A laterally collapsible, user-pushed, four-wheeled rollator, stroller or the like has swiveling front wheels for steering, each mounted in a fork with a vertical post, with a toothed pulley fixed thereto, rotatable in a bearing housing fixed at the front end of right and left side frames. The two swiveling front wheels can swivel to any steering angle but always in unison with each other by virtue of a flexible toothed synchronous belt extending between the toothed pulleys. The interior of each bearing housing closely surrounds each toothed pulley and the belt, preventing any disengagement of the belt from either toothed pulley even when the belt becomes slack when the left and right side frames are folded towards each other. A synchronous chain with sprockets can also be used. Tether means pull the belt/chain rearwardly to a protected position during folding.

There is provided a pram frame (200) comprising a first roller attachment point (221) configured to engage with a first roller set (121) and a mechanism (231) configured to engage with the first roller set (121) via the first roller attachment point (221). The mechanism (231) is configured to provide driven steering of the first roller set (121) when a user steers the pram frame (200).