Endless Track for Bad Conditions of Use
Page 36
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A N endless track, to
f unction satisfactorily, should be made with considerable pre but even if this be se, the conditions of serviee ,soon create inaccuracies. A track designed to work under bad conditions and avoid stresses due to local loads, is dealt with in patent No. 544,711 by the B. F. Goodrich Co., 230, Park Avenue, NewYork, U.S.A.
The drawings show the track and the wheel in elevation, and the track itself in plan. The wheel is built" up from two discs with outwardly turned flanges to form a wide bearing, surface for the tracks."' At the outermost edges the wheel. is.fitted with upstanding projections (2) which form sprocket teeth.
The track consists of a number ,of flexible cables (5) embedded in an endless • tread band (4) of rubberlike material, the exPression being used to coverall possible stibstitutes. At spaced intervals 'axe cross-bars (1)" which engage the. sprocket teeth (2) on their outer ends., The bars are vulcanized to the tread, and the cable,s in the vicinity of the bars are surrounded by metal casings, with or " withclut bonded-in cords. To iodate•the tracks centrally upon the wheels, ' they' are keyed by humps (3) Which" dngage in-agroove formed between. the wheel discs, .
COOLING PISTONS BY JETS-'
OF OIL
THE lubricating oil of an" engine-has a valuable action in cooking :the•pistons. .In many cases, however, the oil is in the form of a mist, and this, according to patent No. 544,783, is not nearly such an -effective coolant as a jet of liquid oil. The patentee, Continental Motors ,Corporation, Muskegon, Michigan, U.S.A., describes 'a method of cooling by definitely directed jets of oil.
The Scheme is shown applied to a horizontally opposed aircraft engine, but it is not limited to this application,
being suitable for all heavy-duty engines, provided they use pressure-, "fed oil to the main bearings. Referring to the drawing, each crank web is provided with a drilledoil passage (2) leading from a main hearing to a bigend; this is normal practice on many engines. Each big-end is fitted Aritli a small hole, or slot (3) which, when in line with the crankshaft hole, permits a jet of oil to escape in the direction of 'the adjacent piston (I). The bigend is thus used as a rotary valve, 'giving the piston a timed cooling jet on every revolution.
_ BRAKE FACING WITH TWO SEPARATE MATERIALS
ACCORDING to patent No. 544,716, brake facings with woven-in metal wire have not such a high frictional value as the non-metallic variety, althOugh -their life is considerably longer. On 'the" other hand, the nonrnetallie.,type, although more efficient frictionally, is-not so durable. To combine -the good points of both is the object`of s rinal weave described in this patent by the Gandy Belt Manufacturing Co., Ltd„ and C. H. Prob.ert, both of Wheatland *Works, Seacombe, Cheshire.
The 'patentees state that the object may be attained by weaving in aMetallicwire at the leading edge of the facing, leaving : the remainder of
• ashestoa yarn only. The recommended proportions are one-third metal yarn, the. remaining two-thirds having no wire. Facings niade in this way must, of course, be attached to the shoes the
,way round', or the effect is lost,
• bat in cases where there is a risk of this, a" strip with both ends wired may be used, only the centre part being non-metallic. The facings described are said to be _completely free from ." grab " and " squeal," yet, it is claimed, give ample braking force.
PNEUMATIC 'TYRE WITH ANTI-STATIC QUALITIES EVERY vehicle running on rubber Eattyres becomes cEarged with static electricity, the most outstanding case being that of a, steam wagon, which has to trail a discharging chain if violent shocks are to he avoided. On other vehicles, the effect is not so pronounced, but is nevertheless present. and may, according to patent No. 544,757, be an Unsuspected cause of lyre deterioration, due to the liberation of ozone, a gas which ia very destructive of rubber, The patentee. . United States Rubber Co.,-1,230, Sixth Avenue, New York, U.S.A., describes a tyre in which an electrical path is provided to prevent the formation of a static charge.
It is proposed to coat the cover, either inside or outside, with a thin layer of rubber mixed with a conducting medium. A suggested mixture is 100 parts of rubber, 50 parts of acetylene black, and the usual other ingredients. This is applied thinly over the tyxe, prier to vulcanization, and leaves a layer of only one or two thousandths of an inch thick, Other schemes are described in which a ring of conducting rubber is embedded in the tread portion; this forms a conducting path for the charge collected on the inside of the cover.
SCRAPER PISTON RING MADE FROM SHEET
ACCORDING to patent No. 544,660, oil-controlling rings, as at present used, are not wholly satisfactory. It is pointed out that both the cast-iron and the spring-steel types have respective -faults, which are expressly named in the specification. The patentee, the Power Research Corporation, Boston, Mass., U.S.A., proceeds to deseribe an improved type of scraper ring claimed to be free from the defects outlined.
The proposed ring may be described as being of M-section. The middle loops (1) are closely shitted all the way' round, and give a considerable resiliency to the ring in respect of thickness. They also permit circum
ferential spring, so that the gap may be completely closed, yet the ring be 'able to expand, 'to take up wear or inequality, without opening the gap.
From the accompanying fragmentary sketches, it will be seen that the outer edges are widened into feet (2) which make contact With the cylinder wall. Although -.he slots are numerous, they are in staggered relationship, so' that no Part of the cylinder wall is untouched. Othet' designs-are shown, and the methods of manufacture by presswork from spring steel aredetailed.