The raising rams are typically pulled up by either hydraulic, air powered, or electric power. Each type has its advantages and dis­advantages, depending on site conditions, design loads, and the designer’s preference. The designer must locate the ram lifters at suitable points on the grid so that loads will be distributed properly over the system. The rams are capable of carrying high loads; as a result, relatively few are needed. Also, each ram is self-contained, allowing for individual control of each raise and also reducing the maze of hydraulic hoses or electric cords needed.