The main objective of presented article is finding the relationship between the change in the intensity of the volumetric flow and values of vibration parameters (indirect measurements – vibration sensors mounted on the pump body). The study was subjected to the multi-piston pump (type PV Plus made by the Parker Hannifin) equipped with built-in volumetric performance controller

Dominik Rabsztyn

Klaudiusz Klarecki

Mariusz Piotr Hetmanczyk

English

Vibroengineering PROCEDIA

 76 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. OCTOBER 2014. VOLUME 3. ISSN 2345-0533  
The influence of volumetric performance settings of a 
multi-piston pump on parameters of forced vibrations 
Klaudiusz Klarecki1, Dominik Rabsztyn2, Mariusz Piotr Hetmanczyk3 
Faculty of Mechanical Engineering, Institute of Engineering Processes Automation and Integrated 
Manufacturing Systems, Silesian University of Technology, Gliwice, Poland 
1Corresponding author 
E-mail: 1klaudiusz.klarecki@polsl.pl, 2dominik.rabsztyn@polsl.pl, 3mariusz.hetmanczyk@polsl.pl 
(Accepted 2 August 2014) 
Abstract. The main objective of presented article is finding the relationship between the change 
in the intensity of the volumetric flow and values of vibration parameters (indirect measurements 
– vibration sensors mounted on the pump body). The study was subjected to the multi-piston pump 
(type PV Plus made by the Parker Hannifin) equipped with built-in volumetric performance 
controller. 
Keywords: multi-piston hydraulic pump, forced vibration, self-excited vibration, pressure 
fluctuation, vibration damping. 
1. Introduction 
Multi-piston pumps are a commonly used source of the hydraulic fluid stream in the average 
and high power hydrostatic drives. They are characterized by high efficiency, ability to work with 
high pumping pressure [1] and minimal discharge flow pulsation [2, 3]. The main advantage of 
the hydrostatic drive is the ability to achieve high power flux-density. 
A noticeable tendency in hydrostatic [4] systems is revealed in the form of minimization of 
the mass, overall dimensions and at the same time increasing a power density delivered by pumps. 
An important task is finding the optimum between a power and a mass. A solution of described 
problem is easy at the construction stage of new pumps. For pumps used in industrial applications 
changing structural parameters are not possible. In such case remains only control of productivity 
factors. The increase in power causes an amplification of vibration, resulting in excessive noise 
and reduced service life of components [5]. 
The article presents the preliminary results of the studies of pressure pulsation and vibration 
of the multi-piston axial swash-plate hydraulic pump, type PV032R1K1T1NMTP manufactured 
by Parker Hannifin. It is a variable displacement pump operating within the LS (Load Sensing) 
system. 
2. Description of the measuring station 
Fig. 1 presents the simplified diagram of the test stand. The hydraulic system comprised of: 
– A multi-piston, variable displacement axial pump [6, 7], type PV032R1K1T1NMTP 
(displacement volume/rotation: 32 cm3, pressure controller), 
– Three-phase asynchronous motor, type FCM 160MA-4/HE manufactured by AC-Motoren, 
driving the tested pump, 
– L90LS distributor manufactured by Parker Hannifin with four proportional sections, 
– Hydraulic receivers (three single rod-end cylinders and rotational hydraulic motor).  
The measurements were taken using: 
– Diagnostic tool Service Master Plus with the SCPT-160-C2-05 pressure sensor and the 
SCFT-060-C2-05 flow meter, 
– A set for vibroacoustic tests featuring a IFM VSE100 data acquisition and processing module 
and IFM VSA005 accelerometers. 
THE INFLUENCE OF VOLUMETRIC PERFORMANCE SETTINGS OF A MULTI-PISTON PUMP ON PARAMETERS OF FORCED VIBRATIONS.  
KLAUDIUSZ KLARECKI, DOMINIK RABSZTYN, MARIUSZ PIOTR HETMANCZYK 
 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. OCTOBER 2014. VOLUME 3. ISSN 2345-0533 77 
 
Fig. 1. Simplified diagram of the test stand 
Measurements of the hydraulic quantities were done with 1 ms sampling and no filtration, and 
the signals from accelerometers were sampled with the resolution of 1.52 Hz and filtered using 
the low pass filter with the frequency of 1950 Hz. The filtered acceleration signals were then 
subject to the FFT analysis FFT. 
Pump tests were carried out for three different pressure settings: 16 bar (stand-by pressure, 
resulting from the settings for the operation within the LS system), 60 bar and 120 bar. 
For the pressure of 60 bar and 120 bar we forced the pump performance settings to be circa 
23 dm3/min and 43 dm3/min (similar to 50 % and 100 % of the nominal efficiency). The pressure 
of 16 bar corresponded with the pump working with minimum efficiency, necessary to repair 
leakage and maintain stand-by pressure with LS control. 
Due to the limit of power caused by the motor driving the tested pump, the tests were not 
carried out with higher pressure, close to the nominal 350 bar. 
3. Pressure pulsation analysis 
The tested pump is a nine-piston one, so the theoretical discharge flow pulsation [8] is lower 
than 1.6 %. The discharge flow pulsation and flow resistance on the discharge side of the pump 
are the cause of the pumping pressure pulsation. Assuming that the hydraulic resistance and 
turbulent flow of the incompressible liquid were constant, the pressure pulsation would amount to 
little over 3 %.  
Fig. 2(a) presents the registered spectrum of the pumping pressure frequency. It is easy to 
observe its periodicity connected with the process of cylinders entering the pumping section. It is 
also possible to notice modulation of the fundamental frequency of pressure pulsation that may be 
a result of the asymmetry of the pump design or irregular leaks in the particular cylinders of the 
pump. 
The assumption that this might be the effect of the leaks is proven by the fact that the mentioned 
modulation of the fundamental pressure pulsation is especially visible for higher pumping pressure 
(Fig. 2(b)). 
The results of the tests are presented in Table 1. Apart from the pumping pressure and its 
pulsation, also its frequency was determined. 
As can be seen, in all cases the pressure pulsation did not exceed the theoretical expectations. 
It may be the effect of the compressibility of the hydraulic liquid. The pulsation frequency 
determined from the time signals are very close to the predicted frequency of circa 218 Hz, 
resulting from the rotational speed of the pump shaft (about 1450 rpm). In three cases (two of 
THE INFLUENCE OF VOLUMETRIC PERFORMANCE SETTINGS OF A MULTI-PISTON PUMP ON PARAMETERS OF FORCED VIBRATIONS.  
KLAUDIUSZ KLARECKI, DOMINIK RABSZTYN, MARIUSZ PIOTR HETMANCZYK 
78 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. OCTOBER 2014. VOLUME 3. ISSN 2345-0533  
which are stand-by pump operation with maintained pressure) significantly lower frequency of 
the pressure pulsation was observed, as shown in Fig. 3. 
 
a) 
 
b) 
Fig. 2. Pressure pulsation with the maximum discharge  
of the pump and pumping pressure equals: a) 60 [bar], b) 120 [bar] 
 
Fig. 3. Pressure pulsation with zero discharge of the pump and pumping pressure of 120 bar 
Such a course of the pressure pulsation may be caused by the inconsistent discharge from the 
particular pump cylinders. For instance, leakage from one of the cylinders might be greater than 
from the other ones. However, the clarifying interpretation of the obtained results will require 
further research. 
THE INFLUENCE OF VOLUMETRIC PERFORMANCE SETTINGS OF A MULTI-PISTON PUMP ON PARAMETERS OF FORCED VIBRATIONS.  
KLAUDIUSZ KLARECKI, DOMINIK RABSZTYN, MARIUSZ PIOTR HETMANCZYK 
 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. OCTOBER 2014. VOLUME 3. ISSN 2345-0533 79 
Table 1. Characteristic parameters of tested pump 
Measure 
No. 
Flow rate 
setting [%] 
Pressure 
setting 
????  
[bar] 
????  
[bar] 
???? 
[bar] 
? 
[Hz] 
Pressure 
pulsation [%] 
1 0 stand-by 15.78 15.89 15.66 214.8 1.46 
2 50 low 60.62 60.95 60.3 31.9 1.07 
3 100 low 58.37 58.81 57.88 214.3 1.59 
4 0 low 59.8 59.91 59.65 34.46 0.43 
5 0 high 120.6 121 120.3 32.81 0.58 
6 50 high 121.2 121.6 120.8 209.2 0.66 
7 100 high 120.6 121.1 120.1 211.8 0.83 
4. Pump vibration analysis 
Two accelerometers were positioned on the body of the pump, one in axial and one in radial 
direction. The acceleration signals were subject to the FFT online analysis and then the received 
spectra of acceleration were registered. The obtained vibration spectra in the stand-by mode are 
shown in Figs. 4 and 5, vibration for the operation of the pump with the greatest load is shown in 
Figs. 6 and 7. 
 
Fig. 4. Spectrum of vibration acceleration in axial direction – pump operating in stand-by mode 
 
Fig. 5. Spectrum of vibration acceleration in radial direction – pump operating in stand-by mode 
The presented spectra indicate that the pump vibration is influenced by the frequency of the 
pump shaft rotation (Figs. 4, 6 and 7) and the frequency with which the cylinders enter the 
pumping section (Figs. 5, 6 and 7). Vibration induced by the cooperation with the electric motor 
and pump shaft rotation reveal not only the impact of the fundamental frequency, but also the 
harmonics (especially the first harmonic). For that reason, the table of results (Table 2) includes 
frequencies and amplitudes for: 
– Frequency of pump shaft rotation (??), 
THE INFLUENCE OF VOLUMETRIC PERFORMANCE SETTINGS OF A MULTI-PISTON PUMP ON PARAMETERS OF FORCED VIBRATIONS.  
KLAUDIUSZ KLARECKI, DOMINIK RABSZTYN, MARIUSZ PIOTR HETMANCZYK 
80 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. OCTOBER 2014. VOLUME 3. ISSN 2345-0533  
– The first harmonic of the pump shaft rotation (??), 
– Frequency with which the cylinders enter the pumping section (??). 
 
Fig. 6. Spectrum of vibration acceleration in axial direction – pump operating  
with maximum discharge and pumping pressure of 120 bar 
 
Fig. 7. Spectrum of vibration acceleration in radial direction – pump operating  
with maximum discharge and pumping pressure of 120 bar 
Table 2. Vibration parameters 
Measure 
No. 
Vibration in axial direction Vibration in radial direction 
?? ?? ?? ?? ?? ?? 
[Hz] [mm/s2] [Hz] [mm/s2] [Hz] [mm/s2] [Hz] [mm/s2] [Hz] [mm/s2] [Hz] [mm/s2] 
1 24.4 130.2 48.8 126.4 – – 24.4 35.0 48.8 36.3 219.7 175.1 
2 24.4 165.4 48.8 132.1 222.8 50.6 24.4 75.5 48.8 55.0 218.2 386.1 
3 24.4 156.2 48.8 185.4 216.7 893.7 24.4 63.5 48.8 268.3 216.7 525.3 
4 24.4 170.2 48.8 115.5 219.7 447.1 – – 48.8 80.6 219.7 654.7 
5 24.4 57.8 48.8 33.6 219.7 260.7 22.9 98.0 – – 219.7 258.4 
6 24.4 198.3 48.8 54.2 216.7 333.4 22.9 139.0 47.3 68.8 216.7 372.2 
7 24.4 175.2 47.3 105.7 213.6 551.0 24.4 96.7 47.3 287.3 213.6 297.1 
In case of vibration in axial direction we may notice the correlation between the amplitude of 
vibration and the pump load for frequencies close to the frequency of pressure pulsation. On the 
other hand, vibration of the pump shaft rotation frequency and the first harmonic present values 
similar to different modes of pump operation. It can be assumed that they are the effect of the 
pump or pump-asynchronous motor operation.  
In case of the radial vibration, the correlation between the pump load and vibration amplitude 
is particularly noticeable not only for the frequency similar to the pressure pulsation frequency. It 
can be observed that with the increase of pump load, the amplitude of radial vibration of the double 
pump shaft rotation frequency also increases. 
THE INFLUENCE OF VOLUMETRIC PERFORMANCE SETTINGS OF A MULTI-PISTON PUMP ON PARAMETERS OF FORCED VIBRATIONS.  
KLAUDIUSZ KLARECKI, DOMINIK RABSZTYN, MARIUSZ PIOTR HETMANCZYK 
 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. OCTOBER 2014. VOLUME 3. ISSN 2345-0533 81 
Seemingly, we might assume that the pump vibration of 220 Hz frequency is the result of the 
pumping pressure pulsation. This is, however, not the case. In fact, both pressure pulsation and 
pump vibration are the result of the same thing: subsequent cylinders engaging in the pumping 
process. This basically results in discharge flow pulsation and then pressure pulsation as well as 
pulsation of force coming from the cylinder – piston assembly at the moment of entering the 
pumping section. 
5. Conclusions 
The spectra of pumping pressure and vibration acceleration on the body, obtained as a result 
of the experimental tests of the multi-piston axial PV pump (by Parker Hannifin), demonstrate 
some correlation. In case of both pumping pressure and spectra of vibration in axial and radial 
direction we may observe the impact of the cylinders engaging in the pumping process [9]. For 
that reason it is not advised to search for casual connection between the pressure pulsations and 
pump vibration; both phenomena are the effects of the third cause [10], as mentioned above. 
Throughout the study, it has been observed that some of the recorded spectra of pumping 
pressure do not reflect the discharge flow pulsation, resulting from the periodicity of the process 
of the subsequent cylinders entering the pumping section. Such spectra may result from the 
inconsistency of discharge from particular cylinders and the impact of the discharge side of the 
pump (that can be treated and the low pass filter). Another reason might be the periodically 
changing leakage between the cylinder barrel and the valve plate. The clarifying explanation of 
this phenomenon would be possible only after some further modeling and experimental research. 
References 
[1] Łataś W., Stojek J. Dynamic model of multi-piston swash-plate hydraulic pump. Mechanics. 
Technical Transactions, Vol. 108, Issue 2, 2011, p. 113-126, (in Polish). 
[2] Ickiewicz J. Hydraulic and mechanical vibrations of gear pump. Hydraulic and Pneumatics, Issue 3, 
2013, p. 12-16, (in Polish). 
[3] Kudźma Z. Damping of pressure pulsations and noise level in hydraulic systems in transient and 
established conditions. Wroclaw University of Technology Publishing, Wroclaw, 2012, (in Polish). 
[4] Milecki A. Linear electrohydraulic servo drives. Poznan University of Technology Publishing, 
Poznan, 2003, (in Polish). 
[5] Tomasiak E., Klarecki K., Barbachowski E. Servo drives in machine construction. Hydraulics and 
Pneumatics, Issue 1, 2009, p. 16-20, (in Polish). 
[6] Materials developed by Parker Hannifin. Direct Operated Proportional DC Valve Series D1FB, 
http://www.parker.com/. 
[7] The hydraulic trainer. Proportional and servo valve technology. Mannesmann Rexroth AG, Vol. 2, 
Lohr a. Main, 1998, (in German). 
[8] Barbachowski E., Klarecki K. Methods for correcting the characteristics of proportional valves. 
Selected Engineering Problems, Vol. 2, 2011, p. 29-34, (in Polish).  
[9] Jakubowski D., Gniłka J., Wszołek G., Czop P. Optimization of a hydraulic damper performance 
with the use of fluid-structure simulation. Advanced Materials Research, Vols. 452-453, 2012, 
p. 1356-1360. 
[10] Kost G., Nierychlok A. Presentation of the concept of stability of the hybrid powertrain by the 
Lyapunov theory. Journal of Vibroengineering, Vol. 14, Issue 1, 2012, p. 183-188. 


The influence of volumetric performance settings of a multi-piston pump on parameters of forced vibrations

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The influence of volumetric performance settings of a multi-piston pump on parameters of forced vibrations

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