Dumb question

JerryS

Well-known Member
Does the piston of a log splitter has the same force on the return stroke as it does on the forward (splitting) stroke?
 
Assuming that the push to split is from extending the cylinder, the force will be more on the return (retraction) stroke since there will be more area for the pressure to work against. On the extension side, the rod reduces the area that the pressure has to push against.
 
You got that backwards.

The piston end has greater area so it can have more force applied.
The rod end the area is reduced and so is the force.
In reality I don't know if you could notice it ?
 
Basic hydraulics. force converted from hyd pressure =PSI times area. the force exerted by pushing the full area of the piston is greater than the force exerted by pressure on the piston minus the area of the rod. A bit of practical information, if the wedge is pushed into the wood you get less split pieces jumping away from the splitter. Found this out the hard way.Have a couple of dents in the truck bumper.We split with a home built unit ,old garbage truck cyl ( 7 inch ) and pump. Power with an old Chevette engine.
 
Score so far
2 correct answers
2 wrong answers
1 wise cracker

There is less force on the return stroke due to the rod area subtracted from the piston area

Make that 3 correct answers
 
Yes, I have some really nice leftover walnut and maple firewood. I want to unsplit the billets in alternate sequence to produce slabs from which I can make tabletops and cutting boards with a checkerboard pattern.
 
generally speaking hydraulic or pneumatic. There are some varibles first to consider. A general answer would be extend has more force due to the piston head being a little bigger than the returen head. The larger head gives it more pushing force.

Now the point of being varied just a couple of mentions. Fluid being egual pressure and flow egual volume on both sides of pump,cylinder ends, valve and hoses. the force should be greater due to surface of piston on the extend applocation.

Now the return will be faster then the extend also because of this surface differences.
 
You are right; I visualized it backwards. You are correct that the difference might not be noticeable unless it is a special cylinder with a large center rod, if the load is approaching maximum capacity in both directions.
 
No such thing as a dumb question. You can get some dumb answers though. What is it they say? the only dumb question is the one that doesn't get asked.
 
I hope you know that I wuz joshing!
You see I failed the Red Skeleton crash course on how to be funny and had to strike oot on my own, that is why I didn't give up my day job.
'Auf wiedersehn!'
 
Double acting cylinder does not care if it is pushing or pulling same force either way
 
No the return stroke has LESS force then the forward push stroke. Still enough force on the return stroke to crush your hand, or whatever is in the way.
 
The area of the piston head on the tail end of the cylinder has more surface area due to the lack of area being taken up by the mass of the cylinder rod. That being the case the cylinder will have more force pushing on the forward stroke than it will on the return stroke.

Below is a chart of various sized cylinders, with various sized rods, and the force they will have both pushing (pressure on tail end/no rod) and pulling (pressure on head end/with the rod).
Cylinder force chart
 
An extending cylinder always has more force than a retracting cylinder due to the lost area of the rod. A backhoe is a prime example, the bucket is made to dig.
 
You are right & anybody that wants to prove it, just put a T in the pressure line & hook it up so you put pressure to Both ends. The piston will slowly push the rod out.
 
You can observe how hydraulic cylinders are installed on a piece of equipment. On cylinders with a piston attached on one end of rod, will always have more force for the reason already mentioned.
If there is one rod with piston attached in the center of the rod and is a double action cylinder design---force will be the same.
 
The rod of the cylinder takes up a lot of surface area so the retracting stroke has much less power due to the decreased surface the oil has to push against. Extending it has the entire surface to push against.
Sorry Old...you ARE wrong.
 
I think you do well at wise cracking myself, much better than some are at giving serious (and correct) answers, Haha!
 
Some people say it can be more power on the retract than when it's extended, but I disagree. I've heard people say, it's more on retract because counting the surface of the shaft and the piston, there's more area for the force to be applied to. I disagree with that line of thought because, the extra area where the force can be applied will not be under pressure in the direction of retraction travel. Only the pressure applied to the piston surface is in the direction of travel.

More importantly, the volume of fluid it takes to retract the shaft is much less that the volume of fluid it takes to extend it, so think of it like going into granny gear. You are geared down so you have more power extending than retracting.
 

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