Komatsu PC210-8, Руководство по ремонту

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UEN00104-00 10 Structure, function and maintenance standard
6
PC210, 230, 240-8
3. The Greasing Cycle
Every greasing cycle consists of four phases. The greasing cycles are carried out alternately by the grease
lines A and B (see figure 3). The 5/2 valve, which is integrated in the pump housing, determines which pri-
mary grease line is connected to the pump and which is connected to the grease reservoir. The total greas-
ing cycle has a predetermined time; however, the length of the four phases depend on the circumstances.
The different greasing cycles and phases are discussed below.
Greasing Cycle A
The pumping phase
The greasing cycle begins with a pumping phase. In this phase the grease is pumped from the reservoir,
through primary grease line A, to the distribution blocks. The pumping phase ends when the pressure at the
pressure switch reaches a predetermined level. The time needed to reach that predetermined pressure
depends on various factors as temperature, grease consistency (thickness) and the dimensions of the
greasing system. The duration of the pumping phase is therefore not directly adjustable. During the pumping
phase, the metering units press a certain amount of grease (the dosage) through the secondary grease lines
to the greasing points.
The re-grease phase
The re-grease phase follows the pumping phase; a period in which the pressure in the primary grease lines
is maintained at a certain pressure. During the re-grease phase, the metering units can deliver the grease
dosage, which (for various reasons) was not yet delivered during the pumping phase. The duration of the re-
grease phase depends on the duration of the pumping phase. This dependency is expressed in the parame-
ter bmf, bleeding multiplication factor.
Example: When the bmf is 1, the re-grease phase is 1/10
th
of the length of the pumping phase. When
the bmf is 10, the re-grease phase is 10/10
th
of the length of the pumping phase.
The pressure decrease phase
The pressure decrease phase follows the re-grease phase. In this phase, the pressure in the primary grease
line is decreased through the 5/2 valve. To accomplish this, the control unit energizes the 5/2 valve, so the
grease pressure in primary grease line A is decreased and the grease flows back to the reservoir.
The duration of the pressure decrease phase is equal to that of the re-grease phase and therefore propor-
tional to the duration of the pumping phase. When the greasing system needs more time to build up the
required grease pressure (because of low temperature or grease with a high viscosity), the system will also
need more time to decrease that same pressure.
The pause phase
The pause phase is the period between the pressure decrease phase and the beginning of the next pumping
phase. The length of the pause phase is equal to the predetermined cycle-time minus the length of the other
phases. When the cycle-time is adjusted too short to carry out a complete greasing cycle, the program will
ignore the cycle-time. The pumping, re-grease and pressure decrease phase will be carried out completely.
However the pause phase will be omitted, because the predetermined cycle-time is exceeded. The greasing
system begins directly with the first phase of the next greasing cycle.
Figure 3 Overview of the various phases of the greasing cycles