Rubber Product
Research and Development
Kiichiro Toyoda also had an interest in organic chemistry.
In December 1932, in the course of diversifying business operations, he
established Shonaigawa Rayon Company which can be counted among organic
chemistry related enterprises. From that December until October 1937,
industrial property rights applications related to the manufacture of rayon
resulted in four patents and five utility model rights being granted. This
demonstrates that research into synthetic fibers was carried out side by side
with automobile manufacturing related research activities.
Exterior of an
imported master cylinder for Toyota trucks
In 1934, when entering the design phase of the Model A1
prototype passenger car, the body styling and chassis were modeled to a certain
extent on the DeSoto cars from Chrysler. The brakes also were to be hydraulic
brakes on all four wheels, similar to the DeSoto models. Since all passenger
cars and trucks from Chevrolet and Ford at the time had mechanical brakes, this
was a move into new territory. The adoption of hydraulic brakes meant that
brake parts and brake oil needed to be imported, and research into these areas
became a necessity.
In November 1934, Kiichiro hired the chemical engineer
Fujinobu Kimura and instructed him to "look into all things
chemical-related to automobiles", and to "try and see what could be
manufactured in-house". Kimura examined and researched materials for automobile
parts at the chemical laboratory within the research laboratory of the
Steelmaking Department. Along with metals, he also analyzed organic materials.
At that time, organic materials used for cars included tires, tubes, fan belts,
anti-vibration rubber mounts for engine mounting and suspension parts, as well
as brake oil.
When research into hydraulic brakes started, studying brake
oil was chosen as the first target of inquiry, because the equipment of the
chemical laboratory was up to this task. From about 1935 was the time when
hydraulic brakes were first found in imported cars and the start of their wider
acceptance, so there was as yet no domestically produced brake oil worth
researching.
The main component of brake oil at the time was vegetable oil,
mixed with an alcohol-based solvent to obtain the required viscosity. Research
at the chemical laboratory showed that adding diacetone alcohol to castor oil
(a vegetable oil) was optimal in terms of adjusting the viscosity. In-house
production of this brake oil was begun on a small scale, and continued at the
Rubber Section of the Kariya Plant until about 1943, when the Rubber Section
separated from Toyota Motor Corporation and became independent.
Research efforts related to hydraulic brakes also included
chemical analysis of rubber piston cups and boots used in the hydraulic brake
cylinders made by Wagner in the United States. In 1935, equipment for trial
manufacturing of rubber parts for hydraulic brakes was installed at a test
plant for brakes, occupying about 260 square meters and adjoining the research
branch of the Steelmaking Department on the east side. This included a rolling
mill (8 by 20 inches) and press (20 by 20 inches). Experimental production at
the facility began promptly.
Brake linings were another target for development. At the
time, brake linings were made by compacting asbestos using a binding agent,
usually asphalt, pitch, rubber, or phenol resin. As an extension of its
research into rubber parts, the chemical laboratory also developed brake
linings using asbestos fiber or fine powder turned into a paste by using rubber
binder. After having been readied for production, these brake linings continued
to be manufactured also after the Rubber Section of the Kariya Plant separated
and became the Nagoya Plant of Kokka Kogyo, supplying the products to Toyota
Motor Corporation.
Rubber Product
Research and Development
In May 1936, upon completion of the car assembly plant
within the Automotive Department of Toyoda Automatic Loom Works, the rubber
product manufacturing process was moved from the brake test plant to a 660
square meter lot at the new facility, becoming part of the chassis assembly
section. The engineers who had been engaged in developing rubber products also
began to work in the new location, while retaining their affiliation with the
research laboratory of the Steelmaking Department. In addition, four new staff
members with experience in rubber product manufacturing were hired, and the
lineup of rubber part manufacturing equipment was further enhanced.
Subsequently, the company embarked on the development of
hoses for hydraulic brakes, and prototypes were produced, using Wagner
hydraulic hoses as reference. The rubber for the inner tube and external cover
was natural rubber of the highest quality, while the pressure-resisting layer
employed long-staple Egyptian cotton thread woven into a tubular shape. The
resulting prototypes proved strong enough for practical use. After the trial
manufacture of rubber parts for brakes had shown some success, the program was
expanded to include other rubber parts such as extruded parts, anti-vibration
rubber mounts, fan belts etc.
From 1938 onwards, the use of imported parts increasingly
gave way to domestically produced parts, and brake master cylinders from Nippon
Air Brake Co., Ltd. were adopted. Also in 1938, hydraulic brake oil
manufactured by Tokyo Rikagaku Kogyo Sho, and refractory brake oil from Nippon
Brake Oil Shokai were designated as genuine Toyota accessories.
In November 1938, with the completion of the Koromo Plant,
the engineers working on rubber parts development who had previously been
affiliated with the chemical laboratory in the research laboratory of the
Steelmaking Department of Toyoda Automatic Loom Works were transferred to Toyota
Motor Corporation and were now affiliated with the rubber works at the Kariya
Plant. According to the employee roster of 1939, the name of the rubber works
was "Kariya Representative Office Research Department".
Another significant development in 1938 was the so-called
"tire drought" In January of that year, the Japanese government
restricted the import of crude rubber in order to address an imbalance in
international payments. As a consequence, shipments of finished tires continued
to fall drastically, until numbers were down to about 10 percent of regular
figures by October. In November, the supply of tires stopped altogether.
Given this situation, focus shifted to the production of
domestically sourced tires, engineers specializing in this area were hired, and
preparations for production facilities were made. Between 1940 and 1941, some
500 tires were produced at the rubber works of the Kariya Plant in a series of
trials.
However, because the supply of crude rubber was threatened
by the war situation, the Ministry of Commerce and Industry did not grant the
required permissions, and trial production of tires ceased. The production
equipment was subsequently moved to the Iho Rubber Plant located at Tianjin in
China. This plant, financed at 1.6 million yen and dedicated to the manufacture
of rubber products, had been founded through equal participation by four
parties, namely Yokohama Rubber Co., Ltd., Chuji Idebuchi, Toyobo Co., Ltd.,
and Toyoda Boshoku Sho. In August 1942, the equipment transferred from Toyota
Motor Corporation was installed at the plant located at street No. 15 in the
"Italian concession" of the city of Tianjin, and used for the
production of aircraft tires.
At the rubber works in Japan, the "tire drought"
of 1938 also prompted a reconsideration of the material used for steering
wheels. Researchers began exploring the possibility of using cellulose acetate
resin instead of the hard rubber that so far had been the norm. Cellulose
acetate was produced by the Shonaigawa Rayon Company as a source material for
rayon yarn and therefore represented a promising choice. However, although the
R&D efforts culminated in the successful production of a prototype steering
wheel using thermoplastic cellulose acetate resin, the raw material for cellulose
acetate, namely pulp, had also become very scarce in the meantime, and the
switch in steering wheel material therefore did not develop beyond the trial
stage.
In February 1942, when trial production of rubber parts was
finally concluded and full-scale production began, the Kariya Representative
Office Research Department was renamed to Kariya Plant Rubber Section.
The Rubber Department of the Kariya Plant was integrated
into Kokka Kogyo in May 1943, following the governmental directive for the
integration of industry. Production equipment was moved to the former Shokufu
Plant, which started to operate as the Kokka Kogyo Nagoya Plant. The former
name of the Shokufu Plant was Toyoda Shokufu Kikui Plant, originally managed by
Sasuke Toyoda. As it specialized in woven fabric and had no spinning
department, it was not included in the merger of five Toyoda and Toyo
Menka-related spinning and weaving companies, and had become in effect an
idling plant.
Source: TOYOTA MOTOR CORPORATION
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