August 2016

August 2016 letter

What a month. It is really like two months. The first when I expected the return of a healthy Harry. The second when I knew he would not come back.

At the beginning I was happy to tell Harry that he had a clear driving license again. Ginger and I were having trouble with a mouse and we got rid of it. Harry got concerned because our phone was dead and call the fire department. They came, the phone was made to work again, but it was something of a surprise to have the fire truck roll up and the firemen in full gear start to look for me. I busied my self with some cleaning, sorting, and shelling walnuts.

Then things changed. Harry stopped improving and one of the doctors said that there was just a chance that he could die, but they were trying new things so he was still hopeful. Harry and I discussed what I would do if he died so maybe he had picked up the vibes from the doctor. Harry said he felt better that I had thought about it and had sensible ideas. That day he looked terrible but when I came the next day he looked pretty good and we talked for an hour or so. I thought he was back to the slow improvement. That evening Harry called and asked me to come right away. Unfortunately I was actually incapacitated and explained that to Harry. He said we should say our goodbyes, just in case, because he would not be able to talk later. And so we did. The next day he was in an induced coma and never was conscious again. It was a very fast death, like he fell over a cliff. The basic problem was a lung infection which in the end could not be cured. The lung problem put a strain on his heart and the treatments put a strain on his kidneys. When he died it is from kidney failure and a massive heart attack on top of lungs filled with fluid. During most of the illness he was cheerful and optimistic. He had practically no real pain just discomfort and no real fear and anxiety until the last few hour of his consciousness. It was perhaps a kind death for someone who was coming to 86 and going blind. Until shortly before going into hospital he was still mentally strong and fairly physically strong so there was not the long twilight that many old people must endure.

So now there is the part of the month in which I cope. I think I am doing that well. I have a mess but a list of things that must be done and I am working my way though it. I have had help from friends and neighbours, the undertaker and the mayor’s office. I have developed a method for dealing with the lack of French. I write down what I want or my question or whatever in English. I use extremely short and uncomplicated sentences and run it through Google translate and then run it through backwards to check. I print it and take it with me to hand to whoever I need help from. It works fairly well so far.

I will not be staying in France but selling up and leaving. But that is easier said then done. It will take a while. Harry and I discussed three things I could do: find a companion to live in France with me who was bilingual, move to the UK, move to Canada. All have pros and cons but I have settled on a visit to the UK but settling in Saskatchewan.

I have items that I was collecting of this month, but I am not putting them in. I have been going through Harry’s papers and I will put some of them in. I do not want to take time this month for more than that. So this month we have the letter above, followed by introductions to some of Harry’s papers, followed by the papers themselves. There will be more in later months.

You may find more than usual typos and errors in this month. I am not taking the time for a careful reading. Sorry.

Intros to Harry’s papers

When Harry was in hospital and ‘getting better’ he decided that he would really put a high priority on getting his ideas down on paper and organized. He was having trouble with writing because he was losing his sight and had lost the feeling in the finger tips of one hand. He asked me to find hardware/applications that would allow him to be talking rather than typing and listening rather than reading. He had in his mind, things he had written but not in the way he wanted, things he had started to write and would like to finish, and things that were in his head but that he had not yet tried to put on paper.

He also realized that he was never going to get around to having his own website and asked if he could put some of his ideas on mine. But that never happened because of his death. It was a change for Harry to ask to be included in my site because I had offered many times but he wanted the sort of site that he had created in his mind and not the sort I had. I believe that he would have written items for my site but he did not get a chance to do that after he decided he wanted to, life was too short. In going through some of his old notes I have found a list of old projects that I think was probably things that he would have put on my site along with new stuff. I will do what I can to bring some of this material to life.

Some is extremely old and very dated. I will put introductions to these pieces in the main post, but put the actual material in a separate post.

It is a great disappointment to me that some things are not recorded in any form anywhere. Harry’s great talents were inventing, designing and teaching. He could come up with unique ideas, he could play with something until its strengths were preserved and the weaknesses eliminated, and he could find ways of communicating difficult concepts. But the documentation is slim. Harry loved the puzzle solving bit but once that is done he was not so great at the less interesting bits: writing, building, selling etc.

This may take a bit of time to organize and post and so it will come as I have time and find things. Here is a start.

1. The tractrix horn

There is the draft of an article for a magazine in his papers which I have copied. The figures he mentioned are not there and were probably never finished to his satisfaction and so the article was never sent. However, I remember the tractrix horn events well. We were living in Wivenhoe and I was working for the Essex University and Harry had a delivery business called The Man with the Van, carrying unusual loads often to unusual destinations. But he also had a good deal of spare time. We were missing a good hi-fi setup because we had not had one for a number of years. Harry really appreciated good sound. He liked to be able to hear the tiny soft squeals of the bow first touching a string – that sort of thing. He also appreciated undistorted low and high sounds. He liked a good bass sound so he could actually hear the full beauty of a string bass or organ. Magazine articles on the tractrix horn took his fancy. First he tried to figure out why this was such a perfect horn. It has to do with managing the transition from the movement at the speaker cone to the propagation of the sound into the room. At the cone each wave front is like a little bubble that is getting bigger as it moves out. The bubble has to be shepherded until it is big enough to enter and quickly fill the room. The tractrix horn has walls that always perpendicular to the edge of the wave front that is against them. This keeps the front intact and strong all the way to entering the room. Linking bass notes to a room is especially difficult and so the tractrix shape is favoured except that it is so long that it is bent around to be put in a reasonable sized box. This is some what old fashioned now that sound tends to be electronic and digital but it was important then. So having convinced himself of this, his next step (which is not in the article) was to figure out how to draw a tractrix curve on his draughting machine. In the end he made a little jointed thing out of a protractor head and some pieces of metal that he could move up a straight line and it would draw a tractrix beside the line. (It was lost long ago). He then got interested in the relationship between the formula that he got from the magazine and the actual behavior of the curve. He worked out the formula (this is in the article below). What he does not mention is that at the point where he recognized the need for calculus he had to work that out as he had never been actually taught calculus. Then he got taken up by the value of ‘e’ in the formula. After weeks of asking and reading without being happy, he finally understood the way ‘e’ was related to the natural expansion of a bubble. I cannot remember his new definition for ‘e’ and I cannot find anywhere that he wrote it down. Anyway he was quite pleased that he was one of a rare group of people who actually had a way of understanding ‘e’. When came the experiments in the bathtub as he could now create tractrix curves at will and had a notion of what the wave fronts should look like. There was still a lot of work in getting the setup with lighting to clearly see the waves, and ways of creating them etc. We were on our knees watching the bath for many nights. But something else overtook the hi-fi project and the horn was never built. The figures never made and the article never sent. But Harry had had a great time solving puzzles and understanding more of the world.

2. Differentially Supercharged Engine

This is a very dated project too. Harry got this idea and was taken by it. He looked into aspects of it for a number of months and then decided to see if some engineering school in the UK would support his research. He had no takers. But he kept the draft of the proposal and felt for some time that it was still a very good idea. I have not found the final version of the proposal or the figures, but there are some rough sketches.

This is an example of how Harry designed. He played with the components in all sorts of ways to get the most out of the design with the least weaknesses.

There is an example of this that was never recorded. When Harry worked in the fuel cell lab at Brush in Loughborough, he redesigned the plastic moldings for the experimental cells. The ones they were using often failed because they were badly made, assembled wrong, had glue trickle to the wrong places, or a lot of other faults. Harry found about twenty awkwardnesses. He designed one that was only a couple of pieces, one used in two orientations, they were cheap to make, they physically could not be assembled wrong, never leaked and so on. It was a little gem of a design.

3. Review of a Workshop Manual

This is also dated. Harry did a review of a couple of manuals published in Communication Quanta, the publication of the Institution of Technical Authors and Illustrators, in the fall of 1970. He worked as a technical writer for some years and also had a lot of experience as a user of repair manuals in garages.

Harry almost never lost sight of the context, the big picture. Although this was written for technical authors, it puts them and their work in the context of the whole industry they are working in rather than just the concerns of the publications office.

He was the sort of tech-auth that went and talked to the designers, the production line, the repair shops and even sometimes the complaints department. He understood what he saw, could write it clearly and always personally proof read the numbers even if there was someone else to do editing.

4. A letter to the editor on the metric system

If I remember correctly, a very well known Saskatchewan lawyer, M Shumiacher, publish something in the local Regina newspaper against the metric system. There was a back and forth of letters on the subject. I think there was some talk of the metric system being OK for science but it wasn’t much good to farmers. Harry sent in the a letter that gave a very apt agricultural example. This way of finding a good case and description was one of the ways that Harry was a good teacher.

Tractrix horn

I have just completed the preparatory work involved in building a set of horn loudspeakers based on the ideas put forward in Mr. Dindale’s 3-part article last year. (For which much thanks!) Because of the amount of work involved, it has struck me that a summary of it with some of the conclusions reached might be a useful time-saver for those of your readers who, like me, find both the mathematics and the experimentation a little daunting.

First, the mathematics. The tractrix is given to us as the curve whose tangent at any point is a fixed length from a straight line (to the point of tangency). See Fig. 1. The length of this tangent is derived from the wave-length of the cut-off frequency (L/2 Pi x 1.2) but can more simply be called ‘a’. It is useful at this point to rotate the drawing through 90 degrees, standing the embryonic horn on its bell. The tangent at any point x,y is b/x. But b=root (a squared – x squared). Thus the tangent of our curve is this expression divided by x, and our curve is the integral of this function. This turns out to be


after a sign change to correct for the negative slope of the tangent. This is Mr. Dinsdale’s expression with a replacing of theta/2pi, and with x as a function of y replaced by the more usual y=f(x). But now a step further: we can simply let a=1. Then all the values for x,y can be multiplied by any value of ‘a’ for a horn of any cut-off frequency. It is as though, having drawn our curve, we super-impose a piece of graph paper of whatever scale we choose. This has the advantages of (1.) giving us a function that can be handled by the simplest programmable calculator





and (2.) having rattled out a set of values of y=f(x), we don’t have to re-do the whole process for every new horn we wish to calculate. In the process we have gained a useful edge in accuracy. The graphic method carries the risk of a cumulative error which can easily digest the ‘safety’ factor 1.2 in the first expression.

The Design. Having been given a starting point of such theoretical beauty as the horn, it seems a terrible pity to throw away whatever it is one loses in folding it into submission. So the first question was, is this violence really necessary? Since we start with the tacit acceptance of the mouth dimensions, it is the length of the horn that poses the problem. But the length is dominantly determined by the throat diameter. By using 12” or even 15” drivers, and by shaving away at the 3:1 safety factor in the L.S.:throat area ratio, we can achieve a 50 Hz corner horn of less than 5 ft. for example. Not bad, if we can find some way of putting 4 ft. of it through a wall into non-premium space. In our case this effered the alternatives of mono bass horn in the middle of the long wall of the lounge (horn going through into under-stairs cupboard and increasing dimensions for wall mounting), or moving the corner positioned horns from the floor-corner intersections ot the ceiling-corner intersections and letting the horns through into the garage. Since this last involved an unknown (efficacy of ceiling-corner intersections as base sources), and cutting through a cavity wall, I re-joined the masses in looking at ways of folding the horn. It seems worth pointing out, however, that in many houses the problem could be solved at this stage. Where a dining space backs onto the lounge, for example, the drive-ends of the horns could be accommodated in a built-in sideboard on one side and a cupboard or side table on the other.

With the quite-manageable horn length afforded by big drivers, I resolved to find a solution involving one bend only, taking the length of the horn upwards towards the ceiling or sideways towards the other horn, in both cases putting these ‘tails’ behind paneling as part of a ‘hi-fi’ wall that could also incorporate useful things like bookcases, shelves etc.

To investigate different bend geometries, I made the quite unscientific assumption that there is a valid relationship between the behaviour of wave-fronts on the surface of a water-puddle of a particular shape and those in the three-dimensional air of a duct of this cross-section. I hope there is a validity in this relationship, but I cannot claim that there is. I am simply using an allegory as a source of data, which is, of course, quite wrong. In all six shapes (representing vertical cross-sections) were tried. The first was derived from a composite horn in which the final bell was symmetrical, changing to asymmetric section around the bend. Of the other five, one is a folded or reflecting horn, the others are curved, and all derived from a asymmetric cross-section. This asymmetry is in the sense that one boundary (the floor of the horn, and terminating into the floor of the room) is straight, and all of the cross-section differences are provided in the contour of the opposite boundary. Theoretically this is attractive because even in the wall mounted case we are talking about a helf-horn, the other (imaginary half feeding into an imaginary room under the floor. This approach seems consistent with the general hypothesis of the tractrix horn that, if the wave-front is perpendicular to both boundaries, and this leads at the floor, so much the better. The alternative case has the wave-front trailing at the floor with respect to the axis, the thus reflecting upward across the rest of the wave-front.

To derive the contours I rejected the idea of drawing a curved centre-line and erecting perpendiculars along it because it makes the inner wall too short. Instead, I used the length of the inner wall as the minimum dimension, letting the outer wall determine its own length. If we imagine a square sausage, the first approach amounts to bending the sausage and have the inner wall crinkle up and the outer wall stretch, the second approach is to cut the sausage almost through in a dozen slices, curve it towards the uncut side, then fill the gaps with extra wedges. This way the shortest wall is the right length, all others two long, This seems the lesser evil.

The observations:

Cross-section 1. The wave-front broke slightly into two around the bend, and reflected badly where the bell terminated at a straight-edge simulating the floor. It established that the scale I was using for the model was too large (with respect to the bath tub), that the method was entirely too extravagant in terms of over-all height, and converted me to the arguments advanced earlier for an asymmetric horn as a starting point.

Cross-section 2. This is the result of trying to keep the horn straight for as long as possible, this to get to a smaller cross section at the curve. In this way the curve itself takes up less room, and by starting, in a sense, closer to the floor, also finishes lower, and results in a minimum over-all height. The wave-form broke badly at the bend. The effect is that art of the wave-front follows the inner wall of the bend out to the mouth, but the part on the outside of the bend carries straight one and is essentially reflected towards the mouth of the horn. This part carries most of the wave energy: its bottom edge leads, with its upper portion trailing the first part of the wave-front, intersecting it at about 2/3 of its height; but the two factions seem to unite, merging into a respectable wave-front at about 1 ½ horn diameters from the mouth.

Cross-section 3. This is an attempt to exploit the effects seen above. The intention is a make the most of the reflected wave and discourage the non-reflected part. It is designed so that the length along the reflected line is correct. The ‘mirror’ is not at 45 degrees, but joins the projected lines of the two curves. (this was the result of a lot of experimentation.) Essentially, the result was the one hoped for. A small but quite strong reflection, or perhaps eddy, occurred with the mirror terminated. This was only sured by radiusing the mirror to blend with the floor in a tangent. A minor part (perhaps 1/5 of the total energy) of the primary wave-front still, ‘spilled’ around the corner into the bell. I thought to inhibit this by installing a ‘filter’. An array of thin, parallel lathes was fitted, extending the first curve to the termination of the mirror. The idea was that these would be transparent to the reflected wave, but would severely damp the primary wave. At best it had no effect at all, at worst (in the case of strong and high frequency waves) it caused serious break-up of the reflected front. This may have been the effect of poor detailing. The shutters (stiff card) were neither perfectly plane not parallel. But, offering so little encouragement, this line was dropped. I tried sharpening the apex of the corner around which these waves persisted, even to the extent of making a small projection into the channel, but with no positive result. None-the-less, the primary wave was smaller than before, and again was caught by the reflacted front a short distance beyond the mouth.

Cross-section 4. This is the opposite extreme. Curling the horn up right from the mouth itself and so easing the curvature of the outer wall to a minimum, I wanted to see whether the primary wave front could be held intact and dominant. Negative. The primary and reflected waves are of about equal strength, and the horn, of course, gets quite long.

Cross-section 6. This is different from the others. I wanted to see what it would take to get an intact wave front around a curve, or at least to have a divided one rejoin within the horn itself rather than out in the room. To get the room necessary for freedom of maneuver within the limit set of no more 3′ front to back, the basic horn was modified. Instead of a 3n by 4n rectangular mouth, I investigated a twinned horn. If mouth geometry of 1n by 2n can a accepted, the horn can consist of two square horns side by side, with total cross-sectional areas always equaling the one indicated by formula, and terminating in two drivers. This gives twice as great a throat area, therefore the root of 2 times the theoretical throat section, and a much shorter overall length. So our curve can be uneconomical in terms of length. The reduction in height of the mouth is (root 6):3 and this makes our ‘depth’ limit of 3′ appear much greater with respect to the horn contour. It works. The wave-form divides but re-joins just within the bell of the horn.

Ironically, in the intended installation in our house, a twin is much harder to fit than a 3×4 one. Together with the extra work of fabrication, and the cost of 4 large drivers instead of 2, this factor has caused us to opt for the reflex horn. In conclusion I a strongly convinced that the feasibility of a straight horn installation should be considered seriously in more cases, remembering the possibilities of ultra-short horns using twinned or even quadrupled forms with large drivers, and I believe my solutions 3 and 6 to be the only ones of those considered that approach the ideal offered by the tractrix horn. Again, thank you and thanks to Mr. Dinsdale for his series of articles.


A Proposed Research Programme for the Investigation of a Differentially Supercharged Engine

The System: Description

The system under discussion is a differentially-blown I.C. engine, (petrol or diesel), centrifugally blown, two-stroke, and blown ‘downwards’ (inlet through poppet valves, exhaust through ports in the cylinder). The primary application of the system is as a vehicle drive.

The differentially supercharged (D.S/C) arrangement is shown schematically in Fig.1. The output shaft of the I.C. engine drives the intermediate member (planet carrier) of an epicyclic set. The annulus drives the load, while the sun wheel drives a compressor which supercharges the I.C. engine. Thus the flywheel torque is always divided in the ratio A to S between the lead and the supercharger. From any steady state condition an increase in the available torque (larger throttle opening) is similarly divided, the supercharger’s fraction of the increase resulting in an increased manifold pressure, this more available torque, etc.

While it is not new, the principle seems to the writer to be badly under-appreciated, and deserves to be compared in importance to the two-shaft turbine in that it introduces a new order of usefulness of the engine type in vehicular applications.

While existing development is concentrated on the constant displacement blower, the centrifugal blower suggests itself as being much more apt. Liberating the blower speed from that of the crankshaft gi ves us a mechanism for over-coming (or perhaps more correctly, for exploiting) the one major drawback of this compressor type, and allows the appreciation of all its advantages: good efficiency at high pressure, virtual absence of lubrication problems, no drive problems, much lower noise level, and lower cost.

Again, while existing development of the scheme is centered on the four stroke cycle, the two-stroke ought to have a separate name, because whereas there is little to distinguish the normally aspirated from the supercharged four-stroke, in the case of the two-stroke the two are completely different engine types. As soon as one can treat the crankcase as a crankcase, and not as part of the breathing cycle, the problems of petroil mixtures, foul exhausts, and overloaded little ends disappear.

Another major improvement is available by blowing ‘down-ward’. Existing blown two-strokes of the single crankshaft or hybrid valve type use the port valves for inlet and the poppet-valves for exhaust. Against the single advantage of an easy life for the pistons, this arrangement has three major disadvantages. Firstly, if poppet valves are bad, then exhaust poppet valves are worse that inlet ones. Secondly, so long as the inlet phase is symmetrical about bottom dead center, the exhaust phase competes with the expansion phase for 180 degrees – ½ inlet duration. The result is hot exhaust gases, hot engines, and high specific fuel consumptions. Thirdly, the mass of burnt charge must change direction between expansion and exhaust. By contrast, the proposed arrangement offers: a poppet valve with very low thermal stress; timing diagram in which 180 degrees – ½ exhaust duration is available for expansion and therefore very low specific consumption; the other half of the diagram does not really suffer because we have the same time of 180 degrees – ½ exhaust duration for inlet and compress, and the inlet pressure under our control, so the mass of the compressed charge is virtually independent of the timing diagram. Lastly, a good scavenge pattern, as the gases expand, they acquire an inertia downwards which results in a more efficient use of exhaust duration.


The main aim of the system is flexibility in the sense of good low speed torque. Thus the reduction (or perhaps even elimination in some cases) of gearbox requirement, and overall system simplicity. The system provides a slight fluid flywheel effect in that the engine revs are allowed to build up in advance of output revs so as to reach a more productive speed range, and a gearbox effect in that more torque is available, but this gearbox effect is achieved in the combustion chamber, While assessing the implication of this, it is important to assume some specific operating mode. While a Grand Prix engine seems a plausible application, the present proposal is centered around the case where no horsepower advantage is sought over contemporary normally aspirated four-strokes, but rather this horsepower is available over a much wider range, peaking perhaps near the middle of the speed range. It is this case that is assumed in the present discussion.

Extracting the same power at a lower speed obviously increases the pressure and therefore the bearing loads, but not a badly as it might appear. The mean pressure is divided by twice the number of power strikes, and recent bearing materials provide adequate capacity provided the highest pressures do not coincide with very high rubbing speeds.

Scantlings, on the other hand, are still largely determined by manufacturing techniques rather than be leads, and, in smaller engines at least, outputs could be multiplied several times with negligible increase in structure weight.

The question of heat dissipation from the piston, seems a very serious one, be again, perhaps not insurmountable. Essentially, of course, this will probably be the limiting parameter, but where those limits lie is difficult to assess before the work is done. There are many reasons of optimism: the heat to be dealt with is a function of power, which is work per time, not work per rev; as mentioned before , a good expansion phase is part of the design; recent work shows that a well controlled and very high speed circulation of the coolant can give a little as 6 degrees C temperature difference across the coolant circuit – it would be interesting to measure cylinder wall temperatures under these circumstances. A recent note suggests that the temperatures of pistons that contain the combustion chamber (Ford v4 and v6, Rover, Audi etc.) run much cooler than anticipated, ‘possibly due to the rapid burning’. All of this is of course too general but it does seem reasonable to go ahead and find out the extent of the problem and then to seek appropriate solutions.

Incoming and outgoing gas separation is obviously the keystone of efficient operation of any blown two-stroke. Swirl of the incoming charge is a well established method of achieving this and swirl through poppet valves is no harder than through cylinder ports. To achieve this with a two valve head would require two separate ports coming in from opposite sides. This introduces an unwelcome complication in the cylinder head both as a casting and in terms of manifolding, but no real difficulty.

The Program

It is proposed firstly to design an analogue programme of the system using real data as much as possible, i.e. real blower characteristics, port-flow characteristics taken from airflow rig tests of existing cylinder heads etc. etc. Assuming confirmation of the basic predictions of the attractiveness of the system, two alternative occur. Depending on the nature of the sponsorship of the research further confirmation or demonstration of the principle could be made in the form of “hardware” quite easily and cheaply. A lightweight twin-cylinder motor-cycle with a 180 degree crankshaft (Honda suggests itself) could be converted by having new cylinders and a camshaft make, and ‘bolting on’ everything else. Such a demonstration could do little to investigate the efficiencies (no control over charge separation, combustion chamber shape, etc.) or to evaluate the real problems ( heating in particular) but could serve to confirm the soundness of the principle. On the other hand it seems reasonable to accept the analogue result (again assuming success) and to design and build a simple engine. A twin is unfortunately the minimum, but cost could be held very low without limiting the usefulness of the unit by using production rods, crank-shafts, valves, etc. Investment casting, while thought of as an expensive production method, would offer very low cost one-off parts. Very efficient blowers are available in a good range of sizes and characteristics.

In all, four months should see it on the test bed.


Review of Work Shop Manual/Austin 3-litre (1969)

More than most pieces of writing, a workshop manual must be evaluated as part of a product support system. There are things one can say about the specific part of the system; but no assessment is complete without at least some reference to the system, including its constituent parts.

The system involved here is unfortunately an unwieldy one. It is composed of the product itself, the repair facilities that exist for it, the methods that have been chosen for servicing and repair, and the manual that instructs the personnel of the repair facility in their tasks.

This view may seem extreme. Surely the Publications Department cannot take complete responsibility for the car! But when manual refers to filling the cooling system with water, are we to take it that the manufacturer is unaware of the water pump’s requirement for a small quantity of anti-freeze for internal lubrication? Or are we to believe that the Publications Department has just copied this from previous versions of a manual dedicated to an out-dated technology? Fifteen years after this manufacturer nominally completed a change to Unified threaded fasteners is there really still a requirement for a complete set of Whitworth spanners, as well as the A/F ones? I don’t know. There may be, and if there is, it reflects of course not only on the technical publication but on the Design Office’s lack of concern for dealer network problems.

But laying aside this extreme notion of responsibilities, we are left with an inevitable and large overlap of the Service Department’s choice of methods and the Publication Department’s description of these methods (why are they separate?)

On the first page of the Introduction, we are told to always fit a new locknut to the pinion flange and to the rear hub flanges. In the appropriate sections in the manual, the simple phrase ‘refit the locknut’ makes no mention of the need to use a new one.

Then we are introduced to a very attractive system of symbols to be used in the illustrations. This system and the extensive use of it is probably the best part of the book. A vocabulary of 17 symbols with meaning as detailed as ‘Move right’, ‘Move left’, ‘Drain’, ‘Inspect’, etc. has been developed in such an easy hieroglyphic form that – for many tasks at least – reference to the text should be unnecessary.

Unfortunately, a Manual has certain functions beyond listing the order of dismantling and re-assembling the components in the simpler repair task. It is there that the book falls down.

Proceeding in an orderly fashion through the manual, we are next presented with Data. Are we to presume that the lack of correspondence between the metric dimensions and the inch equivalents means that technical authors still cannot manage simple multiplication or that they are as sloppy with the one row of figures as with the other? The location of a decimal point may be thought a small point, but dammit, it is an error of ten times. And it occurs both upwards and downwards. Several instances of quite unrelated figures also sit unashamedly side by side. On a more subtle point there is a welcome note. By and large, figures have been reasonably rounded, but torque specification s to two decimal places of a Kg.m still abound. A tenth of a Kg.m is less than one pound-foot. I cannot see the relevance of sub-dividing this into ten.

Finally, we get to Instructions: On the first page we step into the quietly unreal world of the Workshop Manual. Cooling System: ‘The cooling system is under pressure while the engine is hot. Remove the filler cap and the expansion tank cap only when the system has cooled.‘ Where does the writer imagine there is time for so leisurely an approach? One hour to top up the radiator? No mention of how to do it safely while the system is hot. Just the instruction to wait till it cools. And so it goes on. The compression test instruction makes no mention of keeping the throttles open or of checking battery condition of cranking speed. These oversights would invalidate any test result.

A rather nice one under: Tensioner (timing chain) ‘Compress the tensioner and lock be turning the Allen key clockwise.‘ Later, ‘Release the tensioner.’ Then, ‘Turn the key clockwise. (and in heavy type) DO NOT TURN THE KEY ANTI-CLOCKWISE.‘ Not ever? If not, how do we release, etc.? Or just not after we have completed the whole job? But why should we want to do it then?

To refit the engine, we ‘reverse sequence etc. etc.’ No mention of special attention to control linkage adjustments, a common and serious source of mal-function of automatic transmission vehicles.

One more bit of gibberish: under ‘Reassembling, connecting rods and gudgeon pins‘ (No mention of pistons) ‘Press the new bush into the con rod… Ream the bush. Press in the gudgeon pin … selective. Refit and circlips.’ For the benefit of those who don’t know, the piston should have got in there somewhere, but much more important, the pins are a selective fit in the piston, the selection being made at the piston manufacturer’s premises, and not to be mucked about with later.

The main criticism must be reserved, not for this particular manual, but for the whole genre of which it is an all too typical example. What do they set out to achieve? True enough, on the whole they describe, fairly accurately, safe and useful procedures. The easy and obvious ones. The writer excels in describing that which even he understands. But that, unfortunately is what any pretender to the rank of mechanic understands. The difficult bits, the things in which we would welcome some guidance, the writer doesn’t know about, consciously avoids, or misunderstands when they are explained to him and confuses them for his readers. The manual is thick with examples. In particular valve seats in the cylinder head: ‘check the seat face. If necessary (what does that mean?) reface with tools listed, etc.’ Three tools are listed for each valve seat. These are probably of included angles of 60, 90, and 120 degrees. The theory is to use the 90 degree cutter to establish a clean face at 45 degrees, then to cut away this surface at its out circumference with the 120 degree cutter, at its inner circumference with the 60 degree cutter, this to control both the width of the seat that remains, and its location, or more correctly, its diameter. None of this is mentioned in the text. Neither the seat width nor its diameter is quoted.

Another type of error is repeated continuously. A dismantling operation is given in detail. Then under re-assembly, we are told to check clearances. of the components. The only way to do this would be to assemble the thing once, chick the clearances, then do the job again. If enumerating the sequence in detail is to be of any value, then it must be done in a better order than a rank amateur would follow on his first attempt (and would resolve to improve on next time.)

All the difficult areas are the same. In reassembling the rocker bushes, we are told to weld in the retaining rivet. A most unusual technique. Does he really mean it? How does one avoid overheating the part? Again, re-newing the ring gear: Split the ring gear. How? Heat the new gear to 300 to 400 degrees C. No mention of the importance of avoiding overheating. The alternator is a part of the equipment on which most service personnel are fairly weak. Predictably, so are the authors. The wiring diagram is the usual magnificent piece of photo-micrography.

Reverting to the earlier point of the merging of responsibilities of the manual writers and the service department: An example of the dated technology that emerges for this collaboration illustrates the point. In the section of ignition, no mention is made of dwell angle, only of contact breaker gap. This is inevitably the limit of the d.i.y. mechanic, but doesn’t relate to the professional workshop. Oscilloscopes (or at least dwell-meters) exist in anything that can be called a garage today, and are necessary to pick up the out-of-spec components that are commonplace in the contemporary product.

The standard defence for most of this criticisms occurs on the very first line of the introduction: ‘This manual is intended too assist the skilled mechanic in carrying out etc. etc.’ An emphasis on the skilled is usually given as a defence of the whole thing. But it won’t wash. If the main is so skilled that all the trickier parts can be glossed over, and accuracy is unimportant then why on earth publish the self-evident?

Perhaps the most significant conclusion from all this criticism is the recognition of an almost complete remoteness of the Publications Department from the repair work shop floor in the relevant market area, which is the environment for which it ostensibly exists.

The huge gap that exists between the writers of this manual and the realities of the repair workshop is symptomatic of , and a significant part of, the great distance between the board room and the dolly birds sitting on car bonnets at Earl’s Court and, on the users side, the brutal reality of just wanting to buy a reliable car and get with it prompt, reliable and economical service. This manual must, unfortunately, take its fair share of responsibility for the generally unhappy state of motorcar maintenance today.


There was another review on a Honda manual that seemed to have lots of information but Harry’s review starts…

The Honda Shop Manual looks like a Very Good Thing. The sad thing is that it isn’t written in English. It isn’t written in anything else either, come to that, but sits in that weird limbo of the illiterate translation.

And he ends with…

One is therefore forced regrettably to reject this manual as failing in its first function of communicating with its readers. At the same time, I recommend it most highly to those interested in new approaches to making a manual a useful thing – and for the overall attempt to provide all the information – a feature rare in the majority of workshop manuals.


A letter to the editor on the metric system

Questions of tact, etc. having been dealt with, there is a question about choice of system that might deserve consideration. I think it is fair to say that for non-numerate people having the multipliers between units different from each other and from the counting base is an advantage (e.g. 12 inches make 1 foot, 3 feet make 1 yard etc.). If you’re not going to deal with a system of measurements, but only with individual relationships which must be memorized, then 2,4,5,5 ½,8,12,14,20 are easy to identify with the units that they relate. If you can and intend to calculate, then any multiple other than the counting base (10) is silly. You might as well use Roman numerals.

By the way, an outstanding example of the superiority of a rational system not in the scientific sphere occurs in irrigation practice order to relate to rainfall, irrigation people measure water in inch acres. Try relating that to gallons per minute to specify pumping requirements! In the rational system you can do it in your head. 12 millimeters over 8 hectares is 12x8x10=960 cubic meters. In the 16 hour window after the heat of the day, that’s 60 cubic meters per hour, or 1 cubic meter per minute.

A little side note: In Canada there are still relics that use miles etc. although the country has been nominally metric for many decades. What’s curious there is that they defend the previous system as Imperial when they have little notion of what the Imperial system really is. They do not know a stone from a rock, a cwt from a 100 pounds, a ton from 2000, and they do not know that an Imperial fluid ounce is different from an American one. They use them interchangeably, and thus routinely convert American gallons to “Canadian” ones wrongly by about 5 percent. And so it goes. Cheers.

About Janet Kwasniak

Retired pensioner, raised in Canada but UK citizen living in France, interested in Science and many other things.
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