# Questions About Bridgeport J Head Upper Assembly Bearing Lubrication



## Vladymere (Jun 27, 2015)

In the original Bridgeport J head top assembly (image below) where the bearing open or did they have shields?

I can see that the V step pulley bearing pair (items number 5) in the image below may have had shields as it would not have been in an oil bath and there is no way to add lubrication. Would these bearings have a shield on both sides of each bearing or would only the side of the bearing that is on the exterior of assembly be shielded? If these bearings have only a shield on the exterior side of the assembly then what kind and how much grease should be in the middle of the assembly to lubricate the bearings?

What about the bearing assembly on bull gear hub (items61) and the bearings for the bull gear counter shaft (items 51). When this head came from the Bridgeport factory did these bearings have shields? I am thinking that from Bridgeport that these bearings would be open and swimming in an oil bath. The bath being replenished by adding Vactra Heavy/Medium oil through the assemblies Gits cup. It seems that on many of this assemblies rebuilds bearings with shields are used. If bearings with shields are used then are there shields on both sides of the bearings or does only the bearing side external on the assembly have a shield? If both sides of each bearing are shielded then I would think no additional lubrication is necessary. If only one side of each bearing is shielded then what kind and how much grease is to be added in the middle of the bearing pair assembly? If grease is used to lubricate this bearing pair then I would think you would also grease the bull gear teeth and bull gear counter shaft teeth. If grease is used to lubricate the bearings and bull gear then I imagine oil no longer needs to be added to the Gits cup (item 47). This Gits cup could be turned upside down or removed on reassembly.

Does anyone have answers to my questions or opinions they wish to express on this subject?

Thank you,

Vlad

http://www.machinerypartsdepot.com/store/1478157/page/552090


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## Vladymere (Jun 27, 2015)

Gentlemen,

My questions should be answered this coming week as an employee of H&W Machine Repair And Rebuilding (http://www.machinerypartsdepot.com/) has generously offered, in a thread on another site, to allow me to call them and speak to a fellow who has over thirty years of rebuilding Bridgeports heads so as I can get the answers to my questions.

When I have talked to this person I will report what I learned in this thread, if there is an interest for me to do so.

Vlad


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## Inflight (Jun 27, 2015)

Vlad,

Item 5: My machine (circa 1976) has never had the bearing replaced and they are shielded. 

From memory, 51 and 61 are shielded one side. It's been a long time since I had the head appart, so please report back as to what H&W says.  By they way, they have a very detailed printed rebuilding guide available. Well worth the money!

Matt


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## Vladymere (Jun 30, 2015)

Matt, I had confirmation today that your bearings are as they should be.

I spoke with Mr. Barry Walker of H&W Machine Repair and Rebuilding today about the bearings and lubrication of a J head Bridgeport mill.  I stayed specific to the questions I had as his time spent on the phone with me is lost money for his shop, I.E. - if he is on the phone with me he is not rebuilding machinery which is what he is paid for.



Most of my questions where with bearing lubrication and as to weather bearings where to be shielded or not.



What I gleaned was that the spindle bearings both top and bottom, where originally open race bearings.  At the top of the quill there is a round felt “filter”.  This filter fits snuggly both inside the quill skirt and around the spindle shaft.  This filter keeps dirt and swarf out of the quill housing and subsequently the bearings but allows the lubricant added to the gits cup on the quill housing to flow through the filter and down the spindle to the spindle bearings.  This method is a total loss oil system as the oil added will run out of the quill nose cap and be slung by the spindle but that’s OK.



H&W Machine Repair and Rebuilding supplies open race, shielded race or sealed race bearings as requested.  Mr. Walker prefers to use shielded or sealed bearings in rebuilding as can not be sure of the mill being lubricated properly once it leaves his care.



If shielded or sealed spindle bearings are used then the spindle is lubricated for life but the remainder of the quill housing components will still require periodic lubrication.



Moving up the mill we come to the gear box.  Originally, again the bull gear bearings and bull gear countershaft bearings where of the open race design.  Mr. Walker did say that Bridgeport did move to sealed bearings for the counter shaft but in a machine that is 40 or 50 years old you would find open race bull gear countershaft bearings.  The gear box lubrication is again by filling a gits cup with oil.  This oil will, when the gears are turning, splash lubricate the bull gear, countershaft, countershaft bearings and trickle down to the bull gear bearings.



Mr. Walker prefers to use sealed bull gear bearings and countershaft bearings and lubricate the bull gear and countershaft with grease.  These bearings will have a seal on both sides of each bearing.  When this is done there is no need to add oil to the gear case assembly.  Mr. Walker prefers this method as, again, he cannot be assured that the mill will be lubricated as it should be.



Moving to the top, the step pulley assembly, these bearings should be sealed bearings, bearings with seals on both sides of each bearing.



In my case the quill did not have the felt filter though it did seem as there where remnants of felt down in the top spindle bearing.  The top spindle bearing was gritty but I used an ultrasonic tank to clean this bearing and then lubed it up with an ISO 46 oil.  This took the gritty feeling out of the bearing so that it felt fine and I am reusing it.  My gear case had open race bull gear bearings but the bearings and gears where packed with grease.  A lot of this grease had slung out making a mess of the inside of the belt housing as well as the timing belt and V-belt.  As my gear case bearings are still good but of the open race design I will go back to the original Bridgeport total loss oil system for this assembly.  My V-spindle bearings had a shield on only the outside surfaces and grease was packed into the bearings and the cavity between these bearings.  Again, grease had slung out making a mess of things.  These V-elt pulley spindle bearings will be replaced on my mill.



I hope this information on Bridgeport J head bearing lubrication will be of help to others with questions.



Vlad


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## JimDawson (Jun 30, 2015)

Vlad, thank you for that write up.  Very informative.


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## Inflight (Jul 1, 2015)

Thanks for the follow up!  Very informative.


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