Accessibility and Cleanliness.'
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As regards the two points in the title, " Accessibility and Cleanliness," they were so intimately connected, the one with the other, Mr. Martineau said, that he had to consider them tegether. To begin with the ideal of cleanliness : it was, he thought, that the whole exterior of the car should be smooth and easy to clean ; that no mud or dust should be able to be thrown by the wheels on to any part of the mechanism, on to the steps or the carriage body ; that all working parts should be thoroughly protected from grit ; and that all oil drippings from the engine and gear should be caught and retained in a detachable receptacle, easy to remove and clean out. To obtain the ideal of accessibility, it might be laid down as an axiom "that we ought to be able to remove any one part without disturbing any other." This ideal, like all ideals, was practically impossible of attainment ; to approach within reasonable distance of it would neoessitate every part being exposed and in view, which would prevent us obtaining efficient means of protection, and jeopardise our ideal of cleanliness. The best we could do, therefore, was to study the easy removal of those parts liable to wear, and use as a foundation, on which to build up these parts, all pieces not so liable. The body to be used was the item of greatest importance. It should be easily raised or moved so that all running gear can be easily and efficiently inspected. To render every part accessible, it can be made to rise on hinges at the back, which done, the whole of the running gear, and not merely the engine, is at hand and in view. To inspect the engine ad gearbox, separately, the front and back floor boards can be removed, the former for the engine and the latter for the gear. As to the removal of the floor boards for inspection purposes, if these are made to lift out there is a greater liability of the mud and dust collected on them emptied on to the parts below.
With regard to the chassis, he thought, as a general practice, it may be laid down that the whole of the chassis should be erected, and every part should be accessible, from above. The true meaning of that was that, with a car so designed, a pit•is no longer a necessity, and, also, that the most perfect cleanliness can be arranged for, as the imdershield can be made absolutely continuous and permanent.
There are certain items which, although at first sight they appear to have no past in the making of accessibility, yet, in reality, they do so. One of these was the method employed of locking nuts, and another, the size of nuts used and their position. Dealing with the latter point first, he pointed out that it should not be necessary to use special spanners for any nuts. Every nut should be arranged so that it can be got at either with an ordinary tubular box, or flat, spanner.
The number of sizes of nuts used in a car should be reduced to a minimum; in fact. he settled on the sizes to be allowed before the car design was even started, and, now, he used only five sizes on the whole car, which meant that the total number of spanners necessary to undo any nut was greatly reduced. To deal with any nut required only three tubular box spanners (two double-ended and one single-ended) and three ordinary flat spanners (two double-coded and one single). With regard to the method of locking nuts, he divided the bolts up under two heads, namely :—(1) Those used for construction, which seldom, or never, required removing. (2) Those which required removing to make adjustments, or for cleaning.
For No. 1, as a general rule, he preferred to use Castle nuts with spring washers under, and, for No. 2, ordinary nuts and spring washers. A Castle nut, in his opinion, should never be used without a spring washer, as it requires such care in tightening so as to fit the cotter, if it is to be done without either straining the bolt or leaving it too loose.
The repairer's lot was not altogether a happy one, as he is supposed to know all about a car which he may never have seen before, have a new part iii stock to replace a broken one, and charge less for doing the work than the new part is generally worth. It was as well to consider him somewhat, for when a car does get into his hands which is easy for him to handle, he can help a great deal; at the same time, one must remember he can do the reverse.
If the engine was of the vertical type many difficulties existed which might not appear at first sight. To comply with the axiom laid down, it should be possible to withdrawn a piston without disturbing any other part. To do this necessitated a very large hole in the side of the crankcase, or else it must he done from underneath, which was, generally, very inconvenient. If it was arranged to be taken out at the side, to make it really convenient the engine must be fitted very high up in the frame—so high, in fact, that the flywheel and other
paitill would, more or less, interfere with the carriage body. Of course, if there were a hand hole in the crankcase suffi-.
ciently large to take down the big end easily, it would be pos sible to remove a piston by dismounting a cylinder. This method, however, was crude and unpractical, in most engines,. by reason of the number of joints to be broken, and it did not,
at all, fall in with the axiom with which he started. On a horizontal engine it was possible to make the whole of the top side of the crankcase to come off without impairing its strength, and then the whole of the crankshaft, connecting rods, and pistons were in view, and each part could be easily dismounted separately.
As to the cylinders themselves, there seemed to be, at the present time, a great wave in favour of casting them all together.
This might be good from a constructive point of view, but it was not so from the point of view of accessibility and repair. lie had never had to replace a cylinder because it was worn out ; but, still, advocated casting them, separate, on account of accessibility, and so as to be certain of all casting Strains and unevenness of expansion being eliminated. A cylinder should' be easily detached, without removing even an inlet, water, or eshaust pipe, by breaking the joints only. The valves on most
engines, nowadays, were easily removable, but it should not be necessary, in removing them' to have to take off the spring:
This should be arranged to be supported whilst the valve is withdrawn and ground in. At the same time, a valve spring itself should be easily replaceable in case of breakage.
Another part which was, usually, rather difficult to get at was the gudgeon pin. In most cases, this was fixed by two taper pointed screws. As these required careful locking with nuts, and were very close up to the side of the piston, they were, practically, only removable with special tools. At the samo time, they had the disadvantage of causing the piston to oval when hot, as the expansion of the piston and gudgeon pins are slightly at variance. To obviate this, as long ago as 1899 he fixed the gudgeon pin in the small end of the connecting rod by a taper pin, driven through on the side away from the big end. This had been found by experience to be very easily' fitted and dismantled, and had never given trouble; it allowed for perfect lubrication and free expansion, as well as accessibility. To make it easier to fit and remove, it was better made of three diameters, the smallest and largest fitting in the piston and the intermediate in the connecting rod. To fit the taper pin in its place, and also to extract it, holes were made in the piston opposite the ends of the pin.
The ignition distributor or commutator should be arranged so as to be easily taken apart and cleaned. The camshaft should be made to come away sideways ; when made to withdraw from one end it often necessitated the taking down of some other part. It was better, if arranged so as to be inspected by simply taking off a cover. The petrol engine carburetter had received an enormous amount of attention in the last few years, but he was sorry to see that the tendency has always been to add parts, and not to eliminate them. Some of the later types might or might not be more efficient than their predecessors, but they certainly were not more accessible. It was impossible, in most of them, to ascertain if the petrol stood at the correct height in the float-box, for the simple reason that the float valve had its gear on or was guided by the cover.
Why should it not be made independent of the cover? The jet, in many carburetters, was so arranged as to necessitate the removal of quite a number of pieces to clean it out ; in others it was extracted with a tube spanner. In doing so, it generally fell out of the spanner and dropped inside, giving rise to much waste of time and many words. As a jet never gets
stopped up except at a most inconvenient time, it would be as well to provide for its easy removal. There was a great tendency. to place the pump and magneto by the side of the engine ; in this position they covered up space which should be left open for the inspection of the big end brasses and valve gear. The correct position to gain the maximum of accessibility seemed to be to arrange them in front of the engine, and drive : them by a shaft at right angles to the engine crankshaft, in a vertical engine. A horizontal engine could have the magnet) ,
alongside one cylinder or in front of the cylinders, and no pump need be fitted. It was essential to have an under shield, completely enclosing the engine ; it should be quite tight-fitting, and if it was necessary to have a hand hole in it, the hole should be large enough to work through and a good threeeighths bead carried around it. The shield should be oil-tight and fitted with a sump into which all dirty oil will drain and which can be easily removed and cleaned out.
Given that the carriage body is not in the way, there was very little to note with regard to the clutch and gearbox, as they can be made to be very easily dismantled.
The chief features which had to be retained in view in the
construction if the back axle were these : either wheel should be easily removable; the differential should be accessible; it should he possible to correct the adjustment of the drive, be it bevel, chain, or worm; and the brakes should be easily adjusted, and should not require altering to remove a wheel, From the point of view of cleanliness, if chain drive was used, the chains should be encased, if outside, or else the under shie:d should be so prolonged and shaped to protect them.
At the conclusion of the paper, the author showed a number of lantern slides illustrating the various points raised, more particularly with regard to '. accessibility." This young Institution is to be congratulated on the character of the discussion which followed, this being of an eminently practical character, and comparing favourably, in this respect, with some of the discussions which, frequently, take place before older and more pretentious institutions. To Colonel Crompton, no less than those members taking part inn the debate, the credit for this was due, the President, in his opening remarks, laying emphasis upon the desire of the Council to make the debates of the highest possible value to automobile engineers, and we are glad to be able to record that his plea of a ten minutes' limit was loyally observed on this occasion, there being only one offender. A point was raised by Mr. Austin, at a later period, as to the desirability of having copies of the papers read circulated prior to the 'netting, and Colonel Crompton intimated that the Council, recognising that this was a necessary requirement to promote a useful discussion, bad made arrangements to have papers circulated well in advance of each meeting.
The Discussion.
Mr. F. W. Lanchester, who opened the debate, placed himself in the position of the devil's advocate, taking up the standpoint that accessibility was, on the whole, undesirable. He said that, in the early days of his designing, he had endeavoured to render more accessible certain hardened steel parts in connection with the governer, in order to achieve which, it bad been necessary to arrange the valve stem and catch plate in two parts. The existence of those two parts had led to unlimited failures at the joint, and the moral to be hianied was that it was never advisable to make anything in two pieces if it could possibly be made in one. Design was really a question of compromise, and it, frequently, happened that access to a particular part of a machine could only be given at the cost of embodying undesirable features, and this led one to the tnal stage of rendering everything inaccessible. Mr. Lanchestti, also, put forward the view that the designer would find the employment of the horizontal engine a near cut to the bankruptcy court. It was for the customer to decide what type of engine should be employed.
Mr. R. W. A. Brewer, also, considered accessibility as a somewhat dangerous thing in view of the ignorance of users. With regard to the horizontal engine, he thought it was already dead, and he, even, could not agree as to its advantages on the ground of accessibility. It was, certainly, very difficult to make adjustments in an engine that was underneath the body of a car, in a large mass of woodwork or other material, and, even when you lifted the body, the parts, then exposed, were seldom those which required attention. He was particularly glad to note Mr. Martineau's references to the standardisation of nuts and bolts, which was a very important matter, and one which the Institution might well take in hand. On details, he would like to say that he found it more useful to have the gudgeon pin not fixed in any way.
Mr. H. Austin said that it should be borne in mind that motor vehicles were required for town as well as country use. At the present time, great attention was being devoted to the evolution of a town carriage, and it was obvious that, for town use, the vehicle must have a very short wheel base. Mr. Austin reminded the meeting that, in the building of public-service vehicles, the by-laws laid down certain limits in this respect, which had to be complied with. The necessity for a short wheel base determined other points, and he was quite sure that the attempts which had been made to put a vertical engine in a vehicle with a short wheel base were infinitely less desirable than putting a horizontal engine underneath the chassis. Mr. Martineau, in pointing out how seldom it was necessary to repla..e cylinders, had rather played into the hands of his critics, as his statistics made it clear that the ability to dismantle one cylinder, separately, was not important enough to outweigh the advantage of casting the cylinders in one piece. The suggestion made by Mr. Brewer as to leaving the gudgeon pin louse was totally at variance with his experience. Undoubtedly, accessibility could be carried too far, and it appeared to him that making the gearbox accessible might lead, as in Mr. Martineau's example, to an extremely weak design.
Mr. Alexander Craig doubted Mr. Lanchester's entire sincerity in arguing in favour of inaccessibility. It appeared to be forgotten that one great advantage of accessibility was the reduction of repair bills, inasmuch as a great proportion of the cost of making repairs was for stripping the car and putting it together again. In his opinion, it was not necessary to adopt the horizontal type of engine in order to secure accessibility, fer if, in the vertical engine, one side of the crank chamber was exposed, the parts could be easily got at. In motor-omnibus working it was, frequently, necessary to take the piston out, arid to make adjustments, almost daily, and, if the vehicle had to be stripped every time this was done, the cost for commercial work would be altogether excessive The commercial side of the industry called for accessible parts, and to argue to the contrary was ridiculous. The Continent had little to teach us, now, in matters of design; if the requisite attention was paid to accessibility, there was a prospect of English designs taking pre-eminence, and he hoped that the remarks of one or two speakers would not be taken as an indication of the tone of that meeting. Hitherto, we had been led, to a great extent, by fashion, in the matter of the type of engine, but, if a change should come in this respect, then the excellent work done by Mr. Martineau in connection with the horizontal engine would be properly appreciated.
Mr. Henry Sturmey agreed, generally,. with the conclusions stated by the author. Designers had however, to bear in mind the necessity of designing a machine suitable for all purposes, and it was clear that an excessive length of wheel base was undesirable in many circumstances. On the subject of the accessibility of the horizontal engine, a great deal of misconception existed. When the body was designed to form one with the engine, it could be made far more accessible than a vertical engine placed underneath the bonnet. He agreed with Mr. Martineau on the subject of casting the cylinders. He had been making engines for sonic years cast en bloc, hut he was going to give up that practice entirely, the single type being much better in many ways.
Mr. L. A. Legros emphasised a point, not referred to by previous speakers, that the ability to inspect easily enabled one to sec how parts were wearing, so that any serious defect could be averted. This, as the speaker added, applies particularly to heavy traction work, where considerable mileage is called fir, the service conditions of a motor omnibus being very different to those of a private car. A public-service vehicle ran 25,000 miles per year, against the 10,000 miles of a touring car, and it was necessary to provide greater accessibility. Mr. Legros was curious to know how Mr. 3/artineau had got the number of sizes of his nuts down to five.
Mr. Wilson commented unfavourably on the desire to obtain a smooth exterior at the expense of putting certain things inside and pretending that they did not exist, and Mr. T. C. l'ullinger urged the Institution to take up the matter of the adoption of the metric system, which, he believed, would get over all troubles in connection with standardising.
Another speaker put in a strong plea for the standardisation of nut.t and bolts. He reminded the meeting that the question had already been taken up by the Engineering Standards Committee, but they had to consider it on the broad grounds of the requirements of all the industries concerned. The result • had been to effect a compromise, and the Whitworth sizes had been standardised, but these were, generally, too heavy for motorcar construction. Colonel Crompton, who was a member of the Engineering Standards Committee, had done good work for the industry, and had endeavoured to get certain sizes eliminated from the standard list, but only with partial success. It would be desirable for the Institution, he thought, to turn its attention to the standardisation of a lighter nut and the abolition of cert tin sizes. The industry was not sufficiently alive to what was being done in this connection, and it was a matter for consideration whether the fine line of threads authorised were suitable to the requirements of their particular branch of the engineering profession.
Colonel Crompton, in summing up the discussion, urged upon designers the necessity for realising that the time had passed when their expert opinion was to be set aside by the technically-uninstructed buyer. Given the requirements, it was for the engineer to provide the design. One result of the existence of the Institution would be strengthening of the force of engineering opinion. On the question of standardisation, it had to be borne in mind that the industry was a peculiar one, the building of a car, very often, being an assembling of parts from different makers, and, no doubt, in the present condition of the industry, cars were best built in that way. The only way to obtain reform, in the matter of standardisation, was to organise engineering opinion in connection with the industry, when it would be possible to formulate requirements to the Engineering Standards Committee, and have representatives of that Institution placed upon it. They would, then, have the assurance that the work of standardisation would he performed in the manner they desired. It was a very important matter from their point of view.
Mr. Martireau, replying on the discussion, said that the five
sizes of nuts he used were 1,BA, and 4, and a Whitworth, and difficulties, where they existed, were got over by having a small nut on the face of a big nut, so that the same spanner could be used.