WAGON CONSTRUCTION
The wagons built by the Romans were unsurpassed in engineering and technology until well after the Middle Ages. "Altogether, a range of vehicles was created in the Roman era which that would satisfy the needs of European society for the next thousand years."1. To understand the Roman wagon is to know something about the wagons built and used in the Middle Ages. The technology of wagons as it existed in Roman Imperial times underwent no improvements throughout the Middle ages. Instead there is evidence which suggests that the technology declined in the early Middle Ages. The level of Roman wagon technology with suspension systems and single piece fellies was unreached until the 18th century or later. Although some authors cite the importance of dished wheels which were introduced after the Middle Ages2, they did not have the impact on wagon technology that the rediscovery of the Roman pivoting front axis and suspension system did. The reality was that in the Middle Ages, as in Roman times, oxen still pulled the very heavy loads and indeed to support these heavy loads, the heaviest wood was used to build the wagons. In fact John Langdon notes that oxen were used to pull wagons built from oak wood and horses were used to pull wagons font made from lighter woods such as ash 3, since oak is heavier than ash and can sustain a greater load.
So what sort of technology in Wagon construction did the Romans have? The wagons were of either a 2-wheeled, or 4-wheeled variety. A casual look at any Roman iconography will show a wide variety of wagons in use for various purposes.

Fig. 17.Gallo-Roman Wagons4
高卢-罗马货车

Fig 18. Pompeiian Wine wagon5 庞贝运酒马车
The construction of wheels was especially sophisticated. The wheels contain either 8 or 12 spokes and were banded with iron6. Single piece fellies were employed in wheel construction, thereby indicating a high level of woodworking technology7. Roman wheels were discovered in Newstead, Scotland, the fellies of which were made from single pieces of bent ash8. The hub appeared to have been turned on a lathe and is lined with an iron ring9. Archaeological evidence suggests that the skills of the wheelwright deteriorated after the German invasions of Western Europe10. As a matter of fact single piece fellies were not re-invented until after 1775.11
Of even greater import for our knowledge of Roman wagon technology were the excavations at Neupotz at which the remains of numerous plaustra or lorry type wagons were discovered. Based on coins and other artifacts found at the site, archaeologists date the finds to be from A. D. 278.12. It is the first archaeological find of such a lorry, only known from reliefs before.13 One of the most interesting finds is in the area of the construction of the axle. Although the axles were made of wood, they were reinforced with iron bushings. Archaeologists found 48 nave or hub rings used to strengthen the hub, which were preserved with wood pieces and 48 iron nave bushings, which were placed inside of the wheel hub14. (See Figure 19A)