Need hydraulic recommendation

[thegary]

I am building a skid steel boom for setting trusses. It will extend 21 ft. I have gotten most of my fab info from existing boom makers and have put my own twist on it. I have one concern that none of the commercially made booms do not address. I think they are hiding one flaw in this boom attachment.
The boom attaches to a quick attach plate at a 45 degree angle and the idea is to use the bucket tilt cylinders to swing the boom up and down. The problem I anticipate is that at at 20 ft out a very slight move of the tilt cylinder will result in a very large movement at 20 ft and I believe it will make for very violent jerky movement of anything suspended from the boom.

I am thinking of putting a hydraulic flow adjusting valve on the line or lines that control the bucket tilt cylinders. My question is should I just use one flow control on one line that restricts the flow in both direction or should I use one flow control on each of the 2 lines that restrict in one direction and have free flow in the other? I can see some pros and cons to both setups but I want to know what the industry consensus is.

[ronsii]

I think I would put one on each line just for the fun of it I have seen adjustable flow control valves and think this is what I'd do... so you can turn em' way!!! down

Made a 15+ foot boom for my loader a long time ago for setting light poles... Yeah the slightest move on tilt and whoa!!!! was a very!!! tense situation trying to control the valves as mine had some leakdown to them naturally and compensating that along with regular control was very stressful

[scsmith42]

I've used the extended booms before on skid steers to set trusses, and did not have a problem controlling it. You need a gentle touch on the controls, but it's doable.

[thegary]

I've used the extended booms before on skid steers to set trusses, and did not have a problem controlling it. You need a gentle touch on the controls, but it's doable.

Thanks , I will build the boom and try it out before deciding to add a flow control. It is more complicated than I thought at first glance to add flow control. I do know now that one control will not do the job because when regulating the exhaust flow from a cylinder the inlet pressure is multiplied by the piston diameter and can result in very high pressures that can exceed hose and fitting ratings . Plus I will need pressure compensating flow controls because of operating 2 cylinders at the same time.

[BillE.Dee]

don't forget,,,it's a quarter inch by the mounting point and get 20 ft out,,, it's a bunch more movement. I don't know the technical figuring, but i'm sure it's available. BE SAFE.

[thegary]

don't forget,,,it's a quarter inch by the mounting point and get 20 ft out,,, it's a bunch more movement. I don't know the technical figuring, but i'm sure it's available. BE SAFE.

Well its not quite that bad , you multiply the distance between the rod eye and the pivit point of the quick tach plate . Without going out to measure that I am guessing that is about 6 inches so it would be multiplied around 40 times. so 1/4 inch of cylinder stroke would = 10 inches of movement at 20 ft.

[farmersammm]

I built a grapple with a single cylinder to actuate the jaws. Because it had no load on it when closing, it was jerky. It behaved better when raising the jaws.

Anyways, it needed a set of restrictors. These used to be common, but are hard to find these days.

https://www.farmandfleet.com/product...%3EHydraulics#

They MUST be placed on both lines. A double acting cylinder pushes fluid out as it takes fluid in. You need to restrict both sides of the piston.

They come in varying size holes. I believe the one shown in the link was satisfactory for my needs. They don't reduce pressure, just flow. So you get the same power from the cylinder.............just slower.

Adjustable restrictors are nice, but IMHO, aren't worth the price for what you get.

[thegary]

I built a grapple with a single cylinder to actuate the jaws. Because it had no load on it when closing, it was jerky. It behaved better when raising the jaws.

Anyways, it needed a set of restrictors. These used to be common, but are hard to find these days.

https://www.farmandfleet.com/product...%3EHydraulics#

They MUST be placed on both lines. A double acting cylinder pushes fluid out as it takes fluid in. You need to restrict both sides of the piston.

They come in varying size holes. I believe the one shown in the link was satisfactory for my needs. They don't reduce pressure, just flow. So you get the same power from the cylinder.............just slower.

Adjustable restrictors are nice, but IMHO, aren't worth the price for what you get.

That restrictor might be just the ticket for what I want to do. I could put the right on the cylinder fittings . I would need 4 to do both cylinders that way I would not need pressure compesating flow controls and those take up no room so there is no problem with getting them to fit. thanks

[leightrepairs]

A "restrictor" and a needle valve have the same effect on the operation of the cylinders, with the difference being that the needle valve is adjustable and therefore easier to adjust and get the speed that you want. A flow control valve controls the flow only in one direction and has an internal check to allow for unrestricted flow in the opposite direction. If you put a Needle valve or restrictor in either side of the cylinder it will effect the speed in both directions of travel. I would put what ever type you chose in the line before it tee's to the cylinders, this way you can control both cylinders from one point.

[thegary]

A "restrictor" and a needle valve have the same effect on the operation of the cylinders, with the difference being that the needle valve is adjustable and therefore easier to adjust and get the speed that you want. A flow control valve controls the flow only in one direction and has an internal check to allow for unrestricted flow in the opposite direction. If you put a Needle valve or restrictor in either side of the cylinder it will effect the speed in both directions of travel. I would put what ever type you chose in the line before it tee's to the cylinders, this way you can control both cylinders from one point.

I need to restrict flow in both directions . Yes I could control both cylinders with one flow control the problem is there is little room to have the control where needed that is why I am considering the restrictors. The other problem is that using one control for both cylinders can create an inbalance to one cylinder and the the other concern is to have an adjustable flow control you need to have the inlet and exhaust flow controls exactly the same so as not to create a pressure spike on one side of a cylinder. The set orfice of the restrictors already does this. The down side is I would need to remove them when not using the boom. where as an adjustable set could just be opened up when not running the boom. I know the adjustable flow controls do have a well marked setup to be accurate for adjustment so I am still considering using them. I think it will need to be pressure compensating to control flow for the two cylinders at one and I believe that makes them physically larger so they will be harder to install with limited room but I am investigation it still.

[leightrepairs]

Your misconceptions about fluid power are more then can be resolved by me so I will concede to your superior knowledge, I just hope that none of the work that I do day in and day out starts working by your rules of fluid power.

[thegary]

Your misconceptions about fluid power are more then can be resolved by me so I will concede to your superior knowledge, I just hope that none of the work that I do day in and day out starts working by your rules of fluid power.

Sorry I hurt your feeling. I said i was still investigating it. I would rather be safe than sorry.

[leightrepairs]

No hurt feelings here Sir, I just do not understand people that ask for information and when it is given to them they just reject it out of hand with out checking the validity of that information.

[farmshop]

With that much job on a skid steer I wouldn’t use the tilt if at all possible. Most people leave it curled all the way back and use boom lift to change heights.

[thegary]

With that much job on a skid steer I wouldn’t use the tilt if at all possible. Most people leave it curled all the way back and use boom lift to change heights.

Yes thats kind of what I figured was that they used the bucket tilt as little as possible. It will still need to be used some . I believe I have invetigated this problem as far as I can go and after looking at the options and reading quite a few tech articals on flow controls I am going to do what lightrepairs suggested to a point and install 2 needle valve before the lines T to the cylinders. He said all I need is one and that it would work in both directions which is right to a point but is not safe when fluid is exhausted from the cylinders. Using one on both lines is the safest way to do what I want to do according to the articles I read. I thought i might need pressure compensating valves but since the 2 cylinders a connected to the same moving mechanizm it t is not needed. Lightrepairs thinks I do not listen , but I listen and verify . I would be a fool to blindly listen to replies on the internet. I am not one to take an answer ,I need to know why, I have found that this has served me well over the years and I tend to remember it. I believe installing the needle valves will make using a telescopic boom much safer .

[leightrepairs]

If you truly want to make it safer install the single needle vale in the cap end of the cylinder and a counterbalance valve in the rod end of the cylinder. This is assuming that the rod extends to lower the load. The counterbalance valve is a load control valve and would prevent the load from becoming the prime mover when you lower the load. Bad thing is that it would require running a pilot line from the cap end of the cylinder to pilot the counterbalance valve and you would more than likely need to use a four port counterbalance valve since I would assume that the directional valve that controls this function is a valve that the A and B ports are blocked in the center position.

[thegary]

If you truly want to make it safer install the single needle vale in the cap end of the cylinder and a counterbalance valve in the rod end of the cylinder. This is assuming that the rod extends to lower the load. The counterbalance valve is a load control valve and would prevent the load from becoming the prime mover when you lower the load. Bad thing is that it would require running a pilot line from the cap end of the cylinder to pilot the counterbalance valve and you would more than likely need to use a four port counterbalance valve since I would assume that the directional valve that controls this function is a valve that the A and B ports are blocked in the center position.

Your assessment of the configuration is correct. I will investigate a counterbalance valve. I did not run into this setup in any articles I read. What I found was that using the 2 needle valves will keep the pressure from spiking since the fluid flowing into one end would be equal to that being exhausted at the other end not allowing the load to run away and creating a pressure spike.

[leightrepairs]

The flow will not be the same on both sides of the cylinder, this is not possible due to the fact that there is a difference in the area on the opposing ends of the cylinder. The area is less on the rod side of the cylinder because the rod occupies space there. The needle valve on the rod end of the cylinder can be a cause for concern because it meters the oil out of the cylinder, if something blocks this small passage that is when pressure intensification and a cataphoric failure.

[thegary]

The flow will not be the same on both sides of the cylinder, this is not possible due to the fact that there is a difference in the area on the opposing ends of the cylinder. The area is less on the rod side of the cylinder because the rod occupies space there. The needle valve on the rod end of the cylinder can be a cause for concern because it meters the oil out of the cylinder, if something blocks this small passage that is when pressure intensification and a cataphoric failure.

I am not trying to be a smart alec. I am trying to learn. I see what you are saying and yes I guess the flow is not the same persay.The load adds to the pressure when booming down or curling down that does add some pressure to the rod side thus increasing flow of oil being exhausted. If the needle valves were adjusted to move the full movement of the cylinders to the same speed in both directions the rod side needle valve would be set with a slightly smaller opening and the piston movement would be the same in both directions even though there is less flow on the rod side because of needing less volume. It would be possible to have a blockage on the cap side also from dirt and wouldn't that do the same thing? I guess I am thinking a blockage would be very unlikely since there is a filter in the system. Is there something I am missing?

[ronsii]

The thing is most valving setups have some sort of pressure relief to prevent a failure like leight was referring to.. once you put something else inline that could 'possibly' get blocked you don't have that relief safety anymore...

[leightrepairs]

A blockage on the cap side will not result in pressure intensification. The pressure intensification will happen on the rod side due to the differential area of the cylinder. The amount of intensification in dictated by the ratio of the differential area. The differential area is a function of the rod reducing the the effective area of the piston on the rod side. The larger the rod is in relation to the piston the greater the intensification. A needle valve meters the oil both into and out of the cylinder which is why in most cases you can use on valve to control the speed in either direction. The only time that this may not work is if the load starts to runaway and becomes the prime mover instead of the pump. If this happens you will have other problems within the circuit because you will force the cylinder to draw air into the system and cause aeration of the oil. I do not know the exact arrangement of the cylinders on your system if the load is always on one end of the cylinder either rod or cap you can just put a needle valve on that end of the cylinder and it will give you the control you are seeking. If the cylinder goes over center you need to do a little more, either two needle valves or a needle valve and a counter balance valve. The counterbalance valve will give the smoothest operation but is more difficult to plumb in to the system.

[thegary]

A blockage on the cap side will not result in pressure intensification. The pressure intensification will happen on the rod side due to the differential area of the cylinder. The amount of intensification in dictated by the ratio of the differential area. The differential area is a function of the rod reducing the the effective area of the piston on the rod side. The larger the rod is in relation to the piston the greater the intensification. A needle valve meters the oil both into and out of the cylinder which is why in most cases you can use on valve to control the speed in either direction. The only time that this may not work is if the load starts to runaway and becomes the prime mover instead of the pump. If this happens you will have other problems within the circuit because you will force the cylinder to draw air into the system and cause aeration of the oil. I do not know the exact arrangement of the cylinders on your system if the load is always on one end of the cylinder either rod or cap you can just put a needle valve on that end of the cylinder and it will give you the control you are seeking. If the cylinder goes over center you need to do a little more, either two needle valves or a needle valve and a counter balance valve. The counterbalance valve will give the smoothest operation but is more difficult to plumb in to the system.

Ok . The load is always going to be on the rod end of the cylinder because my cylinders are installed rod side down . If I put just one needle valve on the cap end (top) the load is always over center and would allow it to run away. If I put the needle valve on the rod end it will not run away but if the fluid pressuring the cap end when the load is curled down wont that over pressurize the restricted flow side on the rod end and multiply the pressure to the point of failure of either a line or a fitting? If not then I could get away with just one needle valve on the rod end line.

[farmersammm]

I tried to add a restrictor to just one side, and it was a dismal failure. The side without the restrictor messed up the travel, making it jerky as all getout. Restricting both sides smoothed it out.

I'd have to go back over the numbers, if I have them somewhere, but my calculations put the down force at about 800ish (might be as high as 1000) pounds on the actuator arm. This is a tough setup to build, and have it perform well. You're dealing with some radical angles. And................at any given position within the arc of travel, the cylinder is either under load, or free falling.

It should be noted....................all flow restrictors will heat up the oil. It's one of the tradeoffs. I've never seen any negative results when running this thing for long periods, so I'm good with it I guess.

[farmersammm]

I'm not sure about provisions for pressure relief if things get blocked..................................the internal relief in the tractor hydraulic system pops off at anything over 2500psi. It simply bypasses, and the pressure remains at 2500psi even if a cylinder is in a stall situation. You only do damage if the cylinder is in a bind, as in all designs. If the cylinder is free to travel full in/full out without a bind, nothing gets ruined.

[farmersammm]

Also..........some hydraulic systems on Bobcats, and tractors, are set up for fast action. It's more efficient when using them under certain conditions.

My loader is on an old hydraulic system that's not made for fast acting motion. And, I plumbed the loader with 3//8 hydraulic hose, further slowing it down. I don't like fast, I'm sort of a slow thinking guy when it comes to operating equipment. I like it precise, not fast.

Fully extended, this thing is pretty far out there, and it's not jerky. Not 20', but far enough that any sudden movements could kill someone guiding the lift near the thing being lifted, or damage stuff. Slow and easy is my rule.

This isn't the thing in the prior pic I posted, but it's just to acknowledge the problems you're trying to prevent. It's another implement completely different from the cylinder I showed earlier. But anyways..........it's just to give you an idea of what I work with, and how I've had success making it work right.