A self-contained trailer braking system comprises a fifth wheel hitch attached to a trailer frame, where the trailer hitch further comprises a kingpin to engage a fifth wheel of a towing vehicle. A sliding mechanism is attached to the kingpin, where the sliding mechanism is slidingly captured within the trailer frame and can move between a forward position and a rear position. A spring is attached to the sliding mechanism and the trailer frame, where the spring biases the sliding member to the forward position. A brake actuator is mounted to the trailer frame and linked to the sliding mechanism. A brake assembly is attached to the brake actuator, and a power supply is attached to the brake assembly, where power is applied to the brake assembly when the sliding mechanism is away from the forward position.