Slate Trucks are the Skarloey Railway's main type of truck, and can be seen as the narrow gauge counterparts to the Troublesome Trucks. Besides carrying slate, they have been known to carry broken branches, hay bales, cows, and sheep. They dislike Sir Handel because he often bumps them. Peter Sam, on the other hand, never bumps the trucks unless they misbehave.
Once, the slate trucks mistook Peter Sam for Sir Handel, and decided to play a trick on him. At the slate mine, they snapped the chain attached to the winch on the incline and ran into him, cracking his funnel and denting his boiler.
In the fifth season, some empty slate trucks jammed the winch on the incline and ran down the slope into the ravine, causing an avalanche which buried Skarloey. Another time, they broke away from Peter Sam's train, and plummeted into the ravine at the old iron bridge.
In the sixth season, Rusty warned Duncan to be careful with the trucks after bumping them. Unfortunately for Duncan, he got his comeuppance when he jammed the incline winch and crashed into a muddy swamp with the slate trucks.
- The slate trucks' faces would later be used for the Tankers in Toad Stands By.
- One of the slate trucks was sold on Vectis with Peter Sam's Season 4 small scale model.
- ERTL (discontinued)