Answers to Queries.
Page 28
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Our readers will be informed by the Editor on any points connected with the construction or use of commercial motors. Where a direct reply is desired, a stamped and addressed envelope should be enclosed if a request for privacy is not specially made, any query and answer may be published.
Maximum Legal Width.
" F.(i." (Bognor) [1281] writes :—Will you be kind enough to give me the extreme width of a motor vehicle as allowed by the Act. Thanking you in anticipation.
ANSWER—The extreme width allowed under the Motorcar Acts is 7 feet 6 inches, but the Metropolitan police do not allow a motorbus to be more than 7 feet 2 inches in width.
Petrol or Steam: More Details Wanted.
" Westerner " [12821 writes :—I shall feel much obliged if you will help me in regard to the selection of the type of vehicle most suitable for a hilly district. I am the owner of .a wholesale business which supplies almost everything in the provision, crockery, and ironmongery trades throughout a district having a radius, roughly, of 20 miles. The roads are hilly, and the surface, speaking generally, is rather bad. Some of my friends advise me to have a steam lorry, whilst others say that a petrol vehicle is the best type for me to have. What do you suggest?
ANSWER—You hardly give us enough data to reply to your questions as fully as we should like to do, and you do riot say what the average load carried would be. We take it, however, that, as you have to deliver at distances as high as zo miles, you would have perhaps a dozen, or more, separate deliveries on board, aggregating between i1 and 21 tons in weight, and we feel inclined to recommend a steam wagon, and preferably one having a covered top to protect the goods. For longer distances than those you mention, we think that a petrol vehicle would be the better, inasmuch as the loss of time in re-filling the water tanks and fuel bunkers would be eliminated. If you will send a list of more specific questions, with fuller information as to requirements, we can answer in these columns, or direct.
The Storage of Pe roleum Spirit.
" G.H.W." [1283] writes :—Could you give me a few particulars as to the construction of a petrol storage, as regards ventilation, etc., as required by the authorities, to enable me to have one erected to conform with the regulations of the above? I ought to mention that the storage is not for the sale of petrol, but for use on our lorries.
ANSWER—Great variety of construction is allowed under the Home Secretary's Order of the 18th March, 1903, according to which the owner of a motorcar is allowed to store as much as 6o gallons of spirit, without license under the 1871 Petroleum Acts, provided his storehouse is more than 20 feet from any other building. If your intended place of storage is not that distance from any building, you will require to conform to the by-laws of the local authority, and these vary with the personal views of the local building surveyor in charge. The order of the 18th March, 1903, regulation No. 8, merely reads : " Every storehouse shall be thoroughly ventilated." Our correspondent will no doubt be interested in the article which appears on page 285 of this issue.
Calculation of Ton-miles.
" S.M." [ [284] writes :— We run a steam wagon, and I am desirous of working out the cost per ton-mile, but am somewhat at a loss to know quite the correct way to set to work. Could you enlighten me? Thus, supposing a wagon had run 5,000 miles, and carried goo tons, at a cost of £200. what would be the cost per ton-mile, and how would you arrive at it? I shall much appreciate your kind reply.
ANSWER—You cannot work out the cost per ton-mile merely from the aggregate totals of mileage and tonnage. If you do not keep separate records of the weight of each load, and the distance run under load for each trip, you cannot get a strictly accurate record expressed in ton-miles. The next best course is to strike an average from your own knowledge of the performance of your vehicle : for example, if an average load of 44 tons is taken an average distance of 12 miles on every occasion that the wagon goes out, and
the wagon then returns 121miles with empties, whose weight is generally negligible, one may safely infer in a case where your totals apply that the ton-miles would be obtainable as follows :—goo tons± 41 tons =zoo working trips; 200 trips x by 121 miles (loaded)=2,5oo miles; 41 tons x by 2,500 miles (loaded) = 11,250 ton-miles ; 4200—by ii,250 ton-miles = 4.27d. per net ton-mile.
Worn Cylinder.
J. Benson [1285] writes :—One of the cylinders of my 4-cylinder engine is 3-moo inch from being exactly round, by wear, and loses a great deal of compression. Please inform me if new piston-rings, well lubricated, will in time fill up the space and make compression good.
ANSWER—The wear has probably resulted in the rings being slightly open, instead of their closing perfectly at the split. If the new rings are not too stiff, they may accommodate themselves to the cylinder, but we should advise having the cylinder re-ground.
How to Secure a Loose Collar.
" K.T." [1286j writes :—I am making an alteration to the reverse gear in a 3-speed and reverse, sliding-type of change-speed gear, and I shall be glad if you will advise me how to secure a loose collar to a shaft without drilling a hole through the shaft for a bolt, or by the use of setscrews which always work loose. First, I must let you know for what purpose the collar is wanted, and then you will be better able to grasp my requirements. I want a collar on a shaft which is one and a quarter inches in diameter, the collar to be about two inches in diameter, and to take the thrust of a spiral spring which is slipped over the shaft. The spring is used for keeping the reverse pinion out of gear when not required. There will be no tendency for the collar to turn round on the shaft, and, of course, it is only required to take thrust in one'direction. I realise that the best job would be to turn up a new shaft with a collar solid on the shaft, but, if I do this, I shall not be able to thread the shaft through the bearing in the gear-box, as the latter is not split through the reverse-shaft centre. Any assistance you can give me will be much appreciated.
ANSWER—AS the collar is only required to resist thrust in one direction, you can make a very simple and absolutely safe thrust-washer if you follow the line drawing which we give below. We presume you have access to a lathe, and you should first mount the reverse-shaft between the lathe centres, then turn a slight groove (about 1-32nd of an inch deep) with edges well rounded off, next make a ring of spring-steel wire, about 1 of an inch in diameter, which must be split so that it may be sprung into place. The collar may now be turned up, two inches in external diameter by a quarter of an inch thick, and with a hole bored through of such a size that it is a push fit on the shaft; the hole must be counter:bored to such a diameter that it will Just push over the split spring-wire ring, When assembling, the shaft is threaded through one bearing and, as it pa.sses through, the various parts are slipped on to it in the following order : sliding pinion; spiral spring; collar; and the split spring-wire ring. When the last-named of these is in position, push the collar over it so that the counterbore prevents the spring-ring from being opened again. It will now be found impossible to move the collar in the direction in which the thrust of the spring is exerted.