Egerhjul og Vogne

Resumé

Danish Spoked Wheels

In recent years, attention has on several occasions been drawn to disc wheels found in Denmark. New dating and the work of the Dutch archaeologist D. van der Waals have given rise to new interpretations. The present article is concerned with another group of wheels -mainly in the collections of the National Museum of Denmark- namely wheels with 8 or more spokes. The author has based his treatment of these excavated wheels on ethnological studies of the dying trades of the wheelwright and coach-builder.

The main characteristic of the modem spoked wheel is its conical form or camber, arising from the spokes being set obliquely in the hub away from the vehicle. The way certain components are assembled is also characteristic. The spokes are thus fixed in holes in the hub and in holes in the felloes. The identical felloes are shaped to follow the circumference of the wheel and are held together by dowels.

The wheel is shown to be subject not so much to compressive strains as to ultimate strains, since the strongest and most frequent forces are transmitted laterally. In contrast to the disc wheel, the spoked wheel is in principle equally strong, whichever part of the rim is in contact with the ground. With its better use of the natural directional strength of the wood, the spoked wheel also permits a considerable saving in weight. The camber of the modem wheel serves to reduce the constructional weakness of the spoked wheel. The breaking strength at the junction of hub and spokes is low, and when a wheel receives its greatest lateral strain running on a sloping sw-face, the lower wheel will also have to bear the largest part of the weight of the vehicle. Figs. 2 and 5 show how the cambered wheel absorbs this lateral strain.

The oldest known spoked wheels from c. 2000 B.C. were found in Mesopotamia, in connection with two-wheeled carriages. The spoked wheel apparently spread through Europe with the two-wheeled chariot and reached Scandinavia in the course of about five hundred years. Only very few of these early spoked wheels, which are mainly known from pictures, have been preserved. It does not seem to be possible to establish a connection with the later tradition. The many waggon graves of the Hallstatt period in Central Europe point, however, in the sporadic cases where details of construction can be ascertained, to a more recent tradition, at least to the finds of the La Tene period where, for instance, the Danish Dejbjerg waggons are extremely well preserved. In the Dejbjerg waggons a relatively high number of spokes, 12-14, appears for the first time, 800-900 years after a high spoke-number was usual in China. Apparently, the chariot spread quite rapidly in Asia also, and finds from China from c. 1300 B.C. show these vehicles with high wheels, turned spokes, and a spoke number up to 26. A cultural connection between eastern Asia and Europe in the Hallstatt period has been demonstrated, and the author sees the waggon finds of the La Tene period in the light of this connection.

The 4-wheeled waggon later becomes the favoured means of agricultural transport in continental Europe and the first intimations of more humble wheels of this type are found among the Østfold petroglyphs, in groups assigned to 650-400 B.C., or in the find from Rappendam in northern Zealand where large numbers of disc wheels were found amongst several presumed long-waggons. At about the beginning of our era, however, the disc wheel seems to have been replaced by spoked wheels, also for heavy transport. A new, very simple type of many-spoked wheel now turns up in the north European finds.

The excavated wheels in the prehistoric collection of the National Museum are unrepresentative and undated and any conclusions must necessarily be treated with reservation. It is possible to divide these wheels into 3 groups, the first two of which are clearly defined, whilst the third, which largely comprises the remaining wheels, shows certain common features. Group I is characterized by hub shape 1 (fig. 12), 8 or 12 spokes, but always 4 felloes. The spoke-tenons in the hub are flat and rectangular but without a shoulder at the transition to the round shaft of the spoke. Group II comprises wheels with hub form 2, and 12 spokes and 6 felloes, which in contrast to those of group I are decorated with concentric mouldings on one or both sides. The wheels of group III have 10 or 12 spokes (always 2 in each felloe). The felloes are undecorated and have wear pins let into the tread. Diagram p applies this classification to the wheels in question.

The wheel parts of group I stem mainly from an Iron Age deposition in Tranbær bog, with a few parallels, one of which is from the Vimose find. The individual finds in the other groups are very difficult to date, but the sum of available information, supported by analogies in the other Scandinavian countries and in northern Europe, seems to suggest that the grouping employed also has chronological validity.

All the wheels in the prehistoric collection of the National Museum lack the characteristic camber of the modern wheel. The oldest Danish wheel exhibiting this feature is in the medieval collection and was found in the excavation of Boringholm castle. The remains of several cambered wheels were found there and are presumed to belong to the period of the castle, which is believed to have been built around 1300 and relinquished no more than a century later.

Examination of technical details in construction seems to support the view that the classification employed has chronological validity, and it can be demonstrated that the mode of assembly in those wheels which are thought to be the oldest is not the same as in the later wheels where components are assembled in the same order as in modem wheelwrighting.

In conclusion, it may be pointed out that several important details and innovations in the form and manufacture of the wheel can be dated earlier in China than in Europe. This is true of the modem method of assembly, which was known in China in 1300 B.C. and of the camber, which was mentioned in China in 200 B.C., together with the entire iron rim around the wheel, which although known in Europe in the Hallstatt period, was forgotten, to appear again around 1800.

Torben Witt