Examination of Shunted Hydraulic Pumps in Wheel Loaders

Volvo Construction Equipment is a world leading company in construction machinery. To
maintain the best products, development is prioritized. The master thesis regards sound reduction
of the hydraulic system on a wheel loader. The background to the master thesis is a
simulation made on the hydraulic system, performed autumn 2005. The result of the simulation
shows that the energy of the pressure ripple is reduced when the paralleled hydraulic
pumps are phase shifted and reduces each others pump pulsations. The aim of the master
thesis is to investigate if the reduction in pulsations also reduces the hydraulic sound.
The test has been made on a wheel loader, model L180F, by measuring the pressure pulsations
in the hydraulic system and sound in the drivers cabin. The machine is equipped with
two nine pistons hydraulic pumps in parallel to the main hydraulic actuators. The measurements
has been made when the sound is highest from the hydraulic system, which is when
the lifting cylinders has maximum speed. The measurements has been made for different
angels in a range from 0 to 16 degrees phase shift.