1·The screen reel drum and the card-shelf reel drum are fixed above the blackboard, and the picture clip is fixed on the upper frame of the blackboard;
银幕卷筒、卡片架卷筒固定在黑板上方，图片夹固定在黑板的上框上。
2·The four corners of the frame are provided with four pulleys. Wire ropes pass round the pulleys and are tightened on the reel drum of a crane trolley.
框架上面的四角装有四只滑轮，钢丝绳绕过滑轮向上系于起重行车的卷筒上。
3·LD wheel, wheel group, drum group, hook group, pulleys, couplings, wire rope, cable pulley, motor, brake, reducer, cable reel, overload limiter, standard parts.
LD车轮，车轮组，卷筒组，吊钩组，滑轮组，联轴器，钢丝绳，电缆滑车，运行电机，制动器，减速机，电缆卷筒，超载限制器，标准件。