TM-5-3805-254-14-P-2

TRUCK, DUMP, 20 TON, 6X4, ON-OFF HIGHWAY 71,000 GVW, IHC MODEL F-5070 (CCE)

TECHNICAL MANUAL; OPERATOR’S, ORGANIZATIONAL, DIRECT SUPPORT, GENERAL SUPPORT AND DEPT MAINTENANCE MANUAL (INCLUDING REPAIR PARTS INFORMATION AND SUPPLEMENTAL MAINTENANCE INSTRUCTIONS)

JUNE 1980

TM-5-3805-254-14-P-2 - Page 317 of 894

TRUCK SERVICE MANUAL

ENGINE

2.

It cuts off fuel to the injectors above maximum rated

rpm.

During operation between idle and maximum speeds,

fuel flows through the governor to the injectors.

This fuel

is controlled by the throttle and limited by the size of the

idle spring plunger counterbore.

When the engine

reaches governed speed, the governor weights move the

governor plunger, and fuel passages to the injectors are

shut off.

At the same time another passage opens and

dumps the fuel back into the main pump body.

In this

manner, engine speed is controlled and limited by the

governor regardless of throttle position.

Aneroid

The aneroid control, Fig.

5-7, provides a fuel by-pass

system that responds to air intake manifold pressure and

is used for close control of exhaust smoke.

During

acceleration

or

rapid

engine

load

changes,

turbocharger speed (intake manifold pressure) change

inherently lags behind the power or fuel demand

exercised by opening of the throttle.

This lag does not

exist in the fuel system; therefore, an overrich or high

fuel to air ratio, usually accompanied by smoke, occurs

until the turbocharger "catches up".

The function of the aneroid is to create a lag in fuel

system so response is equivalent to the turbocharger,

thus controlling engine smoke level.

Caution:

Aneroids

must

not

be

removed,

disconnected or otherwise rendered ineffective, nor

should settings be altered to exceed specifications

as set at the factory, see "Maintenance Schedule".