Studies on the development of a new yarder which is exclusively used for Iw.U.S. in standing skyline system of cable logging

这台集材机的特点是安装了一个新的特殊设备DRK（Differentialreibungskupplung），它使两个操作线（主线和循环线）的速度简单地平衡，当它应用于Iw. DRK的基本原理是基于差动摩擦离合器，但与美国传统的联锁不同，DRK不是作用在每个主动齿轮和从动滚筒之间，而是直接作用在两个滚筒（主滚筒和从动滚筒）之间。因此，完全可以避免任何复杂、昂贵或笨重的联锁绞缆机的特殊设计，这种绞缆机也可以广泛地应用于一般的其他电缆测井系统，只要DRK保持自由即可。DRK内部的摩擦会造成功率损失，但实际使用时摩擦足够小，在下坡集材时，由于负载重力引起的小车运行时，它可以作为制动器使用，因此不需要控制另一个制动器。在牵引过程中，操作员可以非常容易地用杠杆控制DRK，并且几乎是静止的。1985年开发了功率为48 PS的试验产品，然后通过在岩手大学实验森林中进行的伐木作业实现了其预期性能。该方法的主要贡献是：A.在各种滑移条件下，都能保证连续地将载荷提升到地面以上。B。集材作业的作业效率可高于在无端轮上使用制动器时的作业效率。C.从人体工程学的角度来看，操作员在控制DRK期间的应变非常轻微（而不是放松），这通过操作员的脉搏测量（心脏检查）得到了证明。

This yarder is characterized by the installation of a new special equipment of DRK (Differentialreibungskupplung), which enables the speed of the two operating lines (main and endless line) to be simply balanced, when it is applied to the Iw.U.S.. The fundamental principle of DRK is based on differential friction clutch, but unlike traditional interlocking in America, DRK functions not between every drive gear and driven drum, but direct between two drums (main and endless-drum) each other. Therefore any special design as a complicated, expensive or great and heavy yarder of interlocking is thoroughly avoidable.This yarder can be also widely used for the other cable logging systems in general if DRK is merely kept to be free. The friction inside DRK causes the losses of power but it is sufficiently small to practical use and serves favorably as a brake for running of carriage caused by the gravity of load in the case of down-hill yarding, so that the control of another brake may not be necessary.During inhaul the operator can control DRK with its lever very easily and almost stationarily. The trial product of the yarder with a power of 48 PS was developed in 1985 and then its expected properties were realized through the logging operations performed in the experimental forest of Iwate University. The main contributions of this method were : A. Continuous lifting the load above ground could be guaranteed under every skidding conditions. B. The operational efficiency of skidding could be greater than that when using of the brake on the endless-drum. C. From the ergonomical point of view the strain of the operator during control DRK was very slight (rather in relaxation), which was proved by the pulse measurment (heart checker) of the operator.