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  • Users: harrisj
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  1. harrisj

    "WOBBLE" or "COLLAR" WHEEL BOLTS

    I have come across a wheel-retaining device in UK called a 'Wobble bolt' or 'Collar bolt'. It is a wheel bolt designed to accommodate a difference between a wheel PCD and a hub PCD. It is a bolt with a floating collar which can align itself eccentrically to the bolt axis by a millimetre or two...
  2. harrisj

    HYBRID DRIVE ANALYSIS SOFTWARE

    I am interested in finding analytical software for electric / diesel hybrid road vehicles. I recall about 15 years ago an Israeli company produced an excellent program which did everything I now want. It ran under DOS and was pretty slow (so was the 386 I ran it on!); but it was extremely...
  3. harrisj

    MEASUREMENT OF DIESEL BLOW-BY GASES

    We have been asked by a client to add some instrumentation to an engine test rig to measure 'crankcase blow-by' in order to assess cylinder wear, ring condition etc. The client has only asked for a measurement of pressure, but in a vented crankcase this is likely to be so near atmospheric as to...
  4. harrisj

    FUTURE FOR LEAD-ACID BATTERIES?

    According to an email circulated round my company, there is none. In Europe, lead-acid batteries will be banned some time over the next few years (except for some specific applications, eg military). The reason is the nastiness of lead and sulphuric acid. I don't disagree with the toxicity...
  5. harrisj

    DIESEL DROPLET SIZE

    Diesel fuel is injected into the combustion chamber as a finely divided aerosol spray. I infer that the better the atomisation, the better the burn characteristics. My question is: is there an optimum droplet size? If one could atomise the fuel to ever more finely divided mist, would the...
  6. harrisj

    OTTO CYCLE DEFINITION

    I have researched a number of websites and books to get a definition of the Otto cycle. In most cases it is synonymous with 4-stroke, and in others seems to be associated only with spark ignition. My view is that it describes the 4-stroke cycle, whether spark or diesel, reciprocating or...
  7. harrisj

    TYRE FRICTION ON OILY ROAD SURFACE

    Anyone have any numerical data for the coefficient of friction of tyres on roads contaminated by diesel spillage? I am looking at worst-case conditions for normal road tyres with reasonable tread pattern travelling over damp roads on which diesel has been spilled recently. I would guess...
  8. harrisj

    RAILWAY LOCO EARTH RETURN - EXPLAIN PLEASE

    Electric locos pick up high voltage from an overhead catenary. The return path is through the wheels to the rails which complete the circuit. At least, that's what I understand. But if the wheels are isolated from the rail momentarily (eg leaves on the line!), the circuit is broken and the...
  9. harrisj

    DUCTED FAN vs TURBOJET

    I am looking at the feasibility of a light (100 kg) low-speed (100 kt) unmanned aircraft, similar to those used by the military for drones, reconnaissance etc. Most of these use small turbojets but I am considering using a ducted fan driven by a 4-stroke IC engine. What are the pros and cons? I...
  10. harrisj

    42 Volt Automotive Systems

    I assumed that the so-called 42V systems proposed for the future were based on 36V battery technology. 42 is the voltage when charging. A colleague has suggested that the 42V is the battery potential, giving about 49V when charging. This is to keep the maximum system voltage below the 'magic'...
  11. harrisj

    CONTINUOUS RAIL EXPANSION

    Here's a railway problem I don't understand - haven't found a good explanation on any website, but it can't be rocket science. It goes like this: Continuously welded rail can see temperature variations from -30C to + 50C or more in some parts of the world. Coefficient of expansion of steel is...
  12. harrisj

    fifth wheel semitrailer couplings

    I have come across many different configurations that exist for fifth wheel couplings on semi-trailers (articulated trucks to us Brits). I have also found jargon words which are not self-explanatory and are ambiguous. Is there a good reference website out there which covers 5th wheels? This is...

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