Cylinder travel limiter

[Chilly807]

I have a situation where I need to limit the extension of a cylinder from 44 inches to 36 inches overall length. Using a shorter cylinder isn't an option because of the required length when fully retracted.

My question is, is it as simple as machining an aluminum spacer to fit over the rod and inside the bore, with enough clearance that it won't restrict fluid flow?

Sean

 

[kennyd]

Yes, you can certainly do that. There are ones you can buy off-the-shelf to limit retraction also. Just be sure the spacer does not contact any seals in the gland.

 

[Craig Clayton]

Chilly807
Seeing that you are using the machining word, I would suggest brass collars, the above mentioned off-the-shelf keep the diameter to lenght a 1 to 1 ratio. Not one 8" collar.
I am a little confused because how can you pull back 44" but only extend 36". Got a pic
Craig Clayton
I heard that you had some rough weather.

 

[J_J]

I think he only wants to extend 36in of the 44in he has available, keeping the cyl mounts in the same position.

Outside stroke control. Clips on the rod, outside

 

[Chilly807]

JJ's got it right. I need to limit the extension of the cylinder to no more than 36" total, with no limiter it can go to 44" overall.

Sean

 

[J_J]

Just clip as many as those controls above as needed, and you don't take the cyl apart. There are other version of the limiters.

http://baileynet.com/index.php?id=31&productcategory=1000027

 

[rus_geek]

JJ, I think you've got it backwards. Those rings will limit the retracted length of the cylinder, instead of the extended length.

Chilly, could you switch to a 36" cylinder so you're using max extension and then limit the retraction with those collars instead? That way all the modification is outside the cylinder instead of inside.

-rus-

 

[wdchyd]

My question is, is it as simple as machining an aluminum spacer to fit over the rod and inside the bore, with enough clearance that it won't restrict fluid flow?

Sean

Yes, but you'll have to open up the cyl and yank apart to install......:thumbsup:

 

[J_J]

You are right. I was thinking outside the box today. those are retraction collars. Please forgive me.

But then again, he might want to retract it to 36 in total, and only use the rod from 36 in to 44 in for the operating mode.

If this cyl was controlled by a solenoid valve, it would be easy enough to place a tab on the shaft to operate a switch to break the current at the desired shaft position.

 

[Chilly807]

I think the ones in the picture are extension collars, but you don't have to remove the piston to install them. The cylinder still has to come apart, however.

I've been doing a little research this afternoon. As far as I can tell, there is no way to add anything external to this particular cylinder to prevent it from extending or retracting fully. The split collars will open up when the rod end contacts them, the clip won't withstand the force.

The cylinder I have is a 2 inch dia 18 inch Hy-Spec welded model, with steel tubes on each end for a 1 inch pin, not a clevis or flange mount. If it overextends it will bend the rod, however the retracted length is perfect. So I can either limit retraction or extension. With the rod fully retracted it is protected from the weather for storage, so I prefer to limit extension.

Sean

 

[Craig Clayton]

Now we have a pic of the project. i did a post of a hydraulic rear blade last year, when I set the position for the anchor I swung the blade right and left and used a tape measure to represent the retracted and extended lenghts. when I found the sweet spot that is where the anchor point went. A small suggestion if you had a shorter cylinder .
44 - 36 = 8 divide 2 = 4 , 44-4 = 40 play with math. If you move the base point toward the end pin. How will it change the geometery?
Craig Clayton
You know what Red Green say, were are pulling for you.

 

[Gary Sweat]

A couple of suggestions:

1) Make a longer arm coming off the pivot so that the cylinder has to travel farther in the arc to get the max angle.

2) Install a shorter cylinder with an extension on the cap end. It will mount to the same point but will only travel the 36" or whatever you need it to.

 

[Diamondpilot]

As the others have said there is really no way to limit it without tearing it apart or then if done not damaging the seals. If it were mine I would re-manufacture the mount on the blade end of the cylinder to get the geometry right.

Another easier way would be just to make a limit stop or chain to prevent the blade from moving too far.

Chris

 

[leonz]

Hello Chilly, Craig,

What you need is an "internal stop tube" for your cylinder;

The external cylinder rod locking rings have habit of damaging the rods over time.


The bronze stop tube fits between the packing gland and the piston of the cylinder tod and rests on the piston when stopped.


it needs to be be made of bronze and must have 1/32 of an inch larger inside diameter than your cylinder rod outside diameter and then you can have it cut to length.

The stop tube will be 8 inches long and it will slide up and down the rod while the rod is moving and will cause no internal damage to the cylinder rod, packing, o rings valves etc.

If you have hydraulics repair shope nearby you can have them install the stop tube for you as they will have access to bronze from many suppliers or you can buy bronze blanks from Mcmaster Carr and others for the bar stock.

 

[Chilly807]

You've got a good point there Craig. I have to buy another cylinder anyway, or at least a rod (yes, it's bent like a banana :laughing: )

The blade was set up for hydraulic angle when I got it, but I didn't buy the cylinder and hoses. I used the existing anchor points, which are less than ideal.

As it is, I need exactly 10 inches of cylinder travel to angle the blade 45* left or right (26 retracted, 36 extended). A Hy-Spec 3 inch cylinder with 10 inch stroke is 18 inches long retracted and 28 inches extended. The larger diameter cylinder will give me better (slower) control of the blade, as well as reduce the shock load on hoses and valves if the blade edge hits something solid.
The rod end pivot is actually 10 inches from the blade center pivot, not 8 as someone else thought earlier. At that distance, it would take 5883 lbs of force at the blade end to develop enough pressure to exceed the cylinder rating of 3000 psi of a 3 inch cylinder. I'm thinking that Land Pride 1572 blade is going to give before that happens.

A few hours with the welder and I should be back in business.. and a new cylinder, of course...

Thanks again everyone for your help.

Sean

 

[Chilly807]

As the others have said there is really no way to limit it without tearing it apart or then if done not damaging the seals. If it were mine I would re-manufacture the mount on the blade end of the cylinder to get the geometry right.

Another easier way would be just to make a limit stop or chain to prevent the blade from moving too far.

Chris

I thought about doing that Chris, but it's hard to make the stop strong enough to withstand the force and still be able to easily move it to reverse the blade. The chain would work, but as I mentioned earlier, I may take the opportunity to strengthen the whole set-up and make it safer at the same time.

I think I'll move the base end anchor point, the blade end is hard to do much with, there's not much out there to anchor the bracket to.

Sean

 

[Chilly807]

Hello Chilly, Craig,

What you need is an "internal stop tube" for your cylinder;

The external cylinder rod locking rings have habit of damaging the rods over time.


The bronze stop tube fits between the packing gland and the piston of the cylinder tod and rests on the piston when stopped.


it needs to be be made of bronze and must have 1/32 of an inch larger inside diameter than your cylinder rod outside diameter and then you can have it cut to length.

The stop tube will be 8 inches long and it will slide up and down the rod while the rod is moving and will cause no internal damage to the cylinder rod, packing, o rings valves etc.

If you have hydraulics repair shope nearby you can have them install the stop tube for you as they will have access to bronze from many suppliers or you can buy bronze blanks from Mcmaster Carr and others for the bar stock.

That's pretty much exactly what I was thinking originally Leon, just wasn't sure if I was going about it the right way. Now the guys have me thinking in another direction that will work well too.

Sean

 

[leonz]

Hello Chilly,


The stop tube will give you the protection you need and the flow and pressure will not be diminished; and the stop tube will displace the amount of oil it replaces and the stop tube will become a larger load bearing surface for you for the functione that the cylinder is used for.

The item you need for this is a pair of deceleration valves that control the velocity/speed with which the rod travels and that that slows the rod end of the attachment to a crawl to slow it down until it stops.



The new OEM replacement cylinder will not require any modification nor a new shorter cylinder to be messed with and to have new mounting plates/cylinder base weldments.

A shorter stop tube can be used as the rule is "one inch of stop tube for every foot of extended length" and you will have no further problems


Short of anyhing else a 2 way needle valve will also reduce the problem to zero and the cylinder will be slower in operation and that will avoid any issues with bending as the cylinder will have its power limited to the flow allowed by the 2 way needle valve.

 

[wdchyd]

Hello Chilly,



The item you need for this is a pair of deceleration valves that control the velocity/speed with which the rod travels and that that slows the rod end of the attachment to a crawl to slow it down until it stops.

Can you elaborate on your advice here, where to buy these...??.....:confused2:

Or are you talking about "cushions" built internally in more expensive cylinders..??...:confused2:

 

[wdchyd]

Short of anyhing else a 2 way needle valve will also reduce the problem to zero and the cylinder will be slower in operation and that will avoid any issues with bending as the cylinder will have its power limited to the flow allowed by the 2 way needle valve.

How about teaching us how this works also....:confused2:........:mur:

How does a "2 way needle valve" limit power to avoid bending a hyd cyl to zero problems...... .....??

Do cyls bend from too much flow..??......:thumbdown: