Opinions from Others,
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An Offer from Merryweather's.
The Editor, TRE COMMERCIAL MOTOR.
[1160) Sir,—In your issue of 9th January, Surrey Firemaster " asks—" Can anyone bring along a 350-gallon reciprocating pump which will put out two in. jets at 60 lb. pressure at the pump, with a 50 hp, engine? " We have just tested a 350-gallon motor fire-engine, fitted with a reciprocating pump and a motor of 42 h.p. (R.A.C.), the combination being four years old. The pump pressure obtained was 62 lb. In a further experiment with the same machine, we delivered exactly the same quantity of water through two one-inch nozzles at 120 lb. pressure, which we consider to be the more useful performance of the two.
We shall be pleased to show our pump actually performing this work to " Surrey Firemaster," if he will make an appointment.—Yours faithfully,
MERRYWEATHER AND SONS, LTD.
Greenwich Roa.d, S.E.
I We submiised a copy of thls orTei So "Surrey Firemaster." His rely is published hereunder.— So, The Editor, THE COMMERCIAL MOTOR.
 Sir,—I am not willing, at present, to accept your correspondents' offer to visit their works. If a visit is made to the works to settle contentious matter, let it be by a, nominated committee, the nominees being, say, the editors of motor journals, fire papers and representatives of the Association of Professional Fire Brigade Officers (10, Harrington Chambers, Liverpool). Dealing with the matter of horse-power, the fetish of your correspondents is R.A.C., a. nominal rating which is practically an unknown quantity. I have in mind a 42 R.A.C. engine, fitted to a reciprocating pump, sold as 300 gallons capacity, that has 5i in. by foi in. cylinders (61 b.h.p.). Again, another authority nas a 39 R.A.C. engine with 400-gallon pump of another class and maker, but the bore and stroke is 127 mm. by 180 mm.—nearer 80 b.h.p. On the R.A.C. rating, the weaker-rated engine is often the more powerful ; hence, it is no proper guide in judging the capabilities of the machines. The engines mentioned in my last letter are 127 trim. by 130 ram., or 50 b.h.p. —not R.A.O.
Will your correspondents disclose the maker's name of their engine, together with its stroke, bore, and apan. ? Will they also give the capacity of each of the rams on the pump, and the ratio of engine running to pump revolutions ?
Your correspondents' figures for length, diameter and make of hose are not given, but, say it is 100 ft. of 2/ in. rubber-lined. If so, with 120 lb. pressure at pump, the gallons per minute pumped would be about 450, as near as possible. With the same hose and pressure of 62 lb. on the pump, as stated, the quantity of water passing through would be nearer 600 gallons per minute. How this can be called a 350-gallon pump passes comprehension: it should be rated 500-600 gallons, in the same way as ShandMason's rate their steamers. To say it is 350-400 gallons, is to indicate that'400 gallons is the maximum output of the pumps under the best conditions.
The output of a reciprocating pump is determined by the travel of the ram. The same pump chambers can be used, but the output can be increased, by increasing the velocity of the ram, by using bigger engines and higher gearing, so that "the same pump" can either be a 350-gallon or a 500-gallon, or any other capacity that the rams will travel up to, without being too quick to open and close suction and delivery valves. This, possibly, is the way your correspondents are able to call the pump to which they refer a 350-gallon one ?—Yours faithfully,
One-Man Petrol Lorries ?
The Editor, THE COMMERCIAL MOTOR.
 Sir,—I am glad -Chat you have opened your columns to a discussion on this question of the adequate maiming of petrol lorries. The true state of affairs is by no means revealed if the investigation does not go, farther than consideration of the driving of the vehicle and the control of the mechanism.
I am a shareholder in a transport undertaking which has been trying to work petrol lorries, with such machines turned out with a driver only, and I can assure you, sir, that we have pretty nearly come to grief through doing so. In several instances, the drivers appear to have got drowsy while on the road, and to have allowed the vehicles in their care gradually to run off the metalled part of the highway, either on to the grass verge at the side, or into the lessinviting gulley or ditch. Had there been a "mate," he would either have kept the driver alert tor nis duties by occasional talk, or would have realized that the man was so dropping off to sleep. That is a possibility which you did not mention amongst the points which you put forward in favour of having a second man as a general rule.
Your report of the Dundee summons and tine, for a driver who had to leave his petrol wagon at the roadside when he found he had put some water into the fuel tank by mistake, is merely typical of scores of contingencies which do befall owners of petrol or steam wagons. It is because the owner of the latter class of machine most often has a " mate " for his driver that he does not suffer from like consequences, although one knows quite well that the increased point-to-point speed of the petrol lorry makes good a proportion of these happenings.
My oompany once had a petrol lorry sink into a soft place at side of a narrow road, due to the fact that the driver went a little too far to the left when meeting a hay cart, and we had trouble with the police' although it did not lead to a summons and a fine. The driver of the hay cart would not take any interest in the mishap, which occurred at a lonely spot. No suitable packing blocks could be found, and it was impossible to get the wagon back on to the road, under load, by the use of the single WoodHaley jack that was slung beneath its platform, or to off-load it. While the driver trudged some four miles over the moors to a cottage from which he could borrow a. spade, in order to dig a path for the wheels to run hack on to the hard metal., a constable came along, and the wagon unfortunately was not in a position that it could be claimed it was other than an obstruction, although no actual obstruction had probably occurred. Furthermore, it took three hours to get it out, and the driver had stupidly gone out without his lamps, which meant that he got home after lighting-up time. We did get fined for that. A second man to help him would have made all the difference, and would probably have saved a clear hour, or more.
My experience has been that the second man is most useful, and even positively necessary, when a carrying company's wagon is doing a large amount of work to and from the docks at any port. I write with particular knowledge of Manchester and Liverpool conditions. The second man need not be paid more than 24s. a week, and it is possible to obtain " mates " with the necessary knowledge of dock and warehouse work at that rate, I agree with your earlier statements that a youth at 14s. a week, or less, is net a suitable class of labour for the duties that are involved.—Yours faithfully,
Was not our correspondent's company overworking its drivers ? Even a petrol-lorry driver usually has enough to do to keep him awake, pro vided he be physically fit.-Ev.]
The Editor, THE COMMERCIAL MOTOR.
11163] Sir, —With reference to my article (page 387) and the communication from one of the owners of
vehicles referred to (page 430), let me say how glad I
am that Mr. Bromilow has read the words with critical interest, and that " Opinions from Others" (page 412) contain, three letters on the subject of dohble-purpose motors, i.e., those for char-h-bancs and for industrial work. This shows that interest is taken.
I sought to show how, in well-populated areas, owners could find a double source of revenue, and I aimed at complimenting, in one article, several owners. But if sufficient, honour and praise was not accorded someone—my apologies. I want to stimu late those owners and others who think of investing in heavy motors, not to discourage them. A few of Mr. Bromilow's observations call for comment, though the Editor has answered some.
Mr. Bromilow agrees that I am right in saying most of the Bolton fleet of dual-purpose motors are Ley lands ; but he puts a wrong construction on my qualifying remarks that one Milnes-Daimler was bought second-hand. The reference was by no means a sneer. It was simply stating a fact. The fact that it was second-hand was no reflection ; on the contrary, its having done excellent service for Mr. Bronailow proves the merits of the vehicle.
As to speed being restricted to 12 m.p.h., it is best not to discuss this in public. I repeat that 20 m.p.h.
" can be" registered, and I could say more than that if it were politic to do so. However, to take his own words, Mr. B. says "the 28 h.p. Milnes-Daimler did
the London trip in company with the 40-45 h.p. Leyland, in equally-good fashion." This obviously entailed rather more than 12 m.p.h. ; otherwise a 210miles run to London would have required over hours, without a. stop.
"Palmarn qui rneruit ferat." I am delighted that Connolly and Polack, like Dunlop and Shrewsbury and-Cludliner, tires are doing well. Other buyers should observe Mr. Bromilow's recommendation and his agreement that big tires give best results.
Mr. Bromilow kindly proves me and my first informant to be correct about 10 m.p.g., for his tests of light and four-ton loads (giving 9 and 11 respectively) average 10 m.p.g.
His note inter alia on the growing popularity of motor chars-h-bancs for picnic parties is most inter
esting, and substantiates my observations. I congratulate all those Lancashire owners who have boomed this phase of pleasure travel, and ask them to take stock of Mr. Bromilow's warning aboutcutting prices.
May I venture to say here, as I told him personally, that he was wrong in " correcting " me over the Bolton-Manchester mileage 2 Anyway, I was not writing about Bolton-IVIanchester when I said that 10s. a ton for 10 miles Was being obtained. I had in view the Manchester-Radcliffe or Manchester-Bury routes to certain works ; and I repeat that 10s. is obtained. I have verified this assertion, and give it again without equivocation. If I wanted to add advice thereon to any other lorry-owner, it would be, "Go thou and do likewise," i.e., get good pay.
Mr. Isherwood sees no extraordinary risk in. the char-h-bancs business ; but Mr. Bromilow feels that it is more risky than transport work, on account of the human life involved. The second-named gentleman quoted me his insurance premiums as follow :—
For a lorry (about) £18 5s For a char-h-bancs £35 to 245 This, he says, justifies his contention that passenger traffic is more expensive than merchandise-carrying. On these matters he is interesting, and I wish other owners would come out with facts and figures. His quotations have little or nothing to do with my first article, but are certainly useful additions. I am told that my note that "nearly all the cars cost 1,800 apiece" is correct. Mr. Bromilow says his new Milnes-Daimler-Mercedes chassis alone is costing almost that amount. I think every "CM." reader will welcome the promised accurate figures from him in due course.
Just a friendly query. Mr. Bromilow claims—with that useful saving clause, " as far as I am aware "— that his 1913 model, 3i tons unladen, is the only charh-hancs that has climbed the Trough of Bowland : has he troubled to justify that claim ? I know that stiff hill as well as most men in Lancashire and Yorkshire ; but if he cannot learn from Burnley, Whalley or Clitheroe picnic-caterers, or from the host of the lonely inn at Whitewell (about nine miles from a station), or from the people at Sykes Farm, that other motor chars-h-bancs have negotiated the hill, I can refer him to a 30-35 h.p. Leyland which, I was told last Saturday, has taken 32 passengers up—many times.
May I just add a line—that comments and " corrections " written in good spirit will help "the cause" ; caustic words never make friends. I congratulate Lancashire on its go-ahead men of double-purpose motor enterprise.—Yours faithfully, "THE OCCASIONAL CORRESPONDENT."
fOn the topic of speed, it is legal to reach 12 m.p.h. when climbing any hilt, subject to traffic conditions. A char-a-banes that can get up certain hills even at 6 mph, or less, mast have the power to do more than 12 m.p.h. on the level. There is nothing wrong in that.—En.
Worm-Gear Differe ntial.
The Rd ;tor, TT1E COMMERCIAL MOTOR.
 Sir,—I notice that you published, in your last issue, on one of the " Drivers' and Mechanics' " pages, a description of a worm-gear differential arrangement, which was sent to you by one of your correspondents. Your contributor does not seem to have grasped the reason for the adoption of this device. I happen to be the patentee of it, and I would, therefore, venture to explain this apparatus. I designed it in order to overcome certain disadvantages which are apparent in regard to the ordinary form of differential. These are : (1) liability, when one wheel is on soft ground and the other is on stiff ground for the former to spin round and the latter to remain stationary, thus, of course, securing no movement of the vehicle ; (2) when the propeller shaft is locked by the sudden application of the countershaft brake, one wheel frequently rotates backwards whilst the others continue moving in the forward direction, thus resulting in an entire lack of braking effect and a serious liability to sideslip on the part of the vehicle. Now, by using spiral or worm gears, instead of the more ordinary spur or bevel types, for the differential, it will be apparent that a considerable end thrust is introduced. The friction resulting from this has to be absorbed by the use of suitable washers. It is proportional to the power transmitted, and, in my experience, prevents the spinning of one road wheel while the other is held stationary. As a matter of fact, it transfers nearly all the driving power to the wheel which is on the firmer ground. Very much the same action occurs in the reverse sense, that is, when the brake is suddenly applied. Of course, this friction only occurs when the differential action is going on, and, as this is always 'very slow relatively, there is no heating or appreciable wear. I would suggest that these types. of differential are peculiarly suited for commercial vehicles, which frequently get into awkward positions. I shall be pleased to hear from any manufacturers who are interested in my patent, which is No. 27,123,
1911.—Yours faithfully, GAVIN C. GOODHART.
[The effect of the absorption of power by the worm-gears in no way "transfers nearly all the driving power" to one wheel. When the dif. ferential is in use it will uselessly absorb much-needed power.—Eod