In the 1990s, environmental issues continued to worsen on a global scale, and for many countries, air pollution became a serious problem. Air pollution was not only a challenge for regions undergoing urbanization—downwind means it was a borderless issue that could even affect people living in neighboring countries and regions. Air pollution was thus a major social issue that had to be tackled by industries worldwide in order to ensure global economic development. As a worldwide supplier, for Kubota, the eco-friendliness of its engines became a foremost priority.

In the same way as emissions regulations had been put in place for passenger cars in the 1970s, it was also around this time that regulations were also placed on industrial use diesel engines. In California, CARB ULGE regulations^*1 were imposed on Utility and Lawn and Garden Equipment (ULGE) engines under 19 kW (25.5 HP), and in 1993 Kubota became the first in the world to comply with these regulations. Later, Kubota continued to enhance the mechanical performance of its engines to comply with increasingly stringent regulations.

However, the fourth non-road diesel emissions regulations that were put in place in Japan, the US, and Europe in 2012 could not be met simply through mechanical improvements. Kubota thus set out to maintain the features of its conventional engines—such as their compact, easy-to-mount size—while using electronic and chemical technologies to further increase their basic performance. As a result, its engines succeeded in purifying emissions more efficiently, and compared to previous models not equipped with DPF^*2 and DOC,^*3 the engines could reduce PM^*4 by more than approximately 92%. The new engines also boasted improved output and lower noise.

In 2019, a fifth version of non-road diesel emissions regulations were announced initially in Europe, and Kubota received certification for its compact sub-19 kW (25.5 HP) diesel engines at an early stage. Today, Kubota’s various engine models—including the increasingly in-demand large industrial engines—continue to obtain the relevant certifications. Elsewhere, explosive population growth and economic development in various Asian countries has worsened air population in urban areas, and stricter environmental regulations will no doubt be put in place. Kubota will continue to provide engines that balance environmental conservation and industrial development, and in so doing, aim to enrich the lives of its many users.