SERVICE MANUAL
TIMING, GEAR TRAIN & FRONT COVER
Section 7
GENERAL
The gear train lies under the crankcase front cover. The
gear train is simple in design. The idler gear (2, Fig. 3),
driven by the crankshaft gear (1), drives the engine
camshaft gear (3) and the injection pump gear (4 or6,
depending on pump). If equipped, a tachometer adapter
(5, Fig. 4a) mounts to the injection pump drive gear
access cover (6, Fig. 4a). The tachometer driven by a
slot in the end of the injection pump camshaft for
engines equipped with Robert Bosch Model MW Fuel
Injection Pump. For engines equipped with UTDS*
Model 100 Fuel Injection Pump a plastic tachometer gear
(5, Fig. 3) meshes with the injection pump gear (4, Fig.
3) to drive the tachometer.
Figure 3. - Timing Gear Rotation
1.
Crankshaft
2.
Idler
3.
Camshaft
4.
Injection pump
Engine equipped with
5.
Tachometer
UTDS* Model 100
(if equipped)
Injection Pump
6.
Injection pump
Engines equipped with
Robert Bosch Model
MW Fuel Injection
Pump
The idler gear is supported on a set of tapered roller
bearings. The camshaft gear is keyed to the shaft and
held in place by a press fit. The injection pump gear (5
or 7, Fig. 4 or 4a) is fastened to the pump shaft by
means of a hub.
For engines equipped with UTDS* Model 100 Fuel
Injection pump, the tachometer (6) is fastened by two
nuts and a thrust plate, as shown in Fig. 4.
Figure 4. - Crankcase Front Cover - Engines equipped
with UTDS* Model 100 Fuel Injection Pump
1.
Water pump
5.
Injection pump
2.
Front cover
gear
3.
Lube oil pump 6.
Tachometer gear
4.
Crankshaft
The Crankcase Front Cover (2, Fig. 4 or 4a) serves
many purposes. In addition to housing the gear train, the
front cover carries the water pump (1), lube oil pump (3)
and fuel injection pump (not shown).
*United Technologies Diesel Systems (formerly AMBAC)
CGES-185-3
PRINTED IN UNITED STATES OF AMERICA
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