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  1. NJAus1

    Gear Tooth Surface Finish

    This is a close up view, is this considered normal on gears as a factory finish?
  2. NJAus1

    Gear Tooth Surface Finish

    Hi All, I was wondering if I could get some feedback on the surface finish of gears as shown in the photo below? The gears are new and are carburized. I am unsure what would cause this unusual surface effect? the gear in question is on the left. Thanks
  3. NJAus1

    Gear Train Deceleration

    Hi All, I am just trying to get my head around braking/slowing down a gear set Simple gear set that has a drive gear and driven gear. If I brake the drive gear by applying a negative torque then this torque (and force) is applied at the pitch line of the gear teeth at the opposite face and in...
  4. NJAus1

    Piston Pump Case Drain Temperature

    As the fluid on the case drain increases in temperature then heat needs to be transferred, the pump is generating heat from it inefficiencies that cause the fluid in the case drain to increase? If I treat the case drain as a closed system, then there is no useful work being done by the system...
  5. NJAus1

    Piston Pump Case Drain Temperature

    I get the concept that heat is generated but if heat is the transfer of thermal energy, then what is transferring the heat.
  6. NJAus1

    Piston Pump Case Drain Temperature

    Hi All, I wanted to understand how a piston pump that wears over time results in an increase in case drain temperature. With age the case drain flow increases which I understand. I have had an explanation: Case-drain flow does no useful work and is converted into heat. I don't quite...
  7. NJAus1

    Buffer and Main seal Leaks

    Seals are thermoplastic polyurethane elastomers (TPU), the main is a is TPU and rubber. The wiper seal is spring energized. There is an upper and lower sleeve bearing, but yes due to the high loads and road conditions there will be inevitable radial play. The solution to this would be more...
  8. NJAus1

    Buffer and Main seal Leaks

    They are replacement seals, the cylinders are supposed to get a planned overhaul but have premature oil leaks. Each time they are overhauled, new seals including sleeve bearings are put in. The bearings don't exhibit signs of unusual or accelerated wear. The cylinders use a combination of...
  9. NJAus1

    Buffer and Main seal Leaks

    The rod usually has some pitting on it that will require it to be re-chromed. The rod is orientated like the below image. If I ignore the wiper seal failure as it's primary purpose is to prevent ingress into the cylinder, I am assuming whether the wiper is intact or not once oil passes the...
  10. NJAus1

    Buffer and Main seal Leaks

    Hi, I have a suspension cylinder (from a mining truck) that has a buffer seal, main seal and wiper seal. See below image (in real life this is orientated vertically). The cylinder will be subjected to pressure spikes due to the load the truck carries, ground roughness, cornering etc. I have...
  11. NJAus1

    Epicyclic gears and thrust washer rotation

    I think this was a difficult question to ask, it will depend upon material properties, lubrication and the thrust force etc. I think there would be scenarios where they would rotate together and when they would rotate relative to each other (sliding).
  12. NJAus1

    Epicyclic gears and thrust washer rotation

    Hi All, A quick question with respect to a gearbox with the following configuration. There will be some end play in the configuration shown below. The washer is bronze and lubricated so the friction should be minimal but it will exist. Both the thrust washer and retainer are free to spin. The...
  13. NJAus1

    Bearing Failure SEM Image

    I believe it has rotated downward. Below are some images related to electro fluting, fluting would create a smooth appearance typically, the other image shows a smooth appearance with pitting/spalling
  14. NJAus1

    Bearing Failure SEM Image

    Below is the macro image of the outer raceway, from an AC Generator that is connected to a diesel engine. The bearing is a ball bearing and is lubricated by grease. The balls have no significant damage. This is a low hour failure. Below is an image of the inner raceway, the damage is...
  15. NJAus1

    Bearing Failure SEM Image

    Apologies, yes the balls are steel (iron and carbon is present). See attached
  16. NJAus1

    Bearing Failure SEM Image

    Hi All, I would like to seek some clarification on observations in an SEM image obtained from a bearing outer raceway that appears to be spalled in one section. The spherical balls are Iron as confirmed by SEM analysis. What phenomena would cause the steel in the raceway to become spheres...
  17. NJAus1

    Pinion Gear Contact Surface

    Hi All, I have a pinion gear (drive gear) and a ring gear (driven gear). I have attached a photo and marked up the contact pattern on the tooth. Does the contact pattern appear correct? Should the contact area extend up to the tip? Thanks
  18. NJAus1

    Fracture Surface Failure mode identification

    Yes you are correct there will be cyclic tensile loads applied. In the photos, the weld is not observable however the fracture surface is a weld, it has fractured right through the weld. In the above photo, the shiny silver region is the parent metal (of the rod eye) and the darked surface is...
  19. NJAus1

    Fracture Surface Failure mode identification

    The cylinder has spherical bearings on the rod eye and on the clevis. The cylinders push and pull only during typically use. The spherical bearings prevent bending loads. The hole you are seeing is a locating hole on the cylinder eye, there is a spigot on the rod which locates on this hole and...
  20. NJAus1

    Fracture Surface Failure mode identification

    Hi, I am looking into a failure where the component has two parts (cylinder rod and rod eye) welded together and is subject to tension only. Refer to the attached image. The outer edges (shear lip?) have progression marks indicating that the was a crack present and grew over time. This would...

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