Search Results

Losses reduction and oil flow optimization management in construction machines and, in general, in heavy duty vehicles are two of the most challenging missions of today fluid power research. One of the most promising ideas is to implement multiple hydraulic power sources but this requires a flexible pump switch system; in fact, depending on flow request and machine mode, one or more pumps can be switched to serve each actuator. To put into practice these concepts it is necessary to in-depth design the distribution system, through which hydrostatic transmissions supply the different loads. The new component here presented realizes the pump switch management, creating a matrix framework of the hydraulic flow connections. Putting this concept it into practice the new architecture is able to connect alternatively a pump to one actuator at a time providing also for cross connections, enabling different sources flow summation.

Performance requests and machine automation, in conjunction with new regulations for commercial and heavy duty vehicles, represent a difficult challenge for machine design. Machine control systems complexity and functional safety regulation, are complex requirements to deal with in new machines design. The paper describes a steering system design, of a 6 wheeled agricultural front articulated self-propelled machine, that must comply with new regulations in terms of functional safety. The vehicle steering is driven by an electro-hydraulic system, totally controlled using electronics; the rear wheels are independently steered and controlled. This architecture requires a highly functional safety performance level. The safety analysis of the system lead to a required performance level whose compliance is a challenging task, due to the software quality required, and to the cost of a fully redundant hardware, on both electronics and hydraulics side.