For some interesting reading about how the weight affects axle weights take a look at page 46 of the T300 Body builder manual.
http://www.kenworth.com/brochures/T300_Body_Builder_Manual.pdf
I stumbled upon this the other day looking for other dimensions. It not only gies some useful information about adding a lift but it also applies to weights and balance in general. In their example they add a 1000lbs lift to a 200"WB, the Cg of the lift falling at 246". While the lift is 1000lbs it adds 1230lbs to the rear axle (more than the lift itself) but at the same time removes that same 230lbs from the steer axle. This would of course vary with different WB's and the amount added/subtracted from each axle would be greater with a longer overhang due to increased leverage. Good stuff to know.
There are some points I like and dislike about different types of lifts. Sliders: I like that they add no length, stay out of the way until needed but I don't like that there is pretty much no place to add extra lights out back, you are left with virtually no bumper -leaving a potential for dock damage and it seems like bad things, ok, well worse things, would happen to a car if it rear ended the truck vs having an ICC/DOT bumper and the seem to hang lower than I care for. On that final subject, I saw this Dutch slider on a floral truck (See attached photos - funny they seem to have some of the most interesting straight trucks) that is apparently distributed everywhere but the US and Canada. The brand name is
Dhollandia, and the only reason I can see for them importing one is it does seem to sit a fair bit higher. The photos are bad (cell phone) bud the website has better shots. Another interesting thing on that site is they have a rail type life that can go HIGHER than the floor of the truck.
Tuck-unders I like that they are always there, yet out of the way until needed, a few extra lights can be added to some, they deploy fast and the extension makes a nice step for getting in the box, especially when at a dock. However I see quite a few of these that are bent up pretty good and they is the downside of the extra length. Of course those bent ones make well be from driver abuse/poor maintenance but many seem to have poor support for those vertical side extensions/steps though that could probably be overcome if it wasn't just slapped on like so many shops seem to do.
Railgate seems very durable, almost no need for dock bumpers with the better ones, capacity is great, large platform and some are available with an aluminum platform. Bumper can be retained and no issues with lighting. Downside is having raise/lower it every time, (which is several times daily for me) or use one you can drive around with it lowered.
Anyone got rough costs for different types/brands?