What’s happening here. (You can directly skip to ‘note’ part if you are not the one who likes to go deep in to machines.

When the flow from the pump is directed to rod end side of the cylinders it passes through a set of gear pumps connected to each other mechanically.
Suction or intake side which is connected for all the pumps, receives the oil flow and rotates all the gears at the same speed since they are mechanically connected, making the flow output equal. for e.g. flow of pumps with equal volume rotating at same rpm is equal.
Equal flow reaches the rod end side of all cylinders connected upstream of flow divider and considering their annular area is equal they will lift at the same speed.

When the flow from the pump is directed to piston side of the cylinders, the flow coming out of the rod end side passes through a set of gear pumps connected to each other mechanically, before passing through a counter valve. Counter valve stops the load from free falling.

Note:
1. If the start point of all the cylinders are not the same, the error will remain through the movement. It will not correct mid stroke.
2. If there is a physical obstruction on one side pressure on the upstream side will increase creating back pressure one the gear and stress on the mechanical link with which the gears shafts are connected and can damage the flow divider. The flow divider will not compensate for flow to get the cylinders back to equal stroke once the obstruction is removed.
3. If there is contamination in the oil, volume of each gear pump may be modified by scouring resulting in unequal flow and out of sync stroke length. Refer photograph showing slightly scoured inside surface of gear flow divider and heavily scoured surface if geared flow divider.
4. The counter balance valve has to be set to counter the weight of the load. If over counter is given there will be back movement of piston rod with the down stroke ends. If the under counter is given there will be even or un-even free fall and stress on flow divider’s mechanical linkage and may result in damaged flow divider.

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