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Recently, rubber tracked construction machines, particularly mini-hydraulic excavators, are successfully used for urban construction in Japan, because that have the following features. 1) They cause little damage to road surfaces. 2) Reduced vibration for operators and operating environment. 3) Low noise This paper outlines the development of the rubber track for small size bulldozers (4000 kg, 7000 kg ). The track composition is explained, computer simulations of the development and the performance of the tracks for bulldozers are explained.

After new transmission lubricants are developed there is an extensive validation program where friction durability testing is performed on multiple clutch materials. Each durability test can run for long terms and the entire validation program can take much longer terms. A well designed lubricant and friction material will deliver the necessary friction control for construction equipment to operate at optimum level. A mechanistic construct has been evaluated to calculate friction durability in clutch systems based on fluid and surface tribological properties. Fluid properties include both boundary frictional and rheological effects. Surface properties include elastic modulus, surface roughness, asperity density and asperity tip radius. Using this mechanistic construct friction durability has been predicted.

This paper describes 3-dimensional computational fluid dynamics analysis to estimate the air flow in the construction machinery's engine compartment and accompanying measurements. As the computational grid, tetrahedral cells with rotating reference frame fixed to the fan were used. In the measurement, the single yawed hot wire rotation method was used to measure the 3-dimensional velocity vectors. As a result, the measured values correspond well to the computational results.

Hydraulic fluid (HF) specifications for mobile construction equipment called JCMAS HK and HKB have been established by the Fuels and Lubricants Committee of Japan Construction Mechanization Association (JCMA). The specifications are designated by two viscosity categories of single grade and multigrade. Each category has ISO viscosity grade (VG) 32 and 46. The JCMAS HK oils are recommended for use in hydraulic systems designed at pressure up to 34.3MPa(5000psi) and to heat hydraulic fluid up to 100 °C. These oils also provide wear control, friction performance, oxidation and rust protection, seal swell control and filterability performance. Two piston pump test procedures were developed to evaluate lubricating performance of these oils under high pressure conditions. The JACMAS HKB oils are classified as environmentally friendly oils due to the additional requirement for biodegradability.

KOMATSU has successfully developed and marketed the HYPER GX series computer-controlled, intelligent hydraulic excavators. The development concepts of the HYPER GX series are as follows: 1. To improve safety at construction sites by use of measuring functions which reduce the number of ancillary workers. 2. To improve working environment and the quality of work by use of automatic functions which reduce operator fatigue and time required to complete a job. 3. To solve the problem of shortage of experienced workers by the use of operator support functions which allow easy operation even for inexperienced or older operators. Representative of these is the fully automatic grading function, with which the movement of boom, arm and bucket is computer-controlled to enable automatic excavation at a predetermined gradient.

This paper introduces a laboratory-developed tester for the front suspension of off-highway dump trucks. In dump truck movement at jobsites, the front suspension system is subjected to three-way load, i.e. in the vertical, horizontal and turning (steering) directions. Using three actuators, controllers and a computer, we conducted a lab simulation of such loads. With this tester, various quality assurance tests were carried out to provide reliable data in a short period of time. These tests were as follows: (1) Performance test to measure suspension characteristics such as spring stiffness, damping coefficient and internal friction (2) Stress measurement test to confirm structural strength (3) Endurance test to confirm durability and longevity of parts subject to wear, such as seals and bushings (4) Temperature environmental test to confirm sealing performance across a very low to high temperature range (5) Dust environmental test to confirm sealing performance against dust

The four models of the new PC-Series hydraulic excavators, the PC200-3, PC220-3, PC300-3, and PC400-3, ranging from 18-ton to 40-ton capacity, were brought to the market in 1984, and they have been highly appreciated by the customers for their stability and performance. During the developing stage of these new models, we thoroughly researched and analyzed how hydraulic excavators had been used under various working conditions in order to grasp the qualities which the customer's demand. To realize those qualities, we effectively used mechatronic technology in addition to our unique technologies. The results of the above are the electronic OLSS equipped with a mode changeover mechanism, an automatic decelerating system, a new hydraulic system, etc., which lower fuel consumption, increase workability, lower noise, and improve driveability. In addition, the appearance of each model is improved, and many features including the new monitoring system have been installed.

Electronic control systems using microprocessors for construction machines have been increasing rapidly in response to needs for safety and convenience on the part of operators. Sensors and actuators will play an important role in the proliferation of these systems. Recently, there has been a growing number of applications in which it is necessary to determine the displacement of hydraulic sensors. As a result, many types of sensor systems were developed for this type of application. However, so far there have been no systems capable of working well in construction machines due to these sensors having to be used under extremely severe conditions. Severe impact and high temperature conditions generated by compressed hydraulic oil ended up delaying the development of these systems. In response to these needs, the authors have developed a hydraulic cylinder equipped with a magnetic stroke sensor for use in heavy duty operations.