Thanks, Artūras. This is a trick one. I'm starting to suspect I was way out in what I imagined when I asked the question. It appears that „kreipiančiosios“ may be some sort of long metal things, similar to rails, e.g.
http://www.dagmita.lt/grandiniu-kreipianciosios. The ones pictured here have have chains on them but I suppose „Ratukiniai kreipiančiųjų šliaužikliai“ are some sort of gadgets ("sliders" – šliaužikliai) that slide along the rails ( „kreipiančiosios“) on little wheels (ratukai). Do you think I'm on the write track? Leonardai, where did you find "wheel slide guide"? I have wasted so much time on searching Internet for this!