Load compensation and sound on small-gauge locomotives

The goal of load compensation on digital small-gauge locomotives is to maintain consistent speed in all circumstances and only limited by available power. A decoder featuring load compensation is programmed to monitor the electromotive force (EMF) of the engine in “normal” conditions. Any deviation from this “basic load” will be interpreted as a ramp or slope, causing a variation of the power delivered to the engine. The amount of compensation that a digital decoder can handle can be programmed in the range of between 0% and 100%. It is also possible to adjust the amount of compensation to vary according to the speed factor of the locomotive. Generally, a high percentage of load compensation is suitable for a range of low speed, thereby preventing engine stalling or run-away when the engine runs without load. However, it is desirable to reduce it as speed increases, so that when accelerating, the engine receives all the power, but also to react in a realistic way, ie, with a prototypical change of speed subordinated to the degree of slope. These values ​​should be carefully calculated, and always according to the features of each locomotive.

Realistic applications of load compensation sound

In real life, when a locomotive reaches a ramp tends to reduce the speed, and the engineer will try to maintain it by increasing the power. If engine power is able to overcome the resistance of the sloping of the track, the speed of the locomotive will remain the same; otherwise it will decrease. On a slope, just the opposite is true and it is also necessary sometimes to use the dynamic brake. Considering this, two different factors must be combined to achieve the desired result:

  1. SPEED. The load compensation tries to maintain a constant speed, that depends on both the current speed of the locomotive and slope of the land, changing the amount of power delivered to the electric engine in accordance on both aspects.
  2. SOUND. In order to maintain the speed of a real locomotive on a ramp, engineer will speed up the engine. In the case of a small-gauge locomotive with sound, engine should speed up as much as necessary, even though the locomotive speed is maintained or decreased in proportion to the degree of slope.

The combination of the above two factors result in a realistic behavior of the locomotive, which react to changes in slope and load, like a real train.

Currently, our sound projects are designed taking into account the above conditions, and we are actively working with manufacturers to provide decoders with better adjustment possibilities, including realistic characteristic as changing sound of the engine depending on load, just in order to offer maximum entertainment to the end user with the highest degree of realism.

Photo: 269 tandem with containers crossing Barbantes (Ourense). 
Author: Carlos Núñez Deza en Flick

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