Cushioning a bucket cylinder

[638]

When I dump a load out of my FEL bucket, the bucket hits the stops very hard. I have had to reweld the stops on the loader arms. What I would like to do is machine a new piston to include a cusioning effect on the extended end of the stroke. What I don't know, is the clearance needed between the cylinder and the cushioning end of the piston. This is on a BX23, which has only one bucket cylinder.

 

[oldnslo]

When I dump a load out of my FEL bucket, the bucket hits the stops very hard. I have had to reweld the stops on the loader arms. What I would like to do is machine a new piston to include a cusioning effect on the extended end of the stroke. What I don't know, is the clearance needed between the cylinder and the cushioning end of the piston. This is on a BX23, which has only one bucket cylinder.

Not sure what clearance you will need but to figure flow through an orifice the formula is:

Q = 24.12A *(square root of pressure drop)

Q = flow in GPM
A = area of orifice in inches squared.

Example: .093 diameter orifice at 1000 PSI will pass around 5 GPM

Another possible simpler option is putting an orifice in the rod end fitting. This will have to be sized so that it limits dump speed but does not limit curl function. Since these are regen dump circuits you will have to figure out extend volume on the cylinder in regen mode. To do this measure you rod diameter and then figure extend speed using the rod area and pump volume.

Cylinder velocity in inches per second is figured with the following formula:

Q = VA

Q = flow in cubic inches per second To convert GPM into cubic inches per second multiply GPM by 3.85
V = Velocity in inches per second
A = area in square inches.
Roy

 

[J_J]

I believe there are stroke limiters that go inside the cyl to limit rod travel.

or

Just pad the stops with thick rubber.

 

[PapaPerk]

When I dump a load out of my FEL bucket, the bucket hits the stops very hard. I have had to reweld the stops on the loader arms. What I would like to do is machine a new piston to include a cusioning effect on the extended end of the stroke. What I don't know, is the clearance needed between the cylinder and the cushioning end of the piston. This is on a BX23, which has only one bucket cylinder.

As was said, pad the stops. No need to tear the cylinder apart.

Also paying closer attention to the bucket position helps too.... in other words let up when dumping the bucket.

 

[638]

I have already installed an adjustable flow valve on the dump side (exaust) side of the cylinder. It makes the dump cycle a little slow.

I don't want to just 'limit' the stroke, as I really need the full dump when loading a pickup or trailer. Would like to just slow down the speed about 1/2 to 1 inch before full dump.

 

[Chas in Mendo]

In industrial practice a cushion is actually a tapered etension on the nut end of the piston and it fits inside a conical depression machined into the butt of the cylinder body limiting the flow as the tapered plug enters the tapered socket. it is a simple comcept but requires a specially designed cylinder. Check with a specialy cylinder manufaturer in your area.

 

[Chas in Mendo]

A good explanation of the types of cushioing systems can be found here;

Cushioning in Hydraulic Cylinders,Hydraulic Cylinder Cushioning,Hydraulic Cylinders

 

[RickB]

Or you could just work on the connection between your brain and hand.

 

[leonz]

Good lord!!!!!!!!!!!!!!!!!!!!!!!!!!!



All you need is a standard cushion valve and a machined stop tube for your bucket cylinders thats all!!!!!!!!!!!!!!!!!!!!!!!!

I have described stop tubes here in great detail previously and that will be more benefitial to you than machining new pistons and less costly as you can
simply bore out a piece of bronze bar stock 1/32 of an inch larger than the outside diameter of the cylinder rod. Bronze is preferred as it will not damage the chrome plating on the cylinder rod. _________________________________________________________________
Once you go flail you never go back:thumbsup::licking::drool:

 

[J_J]

Just bolt or glue some tire tread to the stop plates.

 

[jimgerken]

Good lord!!!!!!!!!!!!!!!!!!!!!!!!!!!



All you need is a standard cushion valve and a machined stop tube for your bucket cylinders thats all!!!!!!!!!!!!!!!!!!!!!!!!

I have described stop tubes here in great detail previously and that will be more benefitial to you than machining new pistons and less costly as you can
simply bore out a piece of bronze bar stock 1/32 of an inch larger than the outside diameter of the cylinder rod. Bronze is preferred as it will not damage the chrome plating on the cylinder rod. _________________________________________________________________
Once you go flail you never go back:thumbsup::licking::drool:

LEONZ, perhaps you could point us to the details on this "stop tube" idea. I did three different searches in TBN under your userid, but was unable to find any detail on what you are suggesting. It sounds like an option my JD backhoe attachment badly needs. When retracting the boom fully, that last half inch of cylinder movement makes the boom jump six inches and hit the stops hard. It is practically impossible to move it slowly enough to keep it from slamming into the park position.

 

[leonz]

LEONZ, perhaps you could point us to the details on this "stop tube" idea. I did three different searches in TBN under your userid, but was unable to find any detail on what you are suggesting. It sounds like an option my JD backhoe attachment badly needs. When retracting the boom fully, that last half inch of cylinder movement makes the boom jump six inches and hit the stops hard. It is practically impossible to move it slowly enough to keep it from slamming into the park position.

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The last time I detailed it was in 2009-10:


The stop tube becomes a huge piston where in the stop tube has a greater
surface area than the actual piston of the cylinder.

The addition of the stop tube to the cylinder adds to the surface area of the
piston and reduces the stresses on the barrel, stuffing box and cylinder rod.


The formula for sizing the stop tube is this.


With the cylinder fully extended you determine the lenght of the stop tube(s)
if mount in pairs and they must have two stop tubes if you have two cylinders.


Now: the preferred material is a round bronze slug which is 1/32 of an inch smaller
in diameter than the inside diameter of the cylinder barrel.

The bore in the bronze slug is 1/32 of an inch larger in diameter than the cylinder rod.


If you have a cylinder that has and extended length of 36 inches you need a stop tube
that is 3 inches long. you will loose three inches of stroke but in the scheme of things
you will not notice it.

If you have a partial measurement that is less than one foot add one inch
of stop tube length to the total length to achieve the proper size stop tube(s).

The preferred material is bronze simply because the bronze will not damage any of
the valves as it is very soft.


The bronze stop tube(s) is/are installed between the stuffing box and the piston before you
install it in the cylinder barrel(s).

You can purchase bronze from www.Mcmastercarr.com and other vendors.

If you have a metal lathe you could do your own machining or purchase a Sherline lathe if it
can handle the slug outside diameter.


The Sherline Lathe, Milling Machine and Precision Miniature Machining Page
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Once you go flail you never go back:thumbsup::licking::drool: