I am trying to see what should be the return line size of gearbox based on oil inlet flow.Checked API 613,617,672 all are showing different values.
One thing is common in all above mentioned API is that oil drain line running no more than half full.
How we can calculate or size the return line to be half filled only( considering oil drain line is sloped towards main oil tank and flow is gravity feed on gearbox side and slight vacuum on main oil tank side)?
Why API recommended oil half filled return system?
Also what should be the maximum allowable oil flow velocity in drain line?