Cat 924 G trembling articulation, why?

Hello to everyone, it´s my first time on this forum and starting asking for help.
Last week I bought a used Cat 924G, year 2000. Among a few things I could repair by myself, I noticed that the articulation is trembling too much when I turn the steering wheel and reacts too fast... the pins and bushings are in good condition. Is there any screw, where I can adjust maybe the oil flow, to not react so fast?

thanks for helps
Gerry