User Tools

Site Tools


Locomotives: SBT - Soft Brake Timer


The SBT records can be sorted by clicking on one of the columns headers.


SBT = Soft-Brake-Timer
Deceleration can be used for reducing speed by the Interval and Decelerate parameter.
Be careful with using this option; It can overload the Command Station with too many Speed commands.
Configuring the CV3/4 is a better approach but for some high speed trains this could be difficult.
SBT is not a "Self learning" process like BBT and must be configured manually.


SBT is activated for the selected loc by filling in the default values for that loc. The default values are used everywhere on the layout when the locomotive has to decelerate from a higher to a lower speed (except inside blocks with BBT when the locomotive has to stop). This means that once switched on, SBT applies everywhere - for that loc.
Decelerate speed reduction per interval.
Interval between the speed commands.

  • Important: The option Regulated on this tab need to be activated, for SBT to take effect.

Default override

Where the default values of SBT do not fit, create an individual line with different values for the corresponding block.
This can also be a line with 0 / 0 to completely deactivate SBT there.

This loco option should be set in case SBT should start at the enter event:
See: Reduce speed at enter


The default key for a SBT record.
Format: "BlockID"


If set this value is used as extended key for a SBT record.
Format: "BlockID-TrainID"
If no record was found on entering a block with this extended key the default key is used to look up a SBT record.


Must be set to enable SBT.
The interval between the speed commands in units of approximately1) 100ms.


Decelerate is the speed reduction per Interval, it will be subtracted from the actual speed until the wanted speed is reached.
This option is disabled in case set to zero.

This value does not represent decoder speed steps but a part of the speed range set by V_Max.



A SBT record with the set parameters will be added to the list.


Delete a selected SBT record.

Delete all

Delete all SBT records.


The modified parameters are inserted in the SBT record.


Export all SBT records in a XML file.


Import SBT records from a XML file.

None Regulated Decoders



This option is not active and greyed out by default. It can be used for old-fashioned decoders offering no regulation and mass simulation.

  • Regulated (see below) has to be deactivated in order to enable Interval.

The Interval merges in a pause between the decoder steps with a value of 1 corresponding to 100ms. With modern decoders this parameter is not needed and should be left to zero.

Tip: The Interval can be used to increase the deceleration / acceleration for decoders with a very limited tuning range. Some older Marklin locos with control potentiometers suffer from this limitation. Small interval values, e. g. in the range of 1 to 5, may help in this case. It should be noted that no other locos in need of automatic speed control at inclines (see Regulated below) are present on the layout and that in all blocks the type of incline should be set to "none".


SBT will be disabled in case this option is not set.

If the decoder has motor management (BEMF) this flag should be set to prevent velocity changes by Rocrail when a locomotive enter a block defined as an incline block.
Deactivating this option activates Interval (see above) and automatic speed control at inclines.

Note: Rocrail is able to adjust the speed at inclines within certain limits in auto mode. The type of incline has to be specified in the block properties.

The following table gives hints on the impact of the parameters. It is supposed that the V_Mode-Percent-Option is not set and km/h is applicable.

Speed in steps and time
Interval = 5 (0,5 sec / step)
Speed at the beginning of the braking: 100 km/h
steps 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
time / sec 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0 5,5 6,0 6,5 7,0 7,5 8,0 8,5 9,0
5 km/h
95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 km/h
10 km/h 90 80 70 60 50 40 30 20 10 km/h
15 km/h 85 70 55 40 25 10 km/h
20 km/h 80 60 40 20 10 km/h

:!: Independently of the values in the table, the breaking will end at the speed defined in V_Min.

Hint: At interval = 10 the number of steps = time in seconds.
Higher values for Interval and/or Decelerate reduce the amount of necessary steps respectively speed commands.
This can help to avoid the above mentionned overload of the command station.

Example: At Interval = 5 and Decelerate = 5 the speed is reduced from 100 km/h to 10 km/h in 9 seconds with 18 steps respectively commands.
At Interval = 10 and Decelerate = 10 the reduction takes also place in 9 seconds, but with only 9 steps respectively commands.

Hint: The speed steps are not visible in the throttle, but only in the trace or on the real layout.
Operating System dependent
loc-sbt-en.txt · Last modified: 2021/04/29 00:37 by peter_basti