Cx860, Cx880 - New Holland CX720 Repair Manual

Fuel injector - Static description (B.20.A.29 - C.30.A.20)

CX860, CX880

The pump injector consists mainly of three parts: solenoid (1) pumping element (2) and nozzle (3) These three parts
cannot be individually replaced and cannot be serviced.
The pumping element is operated mechanically upon each cycle by a rocker. It compresses the fuel in the delivery
chamber.
Nozzle configuration and operation are similar to those of conventional injector nozzles. It is opened by fuel under
pressure to inject a fine spray of fuel into the combustion chamber.
The solenoid is controlled directly by the electronic control unit and determines delivery mode on the basis of a control
signal.
An injector case houses the lower part of the pump injector in the cylinder head.
Filling Stage
During the filling stage, pumping element (2) moves upward. The highest point of the cam is passed and the rocker
roller moves toward the cam base ring. Fuel valve (1) is opened and fuel is free to flow into the injector from the
cylinder head lower channel (4) Filling continues until the pumping element reaches the top end of its travel.
Injection Stage
The injection stage begins when the solenoid is excited at a certain point on the pumping element descending stroke
and fuel valve (1) closes. The instant at which delivery starts is processed by the electronic control unit and varies
according to engine service conditions. The cam continues to push pumping element (2) via the rocker and the injec-
tion stage continues until fuel valve (1) remains closed.
POWER PRODUCTION - FUEL AND INJECTION SYSTEM
1
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2
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2 4/7/2006
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