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New Offices. Shiploads.
By "The Extractor."
The clock tower of the new Karrier office is nearly complete, and when the famous Potts of Leeds hoists up the new time teller, Huddersfield eyes will turn gratefully upwards "Come what come may, Time and the hour runs through the roughest day."
I was most interested to be piloted through the new works on a visit last week-end and, although by no means free from labour troubles, the fine shops are well occupied. I do not remember a better planned place nor finer tools, so the Claytons are 13oking well ahead. The comfort and well-being of the office staff, too, has been studied. The administration building, as these places are termed (not by the Claytons, but by some nowadays) is a labyrinth of rooms in which time saving and convenience are brought to a fine point. In the centre underneath the clock tower and the bell, weighing I don't know how many tons (or is it hundredweights, anyhow 1 hope it is firmly fixed), is Mr. Reginald Clayton's office. Long may he wave.
An idea will be gained of the extent of business done in commercial vehicles at the present time when I say that the fes, "British Monarch" has recently arrived at Glasgow direct from the United States with a shipment of 54 G,M.C. trucks and that 31 of them were destined for David Carlow and Sons, Glasgow, for immediate Scottish needs. Messrs. Prances Motors, Ltd., of Manchester, have taken 10 trucks this week, which makes altogether 50 G.M.O. trucks in Manchester district recently. There are, of course, other important centres taking big deliveries, but the above items came before my notice, because I dropped on Mr. W. Turner Smith in Lancashire a few days ago just as he had arrived from Scotland.
It has been decided to extend the time for a few days in the matter of the A:B.C. competition to allow scope for some competitors abroad. We have had many versification efforts sent in from France. some from officers in the A.S.C., and I4think it will meet all requirements if we ,extend the time until 9th March. May I repeat that, if it be thought desirable, more than one effort may be sent in by the same person, but will competitors understand that eaeh two lines must rhyme ? It is a pity, but " reputation " will not rhyme with " deputations," neither will "Lacre " correspond with acres." Another competitor seriously refers to Anglo spirit which he calls perfection," and foes on rightly enough to Berna, which he exclaims is worth our "attention." "Well, " perfection " and "attention " will not mate together in any rhythmic sense, whatever they may do in a domestic capacity. We have received many excellent sets, but I want to see many more, so will you please set to work one evening and figure out the best set of lines possible, posting them so that they reach here on or before 9th March?
B50 011a Podrida.
John Knape and Sons, Ltd., Burnley, is doing well with Karrier cars, and could dispose of more if better deliveries could be had.
An unquestionable authority assures us that " A prophet is not without honour save in his own country "—all the same the Yorkshire steam wagon finds a ready sale in Leeds City.
The new general manager of British Berna Motor Lorries, Ltd., is A. Douglas Barty, at one time chief engineer to the F.I.A.T. Motor Cab undertaking.
On Saturday, 4th March, light up your lamps at 6.12 in London, 6.19 in Edinburgh, 6.14 in Newcastle, 6.21 in Liverpool, 6.18 in Birmingham, 6.22 in Bristol, and 6.39 in Dublin. about 620 lb. per sq. in. Neglecting the pressure and taking into account only the respective areas of cylinder and bearing, an average cif 1 sq. in. of big-end area for 2.73 sq. ins, of piston area is obtained, In the limits of the engines under consideration, say from 31 in. bore to 5 hi. bore, the average diameter of the crank pin in use corresponds very closely with 0.4 bore +
Gudgeon pin pressure may be taken at 2100 lb. per .sq. in., D2 or the area of the pin is given by — in sq. in., D being the diameter of the cylinder. Gudgeon pin diameters show a close approximation to big end diameter-1 1-32 in for the sizes of engines under conrideration.
Crankshaft Bearings.
In commercial vehicle engine design, the three-bearing crankshaft is usually used, and there would appear to be no particular reason for fitting five bearings. At the same time there are two or three very successful engines having fivetearing crankshafts, and one at least with only two main bearings. In seVeral engines of the three,bearing type the middle bearing is the same size as the big ends, and as this may offer manufacturing advantages and seems to be satisfactory in service it is no doubt to be recommended. In the way of standardization and reduction of spare parts, some makers also have the front bearing of the same dimensions. The average lengths, however, for the three bearings, taking the length of the connecting red big-end bearing as 1, are 1.21 for the front, 1.17 for the middle, and 1.48 for the rear.
Setting down the average surfaces as found from the engine examined, where D = cylinder diameter, we have:—
Big end 1—Average pressure, 765 lb.; piston area area, 2.73
diameter of pin, 0.4D -i4 in.
Liclg,eogi pin :—Average pressure, 2100 lb.; DR area, —; 9.6 diameter of pin = big-end diametet -1 1-32 in. Main bearings have the same diameters as the crank pin, and the lengths are respectively 1.21, 1.17 and 1.48 times the crank pin length.
These dimensions may Locm to savour too much of the " rule of thumb," but they have been arrived at after a niose examination of a number of engines running successfully ii ordinary service, and if they do not appear to take all tho factors into account, it is because an attempt has been made to simplify the formulte as much as possible. They are put forward, not as being the ideal, but as representing as closely as possible current practice as shown by the engines of which the requisite data were available.
Ball Bearings for Crankshafts.
The engine to which referenoe is made in the next paragraph is an example of that embodied in the Commer Car chassis.
Only two prominent builders of commercial vehicle engines in this country use ball journal bearings for the crankshaft. The arrangement is clearly shown in Fig. 13. The fact that these are retained shows that the makers are satisfied with the results.
Valves.
Examination of the valve proportions of a number of engines reveals an average effective opening of 10 per cent, of the cylinder area. With the exception of the Daimler vehicles, all British cotnmercial vehicles have engines of the poppet-valve type. These valves are usually of 5 per cent. or 3.5 per cent, nickel steel with seats at 45 degrees. The London General Omnibus Co., after experimenting with other materials, standardized mild steel valves suitably case-hardened and ground to overcome the difficulty of wear in the 335-4 stems. Where trouble has arisen due to excessive wear or pitting of the face, nickel chrome steel has been used with advantage, while one maker has found a remedy in a return to cast-iron heads.
Examination of a number of engines showed an average valve seat bore of 0.46 of the cylinder bore with a lift of cyZin der bOre 112. Taking into account the angle of the seat, this gives a clear valve opening area of 0.108 of the cylinder area, or approximately we have:—
Opening in valve seat = 0.46 cj,linder diameter. cylinder diameter Valve lift 12 cylinder area Effective area of valve opening = 10 Valife tappets adjustable by set-screws at the upper end and fitted with rollers at the lower end are standard. In the case of the Albion, Napier, Tilling-Stevens and White and Poppe engines commendable care has been taken to ensure ample wearing surface in the tappet guides with tappets as light as possible.
Current Ideas as to Valve Setting.
The average taken over a number of settings is shown as a diagram in Fig. 11. This is intended to illustrate current ideas and. is not put forward as an ideal setting.