A tractor-trailer may have several sliding surfaces with locking pins designed for cargo loading and weight distribution purposes. Two common examples are a sliding 5th wheel and a sliding trailer tandem set. A less-common example would be the sliding frame of a trombone trailer.
If the trucks and trailers you operate have these sliding surfaces, you need to pay extra attention to them during your inspections and when using the slides. If the manufacturer has specific instructions, follow them, and always make sure these surfaces see the formal inspections and maintenance that they need.
Always make sure that the locking pins are properly engaged before driving. A 5th wheel or axle set failure can have catastrophic consequences. If you’re not sure if your vehicle has this equipment or you have never been shown how to check/use it, find the help you need before operating the vehicle