Crank arm structure, arm support structure and elevating platform fire truck

The invention provides a crank arm structure, an arm support structure and an elevating platform fire fighting truck, the crank arm structure comprises a crank arm, the crank arm comprises a plurality of connected side walls, the plurality of side walls are encircled to form a mounting cavity, one end of the crank arm is used for being connected with an arm support main body, and the other end of the crank arm is used for being connected with a balance arm; the first driving part is arranged in the mounting cavity, the first driving part is connected with the crank arm, the first driving part is connected with the balance arm, and the first driving part is used for changing the included angle between the crank arm and the balance arm. 本发明提供了一种曲臂结构、臂架结构和登高平台消防车，其中曲臂结构包括：曲臂，包括多个相连的侧壁，多个侧壁合围形成安装腔，曲臂的一端用于与臂架主体连接，曲臂的另一端用于与平衡臂连接；第一驱动件，设于安装腔内，第一驱动件与曲臂连接，第一驱动件与平衡臂连接，第一驱动件用于改变曲臂与平衡臂之间的夹角。