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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.

Since construction machinery manufacturers recommend various brands and types of greases for their machinery, customers would benefit from a standardized grease which can be used in all construction machinery. Furthermore, construction machinery manufacturers have many experiences of field problems caused by commercially available and commonly used EP Lithium greases. Therefore, the Fuels and Lubricants Committee of Japan Construction Mechanization Association (JCMA) has developed a new grease specification called “Japan Construction Mechanization Association Specification (JCMAS) GK,” for construction equipment. The JCMAS GK includes requirements for National Lubrication and Grease Institute (NLGI) No. 1 and No. 2 consistency grades. The JCMAS GK greases have enough lubricating properties for periodical grease fitting of most construction machines, hydraulic excavators, bulldozers and wheel loaders. The JCMAS GK greases are applicable from -20 to +130 degrees Celsius.

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.

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.

Importance of detecting obstacles around construction machines increase rapidly. The millimeter-wave radar is the most useful sensor to keep to detect obstacles in the current technologies. because of its good performance under severe conditions. The signal processing algorithm of this radar is developed, for the using in working conditions by means of eliminating signal fluctuations and instabilities caused by its environments. The developed millimeter-wave radar has a reasonable performance, for example, detecting the rear side of automobiles and many types of construction machinery from the distance of 100m.

Conventional medium to large-sized bulldozers have a powertrain comprised of a manually operated powershift transmission connected in series with a torque converter. There is a growing need, however, for a power train that is more efficient and easy to operate, thereby increasing bulldozer productivity. One answer to this growing demand is the hydromechanical transmission (HMT) developed by Komatsu for medium to large-sized bulldozers. The HMT consists of a powershift transmission combined in parallel with a hydrostatic transmission (HST) featuring a pair of hydraulic units. The HMT has a continuously variable shifting ratio and achieves high efficiency and automatic shifting. Additionally, it has an electronic controller that controls the transmission ratio to maintain engine speed at the maximum power point. As a result, bulldozers with the HMT demonstrate greatly improved productivity over bulldozers with the conventional powertrain.

A new transmission control system which realizes almost the same high level of operability as of a TORQFLOW (T/F) transmission (see Note 1) has been developed and introduced on an efficient HYDROSHIFT (H/S) transmission (see Note 2) for bulldozers. To develop the system, comparison and evaluation were made between H/S transmission machines without torque converter and T/F transmission machines with torque converter to ascertain the advantages and disadvantages of H/S transmission machines. As a result, the disadvantages inherent to H/S transmission machines, such as poor shifting characteristics, fine travel characteristics at low travel speed, and anti engine-stall characteristics were solved by electronically and synthetically controlling all clutches including those incorporated into the steering brake system, without sacrificing any advantages.

Of all the parts used on crawler-type construction equipment, the track bushings in the undercarriage of large bulldozers are subjected to particularly severe load conditions. A new and innovative heat treatment technology has been developed in order to improve the durability of these bushings from the point of their wear and fatigue crack characteristics. A new steel material has also been specified to match this heat treatment technology. The bushings thus developed have been extensively tested on bulldozers in customer service and proved to be successfully applied for production. They also offer a possibility for considerable reduction in manufacturing cost.

Operations involving excavation of bedrock in large-scale civil engineering projects, or quarrying works for limestone or crushed rock can be broadly divided into two methods: blasting, and excavation using mechanical power. Ripping operation using bulldozers is typical example of the second method, and this method is superior because it is safe and does not cause pollutions. For this reason, its applicable range is being expanded including areas where the blasting method was being used. However, ripping operation using bulldozers demands a high level of training from the operator, and in addition to this, shoe slippage causes premature wear of the undercarriage and low fuel economy. The shoe slip control system that we have developed carries out sensing of the acceleration of the machine in forward and reverse directions, and sensing of the input / output speed of the torque converter, and in this way it always knows the traction and the slip ratio of the machine.

A higher versatility is required from medium size bulldozers as vehicles other than large size bulldozers. Therefore the design concept of the transmission for medium size bulldozers has to be changed to that of large size bulldozers. We adopted combination of high capacity torque convertor and low reduction (high output speed) cross ratio gear train for medium size bulldozers' transmission. We also evaluated the advantages and disadvantages of rotating clutches, and decided not to use the rotating clutches in new transmission for medium size bulldozers, because of their disadvantages. By these design concepts and material technology, we can reduce the transmission size and improve the efficiency.

Torqflow transmission, which is composed of planetary gear mechanism, multiple disk clutches and a hydraulic control unit, has been adapted for Construction Machine because it allows an easy selection of speeds (forward or reverse). Recently a rubber facing material with high coefficient friction has been used disk clutch's facing parts for compact design. Meanwhile, it's heat conduction is inferior to metalic disk to be usually used, so at engage time temperature of rubber facing disk is higher than metalic and it's ablasive wear ratio, which is verified to have influence on facing temperature by experiments, is increased far more than before. Therefore prediction of facing temperature has been more important than before. Now, in this report, study on transient thermal analysis is introduced because it's accuracy has come to practical level.

The users of construction machinery demand higher quality. It is especially difficult to satisfy them with large-size bulldozers designed according to conventional design concepts that is, a new design concept is required now. Komatsu is putting the D475A, built by fully redesigning the D455A bulldozer, on the market. When developing this model, its power-train system, undercarriage, frame, etc., were redesigned under a new concept that emphasized moving large amounts of soil effectively, and new structures were developed as a result. In this paper, the design concept of the D475A and the structure that attained that concept will be outlined.

As a direct result of the mining industries need to improve efficiency and production in open pit type operations, the size of dump trucks has increased. In addition, the increase in vertical lift and resultant grades, and the in crease in hauling distances are making the demand for mechanical drive dump trucks. With these mining requirements, we have developed the mechanical automatic transmission, controlled by microprocessor, with 8 forward speeds and 1 reverse speed, which suit 120 mton class dump trucks and 160 mton class dump trucks. This paper shows the design concept and progress made in development of these transmissions.