Compatibility between old and new Hornby locomotives, Tri-ang locomotives, Hornby track and speed control methods

Tri-ang and Hornby compatibility


Tri-ang and Hornby have been producing OO/HO scale model trains for many years some of which can be used together and some of which cannot be used together. This article defines those items that are compatible and those that cannot be used together. Considered are the locomotives, the track, the power supply and the speed control systems.


Over the years, at the time of writing nearly 50 of them, Tri-ang and Hornby have been producing OO/HO scale model trains for all to enjoy with seemingly little change. However, there have been many changes, some small and insignificant and some major but un-noticed by all but the technical amongst us. In this article we hope to highlight the most important changes made by Hornby which limit the use of old and new locomotives on old and new layouts.


The locomotives produced by Tri-ang and Hornby appear very similar from the beginning the the current offerings but there are some significant changes. Below is a list of key differences:

  • The earliest locomotives used a 3 rail system whereby the electrical power to the locomotive was provided by a "3rd rail" in the centre of the traditional outer running rails. The main running rails providing the return path for the electrical current.
  • The earlier locomotives had wheels with a taller wheel flange height than the modern locomotives as the earlier track rails had a higher rail section.
  • The newer locomotives with the aid of modern technologies use far less electrical current to provide the same pulling force as their predecessors.
  • Over time as the electrical motor has moved from the locomotive to the tender and back again so has the electrical pick up from the track. Originally the main drive wheels would pick up the electrical current but the modern solution is that all the main contact wheels will make electrical contact with the track. This includes the tender for steam locomotives and the non-drive bogie for diesel and electric models.

Power supply and speed control

The main analogue power supply solution is largely unchanged over the may years of production. These relatively minor changes do, however, present some problems with compatibility. Below is a list of key points to note:

  • As time has moved on the electrical motors in the Tri-and and Hornby locomotives has consumed less and less electrical current and as a result the power supply has needed to provide less and less electrical power.
  • The advent of low cost electronics has meant that the modern power supply systems can eagerly detect when too much current is demanded and shut down all electrical power to prevent permanent damage to the power supply system. The C990 power adaptor and R8250 speed controller have known problems in this respect.


Old track and new track look very much the same as each other but there have been key changes over time which can cause some significant running problems. Below are the important differences to keep in mind:

  • Earlier track was produced from steel rails electroplated to prevent rusting whereas the modern track rails are produced from non ferrous material.
  • The later track rails have a finer section compared to the earlier track rails which includes the points, crossovers and other more specialised track pieces.


The modern introduction of digital control of a Hornby layout offers very little in terms of compatibility between digital and analogue systems. To offer the benefits of digital control each locomotive is fitted with a digital microprocessor which picks up digital data from the controller via the normal track power supply. This digital information instructs the locomotive to the speed it must go, the direction of travel and which lights to switch on or off, plus other control functions.

The great advantage of the digital control system is that multiple locomotives can be individually controlled on the same piece of track. However there are some important points to take into account with the digital system:

  • Digital and analogue control systems are completely incompatible. The locomotives fitted with digital microprocessors are specified to work on the traditional analogue power system but they do not always do so. Cost cutting from Hornby? We'll probably never know.
  • As each locomotive is controlled via the track with high speed digital data the electrical connection from the microprocessor in the locomotive to the controller is critical. Essentially the digital chip in the locomotive will follow the last command received (not sent) which can lead to loss of control. Cleanliness of the electrical current path is important with an analogue power system and critical with a digital system.

Operating old Hornby and Tri-ang locomotives on newer tack layouts

Operating older Hornby and Tri-ang locomotives on newer track layouts causes some significant concerns which may not seem obvious at first. The key points are:

  • The old 3 rail locomotives can only be used on the old 3 rail track systems. On these locomotives there's no insulation between the 2 outer running rails which mean that if a 3 rail locomotive is placed on a later 2 rail layout it will give an electrical short circuit to that layout. Simply put, 2 rail and 3 rail locomotives and layout power systems are completely incompatible with each other.
  • The older electrical motors in the locomotive consumes more electrical current then the modern power controls can supply. Combined with the over current protection devices fitted to the modern power supply systems means that the older locomotives may stop for no apparent reason. To operate older locomotives will necessitate the use of a power supply and controller from the right period in time. If your locomotive is from the 1970s then you'll need a power system from that period too. If you are not sure then select a power control with up a to 2 Amp or 24VA (24 Watt) power capability. H & M have produced some very good controllers in times gone by.
  • As newer track pieces have a finer rail profile the older locomotives with deeper wheel flanges may struggle particularly over points and crossovers. This can lead to derailment of the locomotive or bogie set. The use of even finer rail sections can make this more prevalent. The best solution is to reduce the flange height of the wheel of your locomotive.
  • Some older Hornby locomotives used a magnet in the chassis to provide extra magnetic grip to the older steel track rails. Clearly this has no function with the modern non ferrous track rails. However, this magnatraction magnet does cause all sorts of problems for the locomotive. The magnet can attract ferrous debris from the track layout which can cause a short circuit if the debris is on the electrical live side of the locomotive. The magnet attracts the steel wheels of the locomotive causing uneven and premature wear of the axle bearing in the chassis. The best all round solution is to remove this magnet as it causes real problems and offers no solutions.

New Hornby locomotives on older tack layouts

Operating newer analogue Hornby locomotives on older analogue track layouts doesn't really cause any significant concerns. However the DCC locomotives are best not used on analogue layouts as not all the digital chips seem to work well with the analogue power controllers.

About the author:

Gary Harding has been working with Hornby model locomotives for over 35 years and now operates Hornby Train Restorations in the UK. Hornby Train Restorations is a Worldwide internet based business that offers for sale high quality Hornby model locomotives, coaches, wagons and Hornby spares from the 1960s to the present day. All the restoration work is carried out to the highest standards with the highest quality parts available. Only the best locomotives are selected and the final result is a locomotive that is genuinely like new.

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