Komatsu Galeo PC800-8 Shop Manual page 151

Hydraulic excavator

Table of Contents

10 Structure, function and maintenance standard

1. Operation of pump

Cylinder block (7) rotates together with shaft (1)

and shoe (5) slides on plane A. At this time, rock-

er cam (4) tilts around ball (11). As a result, angle

(a) between center line X of rocker cam (4) and

the axis of cylinder block (7) changes. Angle (a)

is called the swash plate angle.

If angle (a) is made between center line X of

rocker cam (7) and the axis of cylinder block (7),

plane A works as a cam for shoe (5).

Accordingly, piston (6) slides inside cylinder

block (7) and a difference is made between vol-

umes E and F in cylinder block (7). As a result,

each piston (6) sucks and discharges oil by F –

In other words, if cylinder block (7) rotates and

the volume of chamber E is decreased, the oil is

discharged from chamber E. On the other hand,

the volume of chamber F is increased and the oil

is sucked in chamber F. (In the figure, chamber

F is at the end of the suction stroke and chamber

E is at the end of the discharge stroke.)

If center line X of rocker cam (4) is equal to the

axis of cylinder block (7) (the swash plate angle

is 0), there is not a difference between volumes

E and F in cylinder block (7) and oil is not sucked

or discharged. (The swash plate angle is not set

to 0 actually, however.)

In short, swash plate angle (a) is in proportion to

the pump discharge.

PC800, 850-8

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