Heavy-duty diesel engines built in the early 20th century to power industrial machinery and workboats are fascinating objects that showcase the complexity and precision of internal combustion technology. Many components inaccessible or invisible on modern engines are oversized and mounted on the exterior of these antique heavy-duties, making them excellent tools for educating people about how engines work and are maintained. Heavy-duties were also designed to be far more servicable than modern engines, allowing knowledgable mechanics to disassemble, repair, and reassemble systems within them using ordinary tools and equipment.

Today, few heavy-duty diesel engines remain in the world and even fewer still operate. As technological innovations in the propulsion field increased, older engines were scrapped or relegated to storage lots where they rusted away in the rain. Modern marine engines have become smaller and more efficient, but far noisier and less interesting than the reliable old heavy-duties.

Increasingly, the few remaining heavy-duty diesel engines are becoming artifacts, accessioned into museum collections and donated to non-profit preservation groups. Others continue to work in tugboats and historic vessels, providing reliable and efficient propulsion as they were designed to more than 70 years ago. These engines provide both a tangible record of past technology and a modern illustration of human ingenuity.