Baumaschinen

Abstract

Ing. E. h. Martin Scheffler ist an der TU Dresden am Institut für Fördertechnik tätig.

Reducing Fuel Consumption in Hydraulic Excavators—A Comprehensive Analysis

“…Especially for cycles with low average power demands, this measure is very effective, more so than any optimisation of the hydraulic system. The efficiency improvements resulting from downspeeding have been shown in numerous studies [20,43,44]. What these studies have also shown is that a reduced engine speed also lowers productivity because the engine can no longer supply the same amount of power as at the higher speed.…”

“…To do so the fuel consumption model is extended to include negative actuator power. If a recovery system with an efficiency of η Rec were installed the engine would be required to supply less power and the average fuel consumption would be V Diesel, 1800 rpm l h = 9.5 + 0.6111 · (P Act,pos, AVE -η Rec · P Act,neg, AVE ) (20) Measurements show that the average negative actuator power is always less than or equal to 50% of the average positive actuator power. For cycles such as dig and dump the maximum of 50% is reached but in the case of trenching this value goes down to approximately 30%.…”

“…During fast lifting operations, the load sensing line is directly connected to the boom piston side using a bypass throttle, The implement cylinders are controlled using downstream stream pressure compensated valves. Controlling the swing's large inertia with such a flow controlled valve, causes high pressures during acceleration as the load pressure is primarily determined by inertial forces resulting from acceleration and not by external load forces from the environment [20]. If the acceleration is not controlled appropriately, the system pressure can rise excessively leading to large pressure differences among the various actuators, which cause unnecessary throttling and forces the pump to swivel back thereby delivering less flow in order to avoid overloading the engine [21].…”

“…During fast lifting operations, the load sensing line is directly connected to the boom piston side using a bypass throttle, causing the boom pressure to be the dominant pressure signal that is sent to the pump. This ensures that the swing pressure does not exceed the boom pressure, which results in minimal throttling and maximum pump flow, improving cycle times and efficiency [20]. Some manufacturers also offer an energy efficient boom float function in which the boom down motion does not require any pump flow [23].…”

Reliability Evaluation of Drivetrains: Challenges for Off‐ Highway Machines

“…Besides the technical realization of the drivetrains, other specifics, for example, boom variants (monoblock booms, adjustable booms, embankment booms, etc. ), exist [29], which influence the operating behaviour and subsequently the occurring loads on structure and drivetrain. Furthermore, machines, even with same configurations, are utilized for vastly different tasks.…”