Specifications include, but are not limited to: B. Lifting Column Construction: Each column shall have a rated capacity of 18,000 lbs, 72,000 lbs as a set of four. The minimum total lifting height as measured from the floor to the bottom of the lifting cradle shall not be less than 67 inches. The lifting mechanism shall consist of a threaded screw, load bearing nut and a back up nut. It shall be nonreversible and guaranteed self-locking in operation. The overall height of the column shall at no point exceed 102 inches. Columns which extend in overall height as the lifting height of the carriage increases will not be considered. The lift will have the ability to rise at three different speeds, determined by the operator and dependent on the weight of the load being raised. Vertical displacement of the lifting cradle shall be at the rate of 67 inches per minute when empty and 27 inches when fully loaded. An overload protection device will prevent the operator raising a load faster than permitted by the weight of the vehicle. The motor/gearbox drive should be mounted at the top of the column. The height of the outrigger leg should be no more than 5.5inches for access underneath low vehicles. Each column shall be easily moveable on four wheels consisting of two fixed wheels mounted on the straddle legs and a dual extendable and maneuverable hydraulic jacking unit mounted at the rear of the column. Each column should be fitted with a Hydraulic jacking unit, activated by raising a “dead man” release trigger and pumping a handle. When the trigger is released, the jack shall automatically lower ensuring that the base of the column is on the ground before the vehicle is raised. Rear wheel assembly shall be non-loading and shall provide for at least 180-degree steering. Column construction shall be of a single mast design to facilitate in the maneuverability of the column and to provide for minimal obstruction with vehicle mounted mirrors and accessories C. Lift Operation: One system shall consist of four columns. A four-column set shall be upgradeable to six columns without any modification to the columns and their electrics. The system should be upgradeable by the addition of any secondary column (2, 3, or 4) from another set. The primary “1” column shall come with an interactive touch screen pad. The pad shall be easy to interpret giving the operator the ability to select modes of operation of all columns, pairs and single lifts. The touch screen pad will illustrate the mode of operation selected by the operator. A graphic showing the height of each column in the operational set shall be accessible on the touch screen pad. The screen display located on the primary “1” column shall have the ability to view real time amperage draw, cycles completed, date lifts first used and annual inspection due date. Operational faults shall be communicated in words to the operator on the touch screen pad. Operation of the lifts shall be achieved with a handheld remote control which is detachable and connect into any of the columns in the selected mode. The length of the cable shall be sufficient to allow the operator to stand back at least 9 feet from the column. The control panel on each lifting column shall include a palm operated emergency stop button and an "up" and "down" push button for individual, paired and synchronous operation. Up/down push buttons shall be of a "dead man" design requiring constant pressure while raising or lowering a vehicle. A red emergency mushroom push button shall be located at each column control cabinet to permit immediate deactivation of the entire lifting system. If activated, it should be a simple turn to reset. A power disconnect switch shall be provided on the master control box. The system will automatically detect and shut down an obstruction that would prevent the proper down motion of the carriage be encountered. It shall state on the display screen which column in the set has encountered the obstruction. In this event, it shall not be possible to lower the vehicle and the vehicle must be raised a minimum 1½ inches to allow the obstruction to be removed. D. Self-Leveling System: The lift shall include an automatic leveling system which constantly monitors the exact position of all columns and will automatically adjust the position of the individual columns to maintain no greater than a 3/8-inch height differential between all columns. Initially, the ISO leveling system shall attempt to level the columns by stopping the column at the extent of the synchronization. If the fault is an out of level condition which cannot be corrected, then it shall shut down the entire lift system.