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Technical Information
LPV Axial Piston Pumps
System design parameters
Hydraulic unit life
Mounting flange loads
12 |
©
Danfoss | September 2017
Diagram of external radial shaft loads
Hydraulic unit life is the life expectancy of the hydraulic components. It is a function of speed and
system pressure. System pressure is the dominant operating variable. High pressure, which results from
high load, reduces expected life.
Design the hydraulic system to a projected machine duty cycle. Know the expected percentages of time
at various loads and speeds. Ask your Danfoss representative to calculate an appropriate pressure based
your hydraulic system design. If duty cycle data is not available, input power and pump displacement are
used to calculate system pressure.
All pressure limits are differential pressures (referenced to charge pressure) and assume normal charge
pressure.
LPV pumps will meet satisfactory life expectancy if applied within the parameters specified in this
bulletin. For more detailed information on hydraulic unit life see Pressure and Speed Limits, BLN-9884.
Estimating overhung load moments
Adding auxiliary pumps and/or subjecting pumps to high shock loads may result in excessive loading of
the mounting flange. Applications which experience extreme resonant vibrations or shock may require
additional pump support. You can estimate the overhung load moment for multiple pump mounting
using the formula below.
M
= G
(W
L
+ W
L
+ ... +W
S
S
1
1
2
2
M
= G
(W
L
+ W
L
+ ... +W
C
C
1
1
2
2
Where:
M
= Rated load moment N•m [lbf•in]
C
M
= Shock load moment N•m [lbf•in]
S
G
= Rated (vibratory) acceleration (G's)* m/s2 [ft/s2]
C
G
= Maximum (shock) acceleration (G's)* m/s2 [ft/s2]
S
th
W
= Weight of n
pump
n
L
= Distance from mounting flange to CG (center of gravity) of n
n
(Refer to
Installation drawings
* Carry out calculations by multiplying gravity (g = 9.81 m/s
on the application.
Refer to
Specifications
on page 20, for allowable overhung load moment values.
L
R
e
T
90
R
e
e
F
b
L
)
n
n
L
)
n
n
on page 30 to locate CG of pump.)
2
0
R
e
270
180
R
e
P106280
th
pump
2
[32 ft/s
]) with a given factor. This factor depends
520L0954 | BC00000044en-US0102
R
e
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