PUMP GP-FUEL INJECTION 1260499 - Caterpillar

Leveling Operation
Introduction
The purpose of a leveling operation is to level a ground surface with high accuracy using the combined movement of the boom and stick. During a leveling operation, the boom and stick make fine movements to keep the tip of the bucket against the ground surface.
Stick In Leveling (Movement Of Boom And Stick)
Right Console (Monitor Panel)
(1) Power mode switch. (2) Fine control mode switch.Leveling operations are a slow speed type of work. Fine control switch causes the engine speed to be reduced automatically which controls the power level to a level lower than the power controlled by switch (1). Also, fine control mode switch is turned ON. The boom and stick circuits have an individual pump oil supply to each function. The operations of boom and stick cylinders will not affect each other.Fine Control Circuit
Hydraulic Schematic (Partial) (Fine Control Operation)
(1) Stick cylinder. (2) Boom cylinders. (3) Center bypass passage. (4) Boom I control valve. (5) Stick II control valve. (6) Stick I control valve. (7) Center bypass passage. (8) Boom II control valve. (9) Parallel feeder passage. (10) Fine control solenoid valve. (11) Pilot oil manifold. (12) Upper pump. (13) Lower pump.When the boom and stick control levers are partially moved to the boom RAISE and stick IN position, oils from upper pump (12) and lower pump (13) flow as follows;As fine control mode switch is turned ON, fine control solenoid valve (10) is energized with causes the center bypass passage in stick II control valve (5) to remain open.1. Part of upper pump oil in parallel feeder passage (9) goes through boom I control valve (4) to boom cylinders (2). The remainder of upper pump oil parallel feeder passage (9) goes through center bypass passage (3), boom I control valve (4) and stick II control valve (5), and returns to the hydraulic tank.2. Part of lower pump oil in center bypass passage (7) goes through stick I control valve (6) to stick cylinder (1). The remainder of lower pump oil in center bypass passage (7) goes through boom II control valve (8) and returns to the hydraulic tank.The boom and stick circuits use the separate pump oil which does not affect the movement of the other during fine control operation of the boom and stick. Also, each pump oil that is not used for boom RAISE and stick IN bypasses and returns to the hydraulic tank. This assures an exact fine control operation.Trenching Operation
Trenching Operation (Illustration Of Applied Swing Force)When excavating a ditch, its cross section should be rectangular. The force of the ditch wall acting against the bucket, causes the bucket to move away from the wall of the ditch.
Right Console (Monitor Panel)
(1) Swing priority mode switch.To get a straight (vertical) wall, it is necessary that an additional side force be used to hold the bucket against the side wall. The operator does this by applying partial swing in the direction of the wall. The swing priority mode provides the appropriate partial swing force for