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MAIN HYDRAULIC SYSTEMS -ENGINE DRIVEN PUMP -SUPPLY SHUTOFF VALVE
Purpose
The EDP supply shutoff valve stops hydraulic supply from the reservoir to the EDP when the engine fire switch is in the up position.
Physical Description
The supply shutoff valve is a two-position valve operated by a 28v dc motor. A position indicator shows the position of the valve.
Location
There is a supply shutoff valve in the left side of each engine aft strut fairing near the hydraulic reservoir.
Training Information Point
Because the supply of hydraulic fluid to the pump stops when the fire switch is up, there is no pump case drain flow.
If the engine continues to turn (windmill) with the valve in the OFF position, the EDP may be damaged. You must do an inspection of the EDP filter module.
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MAIN HYDRAULIC SYSTEMS -ENGINE DRIVEN PUMP -SUPPLY SHUTOFF VALVE
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MAIN HYDRAULIC SYSTEMS -ALTERNATING CURRENT MOTOR PUMP
Purpose
The ACMPs are the primary pumps in the center hydraulic system and the demand pumps in the left and right hydraulic systems.
Physical Description
The ACMP has an electric motor that mechanically connects to a hydraulic pump. The motor operates with three-phase, 400 Hz,
115/200v ac power. The pump displacement hydraulic pump. is a nine piston variable-
Case drain flow cools lubricates the pump. the ele ctric motor and c ools and
A ripple damper smooths the pump pressure output.
The ACMPs are rated at 6 gpm at 2850 psi.
Each ACMP has a temperature switch that is a part of the pump. The temperature switch closes to indicate a pump overheat condition.
BEJ ALL PRE SB 777-29-0024
The ACMP temperature switch is not used.
BEJ ALL POST SB 777-29-0024
The ACMP temperature switch is connected in parallel with the ACMP temperature transducer.
BEJ ALL
All ACMPs are the same and weigh 27 pounds (12.3 Kg).
Location
The ACMPs for the left and right hydraulic systems are in the engine struts aft of the reservoirs.
The center system ACMPs are on the keel beam in the right wheel well.
Training Information Point
The center system ACMPs attach to airplane structure through four vibration isolators.
The left and right ACMPs attach to a mounting bracket (not shown) before installation.
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MAIN HYDRAULIC SYSTEMS -ALTERNATING CURRENT MOTOR PUMP
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777 AIRCRAFT MAINTENANCE MANUAL
THIS PAGE IS INTENTIONALLY LEFT BLANK
29-10-00
Page 24 D633W101-BEJ Sep 05/2002
MAIN HYDRAULIC SYSTEMS -ADP ASSEMBLY -INTRODUCTION
Purpose
Two air driven pump (ADP) pumps are the demand pumps for the center hydraulic system.
General Description
Each ADP pump is part of an ADP assembly. The ADP assembly also has an air drive unit (ADU). The ADU contains these components:
*
Turbine gearbox assembly (TGA)
*
Modulating shutoff valve (MSOV)
*
Air drive unit (ADU) heater.
A mount truss assembly attaches each ADP assembly to the airplane structure. The mount truss assembly for ADP assembly C1 is not the same as the one for ADP assembly C2.
The ADP assemblies use airplane pneumatic power to operate. An inlet duct supplies air pressure to each ADU. The MSOVs let air flow to the turbine of the TGAs. The gearbox of TGAs reduces the turbine speed and operates the pump. ADU heaters are on the ADUs to prevent ice formation. The pumps connect directly to the TGAs. The airflow from the TGAs exits the airplane through two exhaust ducts and two exhaust vents directly aft of the ADP assemblies.
The two TGAs have the same components. The turbine housing of ADP assembly C1 is different than the turbine housing for ADP assembly C2 to permit the exhaust ducts to be near each other.
Two ADP logic speed control units (LSCU), one for each ADP assembly, control the pump operation. The LSCUs supply speed control and overspeed protection to the TGAs. The LSCUs are circuit card assemblies and are LRUs.
A wiring harness for each ADP assembly connects the LSCU to the MSOV and the TGA.
The ADP pumps are the same as the engine driven pumps.
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