HOUSING 5I8520 - Caterpillar

Pump Regulator
Illustration 3 g02932719
Drive pump regulator
(11) Maximum angle end of actuator piston
(13) Small end of actuator piston
(15) Actuator piston
(16) Large end of actuator piston
(17) Minimum angle end of actuator piston
(21) Swashplate
(31) Pump control solenoid
(32) Swashplate sensor target
(33) Swashplate angle sensor
(34) Pump displacement spool Illustration 3 shows the separate control sections of the pump control group. The control sections work together to regulate pump flow by changing the angle of the pump swashplate, according to demand and hydraulic horsepower requirements.Pump delivery pressure is directed to the small end of the actuator piston (13) in order to destroke the pump toward the minimum angle. A regulated signal pressure is directed to the large end of the actuator piston (16) in order to upstroke the pump toward the maximum angle.The pump displacement spool (34) directs some of the system pressure oil to and from the large end of the actuator piston (16). The pump swashplate is connected to actuator piston (15).Pump pressure acting on the small end of actuator piston (13) works with pump displacement spool (34) in order to destroke the swashplate when all hydraulic controls are in the NEUTRAL position or during an implement or travel function when hydraulic demand decreases. The large end of actuator piston (16) works with pump displacement spool (34) in order to upstroke the swashplate when the hydraulic demand increases.
Illustration 4 g02933080
Pump regulator (section view)
(13) Small end of actuator piston
(15) Actuator piston
(16) Large end of actuator piston
(31) Pump control solenoid
(32) Swashplate sensor target
(33) Swashplate angle sensor
(34) Pump displacement spool
(35) Drive pump oil supply passage
(36) Passage
(37) Passage
(40) Spring
(41) Passage
(42) Passage Illustration 4 shows a sectional view of the pump regulator components and passages.Pump displacement spool (34) is controlled by pump control solenoid (31) and spring (40).Swashplate angle sensor (33) is used to determine the swashplate position. The machine ECM uses the swashplate angle sensor signal to determine pump displacement. The swashplate sensor target (32) is mechanically connected to the swashplate and swashplate angle sensor (33) is connected to the pump housing. Pump oil is supplied to passage (35) and flows to the small end of actuator piston (13). Pump oil also flows through passage (41) and passage (37). The oil pressure in passage (36) can now be regulated by pump displacement spool (34) in order to supply a signal pressure to the large end of actuator piston (16).When proportional reducting valve (31) receives a PWM driver from the machine ECM, pump displacement spool (34) shifts. Oil pressure can now flow through passage (37), passage (36), and passage (42) to the large end of actuator piston (16). This action causes the pump to upstroke.Regulator Operation (Standby - Full Destroke)
Illustration 5 g02933116
Drive pump regulator (standby - full destroke position)
(13) Small end of actuator piston
(15) Actuator piston
(16) Large end of actuator piston
(21) Swashplate
(31) Pump control solenoid
(34) Pump displacement spool
(35) Drive pump oil supply passage
(36) Passage
(37) Passage
(40) Spring
(41) Passage
(42) Passage
(43) Passage
(44) Case drain oil Illustration 5 shows the pump regulator and swashplate in the destroked position. When all hydraulic control valves are