我们曾对正置三角形小车变幅臂的支撑形式和吊点位置变化对臂架内力及起重性能带来的影响等问题进行过讨论,曾指出:(1)改变吊点在臂纵轴上的位置,可获得不同的起重特性曲线,以保证在不同的使用要求下扩大塔机的使用范围。同时,给出了获得最小应力值的吊点位置的方法。(2)上支撑式的受力状况较为合理,可以比下支撑时的应力减小。我们在设计25吨米、40吨米及60吨米级的塔机时运用了以上结论,其结果是比较满意的。对4吨米塔机进行电测,也证明了上述结论。 We discussed the problems of the supporting form of the luffing horn and the influence of the position change of the lifting point on the internal force and the lifting performance of the boom. We have pointed out: (1) to change the suspension point on the longitudinal axis of the arm Of the location, get different lifting characteristic curve, in order to ensure the use of different tower crane under the expanded scope of use. At the same time, the method of obtaining the position of hanging point with minimum stress value is given. (2) The supported condition is more reasonable, which can reduce the stress than the lower support. We used the above conclusions when designing tower cranes of 25 tons, 40 tons and 60 tons of rice, and the result is satisfactory. The 4-ton Mita machine electrical test, also proved the above conclusion.