MUFFLER AS 1428845 - Caterpillar

Construction
Illustration 1 g06314282
(1) Pump 1 solenoid
(2) Pump 2 solenoid
(3) Stroking piston
(4) Stroking piston
(5) Pump 1
(6) Pump 2
(7) Pilot port 1
(8) Pilot port 2
(B1) Suction port
(Dr) Case drain port
(P1) Pump 1 outlet
(P2) Pump 2 outlet
(Psv) Pilot oil inletSupply oil from the hydraulic tank enters suction port (B1). The single inlet port is common to pump 1 (5) and pump 2 (6). Pump 1 delivers oil flow through outlet port (P1). Pump 2 delivers oil flow through outlet port (P2).Case drain oil from the pump housing flows from port (Dr) to the case drain filter.The main pump assembly consists of pump 1 and pump 2. The pumps are connected in series by a center manifold. Both pumps are variable displacement piston pumps and 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 regulators are controlled by pump solenoids (1) and (2). The regulators control flow by changing the angle of the swashplate. The angle of the swashplate determines pump displacement or capacity. The control system is identical for both pumps.The pump control solenoids are located on the side of the main pump. The solenoids are controlled by the machine ECM. The pump control solenoids control pump pressure to stroking pistons (3) and (4). The pistons control the angle of swashplates in each pump via a mechanical connection.Reference: For more information concerning the main pump regulator, refer to Systems Operation, "Pump Control (Main Hydraulic) (Main Pump Regulator)".Operation
Illustration 2 g06256221
Main pumps (sectional view) (typical example)
(4) Pump 2
(5) Pump 1
(7) Plate
(8) Spring
(9) Case drain oil
(10) Passage
(11) Port plate
(12) Passage
(13) Coupling
(14) Piston
(15) Barrel
(16) Shaft
(17) Swashplate (pump 2)
(18) Center manifold
(19) Port plate
(20) Passage
(21) Passage
(22) Barrel
(23) Piston
(24) Slipper
(25) Swashplate (pump 1)
(26) Spring
(27) Guide
(28) ShaftThe engine crankshaft drives the hydraulic pumps. The engine is connected to shaft (28) through the coupling in the flywheel housing. Shaft (28) is connected to shaft (16) by coupling (13). Barrel (22) is splined to shaft (28). Barrel (15) is splined to shaft (16). Barrel (22) and barrel (15) contain sets of pistons. Pistons (14) and (23) rotate with the barrels. Pistons (23) rotate about swashplate (25), and pistons (14) rotate about swashplate (17). As the angle of swashplate (25) and swashplate (17) increases, the pistons will extend and retract within the barrels. The extending and retracting of the pistons will cause oil to flow from suction port (B1) to outlet ports (P1) and (P2). The pump shafts, barrels, and pistons all rotate together within the pump housing.Each piston (23) is attached to a slipper (24). All the slippers are contained in plate (7). Guide (27) contacts plate (7) and forces slippers (24) against the swashplate with springs (26). Pistons (23) rotate around swashplate (25) with slippers (24).Note: The operation of pump 1 is described below. Pump 2 operates in the same manner as pump 1.When shaft (28) rotates, barrel (22) and pistons (23) rotate.