Body and Implement Mounting Guidelines U500 North America
Hydraulic system
August 2005
Page 219 of
294
6.4 Further information on Unimog hydraulic systems
6.4.1 Hydraulic output / standard values
The installed output is generally calculated according to the fol-
lowing formula:
total
p
Q
P
η
*
29
.
1714
*
=
P = Output
[hp]
Q = Flow
rate
[gal/min]
p = Pressure
[PSI]
η
=
Total degree of efficiency (depends on pressure, flow
rate/speed, temperature, leakage etc.)
Note:
Due to the range of the degree of efficiency, only the output is
calculated from the hydraulic standard values Q
max
(at rated en-
gine speed) and p
rated
(rated pressure) in order to estimate the
required output.
The standard output is thus:
29
.
1714
*
max
Rated
E
p
Q
P
=
with h
total
= 1
Examples:
Power hydraulics, closed circuit:
33.02 gal/min, 4350 PSI
P = 83.8 hp
Power hydraulics, open circuit:
23.78 gal/min, 4060 PSI
P = 56.32 hp
The engine output to be applied for driving purposes is therefore
always higher than the standard value. The hydraulic output pro-
vided is always lower than the standard value.
Corresponding formula in metric units:
total
p
Q
P
η
*
600
*
=
P = Output [kW]
Q = Flow rate [l/min]
p = Pressure
[bar]
η
=
Total degree of efficiency (depends on pressure, flow
rate/speed, temperature, leakage etc.)
600
*
max
ratedn
E
p
Q
P
=
with h
total
= 1
Examples:
Power hydraulics, closed circuit:
125 l/min, 300 bar
P = 62.5 kW
Power hydraulics, open circuit:
90 l/min, 280 bar
P = 42 kW
