How to grease a bearing without overfilling 2

[mdossaji]

I have a connecting rod designed with a plain spherical roller bearing with both sides sealed with a shaft seal. In the con rod I have a grease fitting for applying grease once the con rod is installed on to the crankshaft. normal amount is around 20 manual pumps.

My concern is that during greasing, the air trapped inside the conrod housing creates excess pressure and pushes the seal out of the housing.

Is there a way to remove the air pockets while the bearing is being greased? Also is there a grease fitting available that will prevent excessive greasing?

 

[MikeHalloran]

Lever action grease guns are capable of thousands of psi. The air doesn't create excess pressure; it just transmits what the grease gun applies, softly. Consider using/ specifying a direct action grease gun; no lever.

As for removing the air, you could evacuate the grease reservoir prior to initial greasing. It's probably simpler to provide a bleed; a second channel opposite the grease fitting, equipped with a plug that you loosen or remove while injecting grease, to vent air or old grease.





Mike Halloran
Pembroke Pines, FL, USA

 

[unclesyd]

Instead of a plug you might consider a pressure relief valve. It is not idiot proof but it makes an attack on the system a little harder to achieve.
20 strokes on a lever hand pump is a lot of grease for a bearing system. As stated above normal hand operated grease pumps are capable of significant pressure so you might want to consider a lower pressure pump.

Can you come back with a little more details of your bearing.

http://www.alemite.com/catalog/details.aspx?identifier=fittings_relief

 

[mdossaji]

Please see attached picture of the double row spherical roller bearing. Its a 80/40/23 sized with shaft seals on each end. The reason we are applying 20 strokes is because of the open cavity between the bearing and the seal housing.

Thanks

 

[unclesyd]

Appreciate the information.

Just a question, What do the seal lips run against?

The twenty strokes on the grease gun indicated to me that it was small volume per stroke high pressure system. This was the reason for my question.
Watch your grease selection with your setup.

 

[mdossaji]

The lip seal runs against a crankshaft.

I am afraid that the grease will begin to leak through the relief valve before it begins to fill the cavity.

 

[diskullman]

There are greasefittings with a built-in pressure relief up the side on the threads. You are a prime candidate for a Lubesite unit. A relatively inexpensive automatic grease feeder. It takes out the guess work ensuring proper lubrication and you can see when it is low .

http://www.bijurdelimon.com/products/product/lubricators/Single-Point/LubeSite-200-Series.html

Russell Giuliano

 

[unclesyd]

The Lubsite unit was my first choice until viewing the drawing. Based on my experience a Lubsite unit on a reciprocating component is subject to failure if there is any speed involved.
With this configuration even getting a vent plug to function is going to be a problem.

 

[mdossaji]

I am using a spherical bearing that tends to twist the con rod during operation causing my seals to leak. See attached picture. Any idea as to how I can maintain the perpendicularity of the con rod to the crankshaft under 1800 RPM?

 

[Tmoose]

could be a function of thrust washers fitted to one end of the rod or the other.
For axial guidance Moderately unusual at the wrist pin end as shown here -

http://czmadness.net/techdata/73Manual/73manual05.jpg

pretty typical at big end as shown here -

http://www.ellweinengines.com/ERE15/windage2.jpg

lubrication will require some thought, although life is a little easier at the pin end where motion is << 90 degree oscillation instead of continuous rotation, which is part of why high revving 2-strokes used the pin guided instead of crank guided

 

[MartinSr00]

ULTRAPROBE® 201 GREASE CADDY

http://www.uesystems.com/prod_up_201.asp

I came across this device during some vibration training at our company. It allows ultrasonic "listening" to the grease entering a bearing and is supposed to prevent over-greasing.

Maybe it has some merit? I have no experience in this regard.

 

[MikeHalloran]

You clearly need cheeks on the crank, rubbing on the con rod faces. The bearing is mis-named; it's not really self-aligning; it tolerates misalignment, not the same thing.

Why is the crankpin so very long?



Mike Halloran
Pembroke Pines, FL, USA

 

[mdossaji]

Mike,

The crank is long to accommodate extra con rods. Do you have an example of a cheek on the crank?

Thanks

 

[MikeHalloran]

Huh? EXTRA con rods?

No matter. The 'cheek' is a radial surface that's located near a normal crank's crankpin. In a built-up crank, the cheek may be just the face of a plate or counterweight. In a single piece crank, cheek may refer to the radial ground bearing surface adjacent the crankpin, or to the forged or cast surface that's nearby and mostly parallel to that radial surface.

In your case, you could press or clamp some sturdy rings (like a con-rod's big end without the rod) on the cylindrical surfaces adjacent the bearing, so the con-rod can twist a few thou, but no more.



Mike Halloran
Pembroke Pines, FL, USA

 

[diskullman]

You may want to try a McGill Spherical Roller bearing with integral seals. You may have to keep the old seals for spacers.

http://www.emerson-ept.com/eptroot/public/prod/dynamic_frame.asp?strMain=http://

http://www.emerson-ept.com/EPTroot/Public/bnames/mcgill/mcgill.htm

Russell Giuliano