(2)
Position drain valve on flange. Install mounting bolts and lockwire.
(3)
Lockwire drain valve handle in CLOSED position.
D. Install low level warning switch (4) if not included with reservoir.
E. Install O-rings, unions, and reducers in reservoir ports.
6. Install System B Hydraulic Reservoir
A. Place reservoir in mounting position and install mounting bolts (7, Fig. 401).
B Connect electrical connector (3) to low level warning switch (4).
C. Connect all hydraulic lines to reservoir.
CAUTION: PRIOR TO INSTALLING HOSE HALF OF QUICK DISCONNECT, VISUALLY CHECK FOR DISCONNECT POPPET STRAIGHTNESS. AFTER QUICK DISCONNECT CONNECTION, CHECK THAT INDICATOR PINS ARE EXTENDED A MINIMUM OF 0.06 INCH. IF INDICATOR PINS ARE NOT PROPERLY EXTENDED, FLUID FLOW WILL BE RESTRICTED OR COMPLETELY STOPPED AND RESERVOIR AND/OR PUMP DAMAGE MAY RESULT.
IF EXCESSIVE TORQUE IS REQUIRED WHEN RECONNECTING THE TWO HALVES OF THE QUICK DISCONNECT, DISASSEMBLE THE FITTING AND CHECK FOR POPPET STRAIGHTNESS AGAIN.
D. Service hydraulic reservoir (Ref Chapter 12, Servicing).
E. Pressurize reservoir system and check for leaks (Ref 29-09-300).
F. Close tire burst screen protection doors.
G. Remove tags from hydraulic pump switches.
501
Jun 20/90 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 29-12-11 Page 403
SYSTEM B ELECTRIC MOTOR-DRIVEN HYDRAULIC PUMP - DESCRIPTION AND OPERATION
EFFECTIVITY
Abex Pump
1. General
A. Two electric motor-driven hydraulic pump assemblies (figure 1) supply fluid under pressure to the hydraulically-operated subsystems supplied by system B. Each pump assembly consists of an oil-cooled three phase ac motor, a centrifugal pump and a single stage, variable displacement, pressure-compensated hydraulic pump. With an inlet pressure of approximately 45 psig, each pump output is approximately 6.3 gpm at 2700 psig operating at 5800 rpm. The pump assemblies are installed in the wheel well area and controlled by switches on the forward overhead panel.
B. Hydraulic fluid from the system B reservoir enters the-motor pump through the inlet port in the motor housing and passes around the motor rotor and stator assemblies to an antiswirl ring located at the rear of the pump and motor assembly. The antiswirl ring removes fluid turbulence induced by the rotating motor and directs fluid into the specially designed hollow rotor shaft. A helical impeller acts as an inducer in the rotor shaft and pumps fluid through the rotor shaft to the impeller inlet of the centrifugal boost pump and is pressurized to approximately 15 psig above the inlet pressure. The outlet port of the boost pump is located in the volute closure ring and feeds directly into the attached hydraulic pump.
C. The variable displacement pump-consists essentially of a piston and cylinder barrel rotating group, a splined driveshaft, a pivoting hanger with an inclined cam face, a compensating mechanism, a pump housing and port cap. The pump and motor consists of three circuits: the main circuit, the control circuit, and the cooling and lubricating circuit.
(1) The main circuit is the main path of flow through the inlet passageway, through the rotating group, and out the outlet port under pressure to the system.
(a) The pumping mechanism consists of a revolving cylinder barrel containing nine pistons. The cylinder barrel is supported by a roller bearing and driven by the internal drive shaft. As the drive shaft is rotated by the electric motor, the pistons and cylinder barrel are rotated by the drive shaft, which is spline-mated to the motor rotor shaft. The lapped face of the rotating cylinder barrel is held flush against the lapped face of the stationary valve plate in the cap port by the action of a spring on the drive shaft and cylinder barrel. Rotation of the cylinder barrel ports across the ports in the valve plate provide the valving action of the pump.
Aug 15/79 29-12-21 Page 1
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
F87539
System B Electric Motor Driven Pump 500
29-12-21 Figure 1 Nov 15/67
Page 2
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
(b) The hanger supports the pistons which ride axially in their mating bores in the cylinder barrel. The pistons are held against the inclined cam face of the hanger by a hold-down plate and hydraulically balanced shoes. The hanger is linked to the compensating mechanism, which is normally held at a maximum angle of displacement, with relation to the drive shaft axis, by the action of the rate piston and spring in the compensating mechanism. In this position, the pistons reciprocate in relation to the valving face of the cylinder barrel. On one half of each revolution of the drive shaft, the pistons are drawn away from the valve plate, creating a partial vacuum in the cylinder bores. Oil is forced into the bores to satisfy this vacuum. During the intake phase of each revolution, oil flows from the centrifugal pump through a passage in the pump housing to the inlet side of the valve plate in the port cap and into the cylinder barrel. On the other half of each revolution of the drive shaft, oil is forced out of the cylinder bores by movement of the pistons toward the valve plate. During the output phase of each revolution, oil flows at high pressure from the cylinder barrel, through the outlet side of the valve plate into the passages in the port cap and out through the outlet port into the hydraulic system. The axial thrust of the pistons against the hanger cam plate during the power stroke is balanced hydraulically. Oil at system pressure, is admitted through holes in the pistons and balance shoes to an undercut area in the face of the shoes. This pressure is applied to the undercut area, which is slightly less than the piston area balances the forces so that the shoe is supported on an oil film at all times. The axial thrust of the cylinder barrel is also balanced hydraulically against the valve plate in the port cap.
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