An air-cooled heat exchanger includes a plenum with a fan ring positioned adjacent to the plenum. Support columns support the plenum and the fan ring on a support surface. An X-brace assembly includes a motor mount with leg members extending radially from the motor mount. Each of the leg members is connected to a single corresponding one of the support columns so that the leg members extend between the motor mount and the support columns. A motor including a drive shaft is mounted to the motor mount of the X-brace assembly. A fan having fan blades is mounted to the drive shaft of the motor. The fan is positioned within the fan ring between the motor and the fan ring opening.