TM 55-1520-240-23-7
8-57
MISCELLANEOUS INSTRUMENTS
(Continued)
8-57
HYDRAULIC PRESSURE INDICATING SYSTEMS
Description
The maintenance panel contains indicators for three
hydraulic pressure indicating systems. Two of these
systems measure pressure in the two flight control
hydraulic systems. The other system measures pressure
in the utility hydraulic system. Each system consists of
an indicator and a pressure transmitter. In operation,
hydraulic pressure is applied to the transmitter. The
transmitter generates an electrical signal proportional
to pressure. The signal is transmitted to the indicator
where it is converted to a pressure reading. These
systems are powered by 28 vdc.
NO BREAK - WORK HARDER
The hydraulic pressure indicators are 0 to 5 volt meter
movements with scale indications of 0 to 4000 psi.
Three identical indicators are clamp mounted in the
maintenance panel one for each hydraulic system.
Electrical connections are made through a receptacle on
the rear of each indicator.
NO BREAK - WORK HARDER
The transmitter receives 28 vdc and provides an output
of 0 to 5 vdc. The transmitter contains a flexible
pressure dome which has bonded strain gages. These
strain gages, resistive elements, are connected as a
wheatstone bridge. When pressure is applied to the
dome, the dome distorts and changes the resistance of
the bridge. The change in bridge output is amplified to
drive a conventional moving coil type indicator to display
pressure in psi. There are three pressure transmitters,
utility system, located on the utility system control
module (sta. 534 LH), No. 1 system, located on the
No. 1 system power control module (sta. 123, WL 78),
and No. 2 system, located on the No. 2 system power
control module (sta. 544, WL 86).
8-162
