How Do Motorised Points/Switches Work?

[Sir TophamHatt]

Can anyone give me a quick run down on motorised points?

 

I know obviously there is a motor and electricity but how is it switched?  Can I get the electricity from the bus wires that power the track, or is it best to get a whole new power supply?  I'd only be motorising 5-8 sets I'd think.

 

I guess each switch is singular?  So diverging to another line usually requires two switches - both of these would have to be independently operated, or could I wire one switch to throw them both?

 

Watched the Everard Junction video about switches.  His had a loud buzzing when switched.  Is this easy to fix? (Did't see all of the video so don't know if he fixed it.)  If so, how?

 

Thanks for any help

[34theletterbetweenB&D]

There's a motor and a switch as you surmise.

 

Although if using DCC it is tempting to use the track supply for the point motors, this is not the best plan as a very common cause of a DCC system trip is a point set against a loco, leading to a short circuit. With the DCC track power at very restricted current while in the tripped state, the point motor won't operate if that's where the power has to come from. Better to arrange independent supply to the point motors.

 

If you have a pair of points that must always operate together (for example because they are arrnaged in a crossover formation) then a single switch to operate both is naturally possible: you can use a single motor if you are ingenious and like saving money...

 

Buzzings, clicks and 'whacks!' as point motors actuate are a matter of choice. Slow motion motors operated well below 12V can typically be made to run very quietly. I have come to the conclusion over the years that some among even sophisticated layout builders and operators actually like the noise of them operating...

[Pete the Elaner]

These can be split into 2 categories: solenoid & slow action motors.

Hornby, Peco & SEEP are all solenoid motors. These require a short burst of current to pull a connector into a coil. This can be quite fierce but Peco & Hornby points are tough enough to cope.

Slow action are servos, tortoises, cobalts & some others. These are more gentle, generally more expensive & different to wire in because you don't supply them with a short pulse.

 

Buzzing point motors are usually solenoids. You can stop this by using a CDU which shortens the pulse to a short click or thud. This does not stress the coils so much & significantly reduces any spark you would get when re-opening the circuit.

[Bill Radford]

Everything you need to know about electrics. (I used it - it is invaluable)

 

http://www.brian-lambert.co.uk/

[Ian Morgan]

It is also worthwhile downloading the free eBook from Merg. Chapter 7 tells you all you need to know about all types of point motors, and how to wire them up.

 

https://www.merg.org.uk/ebook.php

 

Ian Morgan

Hampshire

[Sir TophamHatt]

Thanks for the input.

Quick question.  If I was to buy some of these (Hornby point motors):

to fit underneath the baseboard to throw the switch?

 

would they fit points like this:

 

And do points like this (below, left) have a separate name to the above?

Edited November 30, 2017 by anotheruser

[frobisher]

Thanks for the input.

Quick question.  If I was to buy some of these (Hornby point motors):

to fit underneath the baseboard to throw the switch?

 

would they fit points like this:

Yup

 

And do points like this (below, left) have a separate name to the above?

Old... I don't think that Hornby have produced the ones on the right since the late 70's, and the ones on the left since the late 80's. They both however will take the same style of older Hornby point motor which clips to the side. You really want to be using the newer style points above and avoid these older ones (the earlier type are prone to corrosion, and the newer type not that much better).

Edited November 30, 2017 by frobisher

[Sir TophamHatt]

Thanks

I don't have many of the old ones, ha ha.

 

Are the motors above under-baseboard ones or above?

[smokebox]

They are designed to fit under the baseboard, the small metal "legs" will fit into slots in the points to locate and fix them in place. You then need to cut a hole in the baseboard for the motor to fit in. They can also be fitted completely below the baseboard and just a small slot or hole (about 10mm diameter) cut for the operating pin to fit through. There are small lineside huts available which allow them to be surface mounted if desired. https://www.Hornby.com/uk-en/point-motor-housing.html

 

These Hornby point motors will only fit into Hornby points properly. The very similar Peco point motors will only fit properly into Peco points, though some people say the metal legs can be bent to make them fit the other companies points. I tried it and had no success.

[Harlequin]

Regarding crossovers between two parallel lines:

Yes, you could wire the point motors together so that the points are either both in the normal running position or both in the crossover position.

 

Regarding the noise:

The old Hornby/Peco point motors are basically simple electro-magnets fed by a pulse of alternating current. It's that current that makes them buzz and their simple design also makes the points snap from one side to the other with a loud click.

 

There's a more modern alternative these days: DCC controlled servos, which move the point blades in a more gradual and quieter movement. Examples are Peco "PLS-100", DCC Concepts "Cobalt" point motors. I think I'm right to say that these devices usually also have built in electrical switches that allow you to power the frogs of points correctly - very useful if you'e using "Unifrog" points.

 

Edit: Sorry, I should have read the thread properly. Pete and 34<IsItAC?> already said most of this above!

Edited December 1, 2017 by Harlequin

[frobisher]

Thanks

I don't have many of the old ones, ha ha.

 

Are the motors above under-baseboard ones or above?

For the older ones, they are above baseboard... (X404 type)

 

https://www.ebay.co.uk/itm/Hornby-OO-X404-Point-Motors-X6/272951736549?hash=item3f8d30f8e5:g:LYIAAOSwVlVaFyeG

 

Is a current listing for these old style ones (should work with both types of point) but second hand (or the dusty back drawers of one of those little toyshops that has been around forever) is your only source for these pretty much.