hydraulic elevator using telescopic cylinder

Hello everybody ,

I made this thread because i met a problem in my graduation project ,
The project is Hydraulic elevator using telescopic cylinder , and the problem which we met is that we need to move the elevator with constant speed for about 5 floors , we selected the suitable telescopic cylinder with 6 stages .

The problem is we have fixed displacement pump and as you know the telescopic cylinder is changing in the inside volume every stage and we have constant flow rate .

I want to know how i can calculate the suitable flow rate and how i can keep the velocity constant ,
I heard about proportional flow control but i don't know how to adjust it and how to install it in the hydraulic circuit .

If anybody see another solution for my problem please help me


Thanks for All

Keta