Development Story

Automotive Transmission Belts

The Story behind the Development of the "Low Friction Loss Belt"

But can a simple accessory belt actually contribute to reduced fuel consumption? How did we succeed in developing a Low Friction Loss Belt-something that both our customers in the automobile industry and our own engineers thought to be impossible? Mitsuboshi Belting's development team-a group of specialists from our materials development, design, assessment and sales technology departments-tells the story of this development over the course of approximately three years.

Chapter 1

The Start: An Accidental Success That Got the Engineers Thinking

A result no one had expected led us to think we might have the potential for creating a world-first product.

Development began when a business partner asked Masashi Tamura, the sales technology contact person for automakers "Don't you have an accessory belt that can somehow help lower fuel consumption?" He proposed using one of Mitsuboshi Belting's standard-specification products, a ribbed belt with a rubberized back. Although it was common for Japanese manufacturers to use accessory belts with cloth backs, before joining the Sales Technology Department, for many years Mr. Tamura had been working as an engineer in belt design, and he believed that rubber would provide good flexibility, and that flexure would help reduce energy loss. However, he notes that "Truthfully, my expectations were not high." Although a focus for parts on the engine itself, considering fuel efficiency improvements involving belts for generators, air conditioners and other peripheral equipment was just something not normally considered at that time. But testing produced unexpected results. The belt succeeded in reducing fuel consumption by around 0.2%. The person in charge of design at the manufacturer was also surprised that a belt could have such an effect on lowering fuel consumption. The savings was less than 1%, but for the automotive industry, focused as it was on technologies for lowering fuel consumption, even such a small savings was meaningful. Unfortunately, the proposed belt was rejected as being too noisy, but this was now a different problem. If we were only able to eliminate the noise issue, we could provide a groundbreaking product that was technically superior to that offered by our competitors. Mr. Tamura was suddenly convinced that this development was worth a try.

headed the Technology Department, and many others thought this was a wild goose chase. Still, they kept faith with Mitsuboshi Belting's forward-looking manufacturing traditions of "just give it a go." Nobody opposed giving the idea a try.A development team was formed. Hisato Ishiguro, Mr. Hineno's subordinate in the functional development department, was in charge of rubber compounding. Hiroki Imai, from the product technology department, was to handle the production of belts for evaluation and conducting physical property evaluations. Takayuki Shige from the testing department was selected to evaluate friction loss measurements, and Masashi Tamura was assigned to provide overall development direction. Hisato Ishiguro and Hiroki Imai had only recently joined the Company, and Mr. Shige had just been relocated to another department, but they were also called upon to take part in this challenge to develop a world-first product.

Chapter 2

Bringing All Our Technologies and Knowledge as a Belt Maker to Bear in Solving the Puzzle

What about a belt might be effective at reducing fuel consumption? The first step in development was to answer this question.

The first step was to determine which of a belt's three constituents-backing, ribs and core wire-prompted a loss of flexure and theorize why this might be. The person assigned to verify theoretical concepts regarding this reduction was Hisato Ishiguro, who had joined the Company two years earlier. Mr. Hineno chose him on the precept that "People who have long experience in designing rubber compounds are likely to have fixed ideas. To come up with altogether new technologies, we need somebody without any preconceived notions." Never having expected to be involved in new product development so early on, Mr. Ishiguro was both excited at the opportunity and apprehensive about the prospect. Encouraged by the words "It's all right to make mistakes. Just give it your best shot," he proceeded according to his own reasoning and went to work analyzing rubber materials and belt data.

Another urgent issue was to establish a method for measuring friction loss. Takayuki Shige of the testing department was able to come up with a measurement method by using testing equipment designed for another purpose by the head of the technology department, which handled the development and manufacture of testing and manufacturing equipment. His first time using this equipment, he spent each day looking at the testing device's torque meter and a month trying to resolve the issue of variations in the measured results. It became possible to measure friction losses down to a precision of 0.1Nm. From there, he moved on to measure losses for each of the constituent parts of the belt. Ultimately, the team discovered that the compounding of the rib rubber had the greatest impact on reducing loss. This result came around six months after the start of development.

How was the team to ensure friction resistance and productivity, while at the same time achieving the noise generation resistance the customer was calling for? Hisato Ishiguro took the lead in referencing the Company's massive materials database, developing compounds through a process of repeated trial and error and then on the processing front, considering blending and rolling conditions. The process repeated: Mr. Hineno determined whether the result was viable, Mr. Imai collaborated with the factory production department to manufacture the belt for testing, and Mr. Shige conducted sound tests on actual vehicles. Repetitions continued at a fast pace, with a new iteration nearly every week. Team members were busy, as they were doing this testing alongside other tasks, but when Mr. Tamura returned from reporting development progress to the customer, all the members of the technology department gathered together, younger members and veterans alike, putting their heads together to consider the next method of attack.At the start of development, many of the members thought the limiting factor was not the rubber compound but rather the shape. However, once the team had narrowed down the problem to the rib rubber compound, the development vector of resolving noise generation was decided. However, eradicating that noise proved to be a thorny issue. For many years, development had concentrated on reducing internal heat buildup in the belt, but in addition to noise generation resistance these methods also caused friction resistance and productivity to worsen. How was the team to ensure friction resistance and productivity, while at the same time achieving the noise generation resistance the customer was calling for? Hisato Ishiguro took the lead in referencing the Company's massive materials database, developing compounds through a process of repeated trial and error and then on the processing front, considering blending and rolling conditions. The process repeated: Mr. Hineno determined whether the result was viable, Mr. Imai collaborated with the factory production department to manufacture the belt for testing, and Mr. Shige conducted sound tests on actual vehicles. Repetitions continued at a fast pace, with a new iteration nearly every week. Team members were busy, as they were doing this testing alongside other tasks, but when Mr. Tamura returned from reporting development progress to the customer, all the members of the technology department gathered together, younger members and veterans alike, putting their heads together to consider the next method of attack.Recalling an everyday saying of Chairman Nishikawa that "Developing new technologies and new products is a manufacturer's duty," team leader Mr. Tamura continued to motivate the team members. "Let's give it one more try," he would say. "I am convinced that we are going to develop a world-first belt." Even so, there were times when the sound test failed to produce favorable results that the team thought they might be permanently deadlocked on this problem. Around that time, a conference of global departmental heads from throughout the Mitsuboshi Belting Group met. The team was inspired anew by the words of President Kakiuchi that "Our company values people who go out and try new things, regardless of the results."

Finally, the team developed a compound that succeeded in reducing sound. It earned Mr. Hineno's implicit endorsement as an optimal compound, and the development moved into the final stages.

Chapter 3

The Possibilities of the Newly Developed Accessory Belt

Winning out at the last minute, the sound test was judged a success.

At last, a test belt produced by narrowing down rubber compounds generated positive results in in-house vehicle tests. The reduction in sound was even discernible to the ear. Although our customer had hoped to test the belt right away on a customer vehicle that was under development, they were told that the vehicle was nearing mass production, so could not be tested on that model. As proposed by Mr. Tamura and Mr. Shige, a rental car was brought in and a sound test was run together with the person at the customer end in charge of testing engine vibration and noise. The team was taking a last chance; if the belt could not clear sound tests at that stage, it would not be in time for use on the new model.

The test was run on a vehicle with a continuously variable transmission, typically a difficult proposition. During testing, the belt had been confirmed as clearing the sound levels according to conditions set by the customer, but anything was possible in a live trial. Finally the sound test evaluation results were brought to the waiting pair: "OK." They were delighted with the words of the customer representative: "That belt looks like a winner." The two team members phoned the Company to report the results to their waiting colleagues. Mr. Hineno told the team members frankly, "I am both delighted and relieved."

pitch. Although some issues still remained to be resolved as the product went toward mass production, all the difficulty started to seem worthwhile, as new vehicle models containing the newly developed Low Friction Loss Belt began to appear on television, in magazines and on automakers' websites.Three years after the start of development, the automaker that had been pressing forward on efforts to lower fuel consumption launched its mini car. Customers gave the vehicle high marks, including for the results of fuel-efficiency calculations. During the year, the vehicle won an award for its use of fuel-efficient technologies.To date, competitors have not yet developed products equivalent to Mitsuboshi Belting's Low Friction Loss Belt, the first in the world to achieve both low fuel consumption and noise generation resistance. At the same time, Mitsuboshi Belting has continued with its successes in developing next-generation belting products that maintain noise generation resistance while contributing to even lower levels of fuel consumption. Furthermore, an increasing number of Japanese automakers are employing these products.

Thermographic Measurement of Torque Loss Conditions after the Start of Travel

This measurement shows the low amount of heat generated (little heat generated as a result of flexure) by low friction loss products.

Team Members

If we don't tackle new developments, who will?! Maintaining Our Pride as a Belt Maker Developing World-First Belts

Note: Departmental affiliates and histories with the Company are as of the time of development.