Add a flow control valve on the hydraulic hose with a extended rod to the driver's side of the trailer. So as it can be adjusted from a safe standing position. That will fix the problem of the deck dropping to fast. Flow control valve can be found online for about $50. To $100.
Your trying to get it to act as a shock absorber, to do that you should put a restrictor valve on the centre of the hydraulic hose, that will drastically slow down the movement of the hydraulic ram inside the cylinder.
See if you can adapt the hydraulic line down to 3/8 instead of 1/2 and that'll also help you with the rate of oil transfer. Or install a gate valve and close it off a little at a time till it drops like you want. Just remember to load the trackhoe slow enough to give it time to go down or you'll be buying another cylinder.
I was going to say you Could do is run your hydraulic lines to pair of small values and then to a Reservoir then you wouldn't need worry about air [ as long as the inlets was on the Down end of the Reservoir] this combined with thicker fluid should solve the problem. Have you Thought about Just making it Power up and Down?
You should add a small oil reservoir because the piston takes up oil space one direction but not the other. That means the amount of oil in the system changes depending on if the cylinder piston is inside the cylinder body or not. The reservoir accommodates this volume fluctuation.
With the hose connected the way you have it, you NEED air in there somewhere. The rod side of the cylinder take less oil to fill to retract, than what has to come out of the "top" end of the cylinder to retract. You can't compress hydraulic oil to allow for the difference in volume. You CAN compress air to allow for that difference. If you had a reservoir, with some air in the top, and 2 hoses near the bottom, one to each side of the cylinder, it will work without air IN the cylinder. If you want to slow the speed down, add a small orifice in the hose. The smaller the hole in the orifice, the slower it will change position.
Semi and medium sized trucks have the bar that prevents cars from plowing under the truck and decapitating themselves. How about these trailers b/c I see them riding around down without the bar?
Once You get that trailer to open and close the way it should without a wagon jack. Replace those pins with bolts that are tac welded. You just advertised that Your damper can fund someones drug addiction. Then You can show us how to booby trap the next one. I built a hydraulic emasculator for the people steal equipment. They don’t get put in jail anymore so they are fair game.
