Collapsing Trailer Jack-Legs on Transported Trailers

I'll apologize up front if this topic is already covered elsewhere or the information I'm looking for is already widely known (by many more than me).

Can or should the common retractable jack legs on commercial trailers (see pictures) be used for support when restraining these trailers to a flatbed or step deck in transport?

I cranked two trailers down to my step deck using the trailer's extended jack/drop legs. Within only 500 miles on bad (NM) roads and the rattling of the trailers, however, I was forced to switch to dunnage to frame support instead of using the trailer's legs.

This is because the legs retracted (or collapsed) three times in that first 500 miles. One leg twice which obviously and seriously caused the load to become unstable. And once where three of the four legs on both trailers retracted. That final time had my load completely unsafe.

In order for that to happen, there must have been so much vibration and "physics" going on that 1) the combined downward securing pressure on the legs and the internal spring pressure to retract the inner drop leg tube, and 2) the leg pin that is normally kept in place (engaged) with separate spring pressure, failed to keep the leg in place as a support. Something in the pressures and conditions involved allowed legs to retract five times.

I ended up retracting the landing legs and just used dunnage between my trailer and the trailer frames for the remainder of the trip.

Have I missed guidance or directive to NOT use retractable landing legs as support in transport?

 

You know, I asked the shipper (1-800-PACK-RAT) right away when they started loading if I needed to put my dunnage out. They said no. Since I haven't hauled trailers like this before, I went with it. My mistake.

Thanks.

 

Here's language I typed up for the company's safety people to review. I'm no engineer, but it's my shade tree mechanic thinking:

"Here is how I believe the legs retracted.
● Spring pressure in the leg attempts to raise the inner leg square tube when the pull pin is released, and strap or chain pressure during transport adds downward pressure on the leg for a combined force attempting to retract the leg.
● The pull pin may have a tapered end design so that it more easily engages when two holes align in the inner and outer square tubes of the leg assembly, respectively.
● Road vibrations “rattling” the pull pin moved it in the direction it would most likely gravitate–outward, because of the taper–and the forces acting to retract the leg (above) allowed the two engaged holes to close little by little as the pin vibrated out of position. At some point the pin fully disengaged and the leg retracted–until the next set of holes aligned and the pull pin spring pressure re-engaged in THOSE holes."

EDIT: Added to the list above after further inquiry:

● If the pull pins are not tapered, perhaps the length of the pins allows only a slight engagement in the hole of the inner leg, and under the right conditions and clearances/tolerances, the aligning hole could be forced out or away from (and past) the pin.

 

I think that's going to end up being the case. If the manufacturer was to weigh in, they'd most likely say the legs are for static support only.

I'm really just curious if there is anything out there that already addresses this. Unless the answer is as a few guys have already said--always use dunnage or blocking.