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  1. romke

    Cetane and Power

    Unlike a gasoline cycle that does not care whether the fuel used has a higher octane number then minimally required, a diesel engine calls for a fuel with a minimum cetane number where quite a bit higher can lead to engine problems. When using fuel with a far to high cetane number the combustion...
  2. romke

    Fuel Saving Idea?

    Driving a twostroke SAAB with a freewheel was a remarkable experience when not used to it. If you were used to a fourcycle engined car and then entered your first corner in a SAAB, you immediately realised that you had to apply the brakes far more forcefully then you were accustomed to. The...
  3. romke

    Fuel Saving Idea?

    The idea is employed with some more recent models in heavy duty dieselengined vehicles in Europe. When put in cruise control the vehicle is "seeing" the road in front of it based on GPS data. When noticing a hill clime the gearbox automatically shifts down just before the start of the hill and...
  4. romke

    Steady State Bulk temperature of Gear/Pinion tooth under oil jet spray lubrication

    I am not aware whether a analytical estimate with suitable accuracy exists. If so, I wonder whether that is of use anyway. What you want in the end is a situation where sufficient viscosity of the lubricant is available for lubrication the mating gears and a bulk oil temperature that is...
  5. romke

    Hydraulic lifter wear

    The first thing i can think of is indeed water in the oil. That may cause poor lubrication and thus excessive wear of the hardened surface.However, most times when water is the reason for the damage, you will find similar damage on all lifters. Thus the damage is due to specific circumstances...
  6. romke

    Reference to "code latest edition" in engineering standards

    It may be acceptable in some situations. But it is not a exact way of specifying something that for some reason needs to be specified. It may lead to confusion, which is about the last thing you want when specifying.
  7. romke

    Helical Gear teeth temperature measurement

    Why are you interested in the teeth temperature? Long before the teeth temperature causes problems to the teeth, the oil temperature will reach a point that viscosity might be too low to lubricate the gears properly and/or oxidation will shorten the time the lubricant can be used. A reasonably...
  8. romke

    Oil flow rate to gearbox

    What oil temperatures are we talking about? The normal operating temperature of high speed industrial gears results in 90 to 120 degrees C for the oil when highly loaded. If the temperatures you experience are beyond this range you might consider using another way of oil supply or using a oil...
  9. romke

    Oil flow rate to gearbox

    the amount of oil supply to gears and bearings will depend on how you get the oil towards the spots where lubrication is needed. when the flow is supplied by a pump you need to get the oil towards the gear teeth just before they engage - which means just enough oil that a more or less suitable...
  10. romke

    How should I determine sump oil level after a customised sump?

    Apart from the suggested measurements (head of oil above the oil pickup,clearance from the oil surface to the bottom of the crank)there might be a few other things to consider. If the vehicle is to be used in rough terrain and sometimes short steep slopes, the shape of the oil pan may need...
  11. romke

    Deposit Control Additive (DCA) injection, at Terminal tanks or Trucks loading racks?

    In Europe injection equipment is usually located at the loading bay and DCA is dispensed on demand when loading. Depending on the depot usually injection of different additive packages is possible both in dosage and type. That makes it possible to serve different customers who may prefer...
  12. romke

    Hot oil Flashpoint

    The operation of heating oils above flash point is normal practice. It will not cause a problem, as long as there is no flame that can contact the evaporated oil. That the flash point goes down during operation in a system is normal. It is the result of cracking of oil constituents in the...
  13. romke

    Food proof bearing units

    What is exactly meant by a food proof bearing? There are in the food industry requirements to prevent that foodstuffs are contaminated by lubricants or cleaning agents. That requirement usually is met by using bearings that are well sealed or through other means that prevent harm to food like a...
  14. romke

    Why does Mobil1 recommend different oil viscosity for fully synthetic oil than for semi synthetic?

    The oils that are recommended for use in a particular vehicle primarily is based on the technical requirements of the vehicle manufacturer. The manufacturer usually specifies a number of viscosities, depending on the ambient temperature range the car will be used in. Usually you will have a...
  15. romke

    Interval between Gear Box Oil Replacement

    The oil change frequency will depend on the type of oil and the "load" on the oil during use. That means that frequencies given by the manufacturer are just a figure to start with - in practice the useful life of the oil might be lower or larger depending on operating conditions. In this...
  16. romke

    Hello everyone, I have a conveyo

    I am somewhat amazed over the manufacturers instructions. They supply a lot of detail about mechanical things like mounting etc, but seem to fail to give realistic instructions about lubrication of the bearings. OK, they tell you how much grease should be in the bearing. However - they do so...
  17. romke

    Icing problem for a fishing line towing an underwater probe (Arctic mission)

    If I understand the Spectra documentation well, the line is coated with a PTFE coating that has hydrophobic properties - which in my view means "water repellent". That would mean that as the coating is not damaged by for example floating ice, water in the fluid state would not adhere to the line...
  18. romke

    Tesla "autopilot" disengages shortly before impact

    I am no fan of software that takes decisions how the car should be driven in relation to it's surroundings. I cannot yet see those systems getting so sophisticated that they would be failure proof under all circumstances. Even if they do attain that level, there still is the risk of other...
  19. romke

    Bearing Limiting speed

    Some grease manufacturers are able to supply greases that are capable of lubricating bearings with higher n*Dm values up to 750.000 for certain bearing types. Given the n*Dm value in this specific application those might be of interest. The fact that those greases might be able to lubricate the...
  20. romke

    EV gear reducer has black oil, ref my post on over-constrained couplings.

    the oil blackening is due to oxidation, oil components reacting with hot air. that leads to reaction products with a far higher viscosity as the fresh oil and possibly to foul smelling paste like substances. the reason is overheating - possibly caused by faulty assembly or incorrect clearances...

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