I'm glad somebody brought this thread back to life. I too am noticing more and more trailers dropped too high. Pups and City Vans. Almost everyday I'm having to get out and crank down the landing gear. The DOT manual states that you must lift a trailer slighty when backing under it. This is to ensure the proper locking of the Kingpin.
What was it either last year or the year before they put out a memo we had at our monday meeting stating we are not to drop or allow the trialer to drop at all...when we pull out the gear should be lowered enough to where the trailer is already resting on the ground...they said it was causing damage to the landing gear of the trailers...yeah right.
So i think the proper thing is to drop the trailer about maybe an inch or so while pulling out...this would allow for a solid hook when the trailer has to be lifted ever so slightly when backing 5th wheel under...any experience will allow you to notice whether or not the trailer is too high or low before you back either the tractor or the dolly under the trailers. I just went over this with a DSR at my terminal who has been here for about 7 months now. She didnt pay any attention to the trailer height and then had tough times lowering the gear...either lower the trailer a little or raise it if you cannot get under it...and if it is too heavy to crank up then use the 5th wheel of either the dolly or tractor to relieve some of the weight and crank a few turns...long and slow process but it works.