SHIELD AS 2324447 - Caterpillar

Illustration 1. Type 1 injector.
Illustration 2. Type 1 injector tip has identification information which shows orifice diameter in mm, number of orifices, and spray angle.
Illustration 3. Type 2 injector.
Illustration 4. Location of trim bolt on Type 2 injectors.
Illustration 5. Two piece tappet.The plunger scroll type give the injector its most unique characteristics. The characteristics follow: ... SINGLE SCROLL INJECTORS do not have variable injection timing (time when injection starts). The beginning of injection is fixed as the plunger rotates from the low to full fuel position.... DOUBLE SCROLL INJECTORS have variable injection timing. The beginning of injection advances as the plunger rotates from the low to full fuel position.... TIMING RETARD INJECTORS have variable injection timing at lower engine loads and constant injection timing at higher engine loads. The beginning of injection advances as the plunger rotates from the low to mid fuel position, but does not change from mid to full fuel position. In essence, the timing retard injector acts a double scroll at lower fuel position and then as a single scroll injector at higher fuel positions.
Injectors which have either different tip orifice diameters or a different plunger design will have different fuel delivery characteristics. Injectors that vary in these characteristics can not be used as a mixed set in an engine.The charts show differences between part numbers and engine serial number ranges for the injectors. The color code referred to in the chart corresponds to the color of a small amount of paint applied to the top of the follower.
Chart A contains Type 1 injector information (Type 2 injectors that are direct field replacements are also shown). Chart B contains Type 2 injector information. The Engine Fuel Specifications Microfiche can also be used to identify the type of injector assembly used.