most hydraulic cylinders that are discussed here are double acting. Meaning in a nutshell they have two hose fittings, usually one on each end. Remember this and keep in mind how they work.
Inside the cylinder is a piston with a set of seals on it. The seals ride against the inner part of the cylinder itself (the barrel), and the piston rests on the ram rod where it may or may not be sealed. For this discussion I am not going to talk much about the gland (the end where the ram rod comes out) and you'll see why in a minute.
Not all cylinders are created equal....and for a lot of different reasons, the #1 being, cost to manufacture.
So I know we all want a cylinder that is perfectly sealed up and that is not physically possible and here is why. In order for it to be as sealed as posslble at the piston end, a set of tolerances have to be met-and tey have to be extremely tight. The clearance between the piston and the barrel must be held within a few microns. Clearance between the seal groove and the seal must be held very tight. Then the clearance between the ram rod and the piston itself must be held as tight as possible. To get these kinds of tolerances, you are looking at a very VERY labor intensive machining process, which costs a lot more than, for instance, a .001" tolerance. And for the record I don't know what the allowable tolerance is, just using a number for a simple example. To get them sealed up really well, they need to be in the hundred thousandths (.00000) range. Possible? Yes...keep reading.
Then you have different types of sealing systems, Kubota uses several types depending on the application of the cylinder. Many excavators use a much more complex set of seal systems on their cylinders, because that machinery has a completely different set of circumstances than a simple and highly competitive, and much more mass-produced, tractor. The gland end on most of the smaller tractors is fairly inexpensively designed, and it works fine for MOST tractor applications. Same for piston design. They can be designed to seal up a little better but it's going to cost and it's probably also going to be heavier. Remember, we have to tow these things sometimes too. And keep them small enough to be practical.
You take a BX, and let's say you are the manufacturer. You are buying the FEL lift cylinders for, say, $100 each from whoever makes them, or if you (Kubota) are actually making them, let's say $100 to make 'em-in their current configuration. So owners are griping about how they won't stay up after sitting for a few days, and you take note--let's say you (the kubota engineers) decide to make a cylinder that has a much better tolerance stack-up and uses a much more complex cylinder design that will hold for a week on end without issue--and this usually also requires a total change in the hydraulic system of the tractor itself. Now lets say those new style cylinders cost $500 each to make them, plus another $2500 to redesign the entire hydraulic system (grand total $3500)-and add that on top of what it already costs, let's say $25,000 and you add $3500 onto that, so $28,500. Your closest competitor's little baby tractor (1023E?) is also $25,000 but they kept their costs the same, so it's $3500 less expensive with all of the same features. If customers are shopping equipment, who is more likely to get the nod? The cheaper one or the more expensive one? Again, numbers used for example only!
Competition plays into it, as does potential warranty costs, regulations, designed usages, and a bunch of other stuff. Basically it comes down to cost vs the equipment giving an acceptable performance while still being able to last a reasonable amount of time without failure in average applications, while still supplying the manufacturer an acceptable profit margin.
and then we have to define "average usage". For some, that means pushing trees over with a bx. For others it means mowing 3 acres of 4' tall greenery with a push mower.
A tractor/loader/backhoe is a one-size-does-most tool. It does not do one particular j Meaning, those that use their bx's for bulldozers are exempt from "average". ob extremely well, but does a lot of things well enough. Sure you hoe can have a lot more digging power--or you can go buy a mini-ex for 4x the money and dig to your heart's content. Or if you want to push down 4' diamenter trees, a bx can probably do it but it'll take you several days of digging around it.....or you can save time and go buy yourself a used D6 and do it in 15 minutes, at a substantial cost. But can a D6 mow your yard with a belly mower? Can a mini-ex move small loads of dirt around your yard without tearing the yard up? That's where a tractor comes in. A crescent wrench can be a hammer, but not a very good one, yet it can turn a nut where the hammer can't do that very well. You get the idea.
