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| Illustration 1 | g06471531 |
Reference: For more information, refer to supplemental video "320, 320GC, 323, and 325 Excavators Main Hydraulic Pump Systems Operation" on AVSpare Channel1.
Note: Click or copy the following link into a web browser (a CWS login is required to access AVSpare Channel1), or scan the following QR code using a QR enabled device.
https://channel1.mediaspace.kaltura.com/media/t/1_87lno33v
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| Illustration 2 | g06504043 |
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| Illustration 3 | g06607865 |
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(1) Regulator (pump 1)
(2) Control solenoid (pump 1) (3) Control solenoid (pump 2) (4) Regulator (pump 2) (5) Counter piston (pump 2) (6) Swashplate (pump 2) (7) Pump 2 (8) Stroking piston (pump 2) (9) Stroking piston (pump 1) (10) Pump 1 (11) Swashplate (pump 1) (12) Counter piston (pump 1) (A1) Outlet port (pump 1) (A2) Outlet port (pump 2) (MA1) Pressure tap (pump 1 pressure) (MA2) Pressure tap (pump 2 pressure) (S1) Inlet port (supply oil from the hydraulic tank) (T1) Case drain port (T2) Pressure tap (case drain oil) | |
Supply oil from the hydraulic tank enters inlet port (S1). The single inlet port is common to main pumps (10) and (7). Pump 1 (10) delivers oil through outlet port (A1). Pump 2 (7) delivers oil through outlet port (A2).
Case drain oil from the pump housing flows from port (T1) to the case drain filter.
The main pumps consist of pump 1 and pump 2. The pumps are connected in series by center manifold. Both pumps are variable displacement piston pumps. The displacement is controlled by pump regulators (1) and (4). The pump 1 and the pump 2 are identical in construction and operation.
Both pump 1 and pump 2 have an electronically controlled regulator as part of the pump control system. The flow control of the pumps is performed by the operation of the regulators. The control system is identical for both pumps.
Pump control solenoids (2) and (3) for the pump regulators are located on the side of the main pump. The pump control solenoids are controlled by the machine ECM. The pump control solenoid controls the pump pressure signal to stroking piston (9). The stroking piston and counter piston then controls the angle of swashplate (11).
Reference: For more information concerning the main pump regulator, refer to Systems Operation , "Pump Control (Main Hydraulic)" (Main Pump Regulator).
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| Illustration 4 | g06208698 |
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Main pumps (sectional view) (typical example) (6) Swashplate (pump 2) (7) Pump 2 (10) Pump 1 (11) Swashplate (pump 1) (13) Shaft (14) Plate (15) Spring (16) Case drain oil (17) Passage (18) Port plate (19) Passage (20) Coupling (21) Piston (22) Barrel (23) Shaft (24) Center manifold (25) Passage (26) Passage (27) Barrel (28) Piston (29) Slipper (30) Spring (31) Guide | |
The engine crankshaft drives the hydraulic pumps. The engine is connected to shaft (13) through the coupling in the flywheel housing. Shaft (13) is connected to shaft (23) by coupling (20). Barrel (27) is splined to shaft (13). Barrel (22) is splined to shaft (23). Barrel (27) and barrel (22) contain sets of pistons. Pistons (28) and (21) rotate with the barrels. Pistons (28) rotate about swashplate (11), and pistons (21) rotate about swashplate (6). As the angle of swashplate (11) and swashplate (6) increases, the pistons will extend and retract within the barrels. The extending and retracting of the pistons will cause oil to flow from inlet port (S1) to outlet ports (A1) and (A2). The pump shafts, barrels, and pistons all rotate together within the pump housing.
Each piston (28) is attached to a slipper (29). All of the slippers are contained in plate (14). Guide (31) contacts plate (14) and forces slippers (29) against the swashplate with springs (30). Pistons (28) rotate around swashplate (11) with slippers (29).
Note: The operation of pump 1 is described below. Pump 2 operates in the same manner as pump 1.
When shaft (13) rotates, barrel (27) and pistons (28) rotate. As barrel (27) rotates, oil is drawn from inlet port (S1) to inlet passage (25). The oil in passage (25) flows to passage (26) at port plate (18). The oil fills in the voids of barrel (27).
The angle of swashplate (11) causes pistons (28) to be retracted from barrel (27) at passage (26). When pistons (28) align with passage (17), the swashplate causes pistons (28) to be extended into barrel (27). As barrel (27) rotates, passage (26) is closed off from the voids in barrel (27). Swashplate (11) forces pistons (28) into barrel (27). Pistons (28) pressurize the oil inside barrel (27). As barrel (27) continues to rotate, the oil pressure in barrel (27) is able to flow into passage (17) of port plate (18). Oil flows from passage (17) to outlet port (A1). Oil flow is provided to the main hydraulic system.
The angle of swashplate (11) determines the stroke length of pistons (28). The angle of swashplate (11) is controlled by the regulator.