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OPINIONS a d QUERIES Pre-combustion v. Direct Injection.

14th April 1933, Page 49
14th April 1933
Page 49
Page 50
Page 49, 14th April 1933 — OPINIONS a d QUERIES Pre-combustion v. Direct Injection.
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Which of the following most accurately describes the problem?

The Editor, THE COMMERCIAL VOTOR.

[4041] Sir,—May I reply to Mr. Wishart's letter in your issue dated March 24? I take it as a very great

compliment that Crossley Motors, Ltd., has been able to ,spares Mr. Wishart for a few moments from his arduous duties in the drawing office, to write such a sympathetic letter in reply to my humble efforts.

Making up for lost power by increasing the cylinder capacity and reverting to pre-chamber design seem to me to be retrograde l steps, in the light of the highly successful direct-injection engines which are so much in evidence to-day all over the country. They are, to use some well-known words, "an easy way out of a difficult job."

Mr. Wishart refers to the " Comet " head. Whether Mr. Wishart has been badly misled or not, I do not know, but the fact remains that this head is most dis tinctly a pre-chamber, or ante-chamber design, also known as a two-cell engin6. The fact that the whole of the fuel charge is injected directly into a chamber (or cell) entirely separate from.,the main cylinder, except for the venturi, positively decides this point. The actual amount of heat loss, as compared with other types of this design, is beside the point, but at the same time the consumption of this engine, as published on page 186 of your issue dated March 17, 1,e., 0.45 lb. at 1,000 r.p.m. and 0.472 111). at 1,700 r.p.m., certainly seems to prove that the losses are great, more especially when compared with 0.370 lb. at 1,700 r.p.m. and 0.405 lb. at 1,000 r.p.m.—the Gardner figures.

Mr. Wishart refers to, my one-time enthusiasm for the pre-chamber engine. Most certainly, I was tre

mendously keen on the famous Mercedes-Benz engine, which is, I consider, still the world's best pre-chamber engine and a wonderful machine, but, like many other oil-engine enthusiasts and in common with the German engineers. I doubted at that time that the great difficulties of producing a high-speed direct injection

engine, perfectly suitable for all road transport purposes, could be got over. Like all the others who thought thus, I was wrong, and in March, 1930, when tke Gardner direct-injection engine was run on the road, we'realized our mistake, and I was the first to acknow,• •

ledge this both in the Press and in my lectures. Mr. Wishart, I think, at that time was not "in the Diesel game." However, the Gardner engine, in due course, proved to us all the enormous and indisputable advantages of the open-cylinder design, which are too well known to •repent here. •

May I remind Mr. Wishart that he himself arranged the fitting in the chassis of the Gardner (ITO engine, which after some 80,000 miles of hard work in Man

chester is still going strong, and is possibly the most reliable oile:. in that fleet, and certainly the most economical on fuel and the lowest in maintenance costs? Mr. Wishart refers to some Scat/linen tests recently

published. It was unfortunate that in these tests the gear ratios employed were those for the normal highspeed petrol engine, and therefore obviously unsuitable for 1,550 maximum r.p.m. If he will refer to The Commercial Motor of January 6, page 718, he will see the correct results when usineb appropriate gear ratios, which bear out exactly the figures I quoted. These can be verified at any time at Mr. 'Wishart's conveni

ence, if he so desires. W. H. GODDARD. Leeds.

The Value of "The Commercial Motor" Abroad. 7 The Editor, THE COMMERCIAL MOTOR.

[4042] Sir,—Will you please send me a copy of your Tables of Operating Costs? I receive a copy of your journal each mail, and it keeps me up to date in commercial motor design, etc.; without it out here I should be absolutely cut off from the latest developments.

Nigeria. GEORGE D. CRERAR.

Licensing of Goods Vehicles.

The Editor, THE COMMERCIAL MOTOR.

[4043] Sir,—It has come to the knowledge of my executive committee that hauliers are being canvassed In some parts of the country by someone who purports to represent some association set up to obtain licences for them.

It would appear that the method adopted is to suggest that haulage contractors must join the particular association referred to or they will not be permitted to hold a licence when the law provides for such contingency.

May I be permitted to point out to your readers that no authority has been given to anyone to use such threats in connection with this Association and that hauliers should -be chary about trusting such indivinuals who adopt these measures.

Time wilt tell under what conditions a licence will be issued and the Road Haulage Association will be prepared to take every possible step to protect its members, when legislation is affected, and look after their interests. GEORGE A. HOTTER, Secretary, The Road Haulage Association. London, W.C.2.

American Interest in Oil Engines.

The Editor, THE COMMERCIAL MOTOR.

[4044] Sir,—The rapidly growing interest,, and in some cases anxiety, that is being shown by Americans regarding high-speed oil engines is very apparent in recent letters and comments appearing in your journal.

Mr. Cummins has done a tremendous lot of development work and has put up creditable performances with his oil-engined car and lorries, but the difficulties encountered when using different grades of fuel on cross-country journeys were very considerable, which, of course, points to the limited diet of the engine. However, the advertising value of such runs is large and is reflected by the number of .chassis manufacturers now fitting the Cummins engine; also the wonderful performance of the Gardner-engined Bentley at _ Monte Carlo undoubtedly showed the material benefits of this type of power unit in a most popular manner. "

Recently I received a letter from a leading research authority of New York, and I take the liberty of quoting one of his paragraphs: "In this country there is every promise that the year 1933 will see a very material advance in the adoption of high-speed Diesel engines for heavy trucks and motor-buses."

When in America towards the end of last year I found the utmost interest being taken in vehicle oil engines, but at that time the "wait and see" policy was being followed. However, I think it will be only a short time before the leading engine manufacturers begin to produce the units with which they have been experimenting and gaining confidence. This is the aspect which so vitally concerns British oil-engine manufacturers.

It is in the foreign and Colonial markets that we will be most affected by this new competition, but the British engines, on account of their proven reliability and sound engineering, should hold the field if

marketed correctly. P. B. BITRDEN. Manchester.

Oil Pressure on a Morris-Commercial Leader Engine.

The Editor, THE COMMERCIAL MOTOR.

[4045] note with interest the reply of Morris Commercial Cars, Ltd; to your correspondent, W. E. Pile (letter No. 4,015), with regard to the loss of oil pressure On a Leader engine. I had the same experience with my Leader engine, and perhaps the following will be of interest : After having all bearings taken up, on re-assembling and starting up, no oil pressure was showing. The ball valve in the oil-gauge pipe, as mentioned by the maker, had been removed 12 months previously owing to the engine showing no pressure when starting up from cold, as the heavy oil forced the ball up against the end of the pipe and no pressure was shown until the engine became warm and the oil thinned, then the normal amount (about 20 lb.) was registered. The ball was removed for my own peace of mind.

The cure in this case was effected by blanking off the ball-release valve in the bottom of the sump by fitting a flange under the brass casting holding the spring and hall. Since then I have had no trouble with Oil pressure, although I find it imperative that all bearings should be taken up regularly to prevent loss of pressure. This vehicle has run over 63,000 miles over the Yorkshire moors in 20 months and I have nothing but praise for it: For hard work this model is to be recommended.

R. RoTtiwELL, Haulage Contractor. Linthwaite.

The Taxation of Vehicles with " Loose " Bodies. The Editor, THE COMMERCIAL MOTOR.

[4046] Sir,—Having been a reader of your paper for a number of years, I wonder if you would be kind enough to enlighten me on a point regarding the unladen weight of a lorry. Take a 4-ton lorry (platform) under the 4-ton unladen weight tax of 148 for solid tyres and f38 for pneumatics.

If a frame, in the form of a box, that is all in one independent piece, like a furniture container, is made for a lorry of this type, to enable it to carry sheep and cattle, etc., this box to rest on the lorry and be held there simply by its own weight, and not fixed or bolted to existing bodywork in any way, can this be called ' n36 part of the lorry and be taxable and included in the unladen weight of the vehicle?

The licence form says that when the unladen weight of a machine is taken and two types of body are fitted, the heavier of the two has to be included in the weight of the machine.

The point is—can this box or crate in the form of a sheep or cattle frame be taken as a part of the body of the lorry when it is neither fixed to the normal body of the lorry nor to the chassis? Surely, when it is not fixed to the lorry in any way it cannot be called part of the lorry.

If on property one has sheds, etc., which are not fixed on any foundation, but are movable, they are not taxed so long as they are not fixtures. This, surely, represents a fair analogy.

Ought not the case of the sheep frame on a lorry to be the same if it be not fixed as part of the lorry, and should it not be claSsed as part of the load, just in the same way as barrels to carry liquid or bags to carry grain, etc.?

There are several contractors around here who have put frames of different kinds on lorries to carry sheep, etc., and who hzve been forced to have their machines weighed with those frames on. This seems to me unfair, and for the following reason.

I have noticed platform lorries owned by petrol companies with tanks bolted down to the platforms, yet the machines were not taxed with the weight of the tank included. If these are not taxable, surely the crate for sheep, which is not fixed in any way, is less

liable to be taxed. H. MILLAR. Biggar.

The question f whether any addition to a vehicle forms part of the weight unladen of the vehicle, or is to be treated as part of the load, is, as a general rule, a question of fact which has to be decided in each particular case. There has been no reported case in England which is of any assistance. In the only reported case the High Court held that as the question was one of fact, and as it could not be held that there was no evidence which would justify the magistrates in arriving at their decision, the case was not one in which the High Court could interfere. The only reported case in the courts in Scotland of which we are aware is that of Darling v. Burton, which was decided in the Justiciary Appeal Court on November 8, 1927. Although we have seen a copy of the judgment of the Court we do not know whether that case was actually ' reported in any of the law reports. In that case the court held that the trays which a baker placed on brackets iu.a motorvan for the purpose of carrying cakes, etc., were not part of the vehicle, but came within the description of "loose equipment" which was to be excluded when the weight unladen of the vehicle was ascertained. In your case it appears to us doubtful whether that example applies, and, on the whole, we consider it probable that if the point came before the Court the frame which you use would be held to be part of the vehicle for the purpose of ascertaining the weight unladen, on the ground that the vehicle, having a platform body, could not in practice be used for the conveyance of sheep without the frame. We are surprised at your statement that in the case of tank wagons used for the conveyance of petrol the weight of the tank is not taken into account when ascertaining the weight unladen of the vehicle, as it does not appear to us that the tank can be regarded as being "loose equipment."—En.] Why Not Week-day Coach Trips to Cathedral Services ?

The Editor, THE COMMERCIAL MOTOR.

[4047] Sir,—I wonder if it has ever occurred to motor coach proprietors to run cheap excursions for music lovers to our week-day cathedral services. Musicloving car owners should also avail themselves of this opportunity of hearing sacred music in a most perfect setting.

At Wells Cathedral, particularly, the music is exceptional and the choir boys unusually well trained. S. CLAUDE TICKELL, Vicar, Latton-cum-Eysey, Cricklade.


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