not much higher than the standard pressure of 20:6 MPa. The so-called optimal
working pressure is still a controversial issue. In order to reduce structure size
and system weight/power ratio, high-pressure hydraulic systems have been
developed for military aircraft and ground equipment. Some examples are listed
in Table 9.4. Table 9.5 shows the distribution of hydraulic pumps and
electro-hydraulic servo valves in the European and American hydraulic
industry according to working pressure in 1988.
(2) High Temperature
High-temperature working environment (e.g., engine compartment, metallurgical equipment) and high speed, heavy load, long-term operation of hydraulic
system heating temperature rise, due to structural weight and space position
constraints, it is difficult to maintain the normal working temperature of the
ground solely by forced cooling or adiabatic, in recent years, the development
of high-temperature hydraulic system has become a reality. The oil temperature
of the Trident missile hydraulic system is 204*260 °C. The working temperature range of the hydraulic system of the American SR-71 high altitude
reconnaissance aircraft is À54 $ þ 315
C. Hydraulic components installed in
engine compartment (no less than 538
C) are coated with a heat shield (7:6 mm
thick) made of chromium–nickel–iron alloy foil, which is used to limit the oil
temperature of hydraulic oil to below 315
C.
(3) Problems and Key Technologies Caused by High Pressure and High
Temperature
1. Sealing material. Under high pressure, rubber sealing rings will accelerate
tensile aging, extrusion damage, and reliability and service life are reduced.
At high temperature, rubber sealing materials will accelerate aging, reduce
Table 9.4 Working pressure of typical hydraulic systems
Name
Working pressure
F-14 fighter
55
B-1 bomber
27.4
Saturn-V rocket erection transporter
34*35.8
Space shuttle takeoff-separation overload simulator
27.4
25-ton hydraulic excavator
34
Hydraulic platform of marine mining vessel
34
Hydraulic roof pillar in mine
41*69
Table 9.5 Distribution ratio of working pressure of hydraulic pump and electro-hydraulic servo
valve
Working pressure
Hydraulic piston pump
Electro-hydraulic servo valve
<20.6
25
31.4
20.6*34
46.8
60
>34
28.2
8.6
68
9 High-Temperature and High-Speed Gas Turbine Pump …
working pressure is still a controversial issue. In order to reduce structure size
and system weight/power ratio, high-pressure hydraulic systems have been
developed for military aircraft and ground equipment. Some examples are listed
in Table 9.4. Table 9.5 shows the distribution of hydraulic pumps and
electro-hydraulic servo valves in the European and American hydraulic
industry according to working pressure in 1988.
(2) High Temperature
High-temperature working environment (e.g., engine compartment, metallurgical equipment) and high speed, heavy load, long-term operation of hydraulic
system heating temperature rise, due to structural weight and space position
constraints, it is difficult to maintain the normal working temperature of the
ground solely by forced cooling or adiabatic, in recent years, the development
of high-temperature hydraulic system has become a reality. The oil temperature
of the Trident missile hydraulic system is 204*260 °C. The working temperature range of the hydraulic system of the American SR-71 high altitude
reconnaissance aircraft is À54 $ þ 315
C. Hydraulic components installed in
engine compartment (no less than 538
C) are coated with a heat shield (7:6 mm
thick) made of chromium–nickel–iron alloy foil, which is used to limit the oil
temperature of hydraulic oil to below 315
C.
(3) Problems and Key Technologies Caused by High Pressure and High
Temperature
1. Sealing material. Under high pressure, rubber sealing rings will accelerate
tensile aging, extrusion damage, and reliability and service life are reduced.
At high temperature, rubber sealing materials will accelerate aging, reduce
Table 9.4 Working pressure of typical hydraulic systems
Name
Working pressure
F-14 fighter
55
B-1 bomber
27.4
Saturn-V rocket erection transporter
34*35.8
Space shuttle takeoff-separation overload simulator
27.4
25-ton hydraulic excavator
34
Hydraulic platform of marine mining vessel
34
Hydraulic roof pillar in mine
41*69
Table 9.5 Distribution ratio of working pressure of hydraulic pump and electro-hydraulic servo
valve
Working pressure
Hydraulic piston pump
Electro-hydraulic servo valve
<20.6
25
31.4
20.6*34
46.8
60
>34
28.2
8.6
68
9 High-Temperature and High-Speed Gas Turbine Pump …