MAN Centralne smar. Groeneveld 3.pdf

Electrical Axial Piston Pump

The electric axial pump is activated by the electronic timer. The grease will be pumped from the

reservoir (4) out through the main line (19) to the injector manifolds. The pump remains in operation

throughout the entire cycle period. This cycle time is usually 3 minutes when a standard Groeneveld

electronic timer is used. The normally open return valve (21) is closed by the solenoid (22), at the

same time as the pump is turned on, to close off a return passage to the reservoir. The pump then

builds up grease pressure in the pump and main lines during the cycle. When the pressure reaches 95

bar the pressure relief valve (7) opens, allowing some of the grease to flow back into the reservoir.

Maximum grease pressure is, therefore, limited to 95 bar. The standard version is fitted with a 70 bar,

normally open, pressure switch (16). After 70% of a cycle is complete the timer checks to see if the

pressure switch closed. If during a greasing cycle, the grease pressure does not rise above 70 bar to

close the switch, the electronic timer will sound an alarm (or turn on a warning light – depends on the

type of timer). At the end of a cycle, the timer turns off the power, the pump stops, the return valve

opens and grease in the main line flows back to the reservoir. With the grease pressure dropping to

zero, the injectors can refill themselves for the next cycle.

An optional grease level indicator (14) will also provide a signal to the timer and result in an alarm

signal if the grease in the reservoir gets too low.

On the left side of the pump, behind the filling connector (10) there is a tapped hole in the housing for

air venting and grease overflow. When filling the reservoir with grease, the air above the follower

plate escapes through the hole in the center guide rod (5) which is connected to that tapped hole. If too

much grease is put into the reservoir, causing the follower plate to rise above the ‘maximum line’ then

the excess grease will escape out through that hole in the center guide rod and it will come out of the

vent hole.

The Pump is wired for a low level switch to pin #4. A low level switch is optional and

added only when the customer requests it.