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Hornby Points Modification to Make Them Work

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murrayec
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Hi All

 

We've all experienced it- our most favourite model will not go through the points, so lives on a shelf never to be run on the layout.

 

My experience and final investigation on the matter leads to this;-

 

The main problem is with small wheels (10.5mm), the deep well & free air on the frog of Hornby points. The wheel falls into the well, this raises the opposite wheel of the axle up onto the check rail, the wheel in the well then crashes into the frog point which sends the bogie on the opposite route the points are set for- crash!!

 

By adding a .5mm thick x 1.5mm high styrene strip to the check rail with chamfers at each end to check the wheel eliminates the wheel falling into the well at the frog. I used Deluxe Plastic Magic glue to stick them in with 3 cocktail sticks jambed in between the strip and the track rail. Main thing is to insure the strips start before the frog, are opposite the frog and finish after the frog.

 

This photo shows the location to install the strips- this is white styrene so you can see it. Also note I added an extension to the frog point to test filling the well.

 

HB Point-01 IMAG1531.jpg

 

This photo shows the same strips but in black styrene, I have not installed an extension to the frog point on this one, and it still works OK!

 

HB Point-02 IMAG1532.jpg

 

Both examples are the express curve points which cause problems for the DART model with 10.5mm wheels- but not now.

 

I have tested these points with 10.5, 12.6mm & 14mm wheels and they are fine, I have not tested some of my big steam locos wheels yet- their stuck right down at the back of the attic somewhere behind all the boxes!

 

I will report on those tests later

 

The old style chunky wheels- which have no business on a model layout, but I do have a few, don't work- time to re-wheel them!

 

At last I can run that Caledonia single with the tiny wheeled pony truck at the front!

 

Eoin

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Great analysis, Eoin. That really describes it well.

 

The problem is that (with smaller wheeled wagons) the wheel nearest the frog falls into the gap/well just before the point of the frog. When that wheel hits the frog point, it meets resistance, momentarily 'stopping' the wheel. A moment-arm through the centre of gravity of the wagon (generally in the center of the wagon on relatively straight track) causes the axle to rotate toward the 'stopped' wheel/frog which (if unchecked) will allow the opposite wheel (on the stock rail) to rotate toward the check rail and ride up onto it - derailed.

This also aggravated the wagon 'tilting' toward the frog.

 

If the check rail is the correct distance (close enough to) the stock rail, it provide a counterforce on the inside of the flange of the wheel on the stock rail, keeping it in line with the rail and forcing the 'fallen' wheel to remount the frog point and keep rolling.

 

If the space between the stock rail and check rail is too wide counter pressure cannot be applied to the inside of the flange on the stock wheel flange to prevent the axle rotating. Eoin's solution exploits that by narrowing the gap between the stock rail and check rail (on each road) allowing the counter pressure on the stock wheel to occur. This suggest that the distance between the stock and check rail on the Hornby points is too wide opposite the frog. Does anyone know if the Hornby point stems from an era when wheels were a cruder design with deeper flanges and the point design was never improved upon?

 

As Eoin points out, the deeper the well the greater the probability of the a problem. So this would be less of a problem with a Code 75 point than Code 100 (which is all that Hornby make, I think). This seems of be less of a problem with Peco points, so they obviously have the check in the correct position regardless.

The problem does not occur with larger wheeled rolling stock as the wheel crossing the frog is large enough to ride over the gap and frog point without falling and attempting to re-mount the frog point.

 

I suspect that this is also a problem for lighter wagons and maybe bogies more than fixed axles. Since I don't have a layout, this is somewhat speculative so please correct any points that are incorrect.

Edited by DiveController
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Indeed,

 

I have also had similar problems on short Hornby points- the air gap on the frog is shorter but the small wheels can fall in (less) and trip up on the frog point, generally the train goes through but there is a bang when the wheel hits! I have cut a small chamfer on both sides of the point to aid the wheel staying on track- this works.

 

I'm going to put strips like above on the short points check rails when next in test mode....

 

Eoin

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Does anyone know if the Hornby point stems from an era when wheels were a cruder design with deeper flanges and the point design was never improved upon?

 

So this would be less of a problem with a Code 75 point than Code 100 (which is all that Hornby make, I think).

 

I suspect that this is also a problem for lighter wagons and maybe bogies more than fixed axles.

Does anyone have any input on these points?

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Peco all the way, had the same problem with a client that installed Hornby points and a tender on a steam loco kept derailing and causing a short. They are absolute rubbish, and for the money you pay they are a rip off. The better modification to them is replace them!

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+1 for Peco.

 

While Hornby points are targetted at the toy market, it is also the entry route how many of our 'juniors' get into the hobby so they serve a useful temporary purpose. Much of my old Triang stock (70s rubbish) won't even run over Peco points (ie coarse wheel flange depth and width), but 1960s Hornby Dublo wheel sets run fine.

Edited by Noel
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+1 for Peco.

 

While Hornby points are targetted at the toy market, it is also the entry route how many of our 'juniors' get into the hobby so they serve a useful temporary purpose. Much of my old Triang stock (70s rubbish) won't even run over Peco points (ie coarse wheel flange depth and width), but 1960s Hornby Dublo wheel sets run fine.

I presume the wide stock-check rail separation was to accommodate these older wheels. Newer wheels have smaller and shallower flanges and rpobably derail as they effectively have an ineffective check rail on the Hornby points. Still wondering if this is more or less of a problem on Code 75 (although Peco build Code 75 and are better points as everyone has 'pointed' out)

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