The Monjolo: A Primitive Hydraulic Machine for Grain Processing

The Monjolo is a traditional hydraulic machine used for grinding and processing grains. Introduced to Brazil by the Portuguese during the colonial period, it operates without human effort, utilizing falling water as a power source to perform repetitive tasks.

Designed to peel and grind dry beans into a coarse flour, the Monjolo consists of a wooden beam suspended in a way that creates an uneven balance. One end supports a pestle, while the other features a trough. A spout directs water into the trough, gradually raising the pestle. Once the trough reaches capacity, it tips, spilling the water and causing the pestle to drop, striking a mortar and grinding the grain.

As an essential tool for agricultural communities, the Monjolo has historically eased food processing, making it especially valuable for farmers growing multiple crops. Its reliance on a steady water supply has also influenced settlement patterns, encouraging people to establish homes near rivers or streams.