3. DRAIN CIRCUIT Travel motor Swing motor From return line Main pump Turning joint Dr#, dr# R2 Hydraulic oil tank Drain filter Dr Check valve 1.5kgf/cm 2 300S3CI02 Besides internal leaks from the motors and main pump, the oil for lubrication circulates. These oil have to be fed to the hydraulic tank passing through drain filter and return filter. When the drain oil pressure exceed 1.5 kgf/cm 2 (21 psi ), the oil returns to the hydraulic tank directly. 1) TRAVEL AND SWING MOTOR DRAIN CIRCUIT Oil leaking from the right and left travel motors comes out of the drain ports provided in the respective motor casing and join with each other.
These oils pass through the turning joint and join with oil leak line of the swing motor and return to the hydraulic tank after being filtered by return filter. 2) MAIN PUMP DRAIN CIRCUIT Oil leaking from main pump come out and return to the hydraulic tank passing through drain filter. 3-5