Improvements in Circular Saws.
Year: 1895

page_text: Date of Application, 11th Feb., 1895
Complete Specification Left, 30th Sept., 1895-Accepted, 2nd Nov., 1895
PROVISIONAL SPECIFICATION.
Improvements in Circular Saws.
1, HEINRICH EHRHARDT of Reichs Strasse No. 20, Düsseldorf, Germany,
Civil Engineer, do hereby declare the nature of this invention to be as follows:-
This invention relates to an improved construction of circular saws in which the
saw is not constructed, as usual, of a solid disc but is composed of a central body
to which is fixed a toothed rim. The toothed rim is suitably fixed to the body, as
will be presently described. By this arrangement the saw can be maintained
practically always of the original diameter, as after the toothed rim has become
worn, this can be replaced by a new one. With the circular saws of one piece as
heretofore made, the worn teeth have to be removed and the disc has to have new
teeth formed thereon, so that by this means the saw will become gradually smaller
in diameter.
This objection is entirely avoided by the present invention.
On the accompanying drawings are shewn by way of example various
arrangements for carrying out my said invention.
Fig. 1 shews a detached toothed ring.
Fig. 2 shews the central disc.
Fig. 3 shews the disc aud ring secured together.
Fig. 4 shews a section on line a-b Fig. 1;
Fig. 5 a section on line b-c, Fig. 1;
Fig. 6 a section on line c-d Fig. 1.
Fig. 7 shews the edge-view of the central disc.
Fig. 8 shews a section on line d―e Fig. 2.
Figs. 9 and 10 shew side and edge views of the joint of the toothed ring.
Fig. 11 shews a front view of a modified arrangement for fixing the toothed ring
to the central disc ;
Figs. 12 and 13 shew sections on line e-f Fig. 11.
Referring to Figs. 1 to 8, the toothed ring A has formed on its inner periphery
recessed portions Y, and in the parts between the recesses are formed grooves i, as
shewn at Figs. 1 and 6.
The central disc B shewn at Fig. 2 is formed with a series of projections gl
corresponding in number to the number of recesses g in the ring A.
These projections g¹ are of a less thickness than the body of the disc B, and
consequently form ribs or feathers on the periphery thereof, as shewn at Figs. 2, 7
and 8. The fixing together of the toothed ring A and disc B is effected by fitting
the toothed ring with its recesses g over the projections g' of the disc B, and then
sliding the ring partly round so as to bring the projections gl within the grooves i.
The bottoms of the grooves i and the outer edges of the ribs g' are made slightly
excentric relatively to the centre of the disc, in order that by sliding the ring on to
the disc the said surfaces may wedge tightly on to each other.
The toothed ring can either be made as a solid ring, or it may be made of a bent
strip, the ends of which are rivetted together, the meeting surfaces of the joint
being serrated, as shewn at Figs. 9 and 10.
In the modified construction shewn at Figs. 11, 12 and 13 the disc B is formed
with a rounded periphery as at Fig. 12, and the inner periphery of the ring is
formed with a corresponding rounded groove, for preventing any lateral shifting of
the ring. The disc B can also be made with an angular periphery, as at Fig. 13,

page_text: and the ring A be made with a corresponding angular groove.
The fitting
together of the toothed ring and disc formed as shewn at Figs. 11 and 12, is
effected by expanding the ring sufficiently by heating to enable it to be fitted
over the periphery of the disc, so that when it contracts on cooling, the ring will
grip the disc sufficiently to be securely fixed thereon. When the teeth of the
ring are worn out, it can be cut through at one point for enabling it to be removed.
Dated this 11th day of February 1895.
ABEL & IMRAY,
Agents for the Applicant.
I, HEINRICH EHRHARDT, of Reichs Strasse No. 20, Düsseldorf, Germany,
Civil Engineer, do hereby declare the nature of this invention and in what manner
the same is to be performed to be particularly described and ascertained in and by
the following statement :-
This invention relates to an improved construction of circular saws in which the
saw is not constructed, as usual, of a solid disc but is composed of a central body
to which is fixed a toothed rim The toothed rim is suitably fixed to the body, as
will be presently described. By this arrangement the saw can be maintained
practically always of the original diameter, as after the toothed rim has become
worn, this can be replaced by a new one. With the circular saws of one piece as
heretofore made, the worn teeth have to be removed and the disc has to have new
teeth formed thereon, so that by this means the saw will become gradually smaller
in diameter.
This objection is entirely avoided by the present invention.
On the drawings accompanying my Provisional Specification are shewn by way
of example various arrangements for carrying out my said invention.
Fig. 1 shews a detached toothed ring.
Fig. 2 shews the central disc.
Fig. 3 shews the disc and ring secured together.
Fig. 4 shews a section on line a-b Fig. 1;
Fig. 5 a section on line b-c, Fig. 1 ;
Fig. 6 a section on line c-d Fig. 1.
Fig. 7 shews the edge view of the central disc.
Fig. 8 shews a section on line d-e Fig. 2.
Figs. 9 and 10 shew side and edge views of the joint of the toothed ring.
Fig. 11 shews a front view of a modified arrangement for fixing the toothed ring
to the central disc ;
Figs. 12 and 13 shew sections on line e-f Fig. 11.
Referring to Figs. 1 to 8 the toothed ring A bas formed on its inner periphery
recessed portions g, and in the parts between the recesses are formed grooves i, as
shewn at Figs. 1 and 6.
The central disc B shewn at Fig. 2 is forn.ed with a series of projections gl
corresponding in number to the number of recesses g in the ring A.
These projections g₁ are of a less thickness than the body of the disc B and
consequently form ribs or feathers on the periphery thereof, as shewn at Figs. 2, 7
and 8. The fixing together of the toothed ring A and disc B is effected by fitting
the toothed ring with its recesses g over the projectious g¹ of the disc B, and then
sliding the ring partly round so as to bring the projections g' within the grooves i.
The bottoms of the grooves i and the outer edges of the ribs g' are made slightly
excentric relatively to the centre of the disc in order that by sliding the ring on to
the disc the said surfaces may wedge tightly on to each other.

page_text: The toothed ring can either be made as a solid ring, or it may be made of a bent
strip, the ends of which are rivetted together, the meeting surfaces of the joint
being serrated, as shewn at Figs. 9 and 10.
In the modified construction shewn at Figs. 11, 12 and 13 the disc B is formed
with a rounded periphery as at Fig. 12, and the inner periphery of the ring is
formed with a corresponding rounded groove, for preventing any lateral shifting of
the ring. The disc B can also be made with an angular periphery, as at Fig. 13,
and the ring A be made with a corresponding angular groove. The fitting together
of the toothed ring and disc formed as shewn at Figs. 11 and 12, effected by
expanding the ring sufficiently by heating to enable it to be fitted over the periphery
of the disc, so that when it contracts on cooling, the ring will grip the disc
sufficiently to be securely fixed thereon.
When the teeth of the ring are worn out, it can be cut through at one point for
enabling it to be removed.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. A circular saw composed of a toothed ring which is fixed in a removeable
manner on to the circular periphery of a central disc, so that when the teeth of the
ring become worn, the ring can be removed and replaced by a new one, whereby
the circular saw is always maintained of the same diameter, substantially as
described.
2. In the construction of circular saw referred to in the first claim, the method of
fixing the toothed ring on to the central disc by making the inner periphery of the
ring with recessed portions g and with grooves i, while the central disc is formed
with projecting ribs g¹ so that on fitting the ring on to the disc and turning the one
or the other part relatively to the other, the ribs g' are made to enter the grooves i
and to be secured thereto by a wedging action.
3. In the construction of circular saw referred to in the first claim, the method of
securing the toothed ring on to the central disc by forming the disc with a rounded
or angular periphery, and expanding the ring by heating so that it can be fitted
over the periphery of the disc whereupon, on cooling, the ring in contracting will
grip the disc firmly so as to secure the two parts together, substantially as
described.
Dated this 30th day of September 1895.
ADEL & IMKAI,
Agents for the Applicant.