Design and Engineering of VR Bogie Goods Wagons

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1 Design and Engineering of VR Bogie Goods Wagons Introduction Understanding the practices and standards used in the design of VR wagons will enhance your skills in building models of VR rollingstock. This paper looks at the design and engineering of bogie goods wagons by the Victorian Railways, with close attention to wagons built in the period between 1910 and 1950 (many of these were still in operation in the 1970 s). The evolution of the QR-class open wagon is used as a case study to show the progression of wagon design through the first half of the 20 th century. General Conventions The VR used imperial dimensions of feet and inches for their rollingstock design. So it makes sense to work in these units when you are working at 1:1 scale, eg when measuring or making your own drawings of VR rollingstock. However, when working in HO scale it is natural to use millimetre units. To convert feet and inches to HO scale, simply convert the feet and inches to a decimal number (eg, 5 foot 6 inches = 5.5 feet), and multiply by 3.5 to give the HO dimension in millimetres (eg, 5 foot 6 inches in HO scale is approx 19.3mm). Wagon Design Constraints Track Gauge. The VR system was almost exclusively run on 5 3 broad gauge tracks (except for the standard gauge link to Albury/Sydney that opened in 1962, and the four 2 6 narrow gauge branchlines). Four-wheel goods wagons were designed to run on broad gauge, and could not be converted to run on standard gauge. However, bogie wagons had the advantage of bogies that could be exchanged for standard gauge bogies. Some bogie wagons were dedicated to standard gauge usage, while many wagons in the s were modified to allow for fast exchange between standard or broad gauge bogies. Axle loading. Wagon axle loads had to be kept within the allowable weight allowed on the rail. On VR branchlines of 60lb/ft rail, maximum wagon load was only ~12.5 Ton per axle, whereas mainlines allowed for a higher axle loading of ~19 Ton per axle. So many four wheel wagons were designed for a maximum all up weight of 15 Ton. Low capacity wagons on the VR system was not much a concern in the early 20 th century, since many goods consignments were also small (eg from farmers). However, as the typical size of consignments grew in the later half off the 20 th century, bogie wagons with four axles began to have an advantage. An example of this shift is in the railing of bulk wheat on the VR system. The 1960 s designed GJF bogie wheat hopper had an all-up weight of 75.8 Tons (load capacity of 55 Tons), which replaced an equivalent of two and a half loaded GY four wheel wagons. Loading Gauge. The VR had maximum dimensions of wagons known as the Loading Gauge. This ensured that all wagons that ran on the system would safely clear bridges and infrastructure adjacent to the rail line. Floor height of most wagons was standardised to 4 0 on the VR which meant that they were at station platform height for easy unloading. p 1

2 Goods Wagon Loading Gauge [VR General Appendix to the Working Timetable] Hook Couplings. The first couplings consisted of a hook, chain and buffers. The hook was connected at the end sills, and consequently the sills were subjected to high loads. Later in the 1880 s, continuous drawgear was adopted. This provided a rod connected to the hook at each end of the wagon, thus handled the tension loads of the train pulling forces. In addition, the chain was replaced with 3 link screw couplings. The buffers, which absorbed the buffing or compression forces of the train, were centred 6 4 apart and 3 6 height from the rail. Hook and Buffer Couplings [D.Baillie] AAR automatic knuckle couplers were gradually introduced from about 1924 on goods wagons, and buffers removed later on in the 1950 s to save weight and increase permissible wagon loading by 1 Ton. The left hand buffer at each end of the wagon was normally replaced with a shunter s step. The standard for auto coupler height was 2 11 above the rails. Note that much of the passenger car stock was never converted to auto couplers. This is p 2

3 because the auto couplers allowed for longer trains and faster/safer coupling/uncoupling. This allowed for the longer and heavier goods trains, and fast marshalling of trains. However, these factors did not hold a significant importance for passenger trains. Auto coupling (buffers removed and shunter s step fitted) [D. Baillie] Westinghouse airbrakes were used on VR rollingstock throughout the twentieth century. Each wagon has an air hose at each end to connect to the train. Each wagon was fitted with its own auxiliary air reservoir, triple valve and brake cylinder with rigging to provide air braking. Further details on the brakes can be found in the following note: Exceptions were a few departmental service stock, such as workmen s sleeping cars, that did not have air brake equipment. There were strict rules as to how many unbraked wagons were allowed in a train. The other exception was single passenger cars that had dual air brakes for safety reasons. For example the DERM railmotor and single car Tait suburban electric cars were converted to dual brakes in the late 1960 s. Above: Basic Westinghouse Air Brake Arrangement on a VR E Bogie Wagon. From left to right: air reservoir, triple valve, brake cylinder. [D. Baillie] Once VR wagons entered NSW in the later-half of the century on the standard gauge, they also required fitting of a grade control valve. When the grade valve setting was selected on a wagon, the release of air from the brakes was retarded thru an orifice, and resulted in slow release of the brakes. This allowed for departure from stations on an upgrade without the train rolling back. p 3

4 Build locations Modelling Victorian Railways The VR had extensive workshop facilities throughout the state. They were selfsufficient in building and maintaining much of their rollingstock. Typically the VR would buy one new piece of rollingstock (eg loco or wagon from overseas) and then copy it. This is one reason why there was diversity in the design and build of VR rollingstock. Designs were taken from the America (especially bogie goods wagons and passenger cars), UK (especially steam locomotives) and other Australian states (especially with South Australian Railways broad gauge and its alignment with American design and practice). By the 1920 s the VR design office were fully capable of designing a full range of rollingstock (eg, K, X, S steam locomotives and bogie goods wagons). Interestingly, this trend was somewhat reversed, with the design and build of diesel locomotives outsourced (eg, all of the mainline diesel locos were obtained from GM-Clyde, and electric suburban trains from outsourced manufacturers). Newport workshops were the main centre for rollingstock construction throughout the twentieth century. Ballarat and Bendigo workshops did some construction as well as maintenance work on rollingstock. The First Bogie Wagons Westblock, Newport Workshops [D. Baillie] Q1 was the first bogie wagon built by the VR in 1871 at the Williamstown Workshops. It was quite a unique design, and the design practice doesn t resemble the latter bogie wagons built. The R class of bogie wagon built in 1880, is typical of the state of the art in wagon design in Victoria at the time. It was all timber construction, had heavy timber end sills to support the buffer and draw hook loads. They also featured truss rods to prevent the underframe sagging under the loads. But like all wagons with wooden underframes, they needed regular rebuilds and many were withdrawn by the time they were ten to twenty years old. p 4

5 R-Class Bogie Wagon [PROV VPRS P1, H4538] The QR wagon (1890 s design) The QR class of wagon can be used as an example of bogie wagon underframe design from the 1890 s. Wagons QR1 to QR201 were built in the 19 th century and were designed for continuous hook and buffer draw gear. They now had a steel and wood composite underframe able to be loaded to 26 Ton capacity. The use of steel structural members in the underframe cost more to build, but ultimately paid off in terms of reduced maintenance and significantly longer life. Steel channels for the underframe were expensive because it had to be imported from England. QR168 in 1920 s prior to auto coupler conversion [PROV VPRS P4, RS/0266] Later in 1928 the VR started to convert the QR wagons to auto-couplers. Included in the rebuild was conversion to an all steel underframe with strengthening of centre sill to take the auto coupler tensile and compressive loads from the train. The use of steel also enabled increased load carrying capacity to 30 Tons. When the buffers were removed in 1951 (due to completion of the VR campaign to convert most goods stock to auto couplers), the loading capacity was further increased to 31 Tons. At the same time the wagons were in the shop for as the buffer removal, the truss rods under the side sills were also removed. These were no longer required after the 1928 underframe strengthening reworks, but was interesting that it took so many years the VR to finally get around to doing it. I presume this might have been a case of avoiding unnecessary work until a stage when they needed repair due to damage or aging. p 5

6 QR post-1928 rebuilt with strengthened underframe and auto couplers [D. Baillie] Since I m interested in modelling the period where auto couplers were already in use, lets step through the design of the QR underframe from the 1928-update program. Centre Sills (centre longitudinales). The two centre sills are the main structural members of the underframe. Their task is to take the pulling and buffing forces from the train (transmitted through the auto couplers), and also to take the vertical load of the loaded wagon (so they must be stiff in bending). On the QR wagon, they consist of two lengths of 12 x 3.5 steel C- section. C or I-section is employed almost exclusively on centre sills because the upper and lower webs add significantly to its bending strength to provide load carrying capacity and to avoid buckling due to train compressive buffing loads. The length of the wagon as well as the depth of the section determines bending stiffness of the centre sills. On longer wagons than the QR, the centre sill is often much deeper than 12, and can make use of a fishbelly shape to improve bending stiffness (fishbelly outer sills were first evident on the Q39 to Q63 flat wagons built at Newport workshops in 1913). Side Sills (outer longitudinales). The QR wagon side sills are constructed from 10 x 4 C-section steel. When hook and buffer drawgear were used, the side sills used to take considerable amount of the train buffing (compression) forces. Upon conversion to auto-couplers, the main structural function of the side sills is to assist in vertical load carrying capacity of the wagon. To assist in bending strength, the side sills on the QR were built with truss rods (although they were later removed after the centre sills had been strengthened for auto coupling). Alternatively, a fishbelly design of the side sills can also be used for bending strength. As mentioned above, the VR Q39 to Q128 wagons had this feature. By the 1960 s when the auto coupling was in exclusive use, some modern bogie wagons designs had the side sills completely omitted. Two examples are the FVF and TVX flexivan container wagons. On these wagons, the side sills would hinder loading of the trailer containers and were dispensed with altogether. The centre sills on these wagons were designed as very deep fishbellies to take the complete load of the wagon. The next step in the structural evolution was the late-60 s gas tank wagons that are essentially without an underframe because the tank also acts as the structure. End sills (outer laterals). The end sills were constructed from similar steel C- section as the side sills on the QR wagon, except that the flat edge was facing outwards (this enabled a flat surface for mounting of the buffers). A short diagonal steel member was riveted between the buffer and the centre sills to distribute the buffer load between the side and centre sills. p 6

7 Bolsters (laterals). The body bolsters tie the centre sills to the outer sills at the bogie support location. Thus they provide the vertical load path between the side sills and the bogies, which enables the side sills to support the goods load of the wagon. In addition, they provide torsional stiffness to the underframe. Torsional stiffness is important in a wagon frame to prevent body flexing on rough track. Excessive body flex of a wagon can result in a rough ride. The body bolsters are also commonly C or I section of full depth in order to maximise stiffness. Transoms (laterals). The transoms are secondary steel members that link the side sills to the centre sills. So they have the same function as the body bolsters. On the QR they were of quite insignificant size, but as bogie wagons grew longer, they had to be increased in size to give the wagon underframe significant stiffness. An example is the 46 foot ELX wagon which has three sets of major transoms between the body bolsters. The ACF wagons (1925) The next significant stage in the evolution of VR bogie goods wagons came in 1925 when the VR ordered two of the following bogie goods wagons from the American Car and Foundry Export Company from the USA: E 1 & 2 open wagons, S 1 & 2 flat wagons, J 1 & 2 coal hopper wagons, V1 & 2 louvre vans. VR E1 Open Bogie Wagon imported from the USA [PROV VPRS P1, H4694 ] They arrived at Newport workshop as kits, and were assembled there. They were then copied and further wagons of each type were built at Newport. The purchase of the ACF bogie wagons introduced the latest technology in North American rollingstock design to the VR. Most notably these ACF wagons had much higher load carrying capacity than anything else on the VR at the time. For example, the E open wagon had a load capacity of 44 Tons (tare of 18.4 Tons and 43 foot long) compared to the QR at 20 Tons (13.5 Tons tare and 36 foot long). To achieve this increased load carrying capacity, the design of the wagons featured the following AAR practices: All steel construction (including underframe and body) High load bearing bogies p 7

8 AAR automatic couplings (but built autocouplers and with chain and buffers to couple with other VR rollingstock) High capacity ratchet handbrake These innovations were copied in the design of subsequent bogie wagons by the VR. A standard American Car And Foundry Steel Underframe for North American Railways. However, the VR needed strengthened end and side sills to allow for hook and buffer loads. [Car Builder s Dictionary Eighth Edition] Interstate Running and Bogie Exchange (early 1960 s) Prior to the opening of the standard gauge to Sydney, VR broad gauge wagons only ever went interstate to SA on their broad gauge system, and conversely SAR wagons were freely interchanged into Victoria. After opening of the standard gauge link to Sydney, some VR rollingstock was converted to standard gauge, and for the first time VR wagons could complete the entire journey from Melbourne to Sydney. In addition to the standard gauge link, in 1963 three bogie exchange facilities were opened at South Dynon, Wodonga and at Port Pirie in SA. At the facility, each wagon was rolled into a shed and lifted by a crane. The bogies were rolled away from under the wagon, and replacement bogies were fitted. The South Dynon bogie exchange centre could handle 200 wagons a day, and thus saved a lot of time over the traditional process of unloading and reloading wagons of their goods. Now rollingstock could travel on broad and standard gauge systems between Perth and Brisbane. Interstate running forced some commonisation of rollingstock design to ensure compatibility across Australian systems, including: Auto couplers Air brake grade control Standardised method of identifying bogies Common outline dimensions of bogies Common loading gauge Maximum axle load (18.75 Tons per axle / 75 Tons per bogie wagon) Interstate running of rollingstock brought closer co-operation between the states railways. One off spin was co-operation in development of common goods wagon designs. For example, the VR took responsibility for designing a 63ft flat wagon for ISO containers in 1968, and the first FQX wagon entered VR service in March It was built with high tensile steel to reduce weight so that the payload could be maximised. The same wagon design was adopted by the SAR and NSWGR. p 8

9 Model of a FQX container wagon. Designed by the VR and adopted throughout Australia. Integral frames (Late 1960 s) [VR Newsletter, May 1967] Some wagons were designed without separate underframe, rather the body was designed to take the train pulling loads. For example, and oil tanker wagon with integral frame was designed by the VR in 1968 (TWX631 and 9 others). This saves weight, allowing 2000gal of extra weight to be carried, and obviously saves cost in construction materials. Above: TWX tanker with integral frame [VR Newsletter, Oct 1968] p 9

10 Other Modifications Through the Years Here are some other modifications that were made to VR goods wagons through the years: Welded steel replaced rivets in new wagons (1931) Buffer removal program for goods wagons (1950 s). A shunter s steps placed on the left side corner at each wagon end. Steel shunters steps, made of steel mesh replaced wooden steps from These improved safety and reduced maintenance costs. Paint colours and stencilling standards. Refer to my notes on stencilling standards used post Bogies I am not going to mention bogie design in this paper, except to state the obvious that their design was critical in both dictating speed limits and wagon load capacities. Instead, see the following guide on my website for details of the many bogies used by the VR: Modelling Bogie Wagons In modelling wagons, many of the principles used in the structural design of the prototype wagon can be applied to your models in order to produce a rigid model. This is important especially in the modelling of flat wagons where there is no body to assist in model strength and rigidity. The key points to building a rigid underframe is to: Maximise bending stiffness of the side and centre sills (longitudinales). Do this by maximising the depth of the sills. Use C or I sections, or if using plain rectangular section, maximise the thickness. This helps to give the wagon bending strength, and will avoid sagging of the wagon between the bogies. An even better result can be achieved by using rectangular hollow tube for the centre sills if bending is a persistent problem. Maximise number of transoms and their depth (laterals). Adding lateral members will increases the torsional stiffness of your flat wagon models. This will aid in warping and twisting of your underframe. Once again, try to maximise the depth of the transoms to get the most benefit. Refer to my notes on my website about building model bogie underframes for a complete step-by-step guide. References Public Records Office of Victoria (PROV) for some of the photos. Reproduced with the permission of the Keeper of Public Records, Public Record Office of Victoria, Australia. VR Newsletter, various editions VR General Appendix to the Working Timetable, various editions Bray & Vincent, A Brief History of Bogie Freight Wagons of Victoria 1871 to 1979, Volumes 1 and 2, Brief History Books, 2007 Car Builder s Dictionary Eighth Edition, Simmons-Boardman Publishing, 1916 and lastly, my Modelling Victorian Railways website: p 10