of us don't know about. Lobe center at 100 - 105 degrees...
  13. BrianPetersen

    Regarding Beam sizing for Heavy duty trailer

    If you are specifying and buying axles and springs, then the factors of safety for impact loading etc in terms of the axle itself are already built into the axle. If you are looking at the loading imposed on the chassis by the suspension, including bump-impact loads, that's on you. Trailer...
  14. BrianPetersen

    Honda Recall - 3.5L main bearing problems

    For the Ford stuff, are you people talking about the water pump on the transverse-mounted non-ecoboost V6 - the one that when it lets go, leaks coolant into the oil and kabooms the engine if not caught straight away? Doesn't affect the comparable engine used in longitudinal installations - the...
  15. BrianPetersen

    Speed of flash steam formation

    Are you looking for what happens on a micro scale, or on a macro scale? The "release" of heated liquid under pressure involves passing through some sort of orifice or valve or other pressure-and-flow-control device, in the process of going from the high-pressure place to the low-pressure place...
  16. BrianPetersen

    Honda Recall - 3.5L main bearing problems

    When is the last time you've seen something driving down the road belching clouds of blue smoke from burnt oil behind it? That used to happen all the time. Now, the rare time you see this, it's almost always a historic vehicle (or something that someone has modified, thus losing the OEM...
  17. BrianPetersen

    Honda Recall - 3.5L main bearing problems

    Low mileage creampuffs at a collector car auction aren't representative of cars that see daily use in the hands of everybody.
  18. BrianPetersen

    Honda Recall - 3.5L main bearing problems

    The nemesis of many cars of the late 1970s and into the 1980s was the "vacuum hose routing diagram". The vacuum system was basically a primitive engine computer. The car started and ran OK as long as all that was good. When vacuum hoses started leaking, or when mechanical thermostatic switching...
  19. BrianPetersen

    How Can You Prevent Laser Cutting Machine Head Collisions?

    Yup. All of those are only as good as the data you enter ...
  20. BrianPetersen

    How Can You Prevent Laser Cutting Machine Head Collisions?

    Ultimately, the machine itself is blind. It can't see if there's something in its way. One thing we would do when retrofitting weld curtains or splatter guards or personnel barriers in robotic weld cells, is to make a rough prototype out of cardboard and duct tape to position that in the spot...

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