From "Log Splitter Hydraulic Filter, Gauge Questions"
Quote Originally Posted by AKKAMAAN View Post
Homework 1: This addition of total restriction on the suction side, is a little bigger when extending a DA cylinder than when retracting the same. Why is that??
When extending a DA cylinder, the level in tank drop, because the net volume into cylinder (both sides of piston), will increase depending on the piston rod. Level drops in tank, the volume of the extended piston rod, have to be replaced with air. If air vent restricts, we tend to starve pump a little.

Homework 2: Why would it make sense to have a larger sized line between the control valve port and the capped side port of a DA cylinder??
When retracting a DA cylinder, the return flow to tank from the capped side will be larger than pump flow, depending on the volume of the piston rod that enters the cylinder.
A "normal" cylinder usually have a rod diameter that is half the cylinder bore diameter. Retracting such cylinder make return flow from capped side 33.3% higher than pump flow (flow into rod side). Always take this in consideration, especially when using, proportionally, larger sized piston rods. Back pressure can fast get substantial.
Also, some control valves have work port cavities larger for the port that is supposed to connect to capped side of cylinder. This Prince valve have larger cavity under the B-port than under the A-port