Pulldown apparatus

A method of assembling a pulldown apparatus that includes a main stage and a secondary stage, the main stage configured to receive at least a portion of the secondary stage, the main stage including a cylinder, a main head, a main gland, a piston and a main rod, the cylinder defining a chamber that extends lengthwise through the cylinder, the cylinder including a first end and a second end, the main head disposed on the second end of the cylinder, the main head including an aperture that extends therethrough, the main gland disposed in the chamber and adjacent to the main head, the piston disposed in the chamber adjacent to the first end, the main rod disposed in the chamber between the piston and the second end, the main rod having a fluid channel that extends lengthwise through the main rod, the secondary stage including a secondary head, a secondary gland, a secondary rod and a flange, the secondary gland adjacent to the secondary head, the secondary rod coupled to the flange, the secondary rod including a fluid passageway that extends lengthwise through, the secondary rod extending through the secondary gland and secondary head, the method comprising:

• disposing the flange in the chamber between the piston and the first end of the cylinder;
• coupling the flange to the main stage, wherein after the flange is coupled to the main stage, the cylinder is slidable over the flange and the secondary rod;
• disposing the secondary gland in the chamber;
• and
• coupling the secondary head to the first end of the cylinder, the secondary head including an opening extending therethrough, wherein the secondary rod is disposed in the opening,
• wherein the cylinder is slidable over the main rod, the piston and the secondary rod.

A pulldown apparatus disposed on a rotary drill machine, the rotary drill machine including a deck frame and a drilling mast, the drilling mast including a mast frame and a crown, the mast frame including a first mast end and a second mast end, the second mast end of the mast frame mounted on the deck frame, the crown coupled to the mast frame adjacent to the first mast end, the pulldown apparatus comprising:

• a main stage including:
• a cylinder that defines a chamber extending lengthwise therethrough, the cylinder including a first end and a second end;
• a main head disposed on the second end of the cylinder, the main head including an aperture extending therethrough;
• a main gland disposed in the chamber and adjacent to the main head;
• a piston disposed in the chamber adjacent to the first end;
• and
• a main rod disposed in the chamber between the piston and the second end, the main rod including a fluid channel that extends lengthwise therethrough;
• and
• a secondary stage including:
• a secondary head disposed on the first end of the cylinder, the secondary head including an opening extending therethrough;
• a secondary gland disposed in the chamber and adjacent to the secondary head;
• a secondary rod disposed in the opening and coupled to a flange,
• the secondary rod including a fluid passageway that extends lengthwise therethrough;
• and
• the flange coupled to the main stage and disposed inside the cylinder between the piston and the secondary rod,
• wherein the cylinder is slidable over the main rod, the piston and the secondary rod,
• wherein the main rod is coupled to the deck frame, and the secondary rod is coupled to the crown.