Operating Signals, Points and Level Crossings E-Book

Clive Heathcote

• Herausgeber: Crowood
• Kategorie: Lebensstil
• Sprache: Englisch

Seitenzahl: 174

Veröffentlichungsjahr: 2014

Beschreibung

This fascinating, well-illustrated and informative book presents a straightforward guide to points, signals and level crossings and provides all the information that railway modellers need in order to get the trains on their layouts moving effectively. The history of semaphore and colour light signals is outlined and the implications for modellers is clearly explained. A variety of different types of points, signals and level crossings is then illustrated with detailed instructions describing how to make them work. Simple, tried and tested mechanical and electrical methods used by modellers are explained together with modern electronic approaches, which are described in a way that enables them to be easily understood. The reader is taken step-by-step through various projects, and clear diagrams and photographs are provided throughout, including wiring diagrams for frogs, signals and level crossings. Written by an electronic engineer, this book contains invaluable information gained in a lifetime's experience of railway modelling.

Leseprobe

Operating Signals, Pointsand Level Crossings

A MECHANICAL, ELECTRICAL AND ELECTRONIC GUIDE FOR RAILWAY MODELLERS

Clive Heathcote and A. Anderson

THE CROWOOD PRESS

First published in 2014 by The Crowood Press Ltd Ramsbury, Marlborough Wiltshire SN8 2HR

www.crowood.com

This e-book first published in 2014

© Clive Heathcote and Annie Anderson 2014

All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publishers.

British Library Cataloguing-in-Publication Data

A catalogue record for this book is available from the British Library.

ISBN 978 1 84797 864 6

Disclaimer

The author and the publisher do not accept any responsibility in any manner whatsoever for any error or omission, or any loss, damage, injury, adverse outcome, or liability of any kind incurred as a result of the use of any of the information contained in this book, or reliance upon it. If in doubt about any aspect of railway modelling, including electrics and electronics, readers are advised to seek professional advice.

CONTENTS

INTRODUCTION AND ACKNOWLEDGEMENTS

1   POINTS

2   HOW TO GET YOUR POINTS MOVING

3   LIVE FROGS, DEAD FROGS AND ELECTROFROGS

4   A BRIEF HISTORY OF SIGNALLING

5   OPERATING SEMAPHORE AND COLOUR LIGHT SIGNALS

6   MORE ADVANCED OPERATION OF SIGNALS

7   LEVEL CROSSINGS

8   HELPFUL ELECTRICAL AND ELECTRONIC CONCEPTS

9   ELECTRICAL AND ELECTRONIC COMPONENTS AND ASSEMBLY EXPLAINED

INDEX

INTRODUCTION AND ACKNOWLEDGEMENTS

Points signals and level crossings are generally all under the control of a signalman. Things changed so little on the railways that a signalman from the 1870s could have stepped into a 1950s signal box and operated it. Since then railways have undergone rapid modernization and things have changed extensively.

This book tries to explain how to model the operation of a real railway as it seems much more satisfying to understand why things are how they are. We have tried to include a lot of practical information about how to control signals points and level crossings, from the simplest methods to the more complex.

We hope the reader will be able to extend the ideas within this book to suit the circumstances of his model railway. For this reason we have tried to put in detailed explanations of how everything works. We would like to thank Neil Wint for his help with DCC control. Also thank you to Peco for supplying us with photographs of their products. Finally, thank you to the Churnet Valley Railway for kindly guiding us around their signal box and for filling the Churnet Valley with steam trains.

CHAPTER ONE

POINTS

After constructing the baseboard, planning and laying down the track is an important stage in building a model railway. To enable your rolling stock to run on a variety of routes, putting in points is essential.

A point is defined as ‘a section of track used to direct a train onto two or more alternative routes’. It is sometimes, particularly in America, known as a switch or a turnout. Designing your model train layout is much easier than on the real railways. In the past the track plan had to be approved by a railway inspector, who in the early days was usually an army man from the Royal Engineers. Safety was important and standards were very stringent when passengers were involved. This affected how the railways laid out their track and signalling. Often with model railways the limited space available is the main concern, but if you bear these points in mind the model railway will look more realistic.

Full-sized railway points at Cheddleton Station on the Churnet Valley Railway in North Staffordshire. The points allow four sidings to lead into one line. The point at the front of the picture is operated by the white hand lever on its right. The second nearest point is operated from the signal box, which can be seen on the left of the picture. The point rodding from the signal box passes under the line and is protected by a wooden cover. It then goes alongside the track and joins to the point tie bar by an angle crank.

TYPES OF POINTS

RIGHT HAND AND LEFT HAND POINTS

Several types of points are in use on the railways. Simple standard right hand and left hand points are more common because they are more economical to make and maintain. With a right or left hand point, one track is straight and the other is curved. The radius of the curve on the tracks can vary. The bigger the radius of the curve, the faster the train can run over the points. Model railway track is often available with a choice of radius: large radius looks more realistic and gives better running but the points are substantially longer.

Left hand point refers to the side of the point the track diverges at, shown here on the left of the diagram. Generally the straight portion of the point will be on the main line to allow for a faster route. Sometimes the main line is on a gradual curve and the diverging route will then be at a sharper radius.

Y POINTS

Y points are very similar to left and right hand points. The difference is that both diverging tracks curve away in opposite directions. An advantage to this is that the tracks diverge in a shorter distance. Since the point takes up a shorter length of space, this is a big advantage on smaller model railways.

Y point. Since both tracks curve away from each other they separate more rapidly than a left or right hand point. This makes a worthwhile ploy when saving space.

POINT ON A CURVE

Where the main line is on a gentle curve, then this type of point is required. These points can be very useful for saving space on model railways as they allow the line to split into two before a straight piece of track is reached.

An O gauge home-constructed model of a right hand curved point built by one of the authors. Both tracks curve to the right. Strips of copper clad fibreglass are used for the sleepers. This is the material used to make circuit boards and is readily available. It allows the rail to be soldered to the sleepers. An advantage to building your own track is that it can be made to any radius to allow flowing curves of track.

DIAMOND CROSSINGS

Diamond crossings are also used particularly at junctions, but these offer no challenge to the modeller as they contain no moving parts.

The accompanying diagram shows a double junction, where two double-track lines meet. It consists of two left hand points and a diamond crossing. This is a very common track arrangement on fullsize railways. Until recent times safety regulations required a single-track branch line to diverge from a double-track line using a double junction rather than a crossover and point.

A double junction with two left hand points. The junction could equally have two right hand points. Manufacturers arrange the sizes and angles of their track so that formations such as these are easily assembled and the distance between the tracks are consistent to allow room for the model trains to pass.

A 00 gauge model diamond crossing manufactured by Peco. You can see that is has two electro frogs as the nickel silver rails meet to form a V-shape rather than ending in a plastic moulded V-shape frog.

SINGLE AND DOUBLE SLIPS

Where space is restricted, for example at stations, single and double slips are used to save space. Single and double slips are actually diamond crossings with moving parts. With a diamond crossing a train approaching from A can only travel to D, whereas with a single slip a train approaching from A can travel to C or D, depending on how the point blades are set. Note there are two sets of point blades and two point motors are required. However with a single slip a train approaching from B can only travel to C.

Double slips have extra point blades to allow trains to travel from B to C or D, as well as A to C or D. Again two point motors are used to operate a double slip. The same track routing could be obtained by using two simple left or right hand points end to end. Although this would be simpler, it would take an extra length of track to achieve, hence the space-saving advantage of double slips.

Single and double slips are a lot more complicated than ordinary points. This is why they are only used when there is insufficient space to use a simpler arrangement with left and right hand points. At the approaches to busy stations, however, a lot of lines need access to a number of platforms, so this might be the only way to arrange the lines in the limited space available. PECO PUBLICATIONS

A model double slip point manufactured by Peco. There are two tie bars each moving four point blades. Two separate point motors, one for each tie bar, are required to work the double slip. PECO PUBLICATIONS

THREE-WAY POINTS

In goods yards and marshalling yards three-way points are sometimes used to save space. They are seldom used on main lines for safety reasons because they are more complicated than standard left and right hand points and so not suited to a train crossing at high speed. Three-way points also have two sets of point blades and require two point motors.

A three-way point allows the track to split into three in a shorter length than with two standard points. Two point motors are required for the three-way point. It has been constructed in the same way as a curved point.

CATCH POINTS AND TRAP POINTS

Catch points and trap points look the same but serve different purposes. Catch points are used on steep gradients in case a train splits in half and the rear portion rolls backwards down the hill. Their job is to derail the runaway. It is better to derail the train before it reaches tremendous speeds at the bottom of the hill. Trap points are used where a siding joins a main line. Their purpose is to prevent a collision with a train or wagons encroaching on the main line. When the point is set to the main line, the trap point is then set to derail the train. It is not so essential that such safety features are present on a model railway but the model looks more realistic if they are. It is rare that modellers go to the trouble of making these work.

A catch point at Cheddleton Station on the Churnet Valley Railway. If there were a runaway train or wagon on the left hand track, the catch point would derail the train before it could reach the right hand main track, so preventing obstructions on the main line. Interlocking in the signal box makes it impossible to set the main line point unless the catch point is set to derail in this way. When the main line point is set to the left hand track, the catch point can then be changed to allow trains to pass across it. Sometimes instead of using a catch point a normal point is used, followed by a short section of track, a sand drag to slow the train and a buffer stop.

OPERATING POINTS

LEVERS IN A SIGNAL BOX

Traditional railway lines were operated by lots of signal boxes instead of a centralized power box; points were operated by a signalman pulling a lever in a signal box. There are only a very few lines that retain this type of operation. Levers for points and signals are distinguished by colour but otherwise look the same. The levers are coloured black for points and blue for facing point locks. Home signal levers are coloured red and the levers for distant signals are yellow in colour. Spare or disused levers are painted white. Levers for operating gate stop locks for level crossings are brown in colour. There are even black and white chevrons on the levers that operate mechanisms to place detonators on the track in case of fog. When the train wheels hit the detonators, the explosion alerted the driver to come to a stop. It would be an appropriate touch to colour the switches on your model railway control panel using the same scheme. You can obtain coloured rubber covers for toggle switches.

Inside a small signal box at Consall Forge Station. Several different coloured levers can be seen. On each lever is a brass plaque with a number that corresponds to the signal or point on the diagram above the instrument shelf. The function of the lever is also identified by its colour. The cloth hanging on the lever, which is pulled forward, is used by the signalman to stop sweat corroding the metal lever. Signalmen were usually allocated a particular signal box to work in and they treated this as a home from home, keeping it immaculate. One of the authors visited a signal box during British Rail days and discovered the signalman had installed a sofa and cooker. The telephone that communicates with other signal boxes along the line can also be seen, as well as the block instruments used to pass control of the train between signal boxes.

Points in sidings were often controlled by the shunter or guard using a lever alongside the point, as here at Cheddleton Railway Station. The point blades and the tie bar that connects them together can just be seen. This arrangement is safe enough for slow-moving goods trains shunting in sidings but it would never be allowed on passenger-carrying main lines where the point must be interlocked to the signals and under the control of a signalman. Models of these levers can be obtained.

POINT RODDING

Signal box levers are connected to the point by steel bars. This is known as point rodding and can be seen running alongside railway lines.

Cosmetic plastic injection point rodding parts are available in 4mm scale from Wills. Etched brass components are also available for making point rodding. In larger scales it may be possible to make working point rodding from fine brass bar.

Mechanical signal boxes had their levers connected to the points by the square section rodding shown here. Semicircular cranks were used to change the movement through ninety degrees to connect with the point tie bars.

INTERLOCKING FRAME

On the ground floor of a traditional signal box is an interlocking frame. This is a mechanical device that prevents points being moved until the appropriate signals have been put to danger. There is a limit to how far away the point could be from the signal box due to the friction of the steel bars over the supports. For this reason some stations have signal boxes at each end of the station.

GROUND FRAME

Sidings some distance from the station have their own signal box. If the sidings are seldom used there will be a ground frame instead. A ground frame is a bank of levers that is only unlocked when a railway guard or shunter is required to carry out shunting manoeuvres. This should be operated by the guard travelling on the train. Off the main line points on sidings might be operated by levers alongside the point.

A ground frame with three levers for operating three points. The numbers in front are not part of the ground frame but are a speed limit for the engine driver.

ELECTRIC POINT MOTORS

In more recent times electric point motors have been used, allowing points to be operated over great distances from a single signal box known as a power box. A signal box of this type can control many miles of railway route.

DOUBLE TRACKS

The majority of railways in Britain are double-track lines; trains travel on the left as on the roads. The line going towards the major city is always known as the up line and the other track is called the down line. In the USA, in contrast, the tracks are called Eastbound and Westbound, as most routes are transcontinental.

FACING AND TRAILING POINTS

While trains on British double-track main lines travel on the left track, in many other countries trains travel on the right. In the Channel tunnel one track passes beneath the other so that the trains resurface on the correct side for the country they arrive in. As trains always travel in the same direction along a track, a point will always be arranged either to split the line or cause two lines to converge. Facing points are where the lines split and trailing points are where the lines converge.

Facing points enable the train to travel either route and so if the signalman makes a mistake he could send the London express into the back of a siding full of wagons. When a trailing point is used if a mistake is made or a fault occurs with luck the train carries on, without luck it only derails. Mechanical problems with a facing point may cause the point blade to move slightly and it is more likely to derail the train than if this happened with a trailing point. On a trailing point most likely the wheels would push the point blade back into place. In the interests of safety trailing points were always preferred to facing points.

A trailing and a facing point on the left hand track of a double line.

INTERLOCKING

On passenger lines, as well as having a lever to move the facing point, the signalman has a second lever to apply a lock to the point blades. This is called a facing point lock. Until both are in the correct position, the lever to move the signal to clear will not operate. This is an example of interlocking. If you look at old station plans you will find that nearly all the points are trailing points. However, on modern railways facing points are used more extensively to simplify operation.

CROSSOVERS

Crossovers are often present on double-track lines. One reason for this is that when engineering work is carried out on one of the lines, trains will need to be able to cross to the other line. Because of the dislike of facing points, crossovers are nearly always made of trailing points. The train has to reverse over the crossover to reach the other line.

A trailing crossover for trains running on the left. This is by far the preferred option rather than having facing points.

CHAPTER TWO

HOW TO GET YOUR POINTS MOVING

Manufacturers of points produce them ready assembled or in kits. Some modellers build their own points. Some manufacturers, such as Kato, produce track with the motor built into the point, while others build point motors specifically to fit their own points. To some extent the type of point determines the best way of activating it.

The moving parts of the point are called the point blades. There is one for each rail and these are linked together by the point tie bar. Generally the activating mechanism is linked into the tie bar.

The parts of a point. The check rails are intended to guide the wheel flanges through the gap in the track at the point’s frog.

MOVED BY HAND

An advantage of hand-operated points is that they are cheap and simple, but they have the disadvantage that you might accidentally knock rolling stock on the adjacent track. Large model railways will provide excessive exercise as you run to change the points at the end of the room. On small layouts some modellers arrange pieces of stiff wire, such as bicycle spokes, protruding out from the edge of the baseboard. These have a mechanical linkage to the tie bar and the point can be changed by sliding them a few millimetres in and out.

MOVED MECHANICALLY WITH A LEVER