Two-Hole Pump Element (Maximum Feed); Delivery Valve - Valtra 6000 Workshop Manual

22. Fuel system
1. Retainer for delivery valve

2. Delivery valve

3. Pump element
4. Control rod
5. Return spring for pump plunger
6. Roller tappet
7. Camshaft
The purpose of the fuel injection pump is to meter out fuel to
the combustion chamber at the correct time. Plunger (3)
which is driven by the pump camshaft (7) via roller tappet (6)
forces the fuel through delivery valve (2) and further through
the delivery pipe to the injector.
3
2
1
7
A
Two---hole pump element (maximum feed)
A. Bottom dead centre
B. Fuel injection begins
C. Fuel injection ends
4 5
6
B C
1. Inlet passage
2. Cylinder
3. Starting groove
4. Release passage
5. Plunger
6. Metering edge
7. Vertical groove
1. 9. 1992
The pump element consists of one plunger and one cylinder
which are a matched pair and because of the fine tolerances
the whole element should be changed as a complete unit.
The cylinder has two passages: inlet passage and release
passage. Both passages allow fuel to enter the pressure
space. The side of the plunger has one vertical groove and
one metering edge which are used for adjusting the amount
of fuel injected into the combustion chamber of the engine.
The top of the plunger is provided with a starting groove
(delay groove) which delays the injection timing by approx.
8˚. (This should be borne in mind when checking the fuel in-
jection timing). This groove improves the cold starting prop-
erties of the engine. It works fully automatically. When the en-
gine has stopped the control rod in the injection pump turns
the plungers so that the starting groove faces towards the re-
lease passage. When the engine has started and when the in-
jection pump has reached a certain speed, the governor pulls
the control rod back into running position.
4
Delivery valve
1. Holder for delivery valve
2. Valve spring
3. Valve cone
4. Valve guide
5. Valve head
6. Pressure ---reducing piston
7. Vertical grooves
The delivery valve is fitted on top of the pump element and its
purpose is to close the connection between the pump el-
ement and the delivery pipe. This happens when the metering
edge of the plunger passes the lower edge of the release
passage, thus reducing the pressure in the space above the
plunger. Its second purpose is to reduce the pressure in the
delivery pipe. This is important as it enable the nozzle valve
(needle) to close more quickly.
Delivery valve cone contains a pressure ---reducing piston
which, when the valve closes, is first lowered into the guide
and then closes the connection between the delivery pipe and
the pump element. The valve head is then pressed against its
seat and the fuel in the delivery pipe is given the same space
as the displacement of the pressure ---reducing piston.
90
Model Code
6000-- 8750 220
1
2
3
7
Page
6
5
6