A mechanical lawn sweeper collects leaves and other debris, so is a good choice for large lawns. As you push the sweeper along, its wide brush whirls the leaves off the lawn and into the collector. The working height is adjustable for use on paving or lawns, but don't be tempted to use one on gravel, because the brush picks this up and throws it facewards. For this reason, goggles are a sensible precaution if there's any chance of grit, stones or other small projectiles (eg acorns) lying on the lawn.

Sweepers are usually around 60cm or more wide (from around £100), but not widely stocked due to limited demand. There are also towable versions to go behind your garden tractor or ride-on. Look for both types on one of the online garden equipment sites.

Look at these links for pictures:

Agri-Fab mechanical sweeper

Power Porter mechanical sweeper