you can use a cylinder lock valve in the port of each cylinder . It will allow free flow up and back as long as it is plumbed correctly .... or put a velocity fuse in the port . The lock valve does just that .... locks the cylinder where it is , the velocity fuse , or a flow control , allows it to come down at a controlled rate . However , please understand that these are intended to be used in the case of a hose or pump failure and that`s why they go directly in the cylinder port .
If the seals on the piston fail , it`s coming down .... but probably not very fast as the
oil has to go past the piston and the cylinder wall , and that clearance should be fairly small .... acts like an orifice .
Lock valves are pretty much required in any case where a cylinder hose failure will cause personal injury .... such as a roof bolter in a coal mine or a manlift application .