IMPROVEMENTS IN WHEELS FOR TRAMWAY CARRIAGES
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by Robert Hadfield at the Office
of the Commissioners of Patents, with his Petition, on the 5th
December 1874.
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I, ROBERT HADFIELD, of Attercliffe, Sheffield, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN WHEELS FOR TRAMWAY
CARRIAGES," to be as follows :--
This Invention has for its object improvements in wheels for tramway
carriages.
In a Provisional Specification filed by me on the 15th August 1873,
No. 2700, I have explained that although hitherto it has been the
ordinary practice to furnish tramway carriages with American or Swedish
plate wheels, yet such wheels are very deficient in elasticity, lightness,
and durability, and I therein stated that in order to obviate such
disadvantages I had invented a wheel manufactured of crucible steel
possessing in a high degree the requisite qualities of strength, lightness,
and elasticity combined with economy of cost in production. Sinco
filing such Provisional Specification, I have however discovered by
practical experience that such wheels as therein described are not so well

page_text: adapted as I then supposed they were to resist the sudden and extreme
tension to which they are subjected, owing to the frequent application
of the brake power consequent upon tramway carriages, having to make
such numerous stoppages in order to take up and set down passengers,
frequently pulling up within their own length, or to sustain the shocks
experienced at the various points and crossings, or to meet the excessive
wear and tear incidental to heavy gradients, and the other exigencies of
tramway traffic. After devoting much time, thought, and attention to
overcoming these difficulties I have at length succeeded in devising and
perfecting a tramway wheel made preferably of crucible cast steel, (or it
may be of ordinary steel) which combines great strength with lightness,
and is capable of resisting any shock arising from brake power concussion
either at points, or crossings, or elsewhere. It also possesses great
elasticity united to immence wearing power, and is thus well adapted for
heavy gradients at the same time that it ensures freedom from breakage
from any cause connected with tramway traffic. Now in order to
manufacture such wheel, I take a wheel model of the necessary form
and configuration to produce a wheel such as is shewn at Figure 1 of
the accompanying Drawings, and furnished with a nave having a hole
therein for the reception of the axle. Such axle may either run loose,
or it may if desired be keyed and fastened thereto. I then mould the
same in a casting box containing composition, sand, or other material,
and I then pour or otherwise introduce molten crucible cast steel into
such casting box, whereby I obtain at one operation a hollow cored
weldless steel tram wheel, such wheel being complete in itself and
having a nave and curvilinear spokes. I afterwards place such tram
wheel in an annealing furnace taking great care to heat, anneal, and
cool the same gradually.
Figure 1 of the accompanying Drawings is a back view of a tramway
wheel made in accordance with my improved method; a, a, a, a, a, a, are
six hollow cores formed therein, which contribute materially to ensure the
lightness of the wheel; b, b, b, b, b, b, are six curvilinear arms, the centre
of each of such arms being traversed longitudinally in its rear with a
raised rib or corrugation which is cast thereon at the same time as the
wheel itself is being cast. These raised ribs or corrugations are shewn
in the Drawings at Figure 1, and are respectively marked thereon with
the letter d. Such combined curvilinear and corrugated form of arm
constitutes ona of

page_text: possesses considerable advantages over the ordinary curved arms hitherto
in use, inasmuch as I have found that it is perfectly free from any
susceptibility to breakage, at the same time that it does not in any way
interfere with the necessary degree of elasticity requisite to allow for the
expansion or contraction of the metal.
At Figure 2 I have shewn a sectional view of one of such curvilinear
corrugated arms.
A lesser number of cores than six may be formed in the wheel if
thought desirable, and a corresponding diminution may also be made in
the number of the arms. Wheels constructed upon this principle will be
found not only to possess great strength, elasticity, and lightness, but to
combine with these advantages all the strength and solidity of a solid
disc wheel at the same time that they are economical and homogeneous,
and far excel those in present use, as their peculiar combination and
form render them free from the strains, jarring, and concussion existing
in ordinary wheels, and their wearing and lasting qualities are propor-
tionately great.