LUBRICATION OF CROSS-HEAD BEARING IS DIFFICULT DUE TO FOLLOWING REASON :-
- CROSS-HEAD BEARING HAS AN OSCILLATING MOTION HENCE NO HYDRODYNAMIC LUBRICATION IS POSSIBLE.
- THERE IS NO DIRECTION OF REVERSAL OF LOAD AND THE LOWER BEARING OF CROSS-HEAD IS ALWAYS UNDER LOAD.
TO OVERCOME THESE PROBLEM, THE DESIGNERS MADE FOLLOWING CHANGES ON BEARING DESIGN :-
- BEARING SPAN IS REDUCED AND LARGE DIAMETER CROSS-HEAD PIN WITH HIGH SECTION MODULUS RESIST DEFORMATION UNDER THE LOAD. THE LOAD/AREA OF THE LOADED SURFACE IS REDUCED AND CONTINUOUS BOTTOM SHELL IS ADOPTED IN ALL ENGINES. THERE IS AN IMPROVEMENT OF SLIDING VELOCITY ON BEARING SURFACE. THE SURFACE OF THE PIN IS HARDENED AND MADE POLISHED TO A HIGH PRECISION.
- OIL IS DIRECTLY SUPPLIED. IT RECEIVES LUBE OIL WITH AMPLE SUPPLY FOR COOLING AS WELL AS LUBRICATION. OIL LEFT IS SENT TO LUBRICATE CRANK-PIN BEARING. THE SYSTEM AVOIDS DRILLING HOLES THROUGH CRANKSHAFT 7FOR CRANK-PIN BEARING. BLEED GROOVES ON THE BEARING BOTTOM ARE CHAMFERED TO INDUCE WEDGE EFFECT ON THE LUBRICATED SURFACE.