IMPROVEMENTS IN HAMMERS, AND IN APPARATUS FOR WORKING THE SAME
Year: 1859

page_text: PROVISIONAL SPECIFICATION left by Archibald McKechnie at the
Office of the Commissioners of Patents, with his Petition, on the 30th
April 1859.
I, ARCHIBALD MCKECHNIE, of Carron, in the County of Stirling, North
Britain, Engineer, do hereby declare the nature of the said Invention of
"IMPROVEMENTS IN HAMMERS, AND IN APPARATUS FOR WORKING THE SAME," to be as
follows, that is to say :-
This Invention relates to the arrangement, construction, and working of
mechanically actuated hammers of frictional action, whereby variable blows may
be given with great rapidity, ease, and certainty, whilst the machinery is simple,
and the hammer can be suspended at any point required when cessation of work
is necessary. The main framing of the hammer consists of a vertical pillar,
bolted down to a suitable foundation, and fitted or formed with upper over-
hanging brackets like a slotting machine. The lower bracket of the framing
is fitted with an adjustable collar guide bearing, to receive the vertical
wrought-iron hammer bar, which is further guided by an overhead guide
bearing on a pillar bracket carried by the main frame at the top. The
hammer is actuated by a belt pulley on one end of a short horizontal shaft
running in bearings on the top of the main frame, the other end of this shaft.
carrying a fly wheel to insure steadiness. This shaft has upon it a spur pulley
in gearing with a spur wheel fast near the centre of a lower horizontal shaft,
which also carries a broad frictional pulley. The same top framing also
carries another and similar shaft parallel to the one first. described, and on the

page_text: same level, and also fitted with a corresponding broad frictional pulley. It is
between these pulleys that the hammer bar is nipped during the lift, the
second or outer shaft being also fitted with a spur wheel in gear with the
wheel on the other or inner pulley shaft. In this way the belt pulley move-
ment actuates the two frictional pulley shafts in concert, but in reverse
directions. The four end bearings of the two frictional pulley shafts are set in
horizontally traversing blocks fitted into guide apertures in the top framing,
for the purpose of enabling the attendant to bring the two frictional pulleys
into or out of nipping contact with the hammer bar. This movement is
effected by means of a bottom weighted hand lever, set on a stud centre near
the base of the frame, a long link rod passes up from this lever to the outer
end of an overhead lever fast on a short horizontal shaft set in bearings in the
top framing. This shaft carries at each extreme end a short double lever,
each end of the two levers being fitted with a joint stud, for attachment to the
back ends of upper and lower connecting rods, the other ends of which are
respectively jointed to external studs on the sliding bearing blocks of the
frictional pulley shafts. In this way the simple depression of the hand lever
brings the frictional pulleys into nipping contact with the hammer bar, and
when the lever is let go, its counterweight falling down relieves this nipping
contact. Thus, as the belt pulley shaft is a continuous revolver, the attendant
can give very rapid strokes, because a very slight motion of the engaging
lever nips the hammer bar for the lift, and the weight relieves it for the
descent as easily. The adjustable lower collar bearing of the hammer bar is
worked by a horizontal screw spindle passing through the centre of the lower
bracket, and through the main pillar to the outside of the pillar behind. The
projecting end of the screw spindle is here fitted with a weighted lever, so that
the adjustable bearing can at once be expanded or contracted by turning the
lever. In this way the attendant can set the hammer at any required height
when it is at rest. The hammer bar may be nipped either by its two opposite
parallel faces with plain faced frictional pulleys, or by its diagonal faces with
grooved pulleys, the latter being preferred, as affording a superior hold. By
varying the frictional contact of the pulleys with the hammer bar, the blows
may be made hard or soft, just as required.