CENTRAL TYRE INFLATION SYSTEM (CTIS)

•

CTIS SYSTEM IS A MECHANICAL SYSTEM THAT ALLOWS DRIVER TO ADJUST VEHICLE’S TYRE PRESSURE WHILE THE VEHICLE IS IN MOTION i.e. BY INFLATING AND DEFLECTING THE TYRE PRESSURE. •USING CTIS A VEHICLE CAN BE OPERATED WITH TYRE PRESSURE APPROPRIATE TO THE SPEED AND STRENGTH OF THE ROAD SECTION BEING NEGOTIATED AND THE LOAD BEING CARRIED WITH INCREASED VEHICLE MOBILITY. This system is used to inflate/deflate tyres in order to adapt the vehicle's rolling capabilities to terrain conditions, in accordance with several pre-set categories: EMERGENCY, SOFT GROUND, TRACK and HIGHWAY. This function is controlled from the driving position by a special instrument panel •which activates a logic box to inflate/deflate the tyres, sending compressed air to the wheels via a rotary joint on the hub reducer of each wheel.

•

•MAJOR COMPONENETS IN THE SYSTEM •OCP (OPREATOR CONTROL PANEL) •PCU (PRESSUE CONTROL UNIT) •CTIS VALVES

Central tyre inflation system (CTIS) vehicle

Know your

User Instruction

Centralized tyre inflation

Central tyre inflation system (CTIS) vehicle
Press ON/OFF button to switch the device ON

Know your

At power up of system, the empty load signal will first fast blinking and will steady on when ECU is correctly initialized. If Load signal continuously blinks, the ECU initialization fails. The process initialization starts by blinking successively all panel signals (auto-test).

After the initialization sequence and ECU hardware checks, the terrain button previously selected is automatically reactivated.

At each powering up, a pressure check cycle is carried out to verify the conformity of the terrain pressure for each tire.

. If a terrain/load mode change has been previously interrupted, the process will re-activate the new terrain/load selection and will resume the interrupted terrain mode selection.
The check period and load mode are also updated

Central tyre inflation system (CTIS) vehicle
Four terrain mode pressure settings are available for driver to operate on different ground surfaces:

Know your

To change terrain mode, simply push the terrain button when the vehicle is running or stopped. Selected terrain signal will start blinking (slow) and the CTIS process starts to inflate or deflate all tires. The slow blinking signal indicates that a terrain mode selection is in progress whereas the current terrain led state remains steady on. When the target pressures of the selected terrain mode have been achieved, the new selected terrain signal state will be steady on and the previous terrain signal state will be off. To cancel mistaken terrain selection while terrain change is started, select a new or current terrain mode

Example : Terrain mode change from Sand to Track

1 . Current terrain mode (sand).

Central tyre inflation system (CTIS) vehicle

Know your

2 . Terrain change (inflating to track) in progress. Track signal is blinking slowly. Sand signal is steady on.

3 . When new terrain target pressures are reached, sand signal is set to off and a check cycle is done.

4 . New terrain (trail) is set and active. Track signal state is steady on.

Central tyre inflation system (CTIS) vehicle
This feature allows the driver to adapt tire pressures to vehicle load in relation with terrain selection. This feature is useful to optimize vehicle mobility, to prevent tire’s wear and reduce fuel consumption.

Know your

To select load mode, push LOAD button.

Load cycle direction for each load button push .

Pressure target settings for empty, half and loaded vehicle are selected depending to current terrain mode selection. Selected load mode signal will start blinking and the CTIS process starts to inflate or deflate all tires. The slow blinking signal indicates that a Load mode selection is in progress. Once the target pressures of the selected Load mode has been achieved, the newly selected load signal will go into steady state. Similar to terrain mode selection, the system will complete the operation by a check/adjustment pressure cycle for all tires.

Central tyre inflation system (CTIS) vehicle

Know your

The checking of the tire pressures can be done in two ways : Manually or automatically. - Manual Check Operation : The driver can at any moment manually force a pressure check and adjustment cycle for all vehicle tires. Simply by push the current selected terrain mode button to start the check cycle.

- Auto-Check Pressure Feature & Fast Check interval automatic mode : The GRA4 CTIS process includes an auto-check feature to measure, adjust and maintain tire pressures. Regulations will be carried out at two different intervals to monitor and adjust the conformity of tire pressures.

To change the check intervals, simply press the « surveillance » button. - At each manual check cycle interval change, a pressure check cycle is engaged. - After an inflation or deflation the fast periodic interval is enabled automatically for one cycle, this allows the adjustment of pressure changes due to cooling and warming of the tire. - The fast check interval is equally useful for difficult terrain conditions and surfaces that degrade the tires. By verifying the tire pressures at short intervals the tire damages can be detected rapidly. - The normal and fast intervals are preprogrammed factory settings which could be modified using a Téléflow service tool.

Central tyre inflation system (CTIS) vehicle

Know your

OPERATION WARNING SIGNALS There are 3 warnings signals to report CTIS process troubles and warnings to operator : AIR SUPPLY, SPEED and BURST. The air supply warning is set for insufficient air supply resources. The process uses SPEED warning for vehicle over speed conditions and BURST warning for tire faults (leak and burst). The process also uses different blinking signals codes to identify other warning and hardware trouble types. (see the chapter After Sales Services).

LOW AIR SUPPLY WARNING Whenever the air supply pressure at E/PCU input port is insufficient for operations that need air resources, this signal is active. There are different warning conditions: LED fast blinking signal at power up : (an option) This optional feature allows the vehicle’s electrical compressor to be started by GRA4 ECU. There is a wait delay to let the pressure rise in the air tank before starting CTIS process. This is particularly required with small tank volumes and low electrical compressors flow rates.

Central tyre inflation system (CTIS) vehicle
LED signal steady on at power up :

This warning occurs when air supply pressure is below air supply threshold at power up of the GRA4 system. When the pressure exceeds high threshold value, the led turns off and the process starts. LED slow blinking : This warning occurs when air supply pressure is either: - Below pressure required for solenoid valves operations. - Below tire pressure for individual tire inflations. - Below lower terrain target pressure for terrain modes changes BURST DETECTION This signal alerts the driver of a tire leak and burst detections. When the periodic check cycle monitors a low pressure in tire, a warning signal occurs. There are different warnings for BURST condition: Signal on: Severe burst on tire (the tire pressure is inferior of 60%* of the target pressure). Signal Blinking : Slight leak (the tire pressure is between 60%* and 80%* of the target pressure). Signal off : No warning signal (the tire pressure is more than 80%* of the target pressure). The « Puncture » LED also indicates the number of the tire in question (number from 1 to 8 as represented on the pictogram).

Central tyre inflation system (CTIS) vehicle

The CTIS process will try to correct pressure in tire. If the amount of leakage flow rate is lower than air supply flow rate, the process will succeed to inflate tire and the warning led is turned to off. If the leak is too large to increase pressure in tire, the process have 2 options depending of “Jump to next tire” parameter: -If this parameter is enabled, the process temporary leave this tire and jump to next tire for periodic check cycle completion. - If disabled, the process keeps on this damage tire and continuously inflates air up to the limit of compressor flow rate and thus trying to maintain pressure in tire until the vehicle reaches a service location in which to change the damaged tire.

OVER SPEED WARNING The GRA4 system includes a speed monitoring capability to assure that the vehicle will not run at unsafe speeds conditions for reduced tire pressures. The safety of vehicle may be jeopardized if the driver remains in over speed condition. The over speed signal may also be routed to internal buzzer (option) and external buzzer output. A maximum allowed vehicle speed is assigned to each terrain mode (parameters). When the vehicle speed exceeds this limit, the over speed warning signal will be turned to on. The driver should reduce vehicle speed below this limit to prevent over speed in relation with target pressures in tire. If the driver continues to run in over speed condition and if over speed time is elapsed (preset parameter), the GRA4 process automatically begins inflating to the next higher terrain mode (except for Road terrain mode, see below). When automatic inflation is completed, the over speed signal turns to off.

Central tyre inflation system (CTIS) vehicle

Know your

When the operator selects a new terrain mode while the vehicle speed exceeds the speed limits related to the new selected terrain mode (deflations). The over speed signal starts blinking for 5 seconds to alerts the driver that operation is not allowed. To allow terrain change deflation, the driver must either reduce speed below wanted terrain mode speed limit or select higher terrain mode.

Central tyre inflation system (CTIS) vehicle
OPERATOR INSTRUCTIONS FOR CTIS USE INFLATIONS AND DEFLATIONS TIMES

Know your

The inflation time depends mainly of tires volumes and vehicle air supply flow rate. The most rapid inflation time can be achieved by increasing the engine speed (for mechanical transmission truck compressors). The deflations times are directly proportional to air pipes and tire valve flow rates, tire volumes which never vary under normal conditions. The deflation coefficient is determined during set up phases for optimal deflating times. The deflation does not use noticeable air from reserve tank. WARM TIRE TARGET PRESSURES The targets pressures for tire adjustment are warm tire pressure values. If the vehicle stops with warm tire pressures, the cooling of tires during the vehicle’s immobilization will result in a leak or burst warning at next power up of the GRA4 system. The system will then automatically adjust the tire pressure to compensate for the drop in pressure caused by a drop in temperature. WEATHER AND PHYSICAL ENVIRONMENT Téléflow CTIS components have been designed to operate in very cold weather environment or in moist conditions. This implies that the air supply must be keep perfectly dry.

Central tyre inflation system (CTIS) vehicle
WATER IMMERSION OF WHEEL VALVES Téléflow wheel valves are watertight when GRA4 system is stopped. When needed (for strategic military applications). The GRA4 system can be use with full immersion of wheel valves. However, repeated use of GRA4 system in such conditions may result in moisture accumulation in air devices resulting in corrosion of steel components (axles internal pipes and hub, rotating joins, fittings…).

Know your

OPERATOR CONTROL PANEL (OCP)

CTIS

PCU (PRESSUE CONTROL UNIT)

CTIS

CTIS VALVES

CTIS

SCHEMATIC OF AIR SUPPLY FROM AIR COMPRESSOR TO PCU & FROM PCU TO WHEELS

SCHEMATIC CIRCUIT OF ELECTRICAL CONNECTIONS FOR OCP & PCU

(CTIS)