Electronically-Controlled HST Using a 1-Pump, 2-Motor System
● The 1-pump, 2-motor system allows high-efficiency and high tractive effort. Engine power is transmitted hydraulically to a transfer case, then mechanically out to the differentials and out to the four driving wheels.
● HST provides quick travel response and aggressive drive into the pile. The variable displacement system automatically adjusts to the tractive effort demand to provide maximum power and efficiency.
Setting the switch to S-mode provides optimum driving force for operations on slippery road surfaces, like snow-removal on snow-covered surfaces, resulting in reduced tire slippage and facilitation of the operation. Unexpected tire slippage on slippery road surfaces is suppressed by controlling the engine speed and HST motor when traveling at a low speed. (S-mode is effective only in forward mode)
The tractive effort of the machine, when traveling at a low speed, can be reduced by using the traction control switch. Combined with torque proportioning differentials, or optional limited slip differentials this system provides the following benefits.
● Facilitates operation on soft ground where the tires of the machine are apt to slip.
● Eliminates excessive bucket penetration and reduces tire slippage during stockpile loading to improve the work efficiency.
● Reduces tire slippage to extend the life of tires. Furthermore, the maximum tractive effort can be adjusted in three stages (one stage for conventional machines) when the traction control switch is ON. This allows the operator to select the optimum tractive effort for diversified road conditions.
This means lower maintenance costs and higher reliability. Wet disc brakes are fully sealed. Contaminants are kept out, reducing wear and resulting maintenance. Brakes require no adjustments for wear, meaning even lower maintenance. The new parking brake is also an adjustment-free, wet multi-disc for high reliability and long life. Added reliability is designed into the braking system by the use of two independent hydraulic circuits, providing hydraulic backup should one of the circuits fail. Fully hydraulic brakes mean no air system to bleed and no condensation of water in the system that can lead to contamination, corrosion, and freezing.
The front and rear frames and the loader linkage have more torsional rigidity to provide increased resistance to stresses. The frames and loader linkage are designed to accommodate actual working loads, and simulated computer testing proves their strength.
A new multi-function control lever integrated with forward and reverse switch allows the operator to easily operate the work equipment, providing low operator fatigue and good controllability. The adjustable wrist rest provides the operator with a variety of comfortable operating positions.
Noise level at operatorʼs ear: 70 dB(A) Dynamic noise level (outside): 104 dB(A) The large cab is mounted with Komatsuʼs unique ROPS/FOPS viscous mounts. The low-noise engine, hydraulically driven fan, and hydraulic pumps are mounted with rubber cushions, and the cab sealing is improved to provide a quiet, low-vibration, pressurized, and comfortable operating environment.