SAFARI

4 DLT ENGINE

LUCAS DPC FIP - FEATURES

1. EXCESS FUEL SYSTEM

To assist engine starting, the excess fuel system

provides at very low pump speeds the fuel delivery

that is greater than the full load delivery.

The system is incorporated in the delivery control

mechanism, which by the action of a return spring

allows the distance between the pumping plungers to

be increased to a level that is more than the normal

operating levels. This increased outward travel of the

plungers allows an extra quantity of fuel to flow in

during the filling cycle. The same is pumped out during

the pumping stroke.

As the Engine speed increases, the increase in transfer

pressure automatically cuts-off the excess fuel. The

transfer pressure pushes the delivery control system

against the opposing return spring to retain it in the

normal operating position.

2. TWO SPEED GOVERNOR

(MINI-MAXI)

The function of the two speed governor is to

control the idling. Fast idling and the maximum

no-load speed of the engine.

The Governor interferes only during idling and

maximum no-load conditions, to determine the

position of the metering valve and thus control

the fuel delivery.

- During the intermediate phase, the metering

valve is directly linked to the throttle lever

(accelerator pedal), providing a direct control.

ADVANTAGES :

Smooth response to alterations in throttle

position.

Improved driveability.

3. PROGRESSIVE LOW LOAD ADVANCE (PLLA)

The Low Load Advance System overrides the normal

speed advance system. Under low load conditions,

due to reduced fuel supply, there is a tendency for the

timing to retard. The low load advance system

compensates for this characteristic by slightly

advancing the injection at reduced fuel levels.

The type of low load advance system used on Tata

Safari is called the progressive low load advance

(PLLA) system.

The advantage of the PLLA system is, that it

progressively changes the advance to suit the engine

load conditions. Thus helps in achieving better

emissions and also reduces transient noise.

4. SUPPORTED TOOTHED BELT TYPE DRIVE

The assembly consists of drive shaft assembly

supported by two bearings and in the pump

housing the shaft is connected to the pump

hydraulic head by an intermediate shaft.

The bearing opposes the loading created by the

drive belt, thus maintaining the alignment of the

drive shaft and the hydraulic head.

ADVANTAGES :

Smoother Running

Pumping drive draws lesser power from the

engine

Noise reduction

5. BOOST CONTROLLER

(Fig 165)

The Boost Controller is necessary on the FIP fitted to

turbo charged applications, in order to adjust the

maximum fuel delivery in accordance with the

variations in the boost pressure from the turbo charger.

The fuel adjustment plate and the roller shoes on these

pump are provided with ramps to allow for the

progressive change in fuel delivery as the assembly

move axially on the rotor by the action of the actuating

piston moving against a carriage return spring.

The boost controller consists of a piston valve moving

within a valve body. The valve is linked to a pair of

Fig. 165

Backleak return

Boost pressure inlet

Piston

Discharge

to transfer

pump inlet

Valve body

Fuel

adjusting

screw

Spring

Spacer

Diaphragms