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. On the other hand, Peter Sam 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, 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 white slate trucks are based on the 2-bar wooden slate wagons of the Talyllyn Railway. The third style of slate trucks are based on the ornate wooden bodied wagons from the Dinorwic Quarry on the 4ft Padarn Railway. The fourth style of slate trucks are based on the Great Western '2 foot' gauge slate wagon, used on various narrow gauge lines such as the Corris, the Welshpool and Llanfair and the Vale of Rheidol Railways. The Slate wagons are based on a metal bodied wagon featured at the Narrow Gauge Railway Museum.
The slate trucks have appeared in every season since the fourth.
- Chisato Nakajima (Japan; Trucks)
- Yasuhiro Takato (Japan; Trucks)
- Tomohisa Asō (Japan; Duncan Gets Spooked)
- Hisao Egawa (Japan; Snow)
- Ryōichi Tanaka (Japan; Snow)
- 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)