VCADS connections -
I- Shift - Generation C
132
I-Shift - Gen. C
Designation Generation C I-Shift transmissions are available in FM/FH trucks, with D9 and D13 engines.
There are three versions:
AT2412C, AT2512C, ATO2512C Automatic
Transmission Overdrive
2x Nm - max. input torque 12 forward gears
C generation
NoteService information refers to these designations - not ʻI-Shiftʼ.
All versions are available with different types of PTO, oil cooler and retarder.
134
I - Shift - Gen. C
Designation AT2412C
Max. torque: 2400 Nm Forward gears: 12
GCW: 44t (Specific markets with mainly flat road operation can be allowed up to 50t).
AT2512C
Max. torque: 2500 Nm Forward gears: 12
GCW: 60t (Specific markets with mainly flat road operation can be allowed up to 130t, with limited warranty).
ATO2512C
Max. torque: 2400 Nm Forward gears: 12
GCW: 60t (Specific markets with mainly flat road operation can be allowed up to 130t, with limited warranty).
136 I - Shift - Gen. C
COMPONENT AT2412C (SP3190245) SERVICE CATEGORY A COMP. ID 2423455 SERIAL NO. 2005402123
SWEDEN
Identification
plate COMPONENT: Component designation (DSP3190245): Spare part number
SERVICE CATEGORY: Oil quality and change intervals - see IMPACT
COMP. ID: Factory part number
SERIAL NO. Year of manufacture/week/day/consecutive number
138 I - Shift - Gen. C
Gear ratios AT2512C ATO2512C
AT2412C
139
Selection positions - splitter, main and range change
Gear Splitter Main Range
-140 I - Shift - Gen. C
1
3
2
Gen. C vs. Gen. B The main differences between Generation C and Generation B transmissions are:
1. Clutch actuation cylinder and valve/solenoid block.
2. Range change gear assembly 3. Lubrication oil pump
These changes have resulted in a shorter and lighter weight transmission, which has lower internal losses and quieter operation.
142 I - Shift - Gen. C
1 2
Clutch The clutch is a single plate type, which is disengaged by pressure pushing against spring plate (1).
The actuation cylinder (2) is concentric with the input shaft
144 I - Shift - Gen. C
VASE VASD
VAFE VAFD
1
Clutch cylinder
operation Clutch actuation valve block (1) is attached to the side of the clutch housing.
The valve block houses four solenoid valves which control air flow in and out of the cylinder:
VASE - Valve Air, Slow Engage - air exhaust VAFE - Valve Air, Fast Engage - air exhaust VASD - Valve Air, Slow Disengage - air supply VAFD - Valve Air, Fast Disengage- air supply
146 I - Shift - Gen. C
VASE VASD
VAFE VAFD
1
The solenoids are controlled by Pulse Width Modulated (PWM) signals from the TECU.
PWM signals are variable, which means that the valves can be opened and closed progressively by varying amounts.
This allows close and precise control of clutch disengagement and engagement.
Note that, in certain circumstances, the fast and slow valves may be energised together - e.g. for rapid
disengagement, VASD and VAFD can both be energised.
148 I - Shift - Gen. C
1 2
3
Clutch position
sensor A sensor (1) is used to detect the position of the actuation piston and, also, clutch plate wear.
The sensor is a type referred to as ʻ Permanent magnet Linear Contactless Displacementʼ (PLCD).
As the name suggests, this type of sensor detects the linear displacement of one component in relation to another, without contact.
The sensor works on the principle of electro- magnetic induction, where a permanent magnet (2) - attached to the actuator piston - moves in relation to a coil (3) - attached to the clutch housing.
The position of the magnet in relation to the coil determines the amount of induced voltage.
The sensor has two analogue output signals: one
representing piston position, and an inverted signal used during diagnostics.
150 I - Shift - Gen. C
A B
X1 X2
X1 and X2 values The illustration above shows the position of the actuating piston with a new plate (A), and a worn plate (B).
X1 is the stroke start position with a new clutch plate.
X2 is the stroke start position with a worn clutch plate.
Note: The stroke of the actuating piston - i.e. the distance it moves from engaged position to disengaged position - is always the same: it is the stroke start position which alters with wear.
CAUTION
When a new clutch plate is fitted, the X1 value must be measured and stored using VCADS.
If this is not done, the system will have the wrong
information, so clutch wear warnings may not be displayed, which could result in clutch slip and
152
I - Shift - Gen. C
Range change gearset
In common with I-Shift Gen. B, the Gen. C range change gearset is a planetary gearset, with two ratios - low and high.
Gen. C differences are:
- gear teeth are helical cut. - gears are stronger and run more quietly.
- a new, more efficient, type of synchroniser is fitted.
154 I - Shift - Gen. C
1
TECU The Transmission Electronic Control Unit (TECU) has been upgraded:
- memory increase x 3
- computing power increase x 5 CAUTION
If the TECU circuit board must be handled;
- handle with extreme care.
- take precautions to ensure that static electricity cannot be discharged into board components.
156 I - Shift - Gen. C
ATO2512C
AT2512C
Overdrive gearset To provide the overdrive ratio a larger diameter input shaft gear is used with a smaller diameter countershaft gear.
When fitted with an overdrive gearset, top gear ratio is 0.78:1.
Without overdrive, top gear ratio is 1:1.
158 I - Shift - Gen. C
R N
A M
Selector lever The selector lever is similar to that used with I-Shift Gen. B.
A significant difference is that there is no ʻLʼ (Low) lever position.
160
I - Shift - Gen. C
Lubrication The transmission components are lubricated by a combination of oil splash and pressure feed.
162
I - Shift - Gen. C
Oil pump I-Shift Gen. C has a new type of oil pump located in front of the reverse idler gear.
164 I - Shift - Gen. C
UTCOOL TC-MWO
TC-MWOH2 TC-MAOH2
Oil cooling - no retarder URETARD
UTCOOL - no oil cooling.
TC-MWO - Small oil cooler mounted on the oil filter.
TC-MWOH2 - Separate larger oil cooler mounted on LH side of gearbox.
TC-MAOH2 - Separate larger oil cooler mounted on LH side of gearbox, plus extra cooler mounted at the front of the cab.
166 I - Shift - Gen. C
UTCOOL TC-MWO
TC-MWOH2 TC-MAOH2
Oil cooling - with retarder
RET-TH
UTCOOL - no oil cooling.
TC-MWO - Small oil cooler mounted on the oil filter.
TC-MWOH2 - Separate larger oil cooler mounted on LH side of gearbox.
TC-MAOH2 - Separate larger oil cooler mounted on LH side of gearbox, plus extra cooler mounted at the front of the cab.
168 I - Shift - Gen. C
Time/Distance
B F N1
Time/DistanceDC F N1
Time/Distance
FE F N1
Software
packages Four main software packages are available:
B - Basic
DC - Distribution and Construction FE - Fuel and Economy
Heavy haulage
Other options can be added to these main packages.
The package installed is displayed when the gear selector lever is folded forward.
170 I - Shift - Gen. C
Basic Distribution Long haul Heavy
& construction Fuel & Haulage Economy