Research Papers

Increasing the Power Density for Axial-Piston Swash-Plate Type Hydrostatic Machines

[+] Author and Article Information
Noah D. Manring

Mechanical and Aerospace Engineering,
University of Missouri,
Columbia, MO 65211
e-mail: ManringN@missouri.edu

Viral S. Mehta

e-mail: Mehta_Viral@cat.com

Bryan E. Nelson

e-mail: Nelson_Bryan_E@cat.com

Kevin J. Graf

e-mail: Graf_Kevin_J@cat.com

Jeff L. Kuehn

e-mail: Kuehn_Jeff_L@cat.com
Caterpillar Inc.,
Peoria, IL 61656

1Corresponding author.

Contributed by the Design Automation Committee of ASME for publication in the Journal of Mechanical Design. Manuscript received December 19, 2012; final manuscript received February 25, 2013; published online May 10, 2013. Assoc. Editor: Alexander Slocum.

J. Mech. Des 135(7), 071002 (May 10, 2013) (6 pages) Paper No: MD-12-1615; doi: 10.1115/1.4023924 History: Received December 19, 2012; Revised February 25, 2013

Power density is an assumed attribute of an axial-piston swash-plate type hydrostatic machine. As such, very little research has been conducted to examine the nature and limit of this machine's power density and the literature is all but void of this important topic. This paper is being written to fill this void, and to provide a thorough analysis of the machine's power density. This paper is also aimed at identifying the most significant parameters that may be adjusted to increase the power density for a typical machine. As shown in this research, the power density of an axial-piston machine depends upon four dimensionless quantities that are characteristic of the machine's rotating group. As it turns out, the allowable stress for the cylinder block is the most sensitive parameter that may be adjusted for increasing the power density of this machine. It is further shown that increasing the machine's swash-plate angle, and reducing the minimum overhang length for the pistons, will have a significant impact on the power density as well. It is significant to note that altering the number of pistons in the design has essentially no impact on the power density of the machine and therefore the selection of this design parameter must be based upon other design objectives. In conclusion, it is shown in this paper that the power density of a typical machine may be increased by as much as 64% by altering a few of these parameters within a realistic realm of constraint.

Copyright © 2013 by ASME
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Blackburn, J. F., Reethof, G., and Shearer., J. L., 1960, Fluid Power Control, Wiley, New York.
Manring, N. D., 2000, “Designing the Shaft Diameter for Acceptable Levels of Stress Within an Axial-Piston Swash-Plate Type Hydrostatic Pump,” ASME J. Mech. Des., 122, pp. 553–559. [CrossRef]
Ivantysynova, M., 2008, “Innovations in Pump Design: What are Future Directions?” Proceedings of the 7th JFPS International Symposium on Fluid Power, Toyama, Sept. 15–18, pp. 59–64.
Ivantysyn, J., and Ivantysynova., M., 2003, Hydrostatic Pumps and Motors: Principles, Design, Performance, Modelling, Analysis, Control and Testing, Tech Books International, New Delhi, India.
Manring, N. D., 2013, Fluid Power Pumps and Motors: Analysis, Design and Control, McGraw-Hill, Inc., New York.
Achten, P. A. J., 2004, “Power Density of the Floating Cup Axial Piston Pump,” ASME International Mechanical Engineering Congress and Expo, Anaheim, Nov. 13–19, pp. 1–12.


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Fig. 1

The general configuration of the hydrostatic machine

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Fig. 2

Geometry of the cylinder-block layout

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Fig. 3

Geometry for determining the envelope volume of the rotating group

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Fig. 4

Nondimensional power density Π∧ versus dimensionless hoop stress σ (c = 0.2993, N = 9)

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Fig. 5

Nondimensional power density Π∧ versus swash-plate angle α (c = 0.2993, N = 9)

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Fig. 6

Nondimensional power density Π∧ versus dimensionless constant c (σ = 1.3556, N = 9)

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Fig. 7

Nondimensional power density Π∧ versus number of pistons N (σ = 1.3556, c = 0.2993)

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Fig. 8

A comparison of two machines with the same volumetric displacement



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