Troublesome Trucks (Foolish Freight Cars or simply Cars in the US) are so nicknamed because they can be quite troublesome and love to play tricks on the engines, except Edward, Stepney, Hiro, and Salty. The trucks have been the cause of most of the railway's accidents. However, since Douglas smashed the Spiteful Brakevan and Oliver pulled S. C. Ruffey, their leader, apart, they have been frightened of some engines.
There have, however, been some cases where the trucks and engines are on the same side, such as when Diesel was given a third chance on Sodor, but the trucks tricked him into misbehaving and getting sent away again. They also asked Percy to help move them from a ill-mannered and obnoxious barge named Bulstrode, only to end up in his hull and damage him, resulting in him being sent to a beach.
When Thomas and Edward switched jobs back when Thomas was a station pilot, the trucks pushed him down Gordon's Hill all the way to a siding. They then decided to trick James and pushed him into a field. When James was given a second chance after ruining a coach's brake pipe, they tried to discourage him. The tail of the train uncoupled and the rest of the trucks rolled down the hill for James to recover.
They also refused to let Diesel move them out of a siding. This lead to an accident and as Diesel was forced to clear the mess, they taunted him with a song. Diesel blamed Duck for it and to get Duck back, made the trucks insult the three tender engines using Duck's name. Devastated, Duck went to help Edward with his trucks up a hill, only for them to break away and crash Duck into a barber shop. They also pushed Percy into the sea, tired out James, shoved Percy into a brake van and pushing James into tar tankers.
They also bumped Thomas into a condemned track after losing their chance to pay James out and pushed Oliver into the turntable well. When Oliver came back from the works, the trucks still laughed at him, but after he pulled S.C. Ruffey into pieces, they became loyal to him to minimise their chances of being ripped apart themselves.
The trucks also pulled Thomas down a hill into Salty and got James covered in melons.
The trucks teased James when he smashed them into the snow. When the Pack was building a new bandstand, they refused to move until Percy used his "do-as-I-say" whistle. They have since been good, but they soon decided to put a stop to their good streak by pulling Thomas and Percy down a hill, chasing Stephen into Ulfstead Mine. They have since been troublesome after this incident.
Thomas had once accidentally shunted them too hard and were just as confused as everyone else when Thomas blamed an imaginary engine named Geoffrey. They also laughed at Den when he was working for Mavis.
Every wise engine knows trucks cannot be trusted. Trucks could be considered the rebels and the troublemakers of all rolling stock on the railway, as most of them love to cause mischief and trouble and show no remorse for whatever they do. If an engine is having a bad day, makes a mistake, or is easily played upon, then the trucks begin their wild antics of singing, name calling, holding back, shoving, bumping, giggling and so on. They will play tricks on an engine based on how they treat them. Most accidents caused by the trucks are a form of revenge due to mistreatment and they are not known for considering the consequences of their actions; they will carry out their plans even if they result in derailing, damaging or destroying themselves.
Trucks can also be described as territorial; when they get used to certain engines pulling them, another engine in the yard to take them may cause confusion or anger for the trucks. In Daisy the Diesel Railcar for example, Toby and Percy switched jobs, making Toby's trucks furious and causing Percy to crash. In Oliver and the Trucks, the trucks refused for Oliver to take them and demanded Duck, Donald or Douglas instead.
To the trucks, one engine is as good as another, as on one occasion they took their anger out on Thomas when they could not get back at James for bumping them.
The Troublesome Trucks are mostly 7 plank and 8 plank end door open wagons. The van variety are mostly BR 12 ton twin ventilated and BR 12 ton single vent vans with corrugated ends.
Trucks are traditionally painted either dark grey, dark green, or brown with black frames, although in recent years, they have also appeared in red, green, blue, pink and many other colours. Privately-owned trucks typically have their own specific livery.