New generation single bladed tramway points......

[tramcar trev]

I made up a pair of these earlier and they are unreliable as the spring return was "unreliable" as the spring actually was soldered to both the moving blade and the fixed bit of rail, not a great success.... I made a prototype new generation set with a removeable blade that rides on a vertical pin, the spring is soldered to the moving blade and that makes it removeable for cleaning.....​

 

[Madman]

You'll have to help me with the physics of your design. Travelling right to left, I can see how the tram would take the lower route. However, when you throw the single point downward in the picture, how would the tram take the upper route?
Vice versa, how would a tram travelling from left to right, on the upper route, pass through the points without derailing on the single fixed blade?

 

[trammayo]

I would say it would be trailing - i.e returning to the single track.

 

[Gizzy]

Dan, the tram would always take the lower route, and never the upper route, as it is designed as a passing place on a single track tramway.

Coming from left to right, the tram would just push through the spring loaded blade.

As we in the UK and Aus drive on the correct side of the road, this is prototypical....

 

[Madman]

Dan, the tram would always take the lower route, and never the upper route, as it is designed as a passing place on a single track tramway.

Coming from left to right, the tram would just push through the spring loaded blade.

As we in the UK and Aus drive on the correct side of the road, this is prototypical....

I understand the passing siding aspect, for travel from right to left. However, when the tram travels from left to right, on the upper route, wouldn't the fixed blade tend to derail the tram?

 

[Gizzy]

Dan, the tram would always take the lower route, and never the upper route, as it is designed as a passing place on a single track tramway.

Coming from left to right, the tram would just push through the spring loaded blade.

As we in the UK and Aus drive on the correct side of the road, this is prototypical....

I understand the passing siding aspect, for travel from right to left. However, when the tram travels from left to right, on the upper route, wouldn't the fixed blade tend to derail the tram?

No, because the fixed blade is gauged to 45 mm with respect to the opposing rail. The moving blade is what takes up the gauge 'slack' and it cannot go wider than the 45 mm track gauge anyhow....

 

[Madman]

OK we have penetration. Now then, not that I want to belabor the subject nor pick niks, but when the tram, coming from the left, passes over the gap, there would or could be a slight jump or jerk as it does. What say you, ye or ne?

 

[Gizzy]

OK we have penetration. Now then, not that I want to belabor the subject nor pick niks, but when the tram, coming from the left, passes over the gap, there would or could be a slight jump or jerk as it does. What say you, ye or ne?

MIND THE GAP!

Yep there will be a slight bump I guess?

Trev will know for sure though....

 

[MRail]

Normal tramway practice, certainly in UK & Europe.

This one's at Birkenhead, Merseyside.

 

[Wobbleboxer]

OK we have penetration. Now then, not that I want to belabor the subject nor pick niks, but when the tram, coming from the left, passes over the gap, there would or could be a slight jump or jerk as it does. What say you, ye or ne?

I would agree and would suggest that the fixed blade should maybe be less pointed and make a more blunt angle to the stock rail. But testing will prove it one way or another. Any excuse, eh?

 

[trammayo]

It would be fair to add that in grooved track, the groove is raised so that the tram runs on its flanges through points, saving wear and tear both on the truck and the track, a little quieter and more comfortable for passengers.

 

[DoctorM]

It would be fair to add that in grooved track, the groove is raised so that the tram runs on its flanges through points, saving wear and tear both on the truck and the track, a little quieter and more comfortable for passengers.

Groovy!

The same situation arises with dual gauge track where combined narrow and standard gauge tracks separate onto their own routes.

Those grooves are a devil to get right, and it presupposes that all your flanges are of similar depth.

 

[stockers]

It would be fair to add that in grooved track, the groove is raised so that the tram runs on its flanges through points, saving wear and tear both on the truck and the track, a little quieter and more comfortable for passengers.

Just like LGB pointwork then.

 

[Andrew]

Looks very nice and smooth Trev.
i might have a go to build one myself!
Regards from Andrew
Sandbar & Mudcrab Railway

 

[Madman]

This is certainly an interesting topic. I see in the prototype photo, that the movable rail is slightly longer than the fixed point. In studying Trev's photos, I have deduced that the longer rail steers the wheels into the curve preventing the wheels from hitting the stationary point head on. What say you Dr. Watson?

 

[tramcar trev]

It would be fair to add that in grooved track, the groove is raised so that the tram runs on its flanges through points, saving wear and tear both on the truck and the track, a little quieter and more comfortable for passengers.

Yes so true.... in real life this is indeed the case, trams run on the flange thru point work and are when negotiating single bladed points and sharp curves guided by the back of the flange....But here we have rather coarse scale wheels running on sort of scale track... the points are laid out at a scale 35' imperial feet curve as per the real thing... It just dosen't look that way...

Ok so who has plenty of G scale grooved rail??? I have seen it but cant find a source......

In my arrangement there will be lots of clunking and bumping, grinding and now the satisfying hollow metallic thunk when the spring loaded blade slams back against the fixed rail... The squealing of the flanges will however be hard to recreate...

I'm just so pleased that we have cleared the air on this....

 

[tramcar trev]

Normal tramway practice, certainly in UK & Europe.

This one's at Birkenhead, Merseyside.

And to a degree in Australia and NZ. Sydney had more a railway feel about it with cute little ground signals and double bladed points usually controlled by a signal box at busy intersections. However most of the other tramways used this style of point.... It is dissapearing now in existing systems as speeds increase, for some reason articulated trams do not like single blades, I had the pleasure of watching at the intersection of Fitzroy st and the old St Kilda railway line when it was converted to "light rail" a chap with crow bar whose job it was to lever the articulated bogie back onto the track untill the point work was updated.....

 

[tramcar trev]

This is certainly an interesting topic. I see in the prototype photo, that the movable rail is slightly longer than the fixed point. In studying Trev's photos, I have deduced that the longer rail steers the wheels into the curve preventing the wheels from hitting the stationary point head on. What say you Dr. Watson?

Yes exactly as you deduce... There is also a slight widening to allow the moveable blade to steer the tram to the left and generally cope with the rigid axle and longer wheelbase negotiating the curve thus (hopefully) preventing the flange catching and riding up on the rail head. This is far more pronounced in the scale setup than in real life. In real life however its the fixed frog that wears out and I have seen some of them chewed out really badly especially if the points are the originals from 1889

 

[Dtsteam]

Another inspirational piece of work, Trevor. Well done.

On the last note, there was a fixed frog at Blackpool Pleasure Beach loop which had been chewed up so much that the flanges had cut a new one, and left a little sliver of metal behind.

On the previous note about articulateds...
Some low floor suspensions are independent single wheel castors, and probably don't get the lateral kick to send them through the frog.

 

[trammayo]

There is another answer to all this - centre flange wheels (as per KHCT electric days). I'm not sure when Leeds bought some of the Hull trams if they just managed with new (normal) tyres or had to fit new wheels.