Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Crankshaft lubrication

  1. Jun 10, 2010 #1
    as i have seen, usually in ic engines, the oil is forced into the journal bearings and then it travels along passages in the shaft to connecting rod bearings. but how, does it enter the passages in main bearings with so much centrifugal force. if i understand correctly, the cetrifugal force is the reason it is emitted at other bearings.
    also, does the lubricant function as coolant? or do we use lube+coolant?
  2. jcsd
  3. Jun 11, 2010 #2

    Ranger Mike

    User Avatar
    Science Advisor
    Gold Member

    IC engines have mechanical oil pumps, ( vane or rotor) that are bolted to engine block. block (or engine case) has oil galleries or passages that connect the main bearing throws to the valve train and oil filter, oil under pressure is pushed into this gallery and is pushed thru holes in the crank throws ( main bearing caps, crank shaft main bearings) to the con rods

    Attached Files:

    • oil.jpg
      File size:
      44.1 KB
    Last edited: Jun 11, 2010
  4. Jun 11, 2010 #3
    Yes, in theory each main bearing gets oil from the pump and the excess is supplied to the rod bearings. The camshaft is usually oiled through another oil gally that also feeds the tappets, rocker arms and valve tips.
    Some engines feed the crankshaft oil through the cam bearings while others feed the the crankshaft on a "priority" galley and the cam is lubricated from the crankshaft.
    Each system has advantages and disadvantages under specific conditions.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook