Sheepsfoot Roller Packing the Ground

About this drawing

A sheepsfoot roller gets its name from the stubby feet covering its drum, which look like hooves pressing into the ground. The story goes that the idea came from watching flocks of sheep pack soil tight by trampling it over and over, and in Spanish the same machine is called a goat's foot instead.

It works best on clay. A smooth roller would only press the surface, but the feet sink in and knead the soil from within, squeezing out air and water trapped between the grains. With each pass they sink a little less, a sign that the ground is getting firmer.

Compaction is essential before anything gets built. Prepared soil supports road layers, building foundations and the core of earthen dams. That is why crews spread fill in thin layers and compact each one, rather than dumping it all at once.

Engineers check the work with tests that measure how dense the soil has become. Many modern compactors also vibrate and carry sensors that tell the operator when a section has reached the required firmness, so no time is wasted on extra passes.

• sheepsfoot roller
• compactor
• construction
• heavy equipment
• roads