The name ‘TRIAS’ refers to the three-pump hydraulic system that replaced the previous two-pump system for this size of excavator. The third pump helps to maximise efficiency and productivity – without sacrificing fuel economy – by reducing the loss of hydraulic pressure.
The key to TRIAS is the combination of the three-pump system, control valve, multiple pressure sensors and computer-controlled solenoid valves. Tuning the system is vital for efficiency of the control valve – and this Hitachi technology is unique to the construction industry.
The original TRIAS system was developed for the Zaxis-5 medium excavator range in 2011. To explain how a TRIAS I (and conventional) control valve spool works, there is always a significant return of pressurised oil to the tank during the operation of a function, especially at small and medium control lever strokes. This flow of pressurised oil to the tank results in hydraulic power loss.
In 2015, Hitachi launched TRIAS II in its Zaxis-6 range of medium excavators. This system further fine-tuned the control valve spools and added additional pump flow limit solenoid valves. This further reduced hydraulic losses in the control valve.
In 2020, TRIAS III was unveiled with the arrival of the Zaxis-7 range. This system benefits from further fine-tuning of the control valve spools and new features resulting in even less hydraulic losses, greater efficiency and controllability.
One such feature is the pump 3 minimum angle fix control. If the pump pressure becomes high during digging, pump 3 is fixed to a no-load/minimum flow rate and pumps 1 and 2 are used at high pressure and maximum flow rate. This improves pump efficiency by 2%, reducing fuel consumption.