SS2A DC Model Railway Shuttle Controller with Speed Control

About the Product

The BLOCKsignalling SS2A is an automatic DC model railway shuttle controller with built-in speed control, designed to run a train continuously backwards and forwards. It also provides adjustable waiting times and smooth acceleration for realistic automatic operation.

The SS2A works by using an insulated track gap at each end of the shuttle line. When the locomotive crosses the gap, power to the train is interrupted and it stops. After the selected waiting period, the SS2A reverses the polarity of the track supply, allowing the train to automatically depart in the opposite direction.

Waiting times can be adjusted from approximately 1 second up to 10 minutes using the on-board TIME control. The module also includes its own DC throttle, allowing the running speed to be adjusted directly on the SS2A without requiring a separate DC train controller.

For more realistic operation, the SS2A includes adjustable acceleration together with a range of programmable functions. These allow you to customise the shuttle operation with features including random running times, adjustable waiting periods, different forward and reverse speed limits and advanced motor-start settings.

Key Features

• Automatically operates a DC model train backwards and forwards along a single section of track.
• Built-in DC shuttle controller and speed control – no separate DC throttle required.
• Adjustable waiting time from approximately 1 second to 10 minutes.
• Smooth adjustable acceleration for more realistic departures.
• Fixed or random running times.
• Programmable waiting time when operating without end track gaps.
• Fixed or random programmable waiting periods.
• Independent forward and reverse speed limiting.
• Adjustable anti-stiction function to assist locomotives that require additional power to start moving smoothly.
• Forward and reverse LED indicators show the current operating direction.
• Output LEDs on applicable versions provide an indication of the voltage being supplied to the track.
• Can also be programmed to operate as a standard DC speed controller rather than a shuttle.
• Suitable for OO, HO and smaller locomotives.
• Built-in electrical protection.
• High-frequency 26kHz motor drive for smooth and quiet operation.
• Settings are retained when power is switched off.

Adjustable Acceleration

The SS2A gradually increases the power supplied to the locomotive when it starts, producing a smoother and more realistic departure.

The acceleration rate is programmable and can be set from approximately 1 to 60 seconds, allowing the behaviour to be adjusted to suit different locomotives and layouts.

Adjustable and Random Timing

The main TIME control sets the interval between changes of direction and can be adjusted from approximately 1 second to 10 minutes.

For layouts where more variation is wanted, the SS2A can also be programmed for random running times. In this mode, each run varies between approximately 25% and 100% of the time selected using the TIME control.

Additional programmable waiting times can also be used when operating on track without end gaps. These waiting periods can be fixed or random.

Independent Forward and Reverse Speed Control

The SS2A can limit the maximum speed of the locomotive independently in each direction.

This is particularly useful on layouts where a train should travel more slowly in one direction, such as a model mountain railway where different speeds may be required when travelling uphill and downhill.

The forward and reverse limits can each be programmed from 100% down to 10% of the speed selected using the on-board SPEED control.

Advanced Motor Starting Control

For locomotives that require additional power to begin moving, the SS2A includes an optional programmable anti-stiction function.

This can provide a short initial power pulse to help the motor begin turning before reducing the output and starting the normal acceleration sequence. The pulse duration, pulse strength and starting point of the acceleration ramp can all be adjusted to suit the locomotive.

DC Controller Mode

Although primarily designed as an automatic model railway shuttle controller, the SS2A can also be programmed to operate as a conventional DC speed controller.

In this mode, automatic polarity reversal is disabled and the locomotive continues travelling in one direction, with its speed controlled by the SPEED adjustment on the module.

Electrical Requirements

• Power Supply: Regulated 12V DC
• Recommended Power Supply Rating: 0.5A to 1A
• Approximate Module Current Consumption: 0.25A
• Power Connections: VIN and GND screw terminals or DC power socket
• DC Socket Size: 5.5mm outer / 2.1mm inner
• DC Socket Polarity: Centre positive

Do not power the SS2A from the auxiliary output of a train controller.

A compatible plug-in power supply is available separately: PSU2 12V DC 1A Model Railway Power Supply

Built-in Protection

The SS2A incorporates a self-resetting 0.5A fuse together with reverse-polarity, overvoltage and overtemperature protection.

The track output uses a 26kHz pulsed DC supply. This high operating frequency has been selected to provide quiet motor operation and avoid the audible humming or whining that can occur with lower-frequency motor control.

Wiring Diagram

The wiring diagram shows the standard SS2A installation, with insulated track gaps at each end of the shuttle section used to stop the locomotive before the SS2A automatically reverses the direction of travel.

Speed and Delay Time Adjustments

The on-board SPEED control sets the locomotive's normal running speed, while the TIME control determines the interval between direction changes. The TIME control provides finer adjustment between approximately 1 and 90 seconds, with progressively coarser adjustment up to approximately 10 minutes.

Documentation & Support

For full installation instructions, wiring information, programming options and troubleshooting guidance, please download the latest SS2A instruction manual:

Product Instruction Manual