Mining Science and Technology, 13 (1991) 243-255 Elsevier Science Publishers B.V., Amsterdam 243 Comparison of longitudinal and transverse cutting heads on a dynamic and kinematic basis O.Z. Hekimoglu Turkish CoalEnterprises, Beypazan (OAL) Ltgnite Mine, Caytrhan-06922, Ankara, Turkey (Received March 15, 1990; revised version accepted December 19, 1990) ABSTRACT Hekimoglu, O.Z., 1991. Comparison of longitudinal and transverse cutting heads on a dynamic and kinematic basis. Min. Sci. Technol., 13: 243-255. Some dynamic and kinematic characteristics of longitudinal and transverse cutting heads on boom tunnelling machines are described and compared. A dynamic and kinemauc analysis was carried out for the both cutting head types under the same operational and design conditions. The results were compared with those of long term in situ trials of longitudinal cutting heads. The cutting head design was found to have a significant effect on the performance of both cutting head types. The resultant boom force reaction was found to act perpendicular to the boom axis for a longitudinal head, whilst it tended to act parallel to the boom axis for a transverse head. The change in the magnitude of the resultant boom reaction was also seen to be relatively high for the transverse heads during transitions from arcing to lifting. It was further emphasized that the consistency in the product size of a transverse head is likely to be higher in arcing than in lifting. Introduction Boom tunnelling machines have, over the past few years, been increasingly employed in mining and civil engineering due to their versatility and suitability for various cutting conditions. These machines are seen to be equipped with two different types of cutting head. One of them is known as the longitudi- nal (also axial, milling, or spiral-type) cutting head, which is a single head arranged in-fine with the boom axis (Fig. la). The other is called the transverse (also ripper, forward- rotating or drum-type) cutting heads which are two symmetrically positioned cutting head halves with their axis perpendicular to the boom axis (Fig. lb). It seems that certain manufacturers tradi- tionally adhere to the longitudinal heads while some only deal with transverse heads. Among manufacturers, only one (Eickhoff, West Germany) uses both cutting head types. Dif- ferent views have been put forward on the relative merits of these cutting heads. How- ever, it seems that they sometimes contradict each other. As an example, the transverse heads are generally claimed to be better for hard rocks, while the longitudinal heads are reported to be better suited for selective cut- ting in mixed cutting conditions. In spite of these claims, in practice both cutting heads are still used in similar fields of application. It is also noted that the cutting head power rating for transverse heads is, in most cases, higher than that of longitudinal heads for a similar machine weight. This situation can be attributed to the larger diameter of transverse heads. However, this may also be attributed to some dynamic and kinematic factors re- lated to the position of cutting heads with respect to the boom axis. The change in the orientation of axis of cutting head rotation Elsevier Science Publishers B.V.