A slotted nut is a hexagonal nut with opposing slots is cut into the top of the nut through the center of the plane. The groove is located at the end opposite the bearing surface. Slots for the insertion of a cotter pin to hold nuts when used with drill shank fasteners.
They are often used with shank or clevis bolts and are slotted to allow a cotter pin; they are generally used where shear strength is required. The function of slotted nuts in automotive industry is to fix the front and rear wheel axles of the vehicle by tightening the screws that pass through the front and rear wheel axles, so that the frame and tires are fixed together.