Objectives

To relate design knowledge, practical skills and documentation. To help in the development of a final design, considering such things as engineering mathematics, materials technology and commercial implications.

Discussion

My design placement was with a locomotive systems design consultancy, called The Engineering Link (TEL).

The first few days were spent learning how to use the principal design package; MicroStation. This is similar in many respects to AutoCAD. Also, I revised BS 308 drawing standards by producing some simplistic drawings.

I feel that I am now just as efficient with AutoCAD as I am with MicroStation. I think that for a design environment, this is important since these are the two drawing packages predominantly used in the British design office.

Some screen shots of MicroStation can be seen in Figs. 89 and 90 on page 92.

Toward the end of the first week I was asked to help in the planning of a feasibility study. The project in question was to determine whether or not some de-icing equipment could be fitted onto a class 73 locomotive.

Feasibility

Feasibility is the process undertaken in order to be able to give a straight answer to a design problem. In this case, Railtrack just wanted to know whether or not some equipment could be fitted to the locomotive. A yes or no answer would suffice.

In deciding what needs to be done for the course of the feasibility study, all aspects of the job have to be considered. The initial brief can be seen on page 94.

For this job, I identified several steps and processes. These were to:

· Clarify the brief · Obtain technical specifications and costs from the equipment manufacturer · Carry out a site visit to see a class 73 locomotive · Gather all relevant engineering drawings · Think about additional materials. What will be needed and who will supply · Risk assessment · Estimation of job · Safety and standards

These are the tasks to be carried out in order to complete the feasibility study. As a result of identifying these steps, it is possible to put together a project plan, to submit as part of the feasibility study.

While somebody else tried to sort out all of the above, I was asked to identify the key stages in the project plan. After some research, I found that I was able to construct a simple Gantt chart showing the time scales and key indicator points of the project. The Gantt chart can be seen on page 96.

At the earliest time possible, a risk analysis should be carried out since safety, and other factors arising from risk, is the most important thing to consider.

The design process, when carried out from the beginning, has to have several 'review' stages.

1. Initially, there is the design review. This is carried out in order to look at the design and to achieve a sense of direction. 2. The next stage is known as the design verification. This is where all calculations, assumptions, and details are looked at. If the need arises, they are changed and corrected. The checking is usually carried out by a senior engineer. 3. The final stage of the design process is design validation. This is where the final design is checked to ensure that, at least theoretically, it will function correctly.

The other elements I identified for the design plan are all important parts, but I initially missed the concept of procurement. That is, order forms and identification of suppliers has to be planned. For example, it can take a week to place an order and to have the order confirmed by the supplier. This is because the paperwork has to be done as well as be posted.

A company called Geismar make the de-icing equipment. The Engineering Link (TEL) would have needed the designs of the equipment in order to determine whether or not it could be fitted to the locomotive. After contacting Geismar, it became clear that they we not going to be very forthcoming. They were unwilling to supply neither the entire system nor the designs. One can only wonder as to why this might be. Why will they not supply their design drawings? A4e they not passing up the chance of some sales of their equipment? There are several different ways of approaching this problem. An entire new design could be produced, or other suppliers would have to be looked at.

This in all results in a more complicated job if a de-icing system is to be fitted to the locomotive. As a result, the study came to an unscheduled halt.

Records

During my placement, I had the opportunity to look at the drawing library system. After coming across some poor records in Railtrack, it was quite refreshing to see records perfectly labelled, categorised and stored. Available, is a piece of computer software known as PADS (Parts and Drawing System). This allows the user to search for drawings under certain headings, for example, drawing number, keyword search or parts description.

Once found, the number has to be noted. There are several filing cabinets, all in numerical order, and every drawing is kept in the cabinets. The format upon which the drawings are kept is on microfilm. That is, a viewer is needed to look at them. Once the drawing is found, it can simply be printed onto paper.

With regards to the business of Railtrack, this is one possibility of how to keep future records. This may be a lot less expensive than keeping or transferring everything onto computer. Or, in fact, is there any need for Railtrack to keep drawings at all? Since privatisation, Railtrack do not produce drawings. The ones in the records centre are from pre-privatisation. I think that a deal has to be made between Railtrack and all the design consultants to allow the free sharing of reference drawings and data. We all want to run the railways, and to have the divides between information sharing is not a good idea.

Installation design

Another project that is currently underway is to produce drawings for Train Protection and Warning System (TPWS) equipment. That is, the drawings for attaching the equipment to locomotives.

The job is to design how the equipment will fit to the bogies of various on track machines. These include tampers, tramms, and ballast regulators. Since it is a requirement for all rolling stock to have TPWS fitted by 2004, this is an important task. There are many different kinds of on track plant, and page XXXX gives a little detail on what some of the heavy plant consists of.

A foreign company manufacture and supply the equipment, but it is up to the train operator to fit it to the train. I was asked to consider how TPWS would be fitted to a class 08-275 tamper. This involved some design drawing and some calculation.

TPWS

Before I started the design of the installation of TPWS for the tamper, I took a few days to read and understand the principles and engineering systems involved with TPWS.

On the approach to each TPWS fitted signal, an overspeed sensor (OSS) and a train stop sensor (TSS) are provided.

Both the OSS and TSS have two loops, an arming loop and a trigger loop.

TPWS will only be energised if the signal is at red.

If the TPWS loop is energised it emits a radio signal, when a train passes over the arming loop this starts a timer on the train. If the train passes over the trigger loop with the timer still running then an emergency brake application is made. The driver cannot override the brake application for a period of one minute.

The timer on the train is usually set at one second for passenger trains; freight locomotives have a longer setting as freight trains generally run at slower speeds and require a longer distance to stop.

As the timer on the train is fixed, the only way to vary the trip speeds is to alter the distance between the arming and trigger loops. As an instant trip is required at the train stop, the loops are positioned next to each other.

Permanent Speed Restriction's (PSRs) and Buffer Stops will be fitted with an OSS set for the required trip speed.

A typical layout of a TPWS signal can be seen in Fig XXX.

In order for this system to work, the locomotive has to have an antenna attached underneath. This interacts with the track magnets. I was involved with the installation design of this antenna.

Installation design procedure

Since TPWS equipment has to be near to the track in order for it to work, the best place to mount the TPWS is on the bogie of the vehicle. This may seem pretty straight forward, but several elements have to be considered.

One element is the dimensions of the bogie. That is, the physical shape and size. TPWS has to be located so that it is above the centre of the track. Fig. XXX shows a simplified drawing of the bogie that I was dealing with.

As can be seen, there is nothing between A and B, so this gives cause to design a bracket to span this distance. However, because there are other bogies of a similar physical geometry, I was able to make use of an already existing bracket.

So, therefore, since the bracket was already designed, and the TPWS is a bought in part, what actually has to be designed? Well, the design involves deciding where to actually place the TPWS antenna. There has to be a metal free zone surrounding the antenna. This is to prevent interference between the antenna and the on track equipment.

The TPWS has to be mounted at a height between 270 mm and 135 mm. This is a requirement stated in the Railtrack group standards. If the antenna is fitted outside of these dimensions, the TPWS would not work effectively, if at all.

Wheel diameter and wear has to also be taken into consideration. If a wheel wears, and the diameter decreases, will the TPWS receiver still be within the maximum and minimum height? There are two diameters to take into consideration. The diameter of a wheel with no wear, as it would be new, and the scrapping diameter. This is the amount of wear needed in order for the wheels to have to be replaced.

So, the job I was allocated was to place the antenna of the TPWS onto a bracket to be attached to the bogie. Through a method of calculation, I was then able to determine a suitable height for this to be placed.

My calculation sheets can be seen on the following pages XXXXX.

The calculations determine the maximum and minimum height the TPWS antenna can be from the track. This is where vertical curves are considered. This is not the first time we have seen vertical curves, XXXX will give an explanation of what they are. Also, over throw is calculated with regards to horizontal curves. This is similar to end throw, but considers the TPWS antenna and not the entire vehicle.

By looking at the preceding calculations, it can be seen that:

Maximum end throw = 11.41 mm.

All heights on both convex and concave curves are within the absolute maximum and Minimum allowable heights.

Therefore, the conclusion to the calculation s is that the TPWS is suitable to be fitted to the tamper.

Further to this calculation, I was then able to draw the design on MicroStation.

The drawing can be seen on page XXXXXXX.

I was also allocated the task of changing some drawings for TPWS brackets. This was because of the analysis that had been carried out on the bracket. After being analysed with Finite Element Analysis (FEA), it was found that the part could be made to smaller dimensions. This is for the purpose of saving material and therefore reducing costs.

Rail Crane Design

Another job I was involved with was the design of a rail crane jib support. This was a lob for Balfour Beatty Rail plant. The jib on one of their cranes was failing over an extended time period.

Firstly I thought it was important to familiarise myself with on track plant machinery. A precis of what exists can be found on page XXXX.

I further estimated some time scales to the project by following a similar proceedure as mentioned on page XXX. By thinking about what exactly would need to be done, I produced the Gantt chart as seen on page XXX.

Site Survey

Basically, the problem was to do with the hydraulic ram (A) holding the jib in the horizontal position. This was not 100% efficient, and over time allowed the jib to fall in the direction as indicated by the arrow. Now, one might not consider this to be a significant problem, but it is more to do with safety and economics rather than component failure.

If it was possible to ensure that the jib did not creep downwards over time, this would mean that the ram would have to be maintained less often. If it is possible to do less maintenance on a piece of machinery, the better since money is saved in both manpower and less down time.

Once I had completed the project plan, I decided that the best thing to do would be to go and see the crane in question. This involved a trip down to Balfour Beatty's Ashford Depot.

Site Survey

As with any design work, it is always best to go and see the item, place or environment with regards to the design problem.

Myself and a senior vehicles engineer from TEL met with the person who had asked us for design help. We looked at the crane in question conducted a photographic survey. A few sample photographs are shown as Figs XXXXXX.

Ideas formation

In order to come to a solution, I felt that I was best to involve as much expertese as possible. Therfore, upon arriving back at the office, I arranged a few informal meetings between myself, and the structural engineers. This was so thaqt we could discuss the problem at hand, and through the method of brainstorming and ideas input, we came to a sultable basic design sloution.

The derived solution to the problem was to create a support for the jib. This would be in the shape of a horizontal beam held in poseition by two vertical legs.

Upon working throught the basics, for example, how to fit the design, I found the photograophs most useful. This was because I drew onto the photographs I order to help me visualise the solution. Fig XXXX shows the approach I took to visualise and think through the solution.

Structural Calculations

Now that I had an ideas as to how the design was going to look and fit, I decided that the only way to see if it would work would be to do some basic mechanical and structural calculations.

Most of the theory I had seen before, but I went and leant about a few new things, for example the theory of ties and struts.

What resulted was an engineering report, a condensed copy of which, can be seen on pages XXXX. I familiarised myself with the relevant vehicle standards in order to be able to do the calculation properly. The most significant standard is:

Structural requirements for body-mounted equipment on railway vehicles Group Standard GM/TT0179

The aim of the calculation was to determine the dimension of the supporting structure.

It was this report that kept me busy right until the end of my training placement.

Final remarks

I thoroughly enjoyed my time at The Engineering Link. I feel that I have gained sufficient design experience to meet all objectives. This placement has also given me the hands on experience of design, looking at procedures, planning, theory calculations and drawings.

Conclusion

I feel that from this placement, I have achieved several IMechE objectives.

T1 Materials and components

This design placement included material and component selection. The projects I was involved with directly needed the consideration of materials, components and their properties. Since the designs I completed were for specific uses and environments, material and components had to be considered carefully.

T2 Engineering Processes

Design processes have an important role when design is concerned. I studied the relevant processes in order to carry out my design projects according to the rules and regulations. Although these processes are specific to The Engineering Link, they can also be considered for any general design work.

T3 Assembly, installation and commissioning

I had a small input to creating installation procedures. These are made in order to ensure that the design is installed correctly. These are a list of instructions informing how to fit the designed item/s.

T4 Communication and information systems

Through the creation of AutoCAD drawings to relevant British standards this is, in itself, communication of technical data and information.

T5 Design and manufacture

I feel that I was able to operate in the design environment effectively. I learnt how to use MicroStation, a CAD package I had not used before. I have also improved basic mechanical engineering theory by use of creating design calculations.

BP2 Financial implications

When designing, there is a constant consideration to finance. When I was carrying out my projects, I had to consider costs and budgets concerning manufacturing, materials, and life span.

BP4 Inter-personal skills

I feel that meeting new people and working along side them has improved my interpersonal skills.

BP5 Legal and health and safety requirements

Since the work that The Engineering Link is involved with is directly related to locomotives, there are various requirements that have to be met. These vary immensely, but do govern what a design may finally look like.

As well as the above IMechE objectives being met, I also feel that most, if not all Railtrack objectives were met.