We know of Roman construction machinery both through written accounts and through relatively descriptive reliefs and mosaics. Without going to extreme lengths of description the principal functions of Roman construction machinery were the following:
Ropes made in a number of different techniques could be rendered more or less elastic so that they were not only used as a means of binding or pulling but also as a spring capable of conserving energy. This last use can be seen in catapults where a number of such ropes would be bundled and fixed taught at either end. A bar passed through them could be twisted and thus creating tensile force in the ropes.
Pulleys were used to great advantage in order to gear force up or down.
In order to apply force the most common methods involved different types of winches which were mounted either horizontally or vertically. In the horizontal type they were actioned by turning the outward spokes of a horizontal wheel. This could be done either by men or oxen. In the vertically mounted type the men or oxen could tread on the inside, rather like a Hampster wheel. The same technique was re-used in later epochs for construction projects such as Brunelleschi’s dome in Florence.
The application of these sub units, ropes, pulleys, wooden structures (with appropriate joinery) and winches allowed the Romans to create the most varied construction machinery which could be constructed on site according to the needs of the moment. Metal was restricted to particular situations and tasks such clasps which allowed cranes to hoist stone blocks into the air or girders to solidly bind wooden structures or even stone blocks.
At times this machinery could be of such enormous size and strength that it would be difficult, given our relative lack of expertise, to replicate the same results without a whole team of engineers and computer aided simulations. These machines replicated the same functions one would expect in modern construction:
Mills (of stone) to ground the raw materials to make mortar, cranes and hoists to lift materials to great heights, solid scaffolding, trusses of wood or ceramics, piles to drive stakes into the ground and so on.
The only real thing missing out of all this is machinery for moving operations. Clearly there were no engines available at the time but large (and in some cases we really do mean extremely big) stone sections would be carried great distances when necessary. This was primarily achieved through the use of man power and teams of Oxen. Smooth ramps allowed large blocks to be shifted on rolling pins or for greater distances on carts or barges via water.