OPINIONS FROM 'OTHERS.
Page 25
Page 26
If you've noticed an error in this article please click here to report it so we can fix it.
The Editor nrites correspcnidence on all subjects connected with the Use of commercial motors. Letters should be on one side of the 'paper only and typewritten by preference.. The right of abbreviation is reserved, and no responsibility for
views expressed is accepted.
.Spu.ds on Tractors.
The Editor! Tun COMMERCIAL MOTOR, [1766] Sir,—In your issue of November 16th, you have an article headed "A Suggestion to Tractor Designers," in connection with spuds for tractor wheels. The type of spuds illustrated by your contributor and shownfitted to a German gun tractor can be seen at our works at the present time, as some time ago we made this identical device and fitted it to Austin tractors for experimental work. We found in practice that it had very many disadvantages as compared with the new type of detachable spud which has been patented by us, and which, in its tests so far, has not shown any faults. The advantages are that the spuds can be removed in a few moments without the use of any tools, and, further, they can just as quickly be replaced with our rubber pads to enable the machine to be used for road work. Briefly, the idea is—a spud with an automatic self-locking -device to hold it in position, and which is so simple that it appears to be impossible for it to get out of order.
Before putting these on the market we are adopting our usual procedure of very extended tests both on . road and field, and, therefore, it will be some little time yet before we shall be ready to supply.
As aeon, however, as our tests are completed, we shall be glad to give publicity to the details in your columns if you will permit us to do so.
In the meantime, we refer to this matter to let your readers know that the idea suggested in your paper has been thoroughly tested by us, and we have found that it is heavy, needs quite a, lot of attention to keep it in firoper working .order, and it does not lend itself to the. alternative use of rubber pads for road work—Yours faithfully, For THE AUSTIN MOTOR CO., LTD. E. H. ARNOTT.
" C.M.'s" Tables of Running Costs.
The Editor THE COMMERCIAL MOTOR. ,
[17671 Sir,--T was interested in the article by " The 'Skotch " in your issue of the 16th inst. on the " Running Costs of Commercial Vehicles," but I must say that I do not altogether agree with his figures. In the first Place, the east for fuel seems excessive. 'Apparently he only allows 12 miles per gallon for a one-toriner. There are many one-tonners which give a higher mileage than this. The tyres, also, in my opinion, are over-charged, that is if he allows 9,000 miles for the life of a set of tyres, which I think you will agree is a fairly moderate estimate.
Then we come to insurance. I should like to know -the name of that office where " The Sketch " could .get an insurance policy for 6s 3d. per week. '7 Running costs are extremely difficult to arrive at accurately, awing to the varying nature of the work that the trucks are put to, and it may interest you to see the scale of running charges of the Republic truck, which has been based on the actual expenses Of many users.. The great. difficulty, of course, in working out these scales is the question of petrol consumption. It is very difficult to reach a fair average, owing to the different work done by each particular truck. Some trucks have to do 50 stops a day others only a few, and, naturally, the petrol consumption in these cases differs enormously.
The one thing that rather astonishes me in the figures you publish is that you give no better petrol Consumption where a vehicle has pneumatic tyres. Our experience has been that there is a saving in this direction, I notice, too, that depreciation is put at the same figure, whereas, of course, the big claim made for thee pneumatics is that they will save a Considerable amount of depreciation on the vehicle itself. It would be very interesting if others would give us their experience on these lines, and I hope that they will be thicouraged to discuss this question of cost of working—Yours faithfully, W. P. PHILLIPS, Sales Manager, Republic Trucks.
Running Costs of Republic Trucks.
Based on 300 Miles Running Per Week (15,600 per anntun). 30-40 cwt. Truck.
Price of Chassis D315. Cost of Body (approx.) £95.
Total 1710.
. Solid versus Pneumatic Tyres.
The Editor, THE COMMERCIAL MOTOR.
[1768] Sir,—In your issues dated the 15th and 22nd instant, there appear letters on giant pneumatic tyres versus solid tyres in combination with cantilever springs ; these can hardly be regarded as controversy but as opinionative salesmanship. The development of the giant pneumatic cannot he arrested by a mechanical attachment, such as a cantilever spring in combination with solid tyres, for, since 18A8, this question has been amply demonstrated. The merit of the giant pneumatic tyre is that it accommodates itself to the inequalities of the road and carries both the sprung and unsprung weight ; distortion of its cushion of air enables this to be effected.
Can the cantilever spring carry out this function? Surely the spring is under the load tension and the load is in suspended animation. We, therefore, 1:ret resiliency of sprung weight, but this is not cushioning capacity. Are not shock absorbers used to damp out 0 resiliency, which is but vibration? We have, therefore, unsprung weight under a tensional load of 4 tons mounted upon solid tyres (which, as they wear, become less efficient). Surely, it cannot be disputed that the impact over the inequalities of the road surface is considerably more with solid than with pneumatic tyres. Impact tests have been carried out on 4 ton lorries. Two of these were fitted with solid tyres. One had worn tyres 1 in. thick, and the other had new tyres of 21 ins. The third vehicle had 42 in. by 9 in. pneumatics, inflated to a pressure of 142 lb. per square in. Each vehicle, carried a. load of 9,000 lb., which was distributed so that the rear wheels carried 7,000 lb.1,700 lb. unsprung, 5,300 lb. sprung—and each vehicle was run at three speeds with .a 2. in. shock, the,results were as follow:—
The above table may be of interest to those seeking some indication of road impacts in lbs. and will assist them to form their own opinion as to how far cantilever springs or longer springs will diminish the shocks at the road wheels.—Yours. faithfully, London. F. A. SESSIONS.
Should Chassis Be Shown at Shows ?
The Editor, TEE COMMERCIAL MOTOR.
[1769] Sir —I was extremely interested in an article by the " Inspector" entitled " Should Chassis be Shown at Shows?" which appeared in your issue dated November 23rd, 1920. I think that the "Inspector " sums up the whole matter in the last paragraph of that article. He says, "I know very well how you feel, Mr. Editor. You are out for news of course,. always and rightly, but it has to be remembered that you and other journalistic leaders are primarily concerned with the user and not with the draughtsman and designer, and the user should be given all the information that can Leaf value to him."
Now, I ask, who are the purchasers of commercial vehicles, users or designers? The natural reply, is users, and a great many of these men with considerable technical knowledge, particularly when we come to those users running large fleets ; and the man who buys commercial vehicles as additions, to such a fleet is usually the fleet manager, who will certainly not be satisfied without making a, thorough inspection of the chassis. He does not particularly want to see complete vehicles as, in most cases, his choice of bodies is restricted, as he may require anything from one to three types and no more, and these will probably be standard types made by some 'local coact-Alai-Wen The chassis, on the other hand, are of extreme interest to such a man who wants to see where advances in design have occurred, and where weaknesses which may, in the past, have shown themselves; have been overcome. Accessibility is another feature which he cannot afford to overlook, and such little points as the number of places where lubrication is required cannot be seen without extreme difficulty when the show chassis is equipped with a body. 'There is no great difficulty in camouflaging a. shoddy chassis with a very excellent body, and although this might deceive a less practical man the fleet manager wants. to know something more about the chassis before he is willing to buy s in fact, I consider that if the choice lies between complete vehicles and chassis for show, , it will be better to drop complete vehicles.—Yours
faithfully, FLEET MANAGER. Bradford.
Examinations for Drivers' Licences, The Editor, TEE COMMERCIAL MOTOR.
[1770] Sir,—Amongst the " Opinions from Others" contained in your issue dated November 23rd last, I noticed a letter from Mr. R. J. Bevan recommending examinations for drivers before the granting of driving licences. I must say that I emphatically endorse this gentleman's remarks. It is only necessary to watch the streets of London and elsewhere for a short time to note glaring examples of inefficient and da.ngerons driving. Accidents are too prevalent, and anything which can be done to reduce the number of these will certainly be beneficial both to the motor industry and the public. Needless to say, a driver should be examined on a. vehicle similar to that which he intends, to drive. It would be of little use testing a lorry driver on a privale car, or vice versa, and the test should not be restricted to drivers of commercial vehicles and private cars, but should also be applied to motorcyclists. —Yours faithfully, W. J. JONES. Stroud.
The Editor, THE COMMERCIAL MOTOR.
[1771] Sir,—My -objections to an examination of a . driver before granting or renewing a licence are that the examiners must for their credit's sake show a certain percentage of " rejects" (possibly depriving men, of their occupation), and that it is not always the qualified man who passes an examination.— Yours faithfully, M. 'J. BARTON. . . Leeds.