´cause many asked me ´bout to do the easiest way in poser.
ok, a little instruction here 4u poser freaks out there.
first prepare the case and one step in another 3Dprogram, positively save out as wavefront object files and the mtl files at same directory, then poser is able to read the textures.
import to poser, position and scale the objects.
now setup the case and return undone any bone stories to pose room.
next copy the step as often u gonna need to fill up the case.
the trick is, u don´t need to build a closed circle of steps like real escalators function.
this is ´bout to fake unseen by human eyes.
must say, u still can google for weeks, u will find only one download able file of an escalator with an animated pose file 40 frames included.
but doesn´t really help for longer animated scenes to copy the keyframes ´cause your figure jumps back every 40 frame to the start position.
guess the figure hopefully should be brought up or down the whole escalator, that´s why they where founded.
cr2 editor freaks, forget to edit the values, 2 difficult at all.
4 example u gonna need 22 steps to fill up your case, 20 to be seen then one hided before, one after under the plates.
next open the animation palette, mark the keys of all steps at frame one  and choose the linear section for them (color should turn from green to brown).
parent all steps to the case in hirarchy editor window.
press Crtl-2, display right camera and uncheck at animation under properties of the cam.
Go to frame 20 and start to place every step up or down for one step distance beware the direction u wanna run then.
when u done fill in your seperate step from under the plate, go to frame 21 and replace the second seperate step to that position.
retime that process as often till the first seen step actually reaches the end of the escalator.
it´s a little bit work, but useful and the half work process at least.
don´t forget to save your current pz3 several times while workout.
when done the animation should have ´bout 400 frames.
select the case body and save under figure with the + right below naming and subset selected to your library.
ignor the thumb created by poser.
Now save the pose still case body selected under poses with the + right below naming subset selcted as multi frame animation to your library.
( subset select: uncheck ground, check morph channels and body transformation next window)
make a good render of your escalator, save out as png, resize to 91x91 pixels.
open your new created files with cr2 editor (freeware) and save them out to your desktop.
open the original files again in cr2 editor and delete them right in the open window.
ok, replace your files from desktop  to your library with your prepared render png same named.
that´s it folks.
everyone should have an own running escalator for amazing poser scenes.