SUPPORT AS 1530246 - Caterpillar

Float Operation
Illustration 3 g01472375
Float operation
(3) Tilt cylinder
(4) Hydraulic oil tank
(7) Lift cylinders
(9) Implement pump
(14) Bucket tilt control valve
(15) Line relief valve (tilt rod end)
(16) Pilot control solenoid
(17) Bucket lift control valve
(18) Anti-drift valve
(20) Margin relief valve
(27) Relief valve (lift head end and tilt head end)
(28) Accumulator
(30) Flow from the charge circuit of the right drive pump
(31) Dead electronic lower valve (Lift circuit) When the lift control lever is moved to the FLOAT detent position, the pilot oil is directed to the left side of lift valve spool (17). Lift valve spool (17) then shifts to the FLOAT position. Both ends of lift cylinders (7) are now open to hydraulic tank (4) and the FLOAT operation can occur. The movement of the bucket is controlled by external forces during the FLOAT operation.When the lift control lever is moved to the FLOAT position, the machine is commanded to float to the lower kickout. When the lift control lever is moved consecutively into the FLOAT position, the machine is quickly put into the FLOAT position.During the FLOAT operation, electronic snubbing is used in order to help prevent the lift cylinders from stopping immediately.Dead Engine Lower
Illustration 4 g01472388
Dead Engine Lower
(3) Tilt cylinder
(4) Hydraulic oil tank
(7) Lift cylinders
(9) Implement pump
(14) Bucket tilt control valve
(15) Line relief valve (tilt rod end)
(16) Pilot control solenoid
(17) Bucket lift control valve
(18) Anti-drift valve
(20) Margin relief valve
(27) Relief valve (lift head end and tilt head end)
(28) Accumulator
(30) Flow from the charge circuit of the right drive pump
(31) Dead electronic lower valve (Lift circuit) The implement circuit may still be operated when the engine is dead. Accumulator (28) stores potential energy while the engine is running by accumulating a quantity of pressurized hydraulic oil. When the engine is dead, the accumulator supplies this oil to the pilot valve.When the operator moves the lift control lever, oil flows from accumulator (28) to the end of lift valve spool (17). The spool is shifted and the oil that was trapped in the lift cylinders flows back to the hydraulic tank as gravity lowers the attachment to the ground.When the front of the machine is off of the ground, there is pressure on the rod end of lift cylinders (7). Oil from the accumulator can now be used as pilot oil in order to shift lift valve spool (17) to the RAISE position. The oil that was trapped in the rod end of the lift cylinders flows back to the hydraulic tank as the machine lowers.Dead Electronic Lower
Illustration 5 g01472389
Dead Electronic Lower
(3) Tilt cylinder
(4) Hydraulic oil tank
(7) Lift cylinders
(9) Implement pump
(14) Bucket tilt control valve
(15) Line relief valve (tilt rod end)
(16) Pilot control solenoid
(17) Bucket lift control valve
(18) Anti-drift valve
(20) Margin relief valve
(27) Relief valve (lift head end and tilt head end)
(28) Accumulator
(30) Flow from the charge circuit of the right drive pump
(31) Dead electronic lower valve (Lift circuit) If the engine is dead and the electronics are dead then the oil pressure that is stored in the accumulator is not usable for lowering lift