Compensating nail-driving chuck for pallet-making machine

A nail-driving chuck for driving a nail into a board, the chuck comprising:

• hydraulic drive means for driving a drive member in downward and upward directions along a generally vertical axis;
• nail driving means connected to a lower end of the drive member and coaxially aligned with the drive member for driving the nail downwardly into the board;
• a chuck body coaxially aligned with the drive member and the nail driving means, the chuck body having a cavity into which the drive member extends and a bore positioned below the cavity and through which the nail driving means extends;
• jaw means positioned at a lower end of the chuck body for holding the nail;
• means for permitting telescoping movement of the chuck body with respect to the hydraulic drive means;
• wherein at a beginning of a nail driving cycle the drive member, the nail driving means and the chuck body are at upper end positions of their travel along the vertical axis;
• wherein during a first portion of the cycle the drive member is driven downward and the nail driving means and the chuck body move downward with the drive member until a top surface of the board is engaged;
• wherein during a second portion of the cycle the drive member and the nail driving means continue to move downward while the chuck body remains stationary to drive the nail out through the jaw means and into the board so that a top end of the nail is countersunk with respect to the top surface of the board, the drive member moving downward until stopped by engagement with a lower end of the cavity;
• and
• wherein during a third portion of the cycle the drive member and nail driving means move upward toward their upper end positions and wherein the drive member engages an upper end of the cavity to cause the chuck body to move with the drive member toward the upper end position of the chuck body.