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

该船厂的特点是安装了新的DRK专用设备（Differentialreibungskupplung），当它应用于美国时，它可以使两条操作线（主线和无止线）的速度简单平衡。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不是在每个主动齿轮和从动鼓之间起作用，而是直接在两个鼓（主鼓和无穷鼓）之间起作用。因此，任何复杂的、昂贵的或巨大的、沉重的联锁码的特殊设计都是完全可以避免的。一般来说，如果DRK只是保持免费，则该码码器也可以广泛用于其他电缆测井系统。DRK内部的摩擦会造成动力损失，但实际使用时摩擦力很小，在下坡时由于载荷的重力引起的车厢运行时，它可以很好地起到制动作用，这样就不需要控制另一个制动器了。在进料过程中，操作人员可以很容易地、几乎平稳地用杠杆控制DRK。1985年研制出功率为48ps的采伐机试验产品，并在岩手大学的实验林中进行了采伐作业，实现了其预期性能。该方法的主要贡献有：A.在各种打滑条件下，都能保证将载荷连续提升到地面以上。B.在无止回鼓上使用刹车时，打滑的操作效率可能会更高。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），操作员的脉搏测量（心脏检查器）证明了这一点。

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.