Pressure Inside a Gearbox

The reason a pressure gauge cannot be screwed onto it is what, please?

yes normally there is no pressure gauge installed to measure the inside pressure.

Then install one.

normally in these types of gearboxes pressure gauge is not installed to measure the pressure as the pressure created inside is very less. Moreover breathers are provided for the same.

OMG!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Moreover breathers are provided for the same.

Breathers (Lungs) + Pressure (Blood) = CO₂ Exchange ?

I told several times (in my actual avatar not as guest) people do not pause for a moment and think before typing the question.

What is happening to the main capacity that differentiate humans from others ? the capacity to think, infer and induce ?

People are LAZY! And ignorant, too. More and more people want us to do their jobs or homework for them. The sad thing is, they think it's OK.

Also being busy I logged in just a bit late. can OP just explain what is causing the pressure in the afore-said gear box ?

In case it is one of the current ones, it must be a horizontal planetary. This is externally lubricated and most of the lubrications are spray. Also it is not only the breather, most o the seals are supposed to be labyrinth (at least of the designs that I am aware of)

Internal Pressure (Spray Lubricated+ Labyrinth seal + Breather) = ?

I feel it must be about 2 bars (the pressure of the Spray Lube System).

<....just explain what is causing the pressure in the afore-said gear box...>

Is it the rise in pressure owing to a rise in temperature within a closed space? Surely these things are designed to withstand it? If not, then they will leak. If they are, then why is it of any interest?

So the the pressure inside the gearbox is nearly 2bar w.r.t atmosphere; i thought it is around 20mm of water just like in the case of I.C engines.

thanks

That was a joke,

as all others have pointed out. If the design is similar to what we make, it is absolutely and purlely atmospheric. No plus or minus except some momentary transients of a few mili or microbars may be.

BTW: I am sorry for the sarcasm, I thought you will get it.

Remember- Breathers are used for compensating for high/ low pressure. So if there is a breather, that compartment will have atmospheric pressure. Ditto for labyrinth seals (unless it is a high speed machine, and special labyrinths- eg gas Turbines are with pressurised labyrinth sealed, but there is a pressure within chamber) but that is not your case.

What's your problem? He is correct!

I think it is not required as the pressure is very less;

moreover i replied to this yearlier.

These are breathers. With these, there is only atmospheric pressure inside the crankcase.

About 15 psi...

Ignore some of the ruder posts. They mean well or they mean?

There is no one simple answer to you question as each gearbox is different. A pressure build up, or just as likely a vacuum, due to oil flow and windage in a large gearbox can cause many problems, usually of labyrinth leakage, foaming, contamination,varnish formation/oxydation etc..

Nearly all of these gearboxes have breathers. If not fitted, they will all have plugs on the top of the box to accommodate a breather if required/desired.

Using a simple rubber or cork plug with a piece of clear plastic tubing fitted through it install this into the vent/breather/plug. Put in some water (into the tube, not the gearbox) and form a simple u tube. Measure the distance between the levels - you have your answer.

yes, i can use a tube(u-shape) filled with water; one end to the gearbox and another end will be open to atmosphere to measure it.

Thanks

if ur breather chokes then pressure will increase inside and will burst ur oil seals.

other wise if breather is clean then there is no pressure or atm pressure inside

In some cases gear boxes are not shipped with the breathers installed as there may be many different possible mounting positions. Often the persons completing the installation fails to install the breather.

Regardless of what the oil system pressure is, the pressure inside the case itself should be minimal as measured with a slack tube. Most pressures, positive or negative will be due to temperature changes in the oil.

If you do not have a breather handy, there are several ways to accomplish an installation while keeping contaminates out. One that I like personally is using on large boxes is a "spin-on" type oil filter... When you install it on the top of a box with a pipe nipple you allow the box to "breath" and you also keep contaminates out. Other methods that work well on smaller installations are as simple as a length of copper tubing coiled into several loops.