Start: Attach a straight bar to the low pulley. Stand facing the weight stack, and grab the bar with a wide, underhand grip. Hold it at arm's length in front of your thighs, with our knees slightly bent, your back straight, and your shoulders back.
Finish: Curl the bar until your forearms are almost perpendicular to the floor, Pause, then return to the starting position.
Use the rope attachment and a neutral grip to move even more work to the brachialis.
Use an EZ-curl bar and an overhand grip for maximum brachialis involvement.