Threepoint
Veteran Member
- Joined
- Feb 13, 2014
- Messages
- 2,234
- Location
- No. VA
- Tractor
- Kubota B2150HST w/ LA350 loader, Kubota GF1800 HST, Kioti CK3510SE HST w/ KL4030 loader, Kioti NX4510HST/cab w/ KL6010 loader
Good point about the one-directional valves. I don't have them, but think I understand their use on a toplink or top 'n tilt setup. As you note, two are needed, one on the rod-end hose and one on the cylinder-end hose to allow slow speed control in both directions. Their advantage over a single, fixed-orifice restrictor or the single needle valve flow reducer you link to is that they allow the operator to easily fine-tune the orifice size at each end of the cylinder differently. Theoretically in a perfectly designed, closed hydraulic system, including no entrained air and an excellent hydraulic pump, slowing the oil flow going out or coming in at the rod end of the cylinder will equally slow it coming and going at the other end as well. But that's subject to a reported real-world risk that cavitation and induced vacuum in the system can sometimes occur when a very heavy implement forces the cylinder to extend a bit faster than the oil can be replenished at the cylinder-end. From what I've read in discussions on TBN, that cavitation and induced vacuum can cause chatter and jerky movement, and even result in air being pulled past the cylinder and valve seals and into the system.
With fixed-orifice restrictors like I use for my toplink, sidelink, and offset cylinder, that risk of disequilibrium, however small, can possibly be eliminated by using only one restrictor and putting it in the rod-end hose, or if using two restrictors as some folks recommend, having a larger orifice in the restrictor at the cylinder end. That said, I have restrictors that Brian at Fit Rite kindly sent me with identical orifices on both hoses of my toplink and sidelink cylinders, and have never had a problem in three years. For my offset cylinder on my box blade, I use just one restrictor, the 3/8" NPT Swivel Flow Restrictor from TSC, on the rod-end hose.
With the adjustable needle valve flow control, flexibility can be accomplished of course by a second needle valve at the cylinder end. But that valve is more expensive than the unidirectional valve with the same result.
In any event, I think most of us CUT or SCUT owners can get by nicely with just one fixed-orifice or needle valve restrictor on the rod-end hose, leaving the cylinder end unrestricted. That's just my opinion, but I'm no hydraulics expert like Brian and some of the other members here.
Im in MO, build me one 
