The Purchase Department.
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Where to Buy your Supplies. ii 11 You Can Get It At " H.V.S." (North Kensington).—You should get in touch with James Bartle and Co., Notting Hill. This firm undertakes all classes of machining. They would also no doubt quote you for the forgings or stampings.
"Norma" Self-aligning Roller Bearings.
'hat specialists in the manufacture of ball and roller h3 rings are fully awake to the important part which their particular class of productions assumes in the motor industry is evidenced by the many high-class varieties now manufactured. The demands of the heavy branch of the industry have done much to bring out the best practice in this respect.
We recently have had brought to our notice a roller bearing of special design, in that point contact. of the rollers, in addition to line engagement, is incorporated in the construction. It is marketed by Edmunds, Walker and Co., 6, Newman Street, Lon-Ion, W. Our illustration shows a bearing in section.
It will be seen that the inner face of the outer race, instead of being flat in its cross-section, as is usually the case, is formed to a slightly convex surface, the apex meeting the rollers at their mid-sections, thus giving point contact between each roller and the outer race. This construction, so claim the makers, offers a particular advantage over the ordinary form of roller bearing, in that, as the journal load is increased, the elasticity of the steel allows the point contact with the outer race to be transformed into elliptical surface contact, varying according to the nature of the load. Deformation ,of material, however, never approaches the elastic limit under any pressure to which the bearing can properly be subjected, so that the load-carrying surface adapts itself to the loads carried.
This exclusive feature, the makers state, gives Norma roller bearings a remarkable load-carrying capacity, their particular productions being able to withstand temporary overloads to an extent of 50 per cent.
The slightly-curved outer race, combined with the cylindrical rollers, permits the bearings to take up small errors of alignment due to flexure or other causes. The open construction also allows unequalled accessibility to the component parts, and the elements may be separately fitted, or taken adrift as the case may be, and minutely examined. The Aster 10 h.p. Four-cylinder Engine.
In the matter of internal-combustion engine construction, the Aster _Engineering (1913 Co., Ltd., Wembley, Middlesex, of course, occupies a position in the front rank of manufacturers. The concern builds engines of various sizes, the smallest being a 10 h.p. unit, whilst the largest is of 70.5 h.p.
The latest of its preductions which has been brought to our notice is type 42D ; this is a fourcylinder model, giving 10 h.p. on the brake. The bore and stroke respectively are 65 mm. and 100 mm. Our accompanying photograph will convey some idea of the uniformly compact construction of the unit. The cylinders are cast en bloc and are cooled by thermosyphonic circulation. Both inlet and exhaust valves, as is usual with modern practice, are interchangeable, and are placed in one line, the valve-spring and tappet mechanism being enclosed with dust-proof covers.
The symmetrical construction of the crankcase is quite worthy of note. It is cast in one piece and consequently very rigid. The crankshaft is provided with two hearings of ample dimensions, the shaft itself being of particularly stout construction and machined out of high-resistance steel of special quality. The maker utilizes silent-chain transmission for operating the camshaft, and means are provided for its adjustment should occasion arise. Another feature to which we would call attention i3 the large-sized water-outlet casting from the top of the cylinders. We emphasize this feature, because, during a walk round the recent Olympia Show, it was noticeable that in sonic cases, such an important point of engine design as the providing of untrammelled water passages, where thermo-syphoni3 systems of cooling were installed, had received but indifferent attention.
Lubrication in type 42D Aster engine is effected by the splash method, the connecting-rods being provided with scoops which convey to oil ducts the lubricant necessary for oiling the big-ends.