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  1. notnats

    Smooth motion at low rpm with VFD

    If you can change the gear ratio, it should be possible to run a 4 pole motor at speeds up to 120 Hz to meet the high speed requirement. This will let you run the low speed at a higher frequency. This worked for us in a special treadmill to train wheelchair athletes and cyclists up to 40 km/h...
  2. notnats

    Observation on 737 in the rain

    I have seen a shadow on a wing which I assumed was refraction caused by the low pressure in the air above the wing. It moved about a bit with changes of attitude. This was about 15 years ago flying between Sydney and Melbourne in the afternoon and looking over the left wing. The sun would have...
  3. notnats

    Naming problem (hydraulic transmissions)

    Then what was the "pre-selective" gearbox which I think was popular for a while in the 1930s? I got the impression that the next gear was selected then didn't change until the clutch was depressed. Jeff
  4. notnats

    The Y1936 Problem

    Motors and transformers are smaller and lighter on 60 hz, which is probably why it is pretty much standard on ships. I think aircraft use 300hz or similar for this reason Jeff
  5. notnats

    What is the relation between a hub centric wheel and the hub?

    I had several Peugeots, 203, 403 and 404. They all had 3 stud wheels locating on conical seats under the nuts. In addition, the wheel had no hole in the centre, which made it really difficult getting someone to do a wheel balance. Nobody wanted to fit the appropriate adaptors to their balancing...
  6. notnats

    Racing Engine Starter

    I am probably living in the past, but I always thought that when the starter called "Gentlemen start your engines", they used a big electric drill with a starter handle one way dog clutch fitted to it to turn the old offenhausers over
  7. notnats

    FORMULA FOR FRICTION CONE

    Resolve your axial clamping force into the force normal to the mating faces. The maximium torque transmitted is the normal force x the mean radius of the mating faces x the coefficient of friction: T = Fn * Rmean * Mu An appropriate safety factor needs to be applied. If the clutch will be...
  8. notnats

    Rubber pad forming?

    We used to use a rubber pad to cut a polygonal blank about 200mm x 100mm from 1.6mm aluminium in a 40 ton press brake. We never formed anything bigger than 100 x 25mm. Not because we couldn't, but because we didn't need to Jeff
  9. notnats

    Victorian Engineering Brilliance - Do We Still Have It Today?

    "Brakes? I design my cars to go, not to stop" was attributed to Ettore Bugatti in answer to criticism of his cars' brakes. "Guesswork is best ... if it's right" Was the maxim of an old guy I knew years ago who learned his art in the early 20th Century. I think there was a lot of inspired...
  10. notnats

    volume versus pressure

    I think you will need to know the pressure drop across the filter when it has collected the required amount of dust, measured with your water gauge across the filter, and the flow rate required to keep on picking up dust as the filter becomes loaded. Then set up a test rig with 2 orifices, one...
  11. notnats

    Lifting Pumps

    Is this because the pump hits the crane's travelling rail before it is out of the well? Jeff
  12. notnats

    Books I've recently acquired...

    About 10 years ago I read a book called, I think "DC 10" From memory the cargo door problem started with the design being rushed into manufacture to meet the competition from the 747. The locking mechanism was difficult to engage properly, the "door locked" sensor was near the locking drive...
  13. notnats

    History of Ball Valves

    I don't know about ball valves, but some years ago there was an extensive exhibition of artifacts recovered from the ruins of Pompeii which included a bronze tapered plug quarter turn valve very similar to those available today. Jeff
  14. notnats

    Elastic piston

    would that be undesirable?
  15. notnats

    Elastic piston

    Would the inertia of the crown also effectively increase the stroke at BDC at high revs? Jeff
  16. notnats

    hex shaft coupler

    A 5/16 socket spanner with a 1/2" square drive? Push together and fill with araldite? Improvements will probably suggest themselves. Drill a 23/64 hole in the 1/2" shaft, push in the hex shaft and fill with araldite again......or silver solder....or roll pin. jeff
  17. notnats

    How much added mass to raise pressure in vessel?

    Water will compress about 46 parts per million for each atmosphere increase in pressure. ie Delta Vwater = 46*10^-6*P when P in bar The pressure vessel will expand as the shell stretches, so you will need to know the stress in the shell and the modulus of elasticity of the material...
  18. notnats

    Neoprene Specs, Dimensioning & Tolerancing

    What kind of sporting apparel is made to such close tolerances? Jeff
  19. notnats

    Neoprene Specs, Dimensioning & Tolerancing

    If the neoprene is to be cut using high pressure water jet, the cutter can probably be controlled from a DXF file, so it may not be necessary to make or dimension conventional patterns. Whoever is to do the screen printing can guide you. I assume your question relates to positioning the garment...
  20. notnats

    Gyroscopic coupling

    With a solid beam axle, I don't see how you can prevent this without heavily damping the steering. As I remember my theory of machines classes, if the right wheel (for example) rebounds from a bump, the gyroscopic precession will force the steering to the left. Forcing the steering back to the...

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