Although simple enough in principle, it can take a lot of patient practice to provide smooth accurate lateral and arcing movements to order.
As a camera trucks (crabs) across the scene, subjects at different distances appear to pass each other – rapidly in the foreground, and proportionally slower with distance. This parallactic displacement creates a forceful illusion of depth; particularly where the scene contains many vertical features such as posts, columns, or trees.
Trucking alongside a moving subject (a traveling or travel shot) produces a strong impression of speed as background details slide past.
Some dollies are trucked by turning all their wheels sideways (as with the crab or parallel ...