Automatic Greasing System
Twin-3
Principle of operation
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EG1703P03
Pressure retaining phase
The pressure retaining phase follows the pumping phase; a period in which the pressure in the
primary grease line-A is maintained at a certain pressure. During the pressure retaining 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 pressure retaining phase depends on the duration
of the pumping phase. This dependency is expressed in the parameter
vmf
, venting multiply factor.
Example: When the
vmf
is 1.0 the pressure retaining phase is the same length as the pumping
phase. When the
vmf
is set to 10.0, the pressure retaining phase is 10 times the length
of the pumping phase.
Pressure decrease phase
The pressure decrease phase follows the pressure retaining phase. In this phase, the pressure in the
primary grease line-A is decreased through the 5/2-way valve. To accomplish this, the control unit
switches the 5/2-way valve on, so the grease pressure in the 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 pressure retaining phase and
therefore proportional 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.
Pause phase
The pause phase is the period between the pressure decrease phase and the beginning of the next
pumping phase in line-B. 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 perform a
complete greasing cycle, the program will ignore the cycle-time. The pumping-, pressure retaining
and pressure decrease phase will be performed 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.
2.2.2
Greasing cycle B
Greasing cycle B begins when the pause phase of the former cycle A is finished. The control unit
restarts the pump. During pumping phase B and pressure retaining phase B, the control unit
switches the 5/2-way valve on, causing the pump to be connected to primary grease line-B. The
primary grease line-A is shut off from the pump during these phases and connected to the reservoir.
During the pressure decrease phase in primary grease line-B, the control unit switches the 5/2-way
valve (spring return) off, so the grease pressure in the primary grease line-B decreases and the
grease flows back to the reservoir.
