CAT Engine Course (Part 2)

CRANKCASE EXPLOSION RELIEF VALVES
Crankcase explosion relief valves, seen here, are normally attachments but are required on marine engines. They are available for industrial and generator set arrangements. These valves relieve the pressure of an explosion in the crankcase. An
explosion is possible when combustible gases start to burn because of heat or sparks. A common cause of ignition is heat from a failed bearing. Explosion relief valves open to release the pressure of an explosion - then close to prevent a second cycle of combustion. Basically they stop oxygen from getting in, which would permit further combustion.

This is the idler pulley used on some arrangements to tighten or loosen the belts. To tighten the fan (drive) belts, loosen the bolts that hold the bracket of the idler pulley. Move the idler pulley out until the tension of the belt is correct and tighten the bolts.
Install new belts if they show signs of too much wear. Belts come in sets. If one belt is bad, install a new set of belts. If only one new belt is installed, the new belt will carry the load and all belts will fail rapidly.

Some engine arrangements have a bracket with a bolt or a hydraulic cylinder with a grease fitting to tighten the belts. Either

(1) loosen the nut on the adjustment bolt and turn it until the belt tension is correct, then tighten the bolt. Or,

(2) put grease into the fitting with a grease gun until the tension on the belts is correct. After the fan belts are tightened correctly, check the
tension of the alternator belts.

The alternator is located on the right front side and has
two drive belts which must be adjusted
periodically.

To check the tension of the alternator drive belts, push
down in the belts half way between the center of
the pulleys. If the tension is not correct, tighten
the belts.



To make an adjustment to the alternator belts, loosen
the outside nut on the support bracket bolt
several turns. Turn the inside nut until the belt
tension is correct. Then tighten the nut on the
adjustment bolt that holds the bracket.



Two governors will be available on the 3500 Engines.
The Caterpillar 3161 shown will be standard on the Vehicle, Industrial and Marine engines. The Generator Set and Marine Auxiliary will use the Woodward 2301 Governor.

The standard location for the governor or actuator is on the right front timing gear housing. As as option, the 3161 Governor may be located on the left side of
the front housing. The actuator for the 2301 Governor is available only on the right-hand side.



The 3161 Governor is driven by a 2400 rpm gear.

The speed is reduced to 1370 rpm through a bevel
gear set in the governor drive.

The governor has a hydraulic unit inside which has its own oil supply.
The 3161 Governor has a boost-activated smoke limiter.
A manual shutdown liver is provided on the engine.

An electric solenoid or hydraulic cylinder operated
shutdown is also available.

The electric solenoid operated shutdown is used on Vehicle, industrial
and Marine arrangements.

The hydraulic operated shutdown is used with hydramechanical
shutoff or at customer request.



WOODWARD ELECTRIC GOVERNOR
For some applications such as generator sets and marine
auxiliary engines, a Woodward electric governor and
actuator are used.
Here we can see:
1. governor actuator (EG-10P)
2. control rod from actuator to fuel control shaft
3. shaft (control) lever
4. governor drive housing
5. control cable to 2301 governor



The crankcase breather group is normally on the front
left side of the engine. When it is necessary to
locate the governor on the left side, the breather
group location is on the front right side.