The 5140030-52 is a cast aluminum piston for the 2 Stage, Oil Lubricated, Unoair Compressor pump used on Porter Cable air compressors.
The 5140030-52 has a measured diameter of 89.8mm.
The 5140030-52 was used on the following models:
919-16781 type 0
919-16781 type 2
C7550 type 0
C7550 type 2
E7540 type 0
E7540 type 2