DATA PD-214-F101. TEBS G2 Doc. No. Y (EN - Rev. 001) July Product. Lift Axle Control. Function. Operation

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1 Commercial Vehicle Systems Product DATA Function Many trailers have one or more axles having the capability of being lifted so that they carry none of the trailer load. The function is present in the TEBS Brake Module to provide control of the lifting of these axles. TEBS G Doc. No. Y8 (EN - Rev. 00) July 0 Doc. No. Y8 (EN - Rev. 00) July 0 PD--F0 Operation (LAC) The TEBS Brake Module can control the lift axles automatically dependent on the current axle/bogie load and the predefined lift axle control parameters. If RSP is configured and the trailer is equipped with lift axles, these axles must be controlled by the TEBS G Brake Module or their status must be transmitted to the module via the ext LAS input. To achieve lift axle control, one or more lift axle valves should be connected to one of the AUXIO outputs, or for electrically switched lift axle valves and auxiliary output port P 8 for pneumatically switched lift axle valves. See PD-0-00, Document No. Y00 for details of lift axle valves. The following parameters associated with lift axle control may be defined by using the Knorr-Bremse brake calculation program BSD or the Knorr-Bremse diagnostic program ECUtalk using the Components tab then the Change configuration option: Number of lift axles Location of lift axles Number of lift axles that are controlled via one Aux output (there are two controllable outputs, LAC and LAC) Note - LAC must be configured first Knorr-Bremse Systeme für Nutzfahrzeuge GmbH. Moosacher Straße Munich. Germany. Tel: Fax:

2 PD--F0 TEBS G Product Data Doc. No. Y8 (EN - Rev. 00) July 0 TEBS G.0 / G. / G. Standard Using the Auxiliary I/O tab and Change Configuration, select the required AUXIO then enter: the maximum axle/bogie load at which the lift axle should be lowered (see page ) the axle/bogie load at which the lift axle should be lifted TEBS G. Standard Plus Using the Auxiliary I/O tab and Change Configuration, select the Lift Axle option, then select the required AUXIO output. When this has been done, enter: the maximum axle/bogie load at which the lift axle should be lowered (see page ) the axle/bogie load at which the lift axle should be lifted Knorr-Bremse Systeme für Nutzfahrzeuge GmbH. Moosacher Straße Munich. Germany. Tel: Fax:

3 Commercial Vehicle Systems Doc. No. Y8 (EN - Rev. 00) July 0 TEBS G PD--F0 The function of lift axle control is dependent on the air spring pressure. This is continuously monitored by the TEBS Brake Module and used to determine the respective axle/bogie loads based on the configured laden and unladen axle loads and the number of axles. Normally only an axle which is not equipped with wheel speed sensors may be configured as a lift axle, except in the case of: S/M configurations (G.0 and G. only) when the axle on which wheel speed sensors connected to S-E and S-F are installed may be used as a lift axle. S/M configurations on semi-trailers and centre-axle trailers (G.0 and G. with TEPM-S or TEPM-P) when the axle on which wheel speed sensors connected to S-A and S-B are installed may be used as a lift axle. S/M configurations on semi-trailers and centre-axle trailers (G.0 and G. with TEPM-s or TEPM-P) when the axle on which wheel speed sensors connected to S-A and S-B and/or S-E and S-F are installed may be used as a lift axle. Failure to follow this requirement will result in a fault being generated when a lift axle is raised. The status of the lift axle is transmitted to the towing vehicle via the ISO 99 (CAN) interface when the trailer is coupled to a towing vehicle which is equipped with EBS. In such cases it is also possible that the lift axles are controlled from the towing vehicle via the same interface. As the trailer load decreases the first axle to lift must be controlled by LAC. Important: When the trailer suspension control system is two circuit it is important that the connection from the air springs to port of the TEBS Brake Module is taken from the circuit NOT containing the lift axles. Failure to observe this requirement may lead to lift axle instability. The connection from the air suspension system to port should always be chosen carefully so that the lifting or lowering of axles does not significantly affect the pressure in port. Number of lift axles that can be controlled via one AUXIO output It is possible, by using the correct cable harness, to connect two electrically controlled lift axle valves to one AUXIO output; the lift axles will then operate simultaneously. In the same way, more than one pneumatically controlled lift axle valve may be connected to Aux P 8. Determination of the axle load at which the lift axle should be lowered When defining the lift axle control parameters using the diagnostic program ECUtalk (see above), the axle/bogie load at which the lift axles will lower is, by default, the laden axle/bogie load permitted for the trailer - otherwise the axles remaining on the ground would be overloaded. It is possible to configure a lower value than the laden axle/ bogie load, for example to comply with specific national axle loading requirements. Tip: When the trailer is loaded with a large individual load, in order to prevent temporary overloading of an individual axle, the axle/bogie load at which the lifted axles are lowered should be set to a value below the maximum value. Knorr-Bremse Systeme für Nutzfahrzeuge GmbH. Moosacher Straße Munich. Germany. Tel: Fax:

4 PD--F0 TEBS G Product Data Doc. No. Y8 (EN - Rev. 00) July 0 Hysteresis When setting the lift axle parameters for the TEBS Brake Module, it is required to define the position of the lift axle and the number of lift axles controlled by LAC or LAC (see above). This effectively defines the lifting sequence since LAC is always the first axle to lift. In addition it is required that the geometric data of the wheelbase and axle spread is defined, therefore, it is not necessary to define a hysteresis value as this will be calculated automatically using the information above. The diagnostic program ECUtalk, and brake calculation program BSD, will automatically calculate the maximum axle/bogie load at which the axle(s) should lift. It is possible to define a lower axle/bogie load than the default maximum but not higher (hovering the mouse over the weight boxes will display the maximum and minimum programmable values). This calculation takes into consideration a factor which ensures that, irrespective of the position or lifting sequence of the lift axles, or the wheelbase of the trailer, the defined axle lifting loads will ensure that overloading does not occur and the lift axles remains stable. Initiation of lift axle control By means of the diagnostic program ECUtalk, it is possible to define whether the lift axle control should be active when the trailer is stationary and the ignition is switched ON, i.e. the lift axle would raise - provided the load state allows this, or whether the lift axle control should begin only when a speed threshold is exceeded. The thresholds are: TEBS G.0/G./G. Standard Yes - lift axle control is enabled at standstill and all speeds. No (Enable at any speed) - this is the speed at which the wheel speed sensor outputs are detected. No (enable at configured SP speed) - this is TEBS G. Standard Plus linked to the Speed Pulse (SP) which has a default switching speed of km/h. This default will apply in the event that either no SP function is configured, or the SP speed is not changed from the default value. If the SP speed is changed, for example to 0 km/h, then lift axle control will not commence until after this speed has been reached. By linking the lift axle control to the SP speed it is ensured that the suspension is reset to the driving condition before any lift axle control commences. This is desirable as the air spring pressure measured by the TEBS Brake Module may not be representative of the load condition during operation of the raise/lower valve. Once the lift axle is lifted, irrespective of whether at standstill or after the SP speed, it will remain so until either a higher loading state is detected or a lower lift axle control is activated which can take place electrically or pneumatically or the ignition is switched OFF. This means that the option Lift axle active at standstill relates only to the period that the trailer is stationary immediately after switching ON the ignition. When the TEBS Brake Module has an electrical AUXIO configured to Speed Pulse (SP) and raise / lower valve SV80 is connected, the maximum duration of the Speed Pulse signal must not exceed the default setting of seconds otherwise overheating of the module ECU may occur. Knorr-Bremse Systeme für Nutzfahrzeuge GmbH. Moosacher Straße Munich. Germany. Tel: Fax:

5 Commercial Vehicle Systems Doc. No. Y8 (EN - Rev. 00) July 0 TEBS G PD--F0 The priority of lift axle control relative to other functions is shown below: Priority Function Description Highest Auxiliary Design Language (ADL) Lowest Activation of a function will override any action requested by a function with a lower priority ISO 99 or J99 CAN commands Driver request ISO 99 CAN ATC status icorner icargo Automatic (LAC) An ADL program may override any calculated lift axle state. A command such as Raise or Lower a lift axle will disable all lower priority functions. Driver request via a connected manual switch input such as Traction Help or via use of the service brakes. ATC Active will cause an automatic Traction Help request. An icorner command will override any icargo or Automatic command. An icargo command will override any Automatic Lift Axle Control command. If no other request is active then the Automatic Lift Axle Control will take control of the lift axles. Lift axle control is automatically disabled if the pressure in the air bags falls below % of the configured unladen pressure or if the reservoir pressure falls below. bar. Lower Lift Axle (LL) Forcing a lifted axle to lower when the automatic control dictates that it should be in the lifted position is often a desirable function, e.g. to assist manoeuvring, and has been integrated in the TEBS Brake Module. It can be realised by any of the following methods:. Tri-state inputs via single wire connection to either pin or where the following conditions will be recognised as requiring Lower Lift axles : Change of state open circuit to / V Change of state open circuit to ground. AUXIOs, and require a -wire connection (with their respective return lines) to recognise a change in state from open to short circuit or short circuit to open circuit.. Inputs S-E and S-F (TEBS G.0 and G. S/M and S/M configurations only) may be used with a -wire connection, as above, or as tri-state inputs, as above (with the two connections linked).. Activation via actuation of the brakes.. Manual operation via the Trailer Information Module (TIM G). Signal transmitted from the tractor via a specific message request included in ISO 99 (CAN) data communications. A signal received via the ISO 99 communications data link will take priority over normal lift axle control signals (see table above). Knorr-Bremse Systeme für Nutzfahrzeuge GmbH. Moosacher Straße Munich. Germany. Tel: Fax:

6 PD--F0 TEBS G Product Data Doc. No. Y8 (EN - Rev. 00) July 0 When a switched voltage signal or a ground signal is used, the associated switch may be of the momentary type (non-latching) or permanent type (latching) and the TEBS G Brake Module will automatically recognise the single change in state. If a momentary switch is used then the _M function must be configured and if a permanent switch is used the _P function must be configured. Lower All Lift Axles (LL_ALL_M and LL_ALL_P) This function lowers all lift axles when the switch is activated and overrides any normal lift axle control present (see table above). Lower All Lift Axles controlled by LAC (LL_LAC_M and LL_LAC_P) This function lowers all lift axles controlled by LAC when the switch is activated. Lower All Lift Axles controlled by LAC (LL_LAC_M and LL_LAC_P) Notes: Switch type used Momentary (non-latching) Permanent (latching) Functions available LL_ALL_M LL_LAC_M LL_LAC_M LL_ALL_P LL_LAC_P LL_LAC_P This function lowers all lift axles controlled by LAC when the switch is activated. Select ECUtalk option G.0/./. Standard G. Standard Plus Input momentary switch Input permanent switch Momentary Permanent After selection of Lower Lift axle as described above by means of a momentary switch, the lift axle control will remain disabled unless the switch is pressed again or Traction Help is selected or the ignition is turned off. When a permanent switch is used its selection will result in the lift axle being lowered. To re-activate Lower Lift axle the switch must first be deactivated before a second actuation is possible. TEBS G.0/G./G. Standard TEBS G. Standard Plus Knorr-Bremse Systeme für Nutzfahrzeuge GmbH. Moosacher Straße Munich. Germany. Tel: Fax:

7 Commercial Vehicle Systems Doc. No. Y8 (EN - Rev. 00) July 0 TEBS G PD--F0 Advanced (LLTH) This is a combined function which offers the Traction Help (see PD--F0, Document No. Y9) and lift axle lowering via the same input. The following logic is implemented (for momentary switch only supplied through spare pin in the ISO or ISO 098 connector): - signal active for less than seconds = Traction Help - signal active for more than seconds and less than 0 seconds = Lift Axle Lower - signal active for more than 0 seconds = will be ignored, TEBS stays in normal lift axle control mode. With TEBS G.0/G./G. Standard the switch must be selected as momentary. With TEBS G. Standard Plus the switch defaults to momentary and does not allow any change. TEBS G.0/G./G. Standard TEBS G. Standard Plus Knorr-Bremse Systeme für Nutzfahrzeuge GmbH. Moosacher Straße Munich. Germany. Tel: Fax:

8 PD--F0 TEBS G Product Data Doc. No. Y8 (EN - Rev. 00) July 0 via operation of the service brakes Activation of lift axle control ( Lower Lift axle and Traction Help - see PD--F0, Document No. Y9) via actuation of the brakes is a standard feature within the TEBS G Brake Module therefore no additional wiring or system configuration is necessary only configuration of a lift axle is required. To realise the Lower Lift axle function via brake actuation the following criteria must be fulfilled: p [bar].0 0. The vehicle must be stationary with the ignition t s 8s ON. TEBS-G-0 If the towing vehicle is connected via a pin ISO 8 connector no brake application is made from any source (hand brake or foot brake) for a period of seconds. If the towing vehicle is connected via a pin ISO 8 connector no ISO 99 (CAN) brake application is made, irrespective of whether a pneumatic braking demand is present or not, for a period of seconds. Then within a period of 8 seconds, brake applications must be made where the braking demand must exceed bar and then fall to below 0. bar on each application. The figure graphically illustrates the characteristic. This lift axle control function via brake actuation is enabled by default but can be turned off under the Miscellaneous tab and Change configuration. ADL files (see PD--F90, Document No. Y) are available that are able to provide different lift axle control functionality to that described above. Recommended Valves for Part No. Type No. Operation K00 #) * K08 #) K0 #) AE Ports,,, Port V Solenoid M x. M x. V Solenoid Air operated K0988 #) V Solenoid *** PTC** for R8x M x. with exhaust valve For further details on these valves see PD-0-00, Document No. Y00 #) Part No. will carry the suffix N00 denoting that it is supplied without packaging * Replaces valves K008 and K0 ** PTC = push-to-connect *** this valve needs to be connected to AUXIO or. The output voltage for these connections has to be set to V. This is necessary to protect the V solenoid against overheating. Knorr-Bremse Systeme für Nutzfahrzeuge GmbH. Moosacher Straße Munich. Germany. Tel: Fax:

9 Commercial Vehicle Systems Doc. No. Y8 (EN - Rev. 00) July 0 TEBS G PD--F0 Typical Wiring Diagram - TEBS G. with electrical LAC and LAC outputs S-D ISO 8 LAC LAC RD BN WH WH/GN WH/BN RD BN WH WH/GN WH/BN 8 V_VALVE V_ECU GND_H GND_M WL V-CAN-H V-CAN-L AUX IO AUX IO AUX IO In-Out SENS_Sup / TriState SENS_In / TriState SENS_GND Brake-Light V Brake-Light GND S-F Power TEBS G. - ECU 9 V-CAN-L 0 V-CAN-H AUX IO - RET AUX IO - RET ISO 8 S-C S-E TEBS-G-0 Typical Wiring Diagram - TEBS G. with electrical LAC and LAC outputs ISO 8 LAC LAC RD BN WH WH/GN WH/BN RD BN WH WH/GN WH/BN V_VALVE V_ECU GND_H GND_M WL V-CAN-H V-CAN-L AUX IO AUX IO AUX IO SENS_GND In-Out SENS_In / TriState SENS_Sup / TriState Brake-Light V Brake-Light GND V-CAN-L V-CAN-H Power TEBS G. - ECU AUX IO - RET AUX IO - RET ISO 8 S-C S-D TEBS-G.-0 Knorr-Bremse Systeme für Nutzfahrzeuge GmbH. Moosacher Straße Munich. Germany. Tel: Fax:

10 PD--F0 TEBS G Product Data Doc. No. Y8 (EN - Rev. 00) July 0 Typical System Diagram - pneumatic LAC output "Supply" 8 "Control" ISO 8 (N) ECU KNORR-BREMSE TEBS G Lift Axle Valve ISO 8 (Pin) For more information on ECUtalk use the on-line help function by pressing F or see the Product Information Document No. Y09 available at For further guidance on using a lift axle with TEBS see the Installation Instructions Document No. Y89 available at This document forms part of the Product Manual for the TEBS G Family, Document No. Y0 Revision Details Rev. 000 September 0 New document Rev. 00 December 0 Document amended to include different ECUtalk screenshots when using TEBS G. Standard Plus. Table of recommended valves added to page 8. Rev. 00 July 0 Correction - wheel speed sensor configurations on page amended. Knorr-Bremse Systeme für Nutzfahrzeuge GmbH. Moosacher Straße Munich. Germany. Tel: Fax: