Flange greasers

[najaB]

As I understand it, flange squeal is caused by the wheel either under or over rotating when the train is going around a curve, due to trains having fixed axles. What I'm wondering is if it is in any way harmful to the wheel, or are flange greasers solely used to reduce complaints about the noise?

 

[edwin_m]

Any kind of movement with friction involves wear to the surfaces concerned, so both the wheel and the rail will wear. It is likely an unlubricated rail on a tight curve will have a shorter life than rails elsewhere, but for wheels it is just a contribution to general wear so not really noticeable.

 

[lineclear]

Flange squeal is caused by the wheel flanges rubbing against the gauge face of the rail. Wheel flanges do not normally come into contact with the running rails; this only happens on tight curves. It's not necessarily that the wheel is under or over rotating, but that it is at an angle to the rail - hence pacers squeal on curves where bogied stock does not.

Lubricators reduce rail wear and reduce the risk of derailment due to flange climb.

 

[najaB]

Any kind of movement with friction involves wear to the surfaces concerned, so both the wheel and the rail will wear. It is likely an unlubricated rail on a tight curve will have a shorter life than rails elsewhere, but for wheels it is just a contribution to general wear so not really noticeable.

That's a point - I wasn't thinking about the rail - so they may well be provided in 'isolated' places so as to prolong the life of the rail.
--- old post above --- --- new post below ---

t's not necessarily that the wheel is under or over rotating, but that it is at an angle to the rail - hence pacers squeal on curves where bogied stock does not.

In my head at least, fixed axles means that it kinda is. The fact that the wheels can't independently follow the rail geometry means that at least one of the wheels on each axle is forced to either under or over rotate. If the curve is severe enough, the conical shape of the wheel isn't enough to compensate so the wheel ends up with the flange in contact with the rail - but I get what you mean.

 

[theageofthetra]

Re flange climb - isn't that what happened in that low speed ECS HEX derailment at Paddington the other year?

 

[edwin_m]

Re flange climb - isn't that what happened in that low speed ECS HEX derailment at Paddington the other year?

https://www.gov.uk/raib-reports/derailment-of-an-empty-passenger-train-at-paddington-station

Yes, although the case of flange climbing there (on straighish track) was poor setup of the suspension meaning there was very little weight on one of the wheels.

Flange climbing is more common on curves where the lateral forces experienced by the train can cause the flanges to ride up the corner of the rail. The friction between the two also contributes, and flange greasers can also help reduce this type of derailment by making the rail more slippery - see the Ordsall derailment report.

https://www.gov.uk/raib-reports/locomotive-derailment-at-ordsall-lane-junction-salford

 

[Mugby]

Flange lubricators are primarily to counter side cut to the rail. You'd be surprised how many flakes and shards of metal are cut off the running edges of rails on sharp curves by wheels, especially when the rail is new.

 

[derailed]

Greetings!

Does anyone know which wheel flange lubrication systems are most popular in the UK?

 

[civ-eng-jim]

Greetings!

Does anyone know which wheel flange lubrication systems are most popular in the UK?

Whitmore Rail provide various systems and LBFoster

 

[civ-eng-jim]

Any kind of movement with friction involves wear to the surfaces concerned, so both the wheel and the rail will wear. It is likely an unlubricated rail on a tight curve will have a shorter life than rails elsewhere, but for wheels it is just a contribution to general wear so not really noticeable.

Interestingly though on some freight schemes I've worked on overseas, where trains shuttle back and forth from, say, a quarry to a processing plant/port it has been requested that a turning loop is proposed to balance out the wheel wear.

 

[AndrewE]

That's a point - I wasn't thinking about the rail - so they may well be provided in 'isolated' places so as to prolong the life of the rail.
--- old post above --- --- new post below ---
In my head at least, fixed axles means that it kinda is. The fact that the wheels can't independently follow the rail geometry means that at least one of the wheels on each axle is forced to either under or over rotate. If the curve is severe enough, the conical shape of the wheel isn't enough to compensate so the wheel ends up with the flange in contact with the rail - but I get what you mean.

The cone of the wheel tread is supposed to steer the axle on curves by effectively increasing the diameter of the wheel on the outside of the bend, where the curve is too sharp then raising the outer rail gives it a hand from gravity - and stops the flange contacting the rail with such force.

On 2-axle vehicles the axle can't yaw (rotate radially) hence the screaming of pacers, and the use of shorter-wheelbase bogies under longer vehicles. The difficult trick is to grease the flange where it is needed but keep the tread clean.

 

[DarloRich]

flange greaser fnar fnar

( so childish - sorry )

 

[edwin_m]

Interestingly though on some freight schemes I've worked on overseas, where trains shuttle back and forth from, say, a quarry to a processing plant/port it has been requested that a turning loop is proposed to balance out the wheel wear.

The same happens with tram schemes. It is true that if there are more of one hand of curve than the other and the trains/trams aren't turned, one wheel wears more than the other and the overall wheelset needs to be scrapped sooner. However on wider networks the left and right hand curves will balance out so this effect is less significant.

 

[derailed]

Whitmore Rail provide various systems and LBFoster

Thanks for input, from what I know there are a couple of solutions on the market including solid sticks, spray greasers and some innovative smart products.
Major suppliers are LB Foster (previously Kelsan), Schunk, SKF, and Rowe Hankins.

What's your opinion on those systems? Are solid sticks better, more cost efficient?

 

[coppercapped]

The cone of the wheel tread is supposed to steer the axle on curves by effectively increasing the diameter of the wheel on the outside of the bend, where the curve is too sharp then raising the outer rail gives it a hand from gravity - and stops the flange contacting the rail with such force.

On 2-axle vehicles the axle can't yaw (rotate radially) hence the screaming of pacers, and the use of shorter-wheelbase bogies under longer vehicles. The difficult trick is to grease the flange where it is needed but keep the tread clean.

The whole point of the High Speed Freight Vehicle suspension - which evolved into that used on the Pacers - was that the axle could yaw, but under controlled conditions. The spring units at the ends of the horizontal rods connecting the axlebox to the frame visible in this picture supplied the control. This controlled yaw allows the wagon to run stably at 90mph.

The squeal occurs because on tight curves and with long wheelbases the axle cannot rotate suficiently to allow the conicity of the wheel to compensate for the different rolling distances along the inside and the outside rails. The squeal arises either from one or both of the wheels slipping on the railhead or, in extreme cases, the flange rubbing on the side of the railhead.

 

[civ-eng-jim]

The squeal arises either from one or both of the wheels slipping on the railhead or, in extreme cases, the flange rubbing on the side of the railhead.

Indeed - The greatest noise is usually generated by the leading inner wheel and not the flange as many might think.

Friction modfiers (not lubricants) are applied in this instance to the rail head to reduce the stick - slip at the wheel/rail interface.

 

[civ-eng-jim]

Thanks for input, from what I know there are a couple of solutions on the market including solid sticks, spray greasers and some innovative smart products.
Major suppliers are LB Foster (previously Kelsan), Schunk, SKF, and Rowe Hankins.

What's your opinion on those systems? Are solid sticks better, more cost efficient?

Errr, pass.

I'm sure there are pros and cons for both on-train applicators and on-track too. I don't know how on-board applicators determine when to apply (assuming it's not continually applying the friction modifier)

Anything that applies the lubricant/friction modifiers in the controlled manner to a discrete part of the rail is probably best. The track around lubricators is often pretty manky!

Water sprayers have been setup to reduce squeal - Indiscriminate in their application, but water will drain away.

 

[jon0844]

flange greaser fnar fnar

( so childish - sorry )

I'm with you. I can't stop picturing lubricated flanges in my head now...

 

[edwin_m]

Errr, pass.

I'm sure there are pros and cons for both on-train applicators and on-track too. I don't know how on-board applicators determine when to apply (assuming it's not continually applying the friction modifier)

Anything that applies the lubricant/friction modifiers in the controlled manner to a discrete part of the rail is probably best. The track around lubricators is often pretty manky!

Water sprayers have been setup to reduce squeal - Indiscriminate in their application, but water will drain away.

I believe at least some on-board applicators have GPS and are programmed with the locations of curves where they are to operate.

 

[edwin_m]

The squeal occurs because on tight curves and with long wheelbases the axle cannot rotate suficiently to allow the conicity of the wheel to compensate for the different rolling distances along the inside and the outside rails. The squeal arises either from one or both of the wheels slipping on the railhead or, in extreme cases, the flange rubbing on the side of the railhead.

I think you mean the axle can't move laterally sufficiently blah blah...

And I'm not clear why this effect should be any different between Pacers and other trains, since the wheel dimensions and profile are presumably the same but Pacers are demonstrably noisier on tight curves. I'd guess the Pacer suspension compensates for angle of attack to some extent but not fully, so the crabbing effect is still worse than with a bogie vehicle on tight curves.

 

[coppercapped]

I think you mean the axle can't move laterally sufficiently blah blah...

And I'm not clear why this effect should be any different between Pacers and other trains, since the wheel dimensions and profile are presumably the same but Pacers are demonstrably noisier on tight curves. I'd guess the Pacer suspension compensates for angle of attack to some extent but not fully, so the crabbing effect is still worse than with a bogie vehicle on tight curves.

I wasn't as clear as I could have been. There are two effects. The 'angle of attack' is controlled by the axle being able to rotate around a vertical axis at its centre, this motion is controlled by the yaw stiffness of the axle's suspension and the associated damping. This works with the creep forces generated when the wheelset is not running exactly at right angles to the track to pull the body around the curve. The other is as you say and the long wheelbase of the Pacer means that, because the wheelset cannot rotate about its vertical axis too far, the angle of attack is higher than needed for steering and so the creep-slip forces at the contact patch have to slip rather than steer. Hence the squeal.

Clear as mud, right? (Wickens and others published a lot of stuff about this, but I can't find my references right now so I'm going from memory. Which fades with age... )

 

[edwin_m]

I wasn't as clear as I could have been. There are two effects. The 'angle of attack' is controlled by the axle being able to rotate around a vertical axis at its centre, this motion is controlled by the yaw stiffness of the axle's suspension and the associated damping. This works with the creep forces generated when the wheelset is not running exactly at right angles to the track to pull the body around the curve. The other is as you say and the long wheelbase of the Pacer means that, because the wheelset cannot rotate about its vertical axis too far, the angle of attack is higher than needed for steering and so the creep-slip forces at the contact patch have to slip rather than steer. Hence the squeal.

Clear as mud, right? (Wickens and others published a lot of stuff about this, but I can't find my references right now so I'm going from memory. Which fades with age... )

Yes, essentially what I was trying to say too. I was a lowly graduate trainee in the Wickens organisation, though not involved with vehicle dynamics. The first assignment of one of my colleagues was to spend a couple of weeks travelling around on Pacers with a microphone (probably not a very sensitive one).

 

[Cowley]

flange greaser fnar fnar

( so childish - sorry )

The only thing worse than a dry flange is ungreased nipples.

 

[MotCO]

Interestingly though on some freight schemes I've worked on overseas, where trains shuttle back and forth from, say, a quarry to a processing plant/port it has been requested that a turning loop is proposed to balance out the wheel wear.

You don't need to look abroad. The Shuttle trains through the Channel Tunnel turn round clockwise in England, but anticlockwise in France. (Alright, so France is abroad)

 

[derailed]

Errr, pass.

I'm sure there are pros and cons for both on-train applicators and on-track too. I don't know how on-board applicators determine when to apply (assuming it's not continually applying the friction modifier)

Anything that applies the lubricant/friction modifiers in the controlled manner to a discrete part of the rail is probably best. The track around lubricators is often pretty manky!

Water sprayers have been setup to reduce squeal - Indiscriminate in their application, but water will drain away.

On-board applicators are continually applying the lubricant, but they are rather sensible about it not to waste the lubricant unnecessarily.

Do you think its a Train Operator's decision which lubrication system to use or is it Network Rail responsibility?

 

[zn1]

one should always lube responsibly

 

[najaB]

one should always lube responsibly

I agree. Insufficient lube can result in an unpleasant squeal.

 

[AndrewE]

I agree. Insufficient lube can result in an unpleasant squeal.

I believe that some tramways run a trickle of water down the groove to avoid the problem - or they did... (take that whichever way you wish!)