Multiple-Unit

In Derail Valley there are two types of multiple-unit vehicles (MU for short). Integral multiple-units are designed to be permanently connected, such as how steam locomotives are paired with their tenders . Optional multiple-units are those coupled with either MU cables, or wireless MU controllers . To connect optional multiple-units together, you need the Multiple-Unit license .

Only some motorized rail vehicles come equipped with MU cables, as indicated in the vehicle catalog . They have cables on either end, and can be connected with other vehicles that have the same cables, similar to how air line hoses work.

Such vehicles can also be equipped with wireless MU controller gadgets , which let them sync at distance, without the use of cables.

When multiple-units are connected, whether by cable or wirelessly, they operate in unison, all controlled by a single driver, as if they were a single vehicle. This feature is available on some electric , diesel-electric and diesel-hydraulic motorized vehicles. The vehicles need to have their engines and breakers turned on individually for the MU connection to function properly.

It is allowed to have some vehicles in MU configuration oriented differently from others. In such a case their reverser automatically adapts to the desired direction of travel. Headlights and taillights automatically adapt in MU configurations, too.

MU connecting different kinds of vehicles together, or vehicles at vastly different locations, may result in asynchronous behavior, and lead to one unit overheating , losing traction , spending more fuel, or experiencing something else entirely than another unit. To help with this, alerts from any of the affected units propagate to all MU connected instruments.

Multiple-units can be operated with remote controllers , too.