Mallard oo cornering

[RogerBarns]

Hello, I have built my 10yr old son a oo layout. I am a novice and he would like a Mallard for his birthday. I have heard that there may be a problem with the train on curves and I want to make sure he's not dissapointed if I buy this loco. Any help greatfully received.

Many thanks

Roger

[keithp1707821843]

I think the Mallard needs a large curve, so it depends on what track you have used. If its only 2nd radius (like my layout) I do not think the Mallard will curve well, I still think it runs - just not well. It should say somewhere in the packaging what the min curve required is.

Keith

[ColinB]

I think all Hornby main locos are second radius minimum. If you are worried why not buy an old second hand tender driven one which will do the smaller radius bends.

[atom3624]

All Hornby locomotives are said to take 2nd radius and upwards.

Ensure there's good easy side-to-side movement of the main driving wheels.

 

If you add the detailing, nothing less than 4th radius I find - and that's sometimes with 'a few compromises'.

 

Al.

[RogerBarns]

Thanks all. I'm afraid I have no idea what 2nd radius means? I have attached a photo of the layout if it helps.

I saw on  a picture of the box that the Mallard needs a minimum radius of 438mm - but I don't understand what that means either?

Please help!/media/tinymce_upload/ec63d9611ec301a0c78c892e38253c1a.jpg

[Jimbo1707820979]

Welcome to the forum, Roger.  I bought a "Gadwall" for my son which is similar to the "Mallard". It runs very well on 3rd Radius, which I suggest you use. No derailments. Possibly also on 2nd Radius but have not tried it.

[Chrissaf]

...but I don't understand what that means either?

 

Basic Geometry.

 

Take a circle as your starting point. The width of the circle is called the diameter and the radius of a circle is half the length of the diameter. The radius of a circle is measured from the very centre point of the circle to the edge of the circle [called the circumference].

 

/media/tinymce_upload/241c7a69914f3582dcb5fee0bad80606.jpg

 

In Hornby track terms, the radius is measured to the centre line of the track i.e the mid point between the two rails. Hornby have preset radius distances [not all track makers follow the Hornby examples].

 

Hornby Radius 1 = 371mm [track parts R604 & R605]

Hornby Radius 2 = 438mm [track parts R606 & R607]

Hornby Radius 3 = 505mm [track parts R608 & R609]

Hornby Radius 4 = 572mm [track parts R8261 & R8262 - more recent additions]

 

Notice that the mathematical difference (spacing) between the radius is 67mm. Radius 2 is 67mm longer than Radius 1 and Radius 3 is 67mm longer than Radius 2 etc.

 

67mm is the standard track spacing (track centre to track centre) used by Hornby.

 

The shorter the radius, then the tighter the curve. The longer the radius then the shallower the curve.

 

Therefore in Hornby track terms. Radius 4 is the outermost track, Radius 3 lies 67mm within the Radius 4 curve. Radius 2 lies 67mm within the Radius 3 curve and Radius 1 curves lie 67mm within the Radius 2 curve.

 

/media/tinymce_upload/daa0a59749e45e60809b414868db92de.jpg

 

So when a loco box says "Minimum Radius 2" this means that it is not designed to go round Radius 1 curves, but should be OK on Radius 2, 3 or 4

 

All the Hornby track geometry is described in graphical form here:

https://www.thinglink.com/scene/876128215507140609?buttonSource=viewLimits

 

TIP: As a newbie poster on the forum, just be aware that the 'Blue Button with the White Arrow' is not a 'Reply to this post' button. If you want to reply to any of the posts, scroll down and write your reply in the reply text box at the bottom of the page and click the Green 'Reply' button.

.

See also – further TIPs on how to get the best user experience from this forum.

https://www.hornby.com/uk-en/forum/tips-on-using-the-forum/

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[96RAF]

To add to Chris’s explanation you can see on your layout you have two centres of radius due to your outer curve being offset more to this end of the board.

 

You can also see at the outer left hand side you have an odd mix of curves, possibly a bit of flexi track has been used.

 

If you measure between the parallel tracks and half it then you have your radius, or if you can lift the track the R number is stamped on the bottom of each piece.

 

/media/tinymce_upload/35b7c04508d8f84dcb1c6d8de2a32e81.png

[RogerBarns]

Fabulous, many thanks Chrissaf and RAF96, I fully understand now.

Yes, one of the curves is made up of sections we had available.

Thanks again

Roger