While Japan’s bullet train network is globally renowned for its efficiency and punctuality, it is the city bus that serves as one of the true workhorses of daily urban transportation. Every day across Japan, buses help millions navigate the country’s metropolitan areas. However, with Japanese city roads ranking among the most congested in the world, journeys by bus are often stop-start affairs.  

Historically, this environment has created a significant burden for bus drivers, who report feeling stressed due to the frequent need to shift gears manually. Furthermore, buses equipped with automated manual transmissions (AMT) can cause discomfort for both the operator and the passengers every time the bus shifts gear. 

Despite these drawbacks, manual transmissions in buses were preferred for many years due to their perceived cost-effectiveness. Those commissioned throughout Japan prior to 2010 were equipped with manual transmissions, and most drivers became accustomed to driving them. But in the wake of Japan’s recent labor shortages, it’s become increasingly difficult for bus operators to recruit new drivers, many of whom are deterred by the physical demands of the job.

Isuzu Motors is one of Japan’s largest manufacturers of commercial vehicles, offering a diverse lineup of city buses including the “Elga”—a low-floor bus commonly seen in major cities—and the 18-meter “Elga Duo” articulated bus. One of Isuzu’s largest customers is the Keisei Electric Railway Bus Group, which operates approximately 2,300 buses across Tokyo and its neighboring prefectures of Chiba and Ibaraki. Keisei also operates shuttle bus services to two major tourist attractions in the area: Tokyo Disneyland and Tokyo DisneySea.  

Japan’s bus manufacturers have been focused on developing vehicles with high maneuverability and superior performance. To comply with the industry’s stringent emissions regulations, manufacturers like Isuzu have continued to push for engine downsizing. To compensate for the lack of power caused by smaller engine displacements, Allison transmissions have been adopted by Isuzu because of their patented torque converters’ ability to smoothly multiply engine torque.  

The 20,000 milestone 

Automatics easing the burden 

To support customers like Keisei Electric Railway Bus Group, Isuzu completely phased out manual transmissions in its city bus lineup in 2015. Today, the company’s city bus models are equipped with Allison’s Torqmatic® series (Allison T Series™) fully automatic transmissions. Built with torque converters capable of delivering powerful acceleration from Isuzu’s downsized engines, Allison transmissions are now used in more than 70% of large city buses in Japan. Their Continuous Power Technology^TM ensures that engine power is transmitted seamlessly to the wheels, eliminating power interrupts during shifts, easing a driver's workload, and providing a superior passenger experience. 

J-Bus—a major joint venture between Isuzu Motors and Hino Motors—now equips its medium-sized city buses exclusively with Allison transmissions and offers them as the standard option on large-sized buses. With both classes utilizing the same Allison transmission technology, the driving experience is virtually identical, allowing operators to switch seamlessly between vehicles of different sizes.