First of all my english writing is not so good, but I can read it without problems. I've got this mechanical system and I need to get the some transfer functions, we made all the force diagrams and got the respective equations, their eight, now we need to get the transfer function of x1(dot) / v1 , x2(two dots) / v3 , x3 (two dots) / v4 and x4 / v7.

Now, assuming that the equations are correct, what we were trying to do was for the first T.F clear all X2(S) from the second equation and replace it on the first equation, then we clear all sB1,B2X1(S) from the new equation that we just got from replacing X2(S), then we're trying to make sB1,B2X1(S) / V1(s) but there's no way to clear V1(s).

It's very difficult to understand, and I don't know if I explained myself, but if someone can tell us what we're doing wrong I'll be really greatfull.

Thank you.