Boom system and elevating fire truck

The utility model relates to an arm support system and an elevating fire truck, and the arm support system comprises a first section arm, a second section arm and a third section arm, a second knuckle arm; the oil cylinder comprises a cylinder barrel and a cylinder rod, the first end of the cylinder barrel is arranged in the first section of arm and connected with the first section of arm, the second end of the cylinder barrel extends out of the first section of arm and located in the second section of arm, the first end of the cylinder rod is arranged in the cylinder barrel, the second end of the cylinder rod is connected with the second section of arm, and the cylinder rod is configured to drive the second section of arm to move relative to the first section of arm; the guide device is arranged on the cylinder barrel; and the guide rail is arranged on the inner wall of the second knuckle arm and extends in the length direction of the second knuckle arm, the guide rail is slidably connected with the guide de