PECO Announces Bullhead Track for OO

[Ravenser]

I most certainly was not throwing stones. I was attempting to address an earlier post about the Hertz system which is a true narrow gauge system. 00 gauge may be narrow gauge, but is meant to represent a standard gauge system, so I prefer my standard gauge locos not to sway about on points like a narrow gauge loco. 

 

The people who dont want to geddit will never get it.

 

Minimum radius on the DLR equates to 21" in 4mm and that's a standard gauge system

[martin_wynne]

Another thing is the wheel drop issue, the real ones do.

 

No they don't. If that is really happening as you describe, the track is in a dangerous condition and you should report it immediately to Network Rail.

 

Martin.

[Clive Mortimore]

No they don't. If that is really happening as you describe, the track is in a dangerous condition and you should report it immediately to Network Rail.

 

Martin.

The last Class 312 was withdrawn in 2004, so I might just be a little late in reporting it. Maybe some one else has.

[AndyID]

 Those who think they don't never traveled in a Class 312 MBS heading towards Chelmsford  where the slow lines join the main lines at Shenfield, BANG!!! as the wheel under your bottom drops in the void leaving a void between said bottom and seat. You rapidly descend back into you seat, when . CRASH as you are thrown upwards where the wheel tries to mount the crossing vee. It was enough to wake even the hardiest of regular commuters.

 

Those Lima wheels will get you every time.

[81C]

I don't think you would get wheel drop on this crossing. (SNCF)

 

[Joseph_Pestell]

The last Class 312 was withdrawn in 2004, so I might just be a little late in reporting it. Maybe some one else has.

 

I think Martin is right. If that was due to a fault in the crossing a train would have derailed there at some point. From the interaction with your seat and posterior, sounds more like a wet spot or a lack of ballast tamping.

[Joseph_Pestell]

Minimum radius on the DLR equates to 21" in 4mm and that's a standard gauge system

 

So are many other tramways. But they don't use locos and the bogies are short wheelbase and often equipped with various gadgets to get them round the tight curves.

[hayfield]

Minimum radius on the DLR equates to 21" in 4mm and that's a standard gauge system

 

 

But a mainline loco will not run over it !! I would guess a small 0-6-0 tank loco would also struggle.

[Limpley Stoker]

I don't think you would get wheel drop on this crossing. (SNCF)

IMG_1283.JPG

Real frogs!

[Pete the Elaner]

I think Martin is right. If that was due to a fault in the crossing a train would have derailed there at some point. From the interaction with your seat and posterior, sounds more like a wet spot or a lack of ballast tamping.

There were loads of drop joints on the GE late in the 312s lives. I commuted on it at the time. 321s were a more common unit & you would frequently a loud clonk as it felt like the suspension hit a bump-stop. I am not sure if this was caused by point frogs or not.

On the rare occasions I travelled on the WCML, I was amazed at how smooth the P-Way was. The difference should not have been down to the trains because both were using 321s at the time.

 

I have not been on the GE for a while because I moved & now commute using the WCML.

[Pacific231G]

No they don't. If that is really happening as you describe, the track is in a dangerous condition and you should report it immediately to Network Rail.

 

Martin.

Hi Martin

I have actually experienced real wheel drop. It was last year at the CF du Baie de Somme's steam gala where one of the visitors was an ex SNCV metre gauge petrol autorail that ran up and down the quayside line which is mixed gauge. This was to Belgian roadside tramway track standards whereas AFAIK the CFBS's own trackwork uses the same crossing clearances etc as standard gauge. The autorail inched its way over one particular mixed gauge crossing very gingerly indeed but there was still a considerable thud everytime that could be felt as well as heard and looking at it from outside you could clearly see the wheel dropping a little..

Unfortunately I didn't get a clear photo of the relatonship between wheels and track, it was a very rushed visit; by cranking up the gamma these are the best I can manage. The wheel profile did look different from that on other metre gauge "railway" stock present.

.

 

They did have problems at their previous festival in 2013 with a very early metre gaugeDe Dion-Bouton autorail, really just a bus on rails, which did derail a couple of times and I now wonder if slightly incompatible wheel and track standards may have been the reason.

Edited October 11, 2017 by Pacific231G

[PMP]

They did have problems at their previous festival in 2013 with a very early metre gaugeDe Dion-Bouton autorail, really just a bus on rails, which did derail a couple of times and I now wonder if slightly incompatible wheel and track standards may have been the reason.

 

Perhaps if they imagined the standards were compatible, it'd have been all right ....

[Trog]

No they don't. If that is really happening as you describe, the track is in a dangerous condition and you should report it immediately to Network Rail.

 

Martin.

 

I have seen track in a junction due for relaying where there were circular dips in the rail heads in the opposite rail to the crossings, due to impact loads caused by the other wheel on not much suspension small wheeled stock dropping into the rather battered crossings.

[Clive Mortimore]

I think Martin is right. If that was due to a fault in the crossing a train would have derailed there at some point. From the interaction with your seat and posterior, sounds more like a wet spot or a lack of ballast tamping.

Well you learn something every day. So all the banging noise and lurching about that has happened to the trains I have traveled on over the past 60 years when traversing a junction is not due to the interaction between the wheels and the point work. I feel really stupid now. 

 

 

 

 

 

 

Does seem a tad strange that they all have a wet spot or lack of ballast.

[martin_wynne]

So all the banging noise and lurching about that has happened to the trains I have traveled on over the past 60 years when traversing a junction is not due to the interaction between the wheels and the point work

 

There may be banging and lurching. But it is NOT caused by wheels dropping into the crossings.

 

The MAXIMUM width of the gap in the crossings is 4.1/4 inches, measured across just in front of the nose of the vee. If it is wider than that, the track has been damaged or broken and is in a dangerous condition.

 

The MINIMUM width of a wheel is 5 inches (wagons). Coach and locomotive wheels are wider.

 

It is not physically possible for an object 5 inches wide to fall into a gap 4.1/4 inches wide.

 

Here is a relatively new crossing. It is obvious from the wear marks on the rail that the wheel is wider than the gap:

 

 

edit: Just to add that because of the coning angle on the wheel, it does move down a fraction as it rolls along the wing rail. For this reason the nose of the vee is lowered a small amount below the level of the wing rails, so that the wheel can transfer smoothly onto it. Wear of the crossing may increase this effect, but the wheel always remains fully supported on the rail. This is getting a bit technical for a topic about RTR track.

 

Martin.

Edited October 11, 2017 by martin_wynne

[Pacific231G]

Perhaps if they imagined the standards were compatible, it'd have been all right ....

I think the organisers imagined how many fewer delays there'd be to the main service if the de Dion was relegated to running up and down a shorter section of track and that WAS alright.

[Clive Mortimore]

There may be banging and lurching. But it is NOT caused by wheels dropping into the crossings.

 

The MAXIMUM width of the gap in the crossings is 4.1/4 inches, measured across just in front of the nose of the vee. If it is wider than that, the track has been damaged or broken and is in a dangerous condition.

 

The MINIMUM width of a wheel is 5 inches (wagons). Coach and locomotive wheels are wider.

 

It is not physically possible for an object 5 inches wide to fall into a gap 4.1/4 inches wide.

 

Here is a relatively new crossing. It is obvious from the wear marks on the rail that the wheel is wider than the gap:

 

 

edit: Just to add that because of the coning angle on the wheel, it does move down a fraction as it rolls along the wing rail. For this reason the nose of the vee is lowered a small amount below the level of the wing rails, so that the wheel can transfer smoothly onto it. Wear of the crossing may increase this effect, but the wheel always remains fully supported on the rail. This is getting a bit technical for a topic about RTR track.

 

Martin.

So the part of the wheel that has contact with the railhead for most of the journey, drops down into the void, just a fraction, then has to climb back up on the vee. And in my days of commuting this action at Shenfield would wake the hardiest of commuters up. Bang-Crash!!!!!

 

After leaving Shenfield if the next sound to wake me was that of brakes being applied then I knew I would have to ask very nicely if Mrs M would come to Billericay as I had caught the wrong train. This was semi-OK when living in Galleywood. After moving to Little Waltham it was a case of catching a train back to Shenfield and then the next to Chelmsford.

[jamie92208]

Different tack and wheel standards can be tricky.  When a group of us completed the restoration of a horse tram with wheelsets to BS 101 of 1929 , the de facto tramway standard, it was situated on the Middleton railway with track laid to normal railway standards.  It was fine on plain track but to get it onto the stretch of plain track that we used for running it meant going over a point on the exit from the workshop. Trailing the point was fine but in the opposite direction we found that we had to keep it pressed against the stock rail as we negotiated the point, with it being light, only 3.5 tons, and being hand propelled this was easy to do. 

 

Jamie

[Clive Mortimore]

There were loads of drop joints on the GE late in the 312s lives. I commuted on it at the time. 321s were a more common unit & you would frequently a loud clonk as it felt like the suspension hit a bump-stop. I am not sure if this was caused by point frogs or not.

On the rare occasions I travelled on the WCML, I was amazed at how smooth the P-Way was. The difference should not have been down to the trains because both were using 321s at the time.

 

I have not been on the GE for a while because I moved & now commute using the WCML.

Hi Pete

 

Good old Dusty Bins, they still ride as bad. Best were the Clactons, even in the motor coach you hardly felt a bump. On the same bit of track any of the Mk1 suburban EMU trailers could be lively but the motor coaches did make you think was there any suspension. The purple trains, the Desrios are slightly better than a Dusty Bin. About on a par with a 305. Mustn't talk modern image on a thread about bull head track.

[martin_wynne]

So the part of the wheel that has contact with the railhead for most of the journey, drops down into the void, just a fraction, then has to climb back up on the vee.

 

It doesn't have to climb up. The top of the vee is lowered to receive it smoothly. Any banging or lurching was most likely caused by dog-legs where rails were not properly aligned to the curve, and contact with check rails. Plus loose keys, dropped joints, etc. Dips at rail joints are a frequent occurrence.

 

Martin.

[Pete the Elaner]

I am surprised to hear you describe the Desiro's as 'slightly better than a dusty bin'. The WCMLs 350s are quite nice, especially the 350/1 & 350/3 with 2+2 seating. These 2 sub-classes are 110mph units too. I am sure that they also let 350/2's loose when they cover the 110mph services because they don't arrive any later.

 

Who said Bullhead is not modern image? Euston still has some but I think only in the 2 stabling sidings between platform 15 & 16.

[gr.king]

If the crossing nose is slightly lower in order to receive the marginally "dropped" coned tread of the wheel, then at some point the wheel has to climb again to regain normal rail head level, even if that climb is, by design, gradual. If the intention of the designer and the situation on the worn, "bedded in" track are not quite the same things, then a jolt of some sort has to be a possibility. Not the same thing as an outright drop into the crossing gap of course.

[AndyID]

If the crossing nose is slightly lower in order to receive the marginally "dropped" coned tread of the wheel, then at some point the wheel has to climb again to regain normal rail head level, even if that climb is, by design, gradual. If the intention of the designer and the situation on the worn, "bedded in" track are not quite the same things, then a jolt of some sort has to be a possibility. Not the same thing as an outright drop into the crossing gap of course.

 

If the wheel cone slope is 1 in 20 the wheel has a to climb a whopping 50 thou for every inch of horizontal offset between the contact points on the wing rail and the vee.

[martin_wynne]

If the wheel cone slope is 1 in 20 the wheel has a to climb a whopping 50 thou for every inch of horizontal offset between the contact points on the wing rail and the vee.

 

Hi Andy,

 

I did say "a fraction". A typical vee nose has 3/16" (5mm) taken off the top, running out in about 18" (500mm).

 

Martin.

[AndyID]

Hi Andy,

 

I did say "a fraction". A typical vee nose has 3/16" (5mm) taken off the top, running out in about 18" (500mm).

 

Martin.

 

The "whopping" was meant to be sarcasm The ramp is quite gradual. It must exercise the suspension on any vehicle passing over it, but not much.