2. Overview/System description
2.3 General design of a Dual Line centralized lubrication system with one main line with one differential pressure switch
)See Figure 4
The following description applies to a 400
VAC Dual Line centralized lubrication system
with one main line.
The LMC 301 Controller (1) is installed in a
Dual Line control cabinet, with a load unit
and power supply for the pump motor and
the attached valves and sensors.
Depending on the pump design, the
changeover valve described below (3) can
be attached directly to the pump (2) (grease
lubrication pump unit FK, model FK2) or, in
case of systems with high operating pres-
sure, separated from the pump (grease
lubrication pump unit FK, model FK3).
On the latter design, one grease feed line (4)
and a grease return line (5) are flanged to
the pump housing of the Dual Line pump.
These are fastened with their respective
ends to the electrical changeover valve (3).
Two main feed lines (6) (7) proceed from the
electrical changeover valve to the Dual Line
distributors in downstream alignment (8).
Once all feeders have dispensed their
quantity of lubricant (control and metering
pistons are in their end position), the first
half of the connected lubrication points in
section (A) or (B) has been supplied with lu-
bricant. The pressure builds further because
the pump continues to feed lubricant.
A model DDS50/1 differential pressure
switch (9) is fitted ahead of the last Dual
Line feeder. It contains two NO-contacts.
The differential pressure switch measures
the differential pressure between main feed
lines 1 and 2 (6/7).
A signal is sent to the LMC 301 when a dif-
ferential pressure of ∆p = 50 bar is reached.
The LMC 301 then switches the changeover
valve (3), relieving the previously pressur-
ized main feed line, while pressure increases
in the previously relieved main feed line
after a brief interval time. The control and
metering pistons of the feeders (8) are actu-
ated once again and lubricant is dispensed
to the lubrication points or to the progres-
sive feeders in downstream alignment (11)
on the opposite side of the feeders, section
(A) or (B).
Fill level monitoring is performed by an
ultrasonic sensor located in the pump res-
ervoir. The ultrasonic sensor (10) has two
switching points. When the minimum fill
level is reached, switching point 1 passes a
signal to the LMC 301, which then switches
off the pump. When the maximum fill level
is reached, switching point 2 passes a signal
to the system control unit.
This makes it possible to operate an external
filling pump with both signals via the system
control unit.
EN
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