DEXTER: The Application of a Digital Displacement® Pump to a 16 Tonne Excavator

Matthew Green, Jill MacPherson, Niall Caldwell, William Rampen

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Environmental and economic factors are driving the
development of lower emission and more fuel efficient off-
highway vehicles. While a great deal of this development is
focused on hybrid technology and novel system architectures,
the simple application of a Digital Displacement
Pump (DDP)
in place of a conventional pump can deliver significant fuel
savings and productivity benefits, whilst also acting as an
enabler for more radical future development. This paper
describes the ‘DEXTER’ project, in which a tandem 96cc/rev
DDP was installed in a 16 tonne excavator. The energy losses in
the unmodified excavator are calculated based on test data,
confirming the scope for efficiency improvements. Next, the
basic operating principle and efficiency of the DDP and its
application to the excavator system are outlined, alongside
simulation based fuel saving predictions. The model based
design and ‘operator in the loop’ testing of the control system
are then described. Side by side testing of the modified
excavator and a standard excavator showed that when the
modified excavator was operating in ‘efficiency mode’ a fuel
saving of up to 21% and productivity improvement of 10% is
possible. In ‘productivity’ mode, a 28% productivity
improvement was recorded along with a 10% fuel saving.
These results are validated with reference to the higher
efficiency of the DDP and improved control system which
allows the engine to run closer to its torque limit.
Original languageEnglish
Title of host publicationProceedings of the 2018 Bath/ASME Symposium on Fluid Power and Motion Control
Subtitle of host publicationFPMC2018
PublisherAmerican Society of Mechanical Engineers(ASME)
ISBN (Print)978-0-7918-5196-8
Publication statusPublished - 20 Nov 2018


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