Iveco Stralis AT/AD. Manual - part 78

71109

Figure 4

PNEUMATIC DIAGRAM FOR PRE-SELECTION IN SLOW RANGE

At the same time, the valve (6) moves and opens the passage
for the air between the inlet duct (11) and the duct (3)
connecting with the right-hand chamber of the cylinder of
the splitter (2).

On pressing the clutch pedal, the air reaching the inhibitor
valve (14) supplies the double control valve (8) through the
connecting pipe (13).

The air reaching the valve (8) passes through the inlet duct
(11) and, finding the passage clear, supplies the right-hand
chamber of the cylinder of the “splitter” (2) through the
connecting duct (3).

The piston of this cylinder, moving to the left, then drives the
entire train downline, causing the slow range to be engaged.

The air from the services reservoir supplies the inhibitor
valve (14) and the pre-selector (1) simultaneously, through
the connecting pipe (15).

On shifting the pre-selector (1) downwards (position L of
slow range), the air reaching the pre-selector (1) through the
connecting pipe (16) supplies the double control valve (8).

The pressurized air, supplying the above-mentioned valve
(8), pushes the pistons (4 and 9) to the left.

The movement of the pistons (4 and 9) makes it possible for
the valve (7) to return to its seat and discharge the air
contained in the left-hand chamber of the cylinder of the
“splitter” (2) into the atmosphere through the connecting
duct (12).

Pressurized air

GEARBOX ZF 16 S 151 D.D. - 181 D.D./O.D. - 221 D.D.

TRALIS

AT/AD

Base - January 2003

71110

Figure 5

PNEUMATIC DIAGRAM FOR PRE-SELECTION IN FAST RANGE

At the same time, the valve (7) moves and opens the passage
for the air between the inlet duct (11) and the duct (12)
connecting with the right-hand chamber of the cylinder of the
“splitter” (2).

On pressing the clutch pedal, the air reaching the inhibitor
valve (14) supplies the double control valve (8) through the
connecting pipe (13).

The piston of this cylinder, moving to the right, then drives the
entire train downline, causing the fast range to be engaged.

The air from the services reservoir supplies the inhibitor valve
(14) and the pre-selector (1) simultaneously, through the
connecting pipe (15).

On shifting the pre-selector (1) upwards (position S of fast
range), the air passage between the supply pipe (15) and the
double control valve (8) is closed, setting the connecting pipe
(16) in communication with the outlet pipe (17).

As a result of the air being discharged by the double control
valve (8), the reaction of the spring (10) and of the springs (5)
pushes the pistons (4 and 9) to the right.

The movement of the pistons (4 and 9) makes it possible for
the valve (6) to return to its seat and discharge the air
contained in the right-hand chamber of the cylinder of the
“splitter” (2) into the atmosphere through the connecting
duct (3).

Pressurized air

GEARBOX ZF 16 S 151 D.D. - 181 D.D./O.D. - 221 D.D.

TRALIS

AT/AD

Fast range

71111

Figure 6

PNEUMATIC SYSTEM DIAGRAM OF REDUCED SPEED ENGAGEMENT

The movement of the piston causes the contact of the electric
switch to close, which turns on the indicator light in the cab
with the tortoise symbol.

The air from the vehicle’s pneumatic system is reduced to a
pressure of 9.5 bars by the pressure reduction unit (1). It then
supplies the inhibitor valve D.

Now, taking the control lever onto the reduced speed
position (1

H), the body A, integral with the speed control

rod, opens the valve E that, via the pipe F, supplies the
cylinder G.

The piston of the cylinder G, moving to the right, activates
the ERG.

At the same time, the valve B closes, making it possible for
the air from the pipe C to discharge into the atmosphere.

The reduced speeds can be used in both slow range
and fast range conditions, depending on the position
of the pre-selector.

GEARBOX ZF 16 S 151 D.D. - 181 D.D./O.D. - 221 D.D.

TRALIS

AT/AD

Base - January 2003

71112

Figure 7

PNEUMATIC SYSTEM DIAGRAM OF NORMAL SPEED ENGAGEMENT

The movement of the piston causes the contact of the
electric switch to close, which turns off the indicator light in
the cab.

The air from the vehicle’s pneumatic system is reduced to a
pressure of 9.5 bars by the pressure reduction unit (1). It then
supplies the inhibitor valve D.

Now, taking the control lever onto the normal speed position
(2

H), the body A, integral with the speed control rod, opens

the valve B that, via the pipe C, supplies the cylinder G.

The piston of the cylinder G, moving to the right, deactivates
the ERG.

At the same time, the valve E closes, making it possible for the
air from the pipe F to discharge into the atmosphere.

The normal speeds can be used in both slow range
and fast range conditions, depending on the position
of the pre-selector.

GEARBOX ZF 16 S 151 D.D. - 181 D.D./O.D. - 221 D.D.

TRALIS

AT/AD

Normal speeds

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