Injector Units

shaped ports, one on each side at different heights. The plunger operates

up and down in the bushing bore.

(c) The plunger is actuated by a camshaft that is built right into

the engine. The operation takes place through a rocker arm and push rod.

The push rod has a rollertype cam follower and is spring loaded to prevent

component damage in the event of injector nozzle clogging. The plunger is

situated under a follower. This follower is springloaded to make it follow

the camshaft.

(d) The plunger can be rotated in operation around its axis by the

gear, which is meshed to the control rack. Each injector rack is connected

by an easily detachable joint to a lever on a common control tube which, in

turn, is linked to the governor and the throttle.

(e) For metering purposes, a recess with an upper helix and a

lower helix, or a straight cutoff, is machined into the lower end of the

plunger. The relation of this upper helix and lower cutoff to the two ports

changes with the rotation of the plunger. As the plunger moves downward,

the fuel in the highpressure cylinder or bushing is first displaced through

the ports back into the supply chamber until the lower edge of the plunger

closes the lower port. The remaining oil is then forced upward through the

center passage in the plunger into the recess between the upper helix and

the lower cutoff, from which it can flow back into the supply chamber until

the helix closes the upper port. The rotation of the plunger, by movement

of the rack, changes the position of the helix in relation to the ports.

This will advance or retard the closing of the ports and the beginning and

ending of the injection period. This will result in a regulation of the

volume of the fuel charge that is injected into the cylinder.

(f) When the control rack is pulled out completely, the upper port

is not closed by the helix until after the lower port is uncovered. This

means that all the fuel in the highpressure cylinder bypasses back to the

fuel supply and no fuel is injected into the combustion chamber.

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