Shahmukhi : پتھّا
Meaning in English
wooden piece set in the lower grindstone to fix the axle in it or one set in the hub of a wheel for the axle to rotate in it
Source: Punjabi Dictionary
PATTHÁ
Meaning in English2
s. m, The piece of wood in the centre of a lower millstone in which the iron pin is set, the wooden brace with which a millstone when broken is joined and held together.
Source:THE PANJABI DICTIONARY-Bhai Maya Singh