2000 Rangertrail Trailer Question

[bgreig2]

Yes, i know there is a forum just for trailers and I am posting this question here increase it might be brand-specific information. Over the weekend I took my Ranger 518 out of the garage for the first fishing trip of the year. Hooked up the trailer as usual including putting a trailer-lock on after closing the coupling. Halfway to the lake I hit a pretty big dip in the road and the next thing I know the trailer has jumped off the ball of the hitch. Fortunately the safety chains and the emergency trailer brake wire kept this from being a disaster. My question, why did that happen? I would think (since I've had the boat and trailer for 15 years and this is a first) that the padlock through the pin hole of the trailer coupling would have prevented this from happening. Is there some adjustment I can make to the receiver that will prevent this from happening again? Needless to say I am a little spooked by this near-miss.

[bassnman81]

Yes, there is an adjusting nut under the coupling. When the coupling is closed the clamp under the ball is raised and it might have loosened over the years. That needs to fit snug. Only other explanation would be the wrong size ball.