angular contact ball brg.

Just a question - are you stating what you see in the field? Do you have access to the operating/maintenance manuals?

Most centrifugal pumps that I have worked with, when angular contact bearings are used, is that they are installed in pairs (either back-to-back or face-to-face) on the motor side with a "floating" bearing on the pump side. This is to allow for thermal expansion of the shaft into the pump, rather than into the motor/coupling.

Is it possible that your bearings have been installed wrong?

yes i saw in the field and then i refered the manual

bearings are the same one pump motor side there is 6309 ball brg. and pump side 5309 brg.

another pump motor side 5309 and pump side 6309

and what is this back to back

and face to face

which type of brg are floating type

please explain me

Without seeing something from the pump manufacturer, this is only a guess.

The 5309 bearing is twice as thick, with two rows of ball bearings. This bearing should be the one closest to the impeller, to resist the thrust loading from the impeller.

Who is the pump manufacturer?

What is the model number of the pump?

both are pumpetravini make

1)pump type: MC/S 12530/1 -B/A3

2)Pump type: MCU-CHT 50 15/R-A3

Try their web site. http://www.pompetravaini.it/

Angular contacts have a marking on the outer race that shows the direction of the thrust load. Back to back doubles the thrust load that the bearing can carry in one direction. Face to face allows the 2 bearings to carry thrust in both directions. If these markings are absent you can look at the edge of the races - one edge will be thicker - this is the side that carrys the thrust. Ed K

Guest - you are talking about a tandem arrangement where both bearings face in the same direction, take double the thrust in one direction but none in the opposite direction. Back to back and face to face are terms commonly used, but I prefer the terms "O" and "X" arrangement, which both accommodate equal thrust in either direction, but have different fixing methods and the "O" arrangement is stiffer.

i still dont understand this concept of back to back or face to face

and also o and x type arrangement

another thing i want to show 3309 brg. one side it has printed k... is that the thrust side ? how could i know the fitting of it. you can see top of the bearing there is notch both on inner race and outer race.

another side of bearing there is printed k... what is that mean.

Not sure why I am answering this as you can find everything you need to know on the websites of companies like FAG. SKF etc.

Look up angular contact bearings and look at the arrangements. It becomes obvious which is X and which is O.

What you show is a DOUBLE row angular contact bearing. Its only advantage over two angular contact bearings is its smaller axial dimension. Your bearing has filling slots which I do not like. The suffix A (SKF) would give you a bearing without filling slots. Set it up so that your expected thrust direction is such as not to try to push a ball out of a filling slot. By the way 3309 bearing is in O arrangement.

After thinking about it for a while, I have come up with the following possibility. Products are made to normally meet certain operating conditions, some can handle a wide range while other have to be more specific. And as the angular contact bearing is there for thrust purposes, I would like to suggest that the same pump is designed to meet different operating conditions, for example, working under head pressure, or pumping a heated fluid. So if this is the case, the manufactures manual and specifications should tell you. Where as it may not point out the position of the contact bearing, it should state which model is used where and under what conditions.

Regards JD.

Please, we are tooking about a betwen bearings pump?