What Kinds of Seals are used in High Pressure Hydraulic Cylinders

00:01:42 The Teflon provides a wearing surface

So today we're visiting Seal Jet. Seal Jet is one of our main suppliers of seals.

Specifically for hydraulic cylinder. rebuilds, stripdowns and reseals.

Seal Jet has been in operation for quite a number. of years, there are two parts of their operation

This part of this video is actually going. to show us the standard seals that they have

um items that they buy-in from the manufacturers. and then distribute to workshops like ourselves

So part one let's start so these are actually. Wear Bands, wear bands are designed to support

and prevent metal to metal contact of parts.. So they do that by filling in the gaps between

a metal piston and the metal barrel. These are a. teflon lined bearings, usually you'll find them in

the ends of the rod end clevis on cylinders, . you will actually find that they're pressed into a bored

hole on the end of the Barrel and on the end. of the Rod and the pin actually fits in there,

and obviously it's assisted with some grease. that's usually injected and lubricated in

These are a special little seat actually they are called a Flare ....? it is a special name.

for them can't remember it now um designed to. actually, assist in sealing male to female JIC

hose fittings they're actually. a stainless steel tapered

cone and they're actually coated with a solid. Loctite product so if you don't have quite

the right sealing surfaces these will take up any. inconsistencies whether there's a little corrosion

or some machine marks or even. some indentations caused by

foreign matter getting trapped from the last time. you did it up, they are used a lot in marine applications,

very expensive for what they are but better. than changing out adapters and changing out

hose ends. Here's what looks like a high. pressure rotary seal these will get pressed into

a outer casing of a motor or a pump, some of. them will take quite high pressures depending

on their construction, the shaft will rotate. through the hole, there's rubber but within

the rubber there's actually a metal case that actually supports the rubber. This is a series of

what looks like piston seals made up of probably. five pieces, 5 piece piston seals, this is quite a large

size as you can see that's looking up around. sort of the 5" to 8" inch bore so that's

you know getting up there in sizes. as far as cylinders are concerned.

O-rings lots of different types and sizes. and hardnesses of o-rings metric o-rings

silicon o-rings. This is a four-piece piston. seal, two backing rings on either side you've

got the dark o-ring in the middle which. is like what's called the exciter ring

and then on the outside of that you've. actually got a solid teflon or metal and

metal and teflon composite, so. that's what actually takes up the

the pressure and prevents leakage from one side. of a cylinder to the other side of the cylinder.

Here's a (5) five-piece piston seal,. combination of wear bands the dark thick

bands on the outsides probably. the wear bands they take up the metal

metal to metal clearances so that. there is no metal to metal contact

and then you've got the white bands which. are probably, what they call,

they take up the thrust, or backing rings and. then you've actually got the seal Sealing

ring in the middle which is obviously made. out of a flexible synthetic rubber material

the black and the white items are. probably made out of some type of

hard synthetic nylon-like Acetyl or something like that. Lots of different

types of seals mainly piston seals, what. are we looking at here? Here's some tooling

generally used for seal installation measuring. This is. another type of seal it's actually an internal

gland nut seal or a rod. seal because you can see the

the O-ring is on the outside and then the metal. case or sorry the metal impregnated

synthetic material is on the inside so. this is designed to actually squeeze

in and seal oil from leaking out. through the um the rod or the chrome rod.

As you can see that there is a tiny little. internal groove there that groove that step

actually points to towards the pressure so. this that's actually what we call a rod

seal, so that's designed to prevent oil leaking out. as the rod chrome rod moves up and down in and out

on the inside of that seal. Here's another. type of rod seal an internal rod seal

some different types of wear bands. wear bands can actually come in

different thicknesses and obviously a. continuous length and they're actually cut

to length, but this is how it actually. starts life it starts life as a continuous

role of composite product, . this is probably a bronze

bronze teflon composite type of wear band

different type of wear band again this is. obviously, a Hallite product as you can see

uh Hallite probably world famous for. their products and the unique special

trademarked secret materials that. they use are very very high quality

Hytrel backups backup rings are designed to. actually, support an o-ring they actually go

behind the o-ring so the o-ring sees the pressure. first and the backing ring supports the o-ring and

actually prevents it from extruding out, Hytrel is a type of product that has some stretch so

you don't you can actually stretch these backing. rings into a groove without having to actually

cut or slice them in a diagonal way. I really like the. product a lot of people don't seem to use it i'm

not sure if it's an expense issue or something. like that but i think that they're great!

It just a helps in assembly if. you don't actually have a gap

that can actually pop open as you're. assembling things so this is another type of

rod seal obviously quite a large rod seal for. a large chrome rod on a cylinder looking at the

hand this is probably a 4" to 5" inch rodseal, . the white band there is actually an anti-extrusion ring

it helps support the rod sealfrom ......deforming under high pressures

and the rod again you know it will seal inside a. groove in the gland nut and the chrome rod will

slide in and out of that bore. Here's the other. side of that rod seal so it's also got an internal

support or excited ring probably. designed for very high pressures

generally when you see supports on the. inside as well as supports on the outside

you're probably talking very high pressures. here you know maybe up to 10,000 psi