new backhoe need help bad

[case646]

Ok guys im new here and need some help bad i built a back hoe for my case tractor and it looks great will post pics later but i went out to the back forty and pulled a bunch of cylinders off of my old combine to use on the hoe. My question is can i use them on the hoe they only have 1 port comeing out of the cylinders. All the cylinders i have ever used have duel ports why do they only have 1 i have all the valves for them was just trying to figure this out thanks for any help

 

[R W]

Don't think they would be suitable for a BH, seems like they are single acting cylinders, also doubt if they would be robust enough to stand up to BH work overall.

 

[ricky racer]

The cylinders you are describing are single acting cylinders (one port) the two ported cylinders are double acting. Double acting cylinders use hydraulic pressure to both extend and retract the cylinder. As you may guess the single acting cylinder has hydraulic pressure applied to one direction (usually extending the cylinder). The single acting cylinders are only supplied with hydraulic pressure in one direction usually because another force (gravity, spring or a mechanical force depending upon the application) will return the cylinder to the retracted position.
In your application (the backhoe) I'm sure that you will want double acting cylinders. A single acting cylinder will extend the backhoe and the weight of the backhoe arm will allow the cylinder to retract, when the valve is shifted to a neutral position, but will be unable to create down pressure making it pretty much useless.

 

[Renze]

In your application (the backhoe) I'm sure that you will want double acting cylinders. A single acting cylinder will extend the backhoe and the weight of the backhoe arm will allow the cylinder to retract, when the valve is shifted to a neutral position, but will be unable to create down pressure making it pretty much useless.

Over here in Holland we used to have backhoes from the early 60's which had a clamshell bucket, and single acting lift cylinders. Modern backhoes, even with clamshell bucket, are double acting. Indeed, with a standard scoop type bucket, single acting cylinders will make it unable to penetrate anything else than old, well rotten muck.

 

[case646]

ok thank you i get the point of a single acting cylinder now please excuse me of my ignorance but i am new with hydralics my neighbor is a machinist and i was wondering if he could drill and tap me a new port on the single cylinder and would it then work as a double acting set up it would cost me nothing more than a case of beer to get him to do this.thanks for all the help

 

[bobodu]

That would depend on the guts of the cylinder. Some would allow this and others would not. The piston design and the type of seal on the ram would have to take this kind of pressure.
Also,you may need to beef up an added port with a flange welded onto the outside of the cylinder for the hose.Often times,single action cylinders just have a slot or small hole for air to enter and escape.

 

[jenkinsph]

I think you would be better off buying the proper sized cylinders for your applicaion. I would be doubtfull that you could find the needed variety of proper bore and stroke cylinders from an old combine even if they were dual acting cylinders. You need about 7 cylinders to build the backhoe complete and that is some serious money.



Steve

 

[Taylortractornut]

Single acting cylinders can be used on the swing. My old 75 3550 Ford hoe with a 14 foot depth uses 2 single acting cyliners to pull on the ends of a large chain to swing it. Also some other makes use them directly on the swing post to swing them I thin it was on my brother late model Ford that had them like that. When I was younger I worked as a machinist in a hydraulics shop. We often converted single acting cylinders to doubles on farm upgrades and other projects. usually just drilling out the air hole and welding on a prethreaded port fitting. We also had to add a set of chevron seals on the piston to make them take pressure on the new side. Most of the time this was on a fiber/plastiv packing. Thats probably what your combine cylinders have in them. Im about to build a small logging trailer with 2 header lift cylinders off a 300 MF combine with a double chain and sprockets from the same machine to make my knucleboom swing.