Yanmar 4LHA-HTP Operation Manual page 370

Chapter 3 Fuel Injection Equipment
5. Injection Pump Construction and Operation ?n
Cylinder A
Compression stroke
I I Suction stroke
N O R M A L
DIRECTION
Fig. 14 Plunger strokes for cylinders A and B
0
(
ig. 15 Plunger's effective stroke
:
Cylinder B
Cam lift
•
REVERSE
DIRECTION
Control sleeve
Decreasing injection quantity <^
Shorter effective stroke
Reverse rotation prevention
While the plunger is moving in the normal
direction of rotation, the inlet port is open dur-
ing the plunger's return stroke and sufficient
fuel oil is sucked into the pressure chamber.
During the compression stroke the inlet port is
closed and injection is performed.
However, should the engine rotate in the re-
verse direction (e.g. when a stationary, parked
vehicle begins to roll backwards and the engine
is rotated, etc.) the plunger barrel's inlet port
and the plunger's inlet slit will align during
plunger lift, the fuel oil cannot be pressurized
and non-injection will result.
Because of this the engine will immediately
stop.
Injection quantity control
Fuel injection quantity
creased by the effective stroke, which is varied
by the position of the control sleeve.
i ^> Increasing injection quantity
1
Longer effective stroke
3-1-13
, 4LHA Series
is increased or de-
Plunger's
Cut-off port