Linienzugbeeinflussung - Vehicle Equipment

Vehicle Equipment

The vehicle equipment in the original LZ B80 designed consisted of:

• Computers: The on-board equipment centered around a 2-of-3 computer system. The original LZB 80 design used 8085 microprocessors programmed in assembly language. The programs were interrupts driven, with interrupts generated by a 70 ms clock, the track receivers and transmitters, the serial interface, and also within the program itself. Interrupts triggered comparison and output programs. Peripheral equipment was arranged around the computers with all interfaces electrically separated and all grounds tied to the cabinet frame which was tied to the vehicle chassis.
• Redundant power supply: The computers and peripheral equipment were supplied with a redundant power supply based on two identical voltage transformers. Each was capable of supplying the power necessary for all of the equipment. They were normally alternately switched, but if one failed the other would take over. On-board batteries could also supply temporary power.
• Odometry: The vehicle speed and distance travelled is measured on two independent channels by two pulse generators mounted on different axles. Each is linked to a separate microcontroller based unit used to correct any inaccuracies. The central logic polls the two units as well as an accelerometer compares the values and checks for plausibility.
• Receiver: Two pairs of receiving antennas are each fed to selective, self-regulating amplifiers whose output is fed to a demodulator and then a serial-parallel transformer. The received telegrams are then fed byte to byte to the central logic. The receivers also indicate transitions points and whether the signal is present.
• Transmitter: The 2 outputting computers feed serial-parallel transformers. They are compared after conversion, and transmission is only allowed if they are identical. Only one is actually transmitted, with the transmitter transmitting the two signals at 56 kHz with the signals displaced by a 90° phase angle.
• Emergency brake connection: The computers are connected to the brake via a relay. A computer command or loss of current will release the air from the brake pipe applying the emergency brake.
• INDUSI horn connection: The horn signalling the driver is also connected by a relay.
• Serial interface: A serial interface is used to connect the rest of the components, including the driver inputs, display unit, logger, and the tuomatic drive and brake control (AFB) to the computers. Telegrams are transmitted cyclically both from and to the computers.
• Driver input unit: The driver inputs train related data such as the type of braking (passenger/freight), braking potential, maximum train speed, and train length on the driver interface unit. This is then displayed to the driver to verify that it is correct.
• Modular cab display (MFA): The modular cab display shows the relevant speeds and distances to the driver as described in the overview.
• Automatic drive/brake control: When enabled by the driver, the automatic drive/brake control unit (AFB) will drive the train following the permitted speed. When not operating on an LZB equipped line, i.e. under INDUSI operation, the AFB acts as a "cruise control", driving according to the speed set by the driver.

The equipment in newer trains is similar, although the details may vary. For example, some vehicles use radar rather than accelerometers to aid in their odometry. The number of antennas may vary by vehicle. Finally, some newer vehicles use a full-screen computer generated "Man-machine interface" (MMI) display rather than the separate dials of the "Modular cab display" (MFA).