Abstract: Mechanical handling apparatus for moving a load over a support surface comprises an endless powered conveyor device which extends substantially over at least part of the length of the support and is trained round guides or pulleys rotatable about substantially horizontal axes. The endless conveyor device comprises a chain having a working run and a return run the working run of which comprises at least two working parts, which are movable vertically independently or in unison. In a preferred embodiment, each conveyor device comprises two side-by-side chains. The endless chains run in a guide for the working run and a guide for the return run. The guides are mounted one on top of the other, the lower guide being of inverted channel section and the upper guide being of upwardly open channel section which rises and falls within an outer channel on a support plate which is in contact with an inflatable device such as an air bag in order to provide a smooth and uniform raising and lowering.