A mobile lift crane (10, 110, 410, 510) comprising: a) a carbody (12, 112, 412, 512) having moveable ground engaging members (14, 16, 114, 116, 414, 416, 514, 516); b) a rotating bed (20, 120, 420, 520) rotatably connected to the carbody such that the rotating bed can swing with respect to the ground engaging members (14, 16, 114, 116, 414, 416, 514, 516); c) a boom (22, 122, 422, 522) pivotally mounted on a front portion of the rotating bed; d) a mast (28, 128, 428, 528) mounted at its first end on the rotating bed; e) a backhitch (30, 130, 430, 530) connected between the mast and a rear portion of the rotating bed; f) a moveable counterweight unit (33, 34, 134, 434, 534); characterized in that the crane further comprises g) at least one hydraulic cylinder (38, 138, 436, and 536) including a first end and a second end, the second end of the hydraulic cylinder being connected directly or indirectly to the rotating bed; and h) at least one arm (40, 140, 438, 540) pivotally connected at a first end to the rotating bed (20, 120, 420, 520) and pivotally connected at a second end to the first end of the hydraulic cylinder, the arm and hydraulic cylinder being connected between the rotating bed and the moveable counterweight unit such that extension and retraction of the hydraulic cylinder changes the position of the moveable counterweight unit compared to the rotating bed, and wherein the at least one arm comprises a pivot frame (40, 540) and at least one rear arm (36, 538), the pivot frame connected between the rotating bed and hydraulic cylinder, and the rear arm connected between the pivot frame and the moveable counterweight unit. a) a carbody (12, 112, 412, 512) having moveable ground engaging members (14, 16, 114, 116, 414, 416, 514, 516); b) a rotating bed (20, 120, 420, 520) rotatably connected to the carbody such that the rotating bed can swing with respect to the ground engaging members (14, 16, 114, 116, 414, 416, 514, 516); c) a boom (22, 122, 422, 522) pivotally mounted on a front portion of the rotating bed; d) a mast (28, 128, 428, 528) mounted at its first end on the rotating bed; e) a backhitch (30, 130, 430, 530) connected between the mast and a rear portion of the rotating bed; f) a moveable counterweight unit (33, 34, 134, 434, 534); characterized in that the crane further comprises g) at least one hydraulic cylinder (38, 138, 436, and 536) including a first end and a second end, the second end of the hydraulic cylinder being connected directly or indirectly to the rotating bed; and h) at least one arm (40, 140, 438, 540) pivotally connected at a first end to the rotating bed (20, 120, 420, 520) and pivotally connected at a second end to the first end of the hydraulic cylinder, the arm and hydraulic cylinder being connected between the rotating bed and the moveable counterweight unit such that extension and retraction of the hydraulic cylinder changes the position of the moveable counterweight unit compared to the rotating bed, and wherein the at least one arm comprises a pivot frame (40, 540) and at least one rear arm (36, 538), the pivot frame connected between the rotating bed and hydraulic cylinder, and the rear arm connected between the pivot frame and the moveable counterweight unit.