Hydrostatic pump vibration
Hydrostatic pump vibration
(OP)
I have a hydraulic pump assembly mounted to a 4 cyl. engine which analysis shows 2nd order vibrations in excess of 5g at the pump CG.
Given this information, how can I determine how this affects pump duty cycle and durability.
Given this information, how can I determine how this affects pump duty cycle and durability.





RE: Hydrostatic pump vibration
RE: Hydrostatic pump vibration
The pump is bolted to a plate which is bolted to the engine flywheel housing so the two are inline.
There is no additional support for the pump, in hangs freely from the flywheel cover so the vibration accelerations from the engine are being amplified.
AntiqueGuy
RE: Hydrostatic pump vibration
Why the heck is the motor vibrating so much?
RE: Hydrostatic pump vibration
RE: Hydrostatic pump vibration
What is the driving acceleration (I presume the engine itself), is this from measured real-world data?
"Given this information, how can I determine how this affects pump duty cycle and durability. "
Dunno about duty cycle, that would seem to be an operator-dependent term, "how hard does this get used?". Durability...another difficult term to assess, as it involves things not readily calculable (friction/wear on moving parts). You might be able to model the stresses occurring in the pump materials, and compare them to known fatigue life curves for the materials, adding on the stress due to pressure generated by the pump...which of course is dependent on how the pump is used...but maybe that answers the question?
RE: Hydrostatic pump vibration
Its actually a tandem piston pump so it has two pumps in one housing which drives a set of ground drive motors in a mobile unit.
The engine vibration is the driving acceleration at the pump.
Accelerometer data collected at the pump shows high frequency accelerations at about 50 m/s2, of course this varies depending on engine rpm which rated is 2700.
I'm not too concerned with the low frequency vibrations like the ones seen when actually traveling.
The main thing I'm trying to determine is if accelerations are normally this high for this type of mobile application and how this affects the pump durability as well as efficiency.
I'm looking at replacing the pump which has pilot operated servos with one that is EH controlled and am trying specify the requirements I need in the area of durability and efficiency.
Thanks,
AntiqueGuy
RE: Hydrostatic pump vibration
Yes, I could believe 5g accelerations for a heavily loaded engine, if there is not a lot of inertial load on it, and no torque converter or similar device to absorb the torque pulsations from the motor. We had similar trouble with a 2-cylinder motor driving a positive displacement (Roots) blower, turned out that the motor had been designed and delivered to us with a lighter flywheel than "normal", we had a lot of trouble with vibrations that we finally traced to the torque "ripple" from the motor. Are you seeing any fatigue damage on the flexible elements in the coupler; is the coupler a metallic flex, or a rubber-element type? Can you put a larger flywheel on the motor and retest?