OPINIONS FROM OTHERS.
Page 28
If you've noticed an error in this article please click here to report it so we can fix it.
The Editor invites correspondence an all subjects connected with the use of commercial motors. Letters shouN 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
• Roads Bill, 1920.
The Editor, THE COMMERCIAL MOTOR.
[177.80] Sir,—Under section 11 of this Bill, nubsection 2, it appears that there is a penalty for having on a motorbus more people than it is licensed to carry. Thus, if a bus has 26 seats and there are 26 people sitting on those seats, the tax is £48, but what happens 'if 10 other people are standing up, say, at the back? Would one be liable to the penalty noted, if one only had the bus registered to seat 26 people, or would the people who were standing up be allowed-7 , In Form &F. (8) it says that "the tax on a motor hackney vehicle, with a seating capacity of more than 20 but not more than 26 persons, in a co■untry area is 248," and then on the back it goes on to define the term "seating capacity." If, therefore, the 26 seats of the bus. in question conform to the regulations laid down at the back of the form' and the tax is paid, surely one can put on as many other people standing up, withoet extra liability1
Then crops up the point that, supposing there are 26 people on the 26 seats and, say, half a 'dozen other people sitting on their knees, is one liable for a higher tax? Further, there is the question that, assuming one is liable to the penalty for people standing up, over and., above the licensed seating capacity, can one avoid, a penalty by registering at the highest rate of all, that is to say, pay the tax of £70 for seating 32 people or over Clause 11 is not clear to us on these points ; that is to say, we do not know whether the clause is put in to prevent overloading, or to ensure that the vehicle in question pays its tax according to the people who are being "carried" on it. For instance, it is quite a common thing for a 28seated motorbus to go on a party, and for perhaps 35 people to be on it, the extra nine people being accommodated by sitting on boxes or other temporary seats, which are taken out after the trip has been completed. It is not possible to register our vehicles tuitil we know whether we shall be liable to a penalty or not, as one's buses always become loaded at some time or other, such as Saturday nights, a,nd so on.—Yours faithfully, C.1\I,C., LTD.
Steam Boiler Clams.
The Editor, THE COMMERCIAL MOTOR.
[1781] Sir,—In the Patents page of your issue' of November 30th, there is a description of what is tqemed a new boiler for Stearn wagons. I have read this over very carefully, but cannot come to the conclusion that this particular boiler could make steam, at least in the way it is intended. Perhaps my reasons for such a 'statement would be of interest.
The fire supplies heat to the water in the primary generator, and fills the steam space with steam at 400 lb. pressure, and steam at this pressure is at a temperature of 44s degrees Fahr. So far that is all right, if the boiler does not burst, but heavy plates would have to be used, which mean weight. An average motor wagon boiler will evaporate about 600 lb. of water per hour under ordinary running conditions, and this requires about 720,000 s at 200 lb. pressure with feed water at 32 degrees Fahr. Without the external super-heater mentioned in the article, all this heat would need to be extracted from e20 the steam space of the primary generator, and, as the final pressure of the secondary is the same as the primary, it is impossible to get steam; it would only act as a feed water heater, and even then the final temperature could not be the same as the heating medium, as there must be a difference of temperature before there is any transmission of heat. With plenty of heating surface in the secondary we might get a temperature of 400 degrees Fahr.,
equivalent to a pressure of about 230 lb. per sq. in.
If the feed water entered at 32 degrees Fahr. and left at 400 degrees Fehr., we have only added 368 B.T.U.s per lb., and to convert itinto steam we require to add about 825 B.T.U.s more; that makes the external super-heater an absolute necessity, and it would have to add all the latent heat necessary to convert the water at 400 degrees Fahr. into steam at 235 lb., and that would be more than twice as much heat as • is transmitted in the primary and . secondary generator.
In an ordinary wagon boiler we require about 60 sq. ft. of heating surface to supply the steam re quired for the engine, and as the described invention only supplies one-third of the heat., the external super-heater would require to supply the other twothirds or 40 sq. ft. of heating surface With regard to the high speed of the water through the secondary coils, if the speed is sufficient to pre vent the deposit of scale, where will the scale deposit? In the engine? If so., it would be far better and cause less worry if it were left in the boiler. I venture to suggest that' the whole arrangement is based on an erroneous conception of the laws of thermo-dynamics, and would be an absolute failure for the purpose intended.—Yours faithfully, Glasgow. THERMOS.
Articles on Overhauling Chassis.
The Editor, THE COMMERCIAL MOTOR.
[1782] Sir,—I wish to congratulate you most heartily an the extremely interesting and instructive article entitled "flints on Overhauling" contained in your issue dated December 14th. In my opinion, this and the subsequent articles which you promise will, if the latter maintain the same standard of quality, prove extremely valuable to repairers and commercial vehicle cwners, not only in this country, but in others where the repair facilities are either totally absent or very inefficient, and where, consequently, the owners of the vehicles have to undertake their own repairs. I have two suggestions to make, although possibly you have forestalled me in thinking of these. The first is that the article on overhauling the Foden wagon, which appeared in your journal some considerable time back, should be reprinted' so as to feSrm one of the series, especially as it is sometimes difficult to obtain back numbers which contain useful articles of this description.
The second suggestion is that when the series is completed, a booklet should be issued containing the whole of the articles. That would certainly prove of the utmost value to repairers, and particularly to those who have not before. overhauled vehicles of particular makes, as, when dealing with a machine for the first time, it is often a matter of considerable time and labour to ascertain the special points regarding the dismantling and overhauling of the different
units.—Yours faithfully, Scams. [Our correspondents' suggestions are under consideration.—ED, " C.M.]