GW Auto Trailers ..... almost more varieties than Heinz!

[John Candy]

Part 7 : The "Walkover" Seat

What is a "walkover" seat?
A seat where the backrest is not fixed but pivoted, so it can be moved to face the direction of travel; a type more commonly found in electric tramcars (streetcars).

Some diagrams of GWR auto trailer saloons incorporated a bay of this type of transverse seating, flanked by saloons of longitudinal bench seats.

The file contains three components : seat base/squab, end/ arm rest and the back rest.

gauge3.info/downloads/walkover.stl

Diagram "Q" requires 16 of these.
Diagram"U" requires 12. 




Next Up : The (retractable) passenger access steps :

[John Candy]

Part 8 : The Retractable Steps

This is another of those parts which can cause confusion!
In the book by John Lewis, there are two different drawings for these steps.
It is stated that the first drawing is of a type unique to trailer No.1 (borne out by photographs) but it goes on to state that the second drawing is of the type fitted to ALL other trailers.
However, examination of photos shows at least three types in addition to the "unique" type fitted to No.1.
The differences revolve around the lower part of the frame and the manner in which the pivots and steps are arranged. It may be that the position of the underframe trusses had a bearing on the  designs (the steps on central entrances were fitted around the truss rods )but, equally, it could be an improved design to strengthen the support for the steps.

For the purposes of this project, I shall refer to the steps as "type 1" and "type 2"

There are five files available:-

gauge3.info/downloads/type1_1.stl
gauge3.info/downloads/type1_2.stl
gauge3.info/downloads/type2_1.stl
gauge3.info/downloads/type2_2.stl
gauge3.info/downloads/step.stl

Files type1_1 and type1_2 are the frame components for a "type 1" while type2_1 and type2_2 are those for a "type 2".  The "step" is common to both types.

For a "Q" trailer you require 4 x type2_1 plus 4 x type2_2 plus 8 x step
For a "U" trailer you require 2 x type1_1 plus 2 x type1_2 plus 4 x step

Incidentally, if you happen to require replacement steps for a GRS kit (A10) trailer, then the "type 2" is correct.

Photo shows type 1 to the left of type 2


 
NEXT UP : Stepboards for solebar and bogie .

[John Candy]

Part 9 : Stepboards.

A bit tedious but nonetheless important details, the type and positioning of solebar-mounted stepboards was fairly consistent on autotrailers.

The passenger entrances would have retractable steps to permit boarding at halts without normal platforms, whereas the luggage and driver's compartments would have just a stepboard on the solebar.

Bogies would have a variety of steps fitted to suit the type of bogie and were positioned relative to the doors they served. Consult photos of the period being modelled, since although many types were built with stepboards, they had been removed by the 1930's.

For this project, the following solebar steps are required (each file contains multiple stepboards so you need print only the number of files as below).
Diagram "Q" : 1 x gauge3.info/downloads/Qstepboards.stl
Diagram "U" : 2 x gauge3.info/downloads/Ustepboards.stl

Both diagrams were fitted with 9ft Equalised "American" bogies (print only one file, which contains 4 steps, for diagram "U").

Diagram "Q" : NO bogie steps fitted in period being modelled (1930's).
Diagram "U" : 1 x gauge3.info/downloads/bogiesteps.stl

Photos show
1) "Q" type steps (which fit to solebar between retractable step grab rails.
2) The three types of step for "U" type (also suitable for diagram "T").
3) The steps fitted to bogies of "U" type trailers (note they are "handed" as the longer end section projects beyond outer ends of bogies).





NEXT UP : The fixed seating.

P.S. The instructions for assembly will not commence until all necessary parts have been printed/cut,etc.

[John Candy]

Part 10 : The fixed seating.

There were two types of seating (in addition to the "walkover" type (which was covered in Part 7) these were longitudinal bench seats and fixed-back transverse seats, located at the ends of the rows of the "walkover" type.

The transverse type is covered by file
gauge3.info/downloads/endseat.stl

There are three components to each seat (end/arm, squab and back support) which, when assembled, back onto either partition panelling or a bank of longitudinal seating. Note that end/arm is reversible so that same parts can be used for LH and RH positioning.
Where they back onto longitudinal seating, you will also need the "backing panel".
gauge3.info/downloads/backpanel.stl

N.B. The back panels are "handed", having diagonal planking, which slants down towards the centre of the coach (the file will print one of each).

For a "Q" trailer you will require 2 x LH seats plus 2 x RH seats plus 4 x back panels
For a "U" trailer you will require  4 x LH seats plus 4 x RH seats plus 6 x back panels

The bench seating (arranged longitudinally along the walls of the coach) although forming a  continuous seat, was divided into sections by an armrest/leg. The units for this project are of two lengths; 3ft seating two passengers and 4ft 6in seating three passengers, which I shall refer to as short and long. There are six files covering these units : Short and Long each have a LH arm,  RH arm and "no arm" versions, which enables the required configurations to be assembled for the "Q" and "U" trailers,

gauge3.info/downloads/shortLHarmbench.stl
gauge3.info/downloads/shortRHarmbench.stl
gauge3.info/downloads/shortNOarmbench.stl
gauge3.info/downloads/longLHarmbench.stl
gauge3.info/downloads/longRHarmbench.stl
gauge3.info/downloads/longNOarmbench.stl

Required for a "Q" trailer:
2x shortLHarmbench.stl; 2 x shortRHarmbench.stl, 4 x shortNOarmbench.stl,
4 x longLHarmbench.stl, 4x longRHarmbench.stl

Required for a "U" trailer:
6 x longNOarmbench.stl; 2 x longLHarmbench.stl; 2 x longRHarmbench.stl


Photos show : Transverse seat with back panel fitted; sample short and long bench seating; positioning of transverse seat at junction with bench seating.





 



NEXT UP : Electric lighting components.

[John Candy]

Part 11 : Electric lighting components

Lighting : Trailers to Diagrams "Q" and "U" were all gas lit when built but, between October '29 and January '32, all were converted to electric lighting.

Electrical/ battery  boxes came in two types (widths being 4ft 6ins and 3ft 6ins) and can be printed from files
gauge3.info/downloads/BoxLarge.stl
gauge3.info/downloads/BoxSmall.stl
You will need 3 boxes per coach (2 x large plus 1 x small)

Dynamo : gauge3.info/downloads/dynamo.stl

Photo: Large and small boxes (handles added with  wire after printing....positions of holes are marked for drilling) ; dynamo (there are two parts, the pulley being separate from the dynamo body/support bracket).



Note : If modelling a gas lit coach you will need to fit lamp tops and pipework, etc. to the roof; much simpler to electrify your coach!

NEXT UP: Body detailing (including "gong").

[John Candy]

Part 12 : Gong and other driving end bits and pieces.

Gong : Prominent on the driving ends of autotrailers were the warning gongs, fitted from the 1920's onwards, to augment the sound of the whistle when the autotrailer was leading. The gong was operated by the driver via a foot pedal cable linkage.
The most usual position was above the LH driving cab window (looking at the front of the coach) but in a few cases it was located below the window (usually when driving controls had been retro-fitted to the gangwayed end of an intermediate trailer, such as with diagram "R").
The file contains two parts : The gong and a spacer piece, which fits between the gong and trailer end.

gauge3.info/downloads/gong.stl



Regulator : This hangs down and is located by pivot/linkage above the central window in the driving compartment (the location is obvious from the triangular backing plate which can be seen on the outside of the car).

gauge3.info/downloads/regulator.stl



Regulator Backing Plate : The triangular plate on the end above centre window.
I sugggest you print two and use one internally, to act as mount for regulator arm.
Note : On these later-built trailers, the bolt positions are different from those on earlier (e.g. the A10) trailers.

gauge3.info/downloads/backplate.stl



Driver's Vacuum Brake Control. This is the control fitted in the driving cab and sits on top of a vacuum pipe which comes up through the floor of the coach. The base of this component is designed to fit onto a 2.5 mm diameter tube or rod.

gauge3.info/downloads/vacuumvalve.stl



Alarm Communication Gear : Between late 1928 and late 1931, all "Q" and "U" trailers were fitted with passenger alarm chain gear . Externally, the gear consisted of rods and enclosures fitted on the driving end of these cars (on most diagrams the gear was fitted to the non-driving end).
This file will print the enclosure boxes for one car

gauge3.info/downloads/alarm.stl

Note : Being difficult to photograph as loose parts, the photo shows them as fitted on the non-driving end of my diagram A10 trailer.





NEXT UP : Vacuum brake fittings.

[John Candy]

Part 13 : Brake Components.

Vacuum cylinder : gauge3.info/downloads/vaccylinder.stl
Linkage : gauge3.info/downloads/vaclink.stl
V-hangers : gauge3.info/downloads/vhangers.stl (this file prints 4 hangers)

2 x Cylinders and linkages plus 4 x V-hangers required per coach.

Rather than try photographing the components, the attached screenshots show what each file will produce.
Note: This type is NOT suitable for earlier (Dean era) coaches.



 


Next Up : Roof Hoops (internal)

[John Candy]

Part 14 Internal Roof Hoops.

Roof Hoops : These parts are to provide support for the roof planking and lateral strengthening/positioning for the sides (they act in conjunction with the internal saloon partitions and share their upper profile).

Several are required to be spaced along the length of the coach and I recommend a minimum of eight for diagram "Q" and six  for diagram "U" ("U" having two addtional saloon partitions).

gauge3.info/downloads/roofhoop.stl



NEXT UP : Window Bars

[John Candy]

Part 15 : Window Bars

Non-driving Ends : The windows of the non-driving ends of trailers were often (but not always) internally fitted with three vertical bars per pane to protect during loading of luggage and other goods. From the mid-1930's onwards, the majority of windows in non-driving ends were plated over (following a period during which the glazing had been partly painted black, externally, as loco crew complained of being distracted by reflections).

The vertical bars on the end windows are best represented by 60thou. brass wire.

The spacers/frames to aid fitting those bars are contained in the following files:-

gauge3.info/downloads/outerbars.stl (this prints a pair of frames for the outer windows).

Although not required for this project since gangway connectors are fitted, the following file prints the centre window spacer/frame (this, as with the outerbars frame, suits all trailers with a central window).

gauge3.info/downloads/centrebars.stl

NOTE : Whereas the centrebars file prints a symmetrical frame, the outerbars frame is ASYMMETRICAL to fit the available space. The narrower vertical side is the inner edge (the part is invertible to suit both LH and RH windows).





Luggage Compartment Doors : Fitted with internal bars to protect the droplights.
These can be printed from this file gauge3.info/downloads/doorbars.stl (which prints a single item to cover one pair of doors....also use with other GWR coaches (including the E147 brake composite coaches which form the "B Set" from GRS).

Notes : Passenger Saloon Droplights  : On trailers with droplights in passenger saloons (not applicable to the diagrams being constructed here) a single horizontal bar was fitted internally across the droplight opening (presumably to deter passengers from leaning out).

Driver Compartment Windows : Just to confuse matters, from the 1930's, a single white horizontal line was painted (internally) across the three driving end windows of many trailers... to remind the driver that the windows were glazed and not to try leaning out! It can look like a bar in photos.

NEXT UP : More parts for detailing

[John Candy]

As a diversion from the autotrailer bodywork, I have been thinking about mass-production of bogies for the coaches I have in the pipeline. The conventional option would be to have parts laser-cut or milled from steel but this involves lead-time and a lot of manual assembly.

I decided to try a method with the following objectives.:

To use a machine capable of replicating complex shapes repeatedly and with great accuracy (i.e. a production line) requiring minimal manual intervention (time-saving).

Features of "Bogex" (Bogie Experiment):-

Print one-piece suspension block in PETG.

Axles running on inside bearings; designed for (optional) equalisation.

Outer/cosmetic frames : Either make your own or use commercially available frames (e.g. Walsall M I) which can be glued or screwed onto the end blocks.

The only fabricated metal parts will be bearing sleeves, equaliser beams and a mounting block (to screw into printed base block).

Design quickly adaptable to suit any wheelbase.

Photos show rendering of the file for the main unit block (9ft WB and suitable for the "American" frames shown earlier in this thread).
Further report when the test print has been completed.

John.

P.S. Currently printing in black PETG using "Precision and Strength" setting in Luban (the Snapmaker dedicated slicer) which will take a little under 18 hours.

[cabbage]

John,
I have never had much luck printing with PETG. I find it to be overly fussy of settings.

Regards

Ralph

[John Candy]

Ralph,

It is now just over halfway into the 18 hours and (at the risk of tempting fate, no doubt) will say that all is looking good. Barring a long power outage, more than the UPS can cover (the wind is blowing), I am hoping all will be well.

I simply selected black PETG in the Luban option settings and the screen indicates a bed temp of 70 and nozzle temp 235. I am using "Sunlu Gold Award" filament.

I have previously used green PETG successfully for smaller items (e.g. some Gresley coach parts as reported last year).
The Luban app is specifically tailored for Snapmaker machines and the default settings for the materials I have used have given good results.

Regards,
John.

[John Candy]

This morning I woke to find the completed test print waiting for me.

It is extremely strong and dimensionally correct.

I will print the test axlebox later today.

John.

 

[John Candy]

A Bevy of (GWR) Bogies.

The Auto trailer and "Siphon" projects require a variety of bogie types, so here are some of the common types fitted.

1) Dean 8ft 6in Bogie : Dean bogies were produced in a variety of wheelbases from 6ft 4in to 10ft but the early types of Auto trailers and steam railmotors mostly ran on the 8ft 6ins version (a few ordinary clerestory carriages adapted as auto trailers did run on a 10ft version). Although the same size bogie ran under other stock, be aware that there were differences in spring length and the design of the scroll irons and dampers (the parts which connected the bogie to the solebar) when employed under clerestory and other Dean era stock. I shall, initially, be using this under the diagram "Z" auto trailer.

2) Equalised 9ft ("American") Bogie : Designed by Churchward this type ran under a wide range of auto trailer diagrams (including the "Q" and "U" types being built here) as well as a wide range of other coaching stock. Again, there were variations in detail over the period during which they were produced. Visually, they are easily identified as being the 9ft wheelbase type (as opposed to 8ft) by having three sets of transverse leaf springs (the 8ft type had two).

3) Equalised 8ft ("American") Bogie : A variation on the 9ft type, not so common as the 9ft version and rarely used under auto trailers.

4) Collett 7ft : This was used under some newly-built trailers also as replacements under some older Churchward era trailers. Again this came in more than one version (including "light" and "heavy") with detail differences. It was also used under some "Siphons" as well as ordinary coaching stock.

Here are files for the Dean 8ft 6in type:-
gauge3.info/monobloc/Dean_8_6_bogie.zip

The "mounts" file includes the plates which fit onto the solebar and locate the "scroll irons".

You will need to supply wire/rod for the scroll irons and damper rods (as well as equalisation beams and inside axleboxes.... there will be a printed version available to suit the "block"). There are decisions you will need to make, in view of the manner in which Dean mounted bodies on bogies. Dean did not employ the familiar bolster/pivot arrangement but mounted externally via the solebar and, in model form, this is impractical since bogie swing is severely limited (this will be covered in the notes on assembly which will follow). A suitable ring type bolster mount will be provided with the next upload which will be for a bolster type Collett bogie.



Next : Collett 7ft Bogie.

[John Candy]

Collett 7ft Bogie.

The file to print this bogie :

gauge3.info/monobloc/Collett_7ft_bogie.zip

The ring mount file is common to all bogies in this project.
The design is intended to be fitted to the bogie block and to interface with a plain surface fitted to the underside of the carriage body and spaced to provide correct ride height when mounted on the bogies. You will note that there are four spherical points of contact, one pair being deeper than other. The object is to stabilise against lateral "wobble" by setting one bogie with a ring where the two deeper spheres are are aligned laterally (across the width of the bogie) while the other bogie has the ring mounted at 90 degrees to the first (i.e. the deeper spheres aligned with the longitudinal centre line of the body) to maintain correct ride height, while permitting a restricted lateral "twist" to handle track cant transitioning and any track defects (effectively a three-point suspension). The pivot mounting bolts should be slackened to allow a limited (1 mm) vertical play at the pivot. I suggest that the rings should be screwed to the block to permit replacement if wear should occur.

Being black, the printed parts are difficult to photograph, so the parts are also illustrated by rendering the source files. 



The hornblocks (for the internal bearings of the bogie "block") are at gauge3.info/downloads/bogiehornblock.stl
Intention is that (as with the bogie block) they be printed in PETG which is oil/chemical/water resistant (unlike PLA) and drilled to accept a brass sleeve/bush.

A printable pattern will follow, from which to mark out the equalising beam (which will be shaped from brass).

Next : The "American" bogies (8ft and 9ft).