Year: 1888

page_text: 1
1, LUDWIG WITTHÖFFTT, Engineer, of Bochum, Westphalia, in the German Empire,
do hereby declare the nature of my invention, and in what manner the same may
be performed, to be particularly described and ascertained in and by the following
statement:-
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4.2
The circular saw or saw frame, hereinafter described, is chiefly intended for use as a
hot-iron-saw, the piece of work being stationary, while the saw blade receives a feed
motion towards the same.
In the accompanying drawings, Fig. 1, is a longitudinal section, and Fig. 2, a plan
of a circular saw embodying my invention, while Figs. 3, 4 and 5 are vertical sections
along lines A-B, C-D and E-F of Fig. 1.
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The circular saw comprises a stationary cylinder a and a double acting piston
adapted to be propelled by hydraulic or steam power, or by compressed air.
With the piston rod is connected a sliding frame or plate c carrying the bearing for
the three axles d, e and f.
The axle d carries the saw-blade g, while e and fare intermediate shafts serving to
transmit motion to the saw-shaft at the required speed, by means of spur-wheels h, i
and k, 1.
On the axle situated next to the cylinder a are also mounted spur-wheels m, m
gearing into the toothed racks n, n fixed to the main frame S of the sawing
machine.
If now the piston b, and consequently also the sliding frame c, is pressed forward,
the toothed pinions m, m will roll along the racks n, n and transmit rotary motion to
the saw axle d by means of the spur-wheels h, i and k, l. When the piston 6 has
reached the end of its travel, and the desired cut has been made, the sliding frame c is
withdrawn by reversing the mechanism.
It is necessary, to provide a contrivance for preventing violent shocks and breakages
which might be caused by the inertia of the saw blade, when the slide c is suddenly
stopped. This object may be obtained by making the shaft e of two parts and inter-
posing between the same a coupling p which transmits rotary motion in one direction
only. The coupling, shown in the drawing by way of example, carries on one half a
pawl o acting on a straight tooths of the other half, which tooth is curved or inclined
[ Price 1

page_text: on the opposite side. Owing to this construction, one half of the shaft e is allowed
to continue its motion after the cut has been made, and the slide c may be withdrawn,
because the two halves of the shaft e can turn in opposite directions.
The pressure on the piston and the stroke of the same must be so calculated, that
the saw-blade will already have acquired the speed necessary for cutting, when the cut
commences.
To the rear part of the slide c are applied a pair of rods t, t surrounded by buffer
springs vv, and w, w which are designed to react on the piston shortly before reaching
its extreme positions, so as to prevent shocks.
It is evident, that instead of the two tooth-wheels m, m and racks n, n, one wheel
or toothed pinion and one rack only may be employed, but two are preferred to render
the motion more uniform. The number of intermediate or counter shafts on the sliding
frame c may also be varied to suit different requirements:
Instead of transmitting rotary motion from the shaft f to shaft d by means of tooth
wheels, a belt and pulleys may be employed for this purpose.
The advantages of the present sawing machine in comparison with ordinary saws
driven by steam engines and belts, are reduction of first cost, saving of space and of
working expenses.
.
Having now particularly described the nature of my invention and in what manner
the same may be performed, I declare that I claim:
1. In circular saws or sawing machinery (hot iron saws) in which the saw-blade
axle has its bearings on a sliding frame caused to approach the piece of work and to
recede from the same, together with the saw-blade, by means of a piston propelled by
steam or hydraulic power or by compressed air, mechanism for driving the saw-blade
axle d from the piston b which moves the slide e, said mechanism comprising a tooth-
wheel m-mounted on an intermediate shaft f of the slide c and rolling on a stationary
rack n, and tooth wheels for transmitting the rotary motion thus produced upon the
saw-blade axle d.
2. The modification of the saw or machine specified by clause 1 by substituting a
belt and pulley for the tooth gear which transmits the rotary motion from shaft upon
saw-blade axle d.
3. In the saw or machine characterised by clause 1, a coupling on the intermediate
shafte adapted to allow the saw-blade to continue its rotary motion in the same direction,
while the sliding frame crecedes, for the purpose of preventing a rupture or violent
shocks, when the sliding frame is suddenly stopped.
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LUDWIG WITTHÖFFTT.
By Fairfax & Wetter,
433, Strand, London,
Agents.