how possible is this?

Just last year I was behind a big MH and the slide came out and they just continued to drive on! Which tells me just how often NOT they check their side mirrors while driving! :B

How possible? Since it happened, it is 100% possible.

How probable? It depends on the type of slide mechanism, and the likely modes of failure for that type. Pretty easy if the mechanism has no locks and has hydraulics to leak or cables to break. Less likely if gears have to shear, but still possible.

I see a lot of slide outs going down the road open a few inches, creeping out slowly.

Most slide out systems that could fail disastrously get delivered with locking bars. Using adequate locking bars properly will make the even unlikely for any type of mechanism.

My brother used to have a 5th wheel with a slide that he had to crank our manually. To ensure it would stay in he would stand up on the couch and stick a 2x4 between the slide and the wall of the RV.

Nothing has ever gone wrong with a slide to me or anyone I know with the exception of one I know who left something loose inside their 5er and the item literally fell up against the switch and ran the slider out while driving down the road.

In my mechanically inclined view, unwanted opening, or a failure allowing it to open during travel, all just depends on the type of slide mechanism.

Hydraulic slides could easily be "locked" on their own, without any extra step from the user, if the system has a pilot operated check valve that ensures the cylinder can't move without system pressure. It's a simple part that can be added separately or built in to the cylinder itself. This is very common practice for mobile hydraulic equipment which having it drift / move on it's own would be detrimental.....I wonder if the RV MFR's have thought of this or not?......

The slides on my TT are cable driven. One snapped cable and the slide could moved on it's own, but I check over everything at least once a season - so far no frayed cables or loose hardware.....

I would think the slides with screw jack drive could not "slip" and unwanted movement would have to be a major failure situation.

The slides I have seen with a motor and pinion actuating a long rack type gear do also seem like a loose / stripped pinion would allow it move easily, too.

My first 5th wheel, a 1999 Wilderness, had the rods to lock the slide. Every RV I have had since do no have a manual way to lock them. Had a Fuzion TH with two slides and no slide locks, never a problem. Traded it for a 2013 Cardinal 3800FL with five slides and n locks now have a 2015 Georgetown XL 377TS motorhome with three slides and no locks. No problems with any of them. Not sure any new rv's come with slide locks.

About 5 years ago I bought a 27' TT with a 13' slide out. I asked the person I was buying it from about slide out locks and he said that you just push the button to bring them in and GO. While we were going through the stuff that came with it I pulled out 2 rods with rubber ends on them and asked him what they were for. He said that they were closet rods. I read the label on them to him. The labels said "Slide out rods. Secure before moving trailer". He had traveled from coast to coast with the TT and never used the slide out locks.

This is very real and happens more than those who have had it happen care to talk about. It is so easy to prevent. If the manufacturer hasn't provided positive means to prevent this it is easy to make your own stops. The next thing would be to get in the habit of always using them. Also have to remember to remove them before trying to move the slide out.

Our 5v has an clutch lock on electric motor drive for bedroom slide
And the two hydraulic slides stay closed due to hydraulic fluid on retract side of piston

If hydraulic solenoid leaked thru or leak on line/fittings then slide outs could move while in transit

If clutch lock failed in motor then bedroom slide could move while in transit

If ANY mechanism designed to 'lock' slide failed then they could move while in transit


Typically IF mfg. provides 'locking bars' to install on retracted slides it is because the MFG. knows w/o them the slides can move while in transit. And if they do MFG. can claim no responsibility due to owners lack of using them.

Our motorhome with 2 slides came with 4 manual locks, as described by djgarcia. During the PDI when we bought it, the demo tech told us that he's never heard of a slide coming out while driving, but he told us we should use the locks just in case. We used to use them when we first got the motorhome, but it's been a few trips since we've used them.

-Michael

It happened to me with my 2001 Beaver 40' DP. I had just had the rv in a shop for slow moving slide out operation just prior too. They didn't check the reservoir for fluid as it is a hydraulic actuated slide out. The fluid was so low that the slide came all the way out when I made a right turn onto a main highway. Luckily no one was near me when it happened.

Now I have a rod between the wall and slide for safety issues.