22
Bentone B 2
General
NC
V P1
S
R
G
C
E
A
H
D
P
1
5.2.5 BFP41L3 operating principle
When the pump is started, oil is drawn from the suction port (S) through the
filter (H) to the suction port (C) of the gear-set.
The oil then moves to the pressure side of the gearwheel and is thus
pressurised. The pressure is controlled and maintained at a constant pre-set
level by diaphragm (D) of the control valve (P
1
)
The control valve (P
1
) distributes the oil supplied by gear-set (C) between the
nozzle connection (E) and the return port of the pump (R).
The amount of oil consumed is determined by the pressure set on the control
valve (P
1
) and by the size of the oil nozzle in the nozzle line.
The control valve (P
1
) operates as follows:
• When the oil attains opening pressure, the port to the return side
opens.
• The diaphragm and the spring keep a constant pump pressure at the
set value.
• If the pump becomes overloaded, i.e. if an attempt is made to take out
more oil than the gear-set can deliver in the prevailing circumstances,
the oil pressure will fall below the set value causing the valve to close,
by diaphragm (D), to the return port (R) and return to the starting
position.
This can be remedied by:
• Lowering the pump pressure.
• Reducing the amount of oil delivered, i.e. changing to a smaller nozzle.
• Changing to a pump with higher capacity.
To Next Page