pros and cons of brass bearings?


Robert kirkham
 

Having read all the efforts some go to changing out wheel sets in trucks to get just the right rolling characteristics, I've wondered why I don't ever see anyone talk about using brass bearings in the trucks. I see them for sale on many UK OO scale sites - not sure why those modellers needs them and we don't. they come in shouldered and flush mount, in 2mm size. At the same time I've wondered about Tichy nylon bearings.

Any one here done testing or otherwise worked with these products? What worked? What didn't?

Rob Kirkham


dennyanspach <danspach@...>
 

The coefficient of friction between the steel and/or brass axle ends (journals) and cylindrical brass bearings is greater, probably by a significant degree, than that between the same axle ends and the ubiquitous engineering plastic side frames that we mostly deal with these days. Also, it is pretty uncommon these days to have good wheel sets that have cylindrical rather than conical axle ends.

The Tichy nylon bearing inserts are pretty good, and are designed to offer better rolling and wearing characteristics in truck frames made of soft styrene. The downside is that such use commonly results in either trucks that with the inserts are too narrow to accommodate almost any commonly available axle sets, or if they do fit, the truck is far too wide to begin with.

Athabaska made some very fine low profile conical brass bearing inserts designed for styrene E&B passenger trucks, if I recall; and Reboxx also once made some excellent engineering plastic bearing inserts.

All in all, IMHO bearing inserts have little application in the present world of current freight and passenger trucks, but have found limited use with imported brass trucks, and the few trucks still being made of soft plastic.

Denny

Denny S. Anspach MD
Sacramento


Robert kirkham
 

Thank you for explaining Denny. I hadn't realised the friction would be worse with brass bearings.

Seems the only remaining purpose might be to add wear tolerance in RP'd trucks.

Rob

--------------------------------------------------
From: "dennyanspach" <danspach@...>
Sent: Saturday, December 15, 2012 11:15 AM
To: <STMFC@...>
Subject: [STMFC] Re: pros and cons of brass bearings?

The coefficient of friction between the steel and/or brass axle ends (journals) and cylindrical brass bearings is greater, probably by a significant degree, than that between the same axle ends and the ubiquitous engineering plastic side frames that we mostly deal with these days. Also, it is pretty uncommon these days to have good wheel sets that have cylindrical rather than conical axle ends.

The Tichy nylon bearing inserts are pretty good, and are designed to offer better rolling and wearing characteristics in truck frames made of soft styrene. The downside is that such use commonly results in either trucks that with the inserts are too narrow to accommodate almost any commonly available axle sets, or if they do fit, the truck is far too wide to begin with.

Athabaska made some very fine low profile conical brass bearing inserts designed for styrene E&B passenger trucks, if I recall; and Reboxx also once made some excellent engineering plastic bearing inserts.

All in all, IMHO bearing inserts have little application in the present world of current freight and passenger trucks, but have found limited use with imported brass trucks, and the few trucks still being made of soft plastic.

Denny

Denny S. Anspach MD
Sacramento










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spsalso
 

These brass bearing inserts might be very useful for trucks made with soft metal sideframes. I think the old Red Ball/Cape Line trucks were made with soft metal. The Brits may well still be producing this kind of truck. They sometime do things a little differently than us.


Ed

Edward Sutorik


midrly <midrly@...>
 

When I look in the otherwise excellent UK model rail magazines like Model Rail and Model Railway Journal (MRJ authors are as particular about UK steam-era freight rolling stock as we are about North American freight cars--maybe more so), I wonder why Tichy hasn't sold a container or two full of their nylon journal bearings to the Brits instead of those brass journal bearing ("oil box") insert devices that they seem so fond of...

Steve Lucas.

--- In STMFC@..., "Rob Kirkham" <rdkirkham@...> wrote:

Thank you for explaining Denny. I hadn't realised the friction would be
worse with brass bearings.

Seems the only remaining purpose might be to add wear tolerance in RP'd
trucks.

Rob

--------------------------------------------------
From: "dennyanspach" <danspach@...>
Sent: Saturday, December 15, 2012 11:15 AM
To: <STMFC@...>
Subject: [STMFC] Re: pros and cons of brass bearings?

The coefficient of friction between the steel and/or brass axle ends
(journals) and cylindrical brass bearings is greater, probably by a
significant degree, than that between the same axle ends and the
ubiquitous engineering plastic side frames that we mostly deal with these
days. Also, it is pretty uncommon these days to have good wheel sets that
have cylindrical rather than conical axle ends.

The Tichy nylon bearing inserts are pretty good, and are designed to offer
better rolling and wearing characteristics in truck frames made of soft
styrene. The downside is that such use commonly results in either trucks
that with the inserts are too narrow to accommodate almost any commonly
available axle sets, or if they do fit, the truck is far too wide to begin
with.

Athabaska made some very fine low profile conical brass bearing inserts
designed for styrene E&B passenger trucks, if I recall; and Reboxx also
once made some excellent engineering plastic bearing inserts.

All in all, IMHO bearing inserts have little application in the present
world of current freight and passenger trucks, but have found limited use
with imported brass trucks, and the few trucks still being made of soft
plastic.

Denny

Denny S. Anspach MD
Sacramento







[Non-text portions of this message have been removed]



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Mikebrock
 

Denny Anspach writes:

"Athabaska made some very fine low profile conical brass bearing inserts designed for styrene E&B passenger trucks, if I recall; and Reboxx also once made some excellent engineering plastic bearing inserts."

I have at least one pair of Eastern Car Works 70 ton trucks operating on a UP CH-70-1 [ covered hopper ]. This truck is made of "soft" plastic, is without any insert, and the metal wheels are expected at some time [ no doubt during an op session ] to cause a hot box...thus spreading the unhappy car's contents on Sherman Hill...probably in Brucef...uh...Buford. Believing that realism is to be welcomed, I look forward to this event...although I doubt the population [ 1 ] of Buford will be as pleased.

Mike brock


Bruce Smith
 

The ever resourceful folk of Bruceford have been known, as were many other lineside dwellers in the steam era, to salvage the contents from wrecked freight cars. Hopefully, the cargo of said hopper might be useful...

Regards,
Bruce

Bruce Smith,
Auburn AL (and sometimes Buford)

________________________________________
From: STMFC@... [STMFC@...] on behalf of Mike Brock [brockm@...]
Sent: Saturday, December 15, 2012 5:57 PM
To: STMFC@...
Subject: Re: [STMFC] Re: pros and cons of brass bearings?

Denny Anspach writes:

"Athabaska made some very fine low profile conical brass bearing inserts
designed for styrene E&B passenger trucks, if I recall; and Reboxx also once
made some excellent engineering plastic bearing inserts."

I have at least one pair of Eastern Car Works 70 ton trucks operating on a
UP CH-70-1 [ covered hopper ]. This truck is made of "soft" plastic, is
without any insert, and the metal wheels are expected at some time [ no
doubt during an op session ] to cause a hot box...thus spreading the unhappy
car's contents on Sherman Hill...probably in Brucef...uh...Buford. Believing
that realism is to be welcomed, I look forward to this event...although I
doubt the population [ 1 ] of Buford will be as pleased.

Mike brock



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http://docs.yahoo.com/info/terms/


Barrybennetttoo@...
 

Here in the UK the underframes sold for freight cars tended to be moulded
in styrene type plastics, so the brass bearings are to protect the axle
boxes against wear. Much of the newer stock is moulded in engineering type
plastics as in the US market so the brass bearings are becoming very much of an
anachronism.

Barry Bennett
Coventry, England.

In a message dated 15/12/2012 05:17:33 GMT Standard Time, rdkirkham@...
writes:




Having read all the efforts some go to changing out wheel sets in trucks to
get just the right rolling characteristics, I've wondered why I don't ever
see anyone talk about using brass bearings in the trucks. I see them for
sale on many UK OO scale sites - not sure why those modellers needs them and
we don't. they come in shouldered and flush mount, in 2mm size. At the
same time I've wondered about Tichy nylon bearings.

Any one here done testing or otherwise worked with these products? What
worked? What didn't?

Rob Kirkham

[Non-text portions of this message have been removed]


Des Norman
 

Hi all,
Again in the UK, steam-era freight stock was predominantly 4-wheeled with say a 10-12ft wheelbase. The sprung axle boxes were mounted on separate frames (W-irons), one at each corner.

In model form the axle boxes are often in plastic or white-metal and the axle holes are not necessarily true. So these are drilled out and brass bearings inserted. Some modellers include individual springing, or, particularly in Scalefour (the equivalent of P87), to ensure the 2 axles are parallel but can also cope with any uneven track, the axle at one end and its W-irons are mounted on a subframe which can pivot on the longitudinal axis of the vehicle.

Des Norman
Perth, Scotland

Posted by: "Barrybennetttoo@..." Barrybennetttoo@... barryb2again
Date: Sun Dec 16, 2012 4:21 am ((PST))

Here in the UK the underframes sold for freight cars tended to be moulded
in styrene type plastics, so the brass bearings are to protect the axle
boxes against wear. Much of the newer stock is moulded in engineering type
plastics as in the US market so the brass bearings are becoming very much of an
anachronism.

Barry Bennett
Coventry, England.



In a message dated 15/12/2012 05:17:33 GMT Standard Time, rdkirkham@...
writes:




Having read all the efforts some go to changing out wheel sets in trucks to
get just the right rolling characteristics, I've wondered why I don't ever
see anyone talk about using brass bearings in the trucks. I see them for
sale on many UK OO scale sites - not sure why those modellers needs them and
we don't. they come in shouldered and flush mount, in 2mm size. At the
same time I've wondered about Tichy nylon bearings.

Any one here done testing or otherwise worked with these products? What
worked? What didn't?

Rob Kirkham


Monk Alan <Alan.Monk@...>
 

Hi Rob,

Y'know... I'm not entirely sure why we use them either!

Okay, on etched brass kits, they do provide a better bearing surface than just a hole in thin etched brass sheet (on our 4-wheel wagon underframes), but we also use them on plastic-chassis'ed kits, though this is a more recent thing - I certainly recall plastic kits without them, back when I started (30+ years ago).

And most of our RTR rolling stock just has the pin-points running in the plastic underframe or trucks/bogies without bearings.

It could be a wear thing, though my oldest UK stock running on pinpoints in its plastic chassis show little obvious signs of wear

Most brass bearings are coned internally to suit a 'standard' pin-point axle, externally they are 'top-hat' or 'waisted' style - the top hat version is cylindrical, approx 2mm diameter and 2-3mm long. They get inset into a 2mm dia hole drilled or moulded into the axlebox. The waisted ones have a much smaller, stepped exterior to allow fitting where there isn't as much 'meat' to drill or mould into.

There are some that are parallel bearings, bored 1mm through to take a 1mm axle (non-pinpoint). More prototypical, but they haven't really taken off.

But... rolling resistance is greatly reduced with pinpoints and brass bearings, so our locos can haul more/we don't have to load our locos (and motors) with so much lead.

And don't forget that we're not as obsessed about car weight as you guys seem to be - I run my finescale UK stock (built to 'EM' standards, though I have dabbled in 'P4' exact scale, our equivalent to P87) weighted to approx 1oz/25g *per axle*, without problems, ultra-fine flanges and all - it's that consistent weight per axle that is the key to good running, I've found. On my O gauge stock, I up that to 2oz per axle.

HTH,
Alan Monk,
London, UK



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Robert kirkham
 

Thanks for this note Alan.

I note your observation that rolling resistance is greatly reduced with pinpoints and brass bearings has the appearance of running contrary to Denny's observation about the coefficient of friction of brass bearings and metal wheel-sets. Not trying to get anyone worked up, but I am wanting to understand this well. It seems to me a pin-point contact between any bearing material and axle will have considerably lower friction than a cylindrical bearing - and if that was the comparison you were making, I follow. But it isn't immediately obvious to me that the coefficient of friction applicable at a pin point bearing is meaningfully affected by the materials because it is a pint point. Is there some data out there that shows this is not so?

Rob Kirkham
--------------------------------------------------
From: "Monk Alan" <Alan.Monk@...>
Sent: Tuesday, December 18, 2012 3:18 AM
To: <STMFC@...>
Subject: [STMFC] Re: pros and cons of brass bearings?

Hi Rob,

Y'know... I'm not entirely sure why we use them either!

Okay, on etched brass kits, they do provide a better bearing surface than just a hole in thin etched brass sheet (on our 4-wheel wagon underframes), but we also use them on plastic-chassis'ed kits, though this is a more recent thing - I certainly recall plastic kits without them, back when I started (30+ years ago).

And most of our RTR rolling stock just has the pin-points running in the plastic underframe or trucks/bogies without bearings.

It could be a wear thing, though my oldest UK stock running on pinpoints in its plastic chassis show little obvious signs of wear

Most brass bearings are coned internally to suit a 'standard' pin-point axle, externally they are 'top-hat' or 'waisted' style - the top hat version is cylindrical, approx 2mm diameter and 2-3mm long. They get inset into a 2mm dia hole drilled or moulded into the axlebox. The waisted ones have a much smaller, stepped exterior to allow fitting where there isn't as much 'meat' to drill or mould into.

There are some that are parallel bearings, bored 1mm through to take a 1mm axle (non-pinpoint). More prototypical, but they haven't really taken off.

But... rolling resistance is greatly reduced with pinpoints and brass bearings, so our locos can haul more/we don't have to load our locos (and motors) with so much lead.

And don't forget that we're not as obsessed about car weight as you guys seem to be - I run my finescale UK stock (built to 'EM' standards, though I have dabbled in 'P4' exact scale, our equivalent to P87) weighted to approx 1oz/25g *per axle*, without problems, ultra-fine flanges and all - it's that consistent weight per axle that is the key to good running, I've found. On my O gauge stock, I up that to 2oz per axle.

HTH,
Alan Monk,
London, UK



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The contents of the e-mail and any transmitted files are confidential and intended solely for the use of the individual or entity to whom they are addressed. Transport for London hereby exclude any warranty and any liability as to the quality or accuracy of the contents of this email and any attached transmitted files. If you are not the intended recipient be advised that you have received this email in error and that any use, dissemination, forwarding, printing or copying of this email is strictly prohibited., If you have received this email in error please notify postmaster@...., This email has been sent from Transport for London, or from one of the companies within its control within the meaning of Part V of the Local Government and Housing Act 1989. Further details about TfL and its subsidiary companies can be found at http://www.tfl.gov.uk/ourcompany, This footnote also confirms that this email message has been swept for the presence of computer viruses.
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soolinehistory <destorzek@...>
 

--- In STMFC@..., "Rob Kirkham" wrote:

Thanks for this note Alan.

I note your observation that rolling resistance is greatly reduced with
pinpoints and brass bearings has the appearance of running contrary to
Denny's observation about the coefficient of friction of brass bearings and
metal wheel-sets. Not trying to get anyone worked up, but I am wanting to
understand this well.

Rob,

I think if you re-read Doc's post, you will see he was commenting on brass CYLINDRICAL bearing inserts, since that is the only style of brass inserts we commonly see on this side of the pond. Fitting any truck that already has cone shaped bearings for needle point axles with cylindrical bearings of any material is a step backwards, and I think is the basis for his comments.

The reason the coefficient of friction is still a factor is model trucks are not true needle point bearings. First off, neither the cones or axle ends are sufficiently sharp, Secondly the axle length typically doesn't perfectly match the distance between the bearing cones, and third, the 1 deg. of clearance the NMRA specifies between the axle end and cone bearing typically gets used up accommodating misalignment in the truck. So, what we really end up with is a line of contact, rather than a point, at least in some of the bearings, that constantly shifts from one bearing to the other as the truck tries to accommodate itself to the track.

Dennis