Patient lift systems and lift accessories for the same are disclosed. In one example, a system may include a rail having a carriage support channel formed in the rail, the channel having a width, the rail has a working load rating; a carriage slidably disposed in the rail for relative movement to the rail, the carriage comprising a shaft having a length; and a lift unit coupled to the carriage and operable to raise and lower a lifting strap, wherein the lift unit has a working load rating; wherein the length of the shaft of the carriage is less than the width of the channel when the working load rating of the lift unit is equal to or less than the working load rating of the rail. In this manner, lift units that are incompatible with the working load rating of the rail cannot be connected with the rail.