cylinder direction

bfullmer

Member
Watching video on giant excavator and the cyl.from boom to machine looked odd, the rod end was connected to machine-I have 2 tractors with loaders and they mounted different- is it just a company preference on which direction they are mounted ?
 
Two things come in to play when a manufacture chooses how or which direction to mount a cylinder. Frist on the excavator by mounting the cylinder backward they moved the rod away from the dirt or put it in a safer location then second thing is a cylinder will always have more power as it extends rather than retracting as the fluid is pushing on the complete piston and retracting the diameter of the rod is not working surface.
 
Weather cylinder is rod or tube up won't affect push or pulling force. It's usually done for hose routing or rod protection as you mentioned
 
Market ,I don,t know where you are getting your information but the PULL will always be less than the push how much less depends on the diameter of the rod but in smaller cylinders the pull can easily be 30 to 40% less. THE FLUID HAS THE FULL SURFACE OF THE PISTON ON THE PUSH stroke but on the pull in it is less because of the lack of surface area.
 
It doesn't matter which way the cylinder is mounted, it is still extending to raise the boom. Like Mark said, it has to do with hose routing preference.
Dennis
 
Oil going into the rod end of a cylinder, on top of the piston, has less surface area to act upon due to the rod, and will therefore create less force than the end of the cylinder below the piston. Due to the rod it also takes less volume to fill the cylinder, thus causing the cylinder to move faster for a given volume of oil going in that end -vs- the other end.

As others have said, the reason for putting a cylinder rod end down is nothing more than an engineering decision made based on the attributes they want to exploit.

In other words, if the cylinder will have enough force to accomplish the task at hand using the rod end, they may choose to turn the cylinder 'upside down' and fill the rod end. By doing this, they achieve not only the force necessary for the job, but also do it faster than they would if the cylinder was turned the other direction do to a lower volume of oil being needed to move the piston through the length of it's stroke.

At the same time if the cylinder will do the job 'upside down', and placing it in that position helps with hose routing, protection of the rod, etc, etc, why not install it that way to simplify things?

In any case, as I said, it's nothing more than a decision, made by the engineers, to capitalize on the attributes of the cylinder most needed to accomplish the task at hand.
 
Yes I'm well aware of that, but if you have it rod up vs rod down it's still pulling or pushing to do the same function
 
The first excavators I seen inverted cylinders on were the MC and SC series Poclain round the early seventies and was led to believe it was for neater plumbing and servicing of the cylinders,the performance was still the same extend to lift and retract to lower.
AJ
 

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