A weightlifting machine comprising: a user-engaging device configured to be engaged by a user during an exercise on the weightlifting machine; a carriage support comprising a track extending upward from a base; a carriage moveably mounted on the carriage support and configured to move vertically along the track, wherein the carriage is configured for engaging a weight for resistance against vertical movement; a locking mechanism comprising a pivoting body and a locking member connected to the pivoting body, the pivoting body connected to a pivot connection; and characterized by: a cable system comprising a cable operably connected to the user-engaging device and the carriage and one or more pulleys connected to the weightlifting machine to guide a path of the cable, such that movement of the user-engaging device by the user during the exercise moves the carriage vertically along the track via the cable system; and the pivoting body comprising a base member and a vertical member connected to the base member and extending upward from the base member, wherein the locking member is connected to the base member, and the pivot connection defines a horizontal pivoting axis, wherein the base member, the vertical member, and the locking member are moveable by pivoting together about the horizontal pivot axis between a locking position, where the locking member engages the carriage and supports the carriage at an elevated position above a lowermost position of the carriage, and a release position, where the locking member does not engage the carriage, and the carriage is free to move below the elevated position. a user-engaging device configured to be engaged by a user during an exercise on the weightlifting machine; a carriage support comprising a track extending upward from a base; a carriage moveably mounted on the carriage support and configured to move vertically along the track, wherein the carriage is configured for engaging a weight for resistance against vertical movement; a locking mechanism comprising a pivoting body and a locking member connected to the pivoting body, the pivoting body connected to a pivot connection; and characterized by: a cable system comprising a cable operably connected to the user-engaging device and the carriage and one or more pulleys connected to the weightlifting machine to guide a path of the cable, such that movement of the user-engaging device by the user during the exercise moves the carriage vertically along the track via the cable system; and the pivoting body comprising a base member and a vertical member connected to the base member and extending upward from the base member, wherein the locking member is connected to the base member, and the pivot connection defines a horizontal pivoting axis, wherein the base member, the vertical member, and the locking member are moveable by pivoting together about the horizontal pivot axis between a locking position, where the locking member engages the carriage and supports the carriage at an elevated position above a lowermost position of the carriage, and a release position, where the locking member does not engage the carriage, and the carriage is free to move below the elevated position. a cable system comprising a cable operably connected to the user-engaging device and the carriage and one or more pulleys connected to the weightlifting machine to guide a path of the cable, such that movement of the user-engaging device by the user during the exercise moves the carriage vertically along the track via the cable system; and the pivoting body comprising a base member and a vertical member connected to the base member and extending upward from the base member, wherein the locking member is connected to the base member, and the pivot connection defines a horizontal pivoting axis, wherein the base member, the vertical member, and the locking member are moveable by pivoting together about the horizontal pivot axis between a locking position, where the locking member engages the carriage and supports the carriage at an elevated position above a lowermost position of the carriage, and a release position, where the locking member does not engage the carriage, and the carriage is free to move below the elevated position.