Improvements in Packing for the Spindles of Rock Drills.
Year: 1896

page_text: Date of Application, 22nd Feb., 1896
Complete Specification Laft 23rd Nov 1806 Accented 9th Jan 1897
PROVISIONAL SPECIFI
Improvements in Packing for the Spindles of Rock Drills.
I, JAMES MCCULLOCH, of Bella "Vista" Portreath, Cornwall, Engineer, do
hereby declare the nature of this invention to be as follows:-
This invention relates to packing for the spindles of rock drills.
The methods of packing heretofore adopted for firmly supporting the piston rod
and preventing leakage around said rod have been faulty and a source of great
trouble and inconvenience some of them chiefly owing to the difficulty of keeping
the packing tight and others of them by reason of the excessive friction set up by
them. For example the gland method of packing whether the gland is screwed.
into the stuffing box or adjusted by means of bolts or studs and lock nuts is
unsatisfactory owing to its tendency to work loose due to the vibrations caused by
the drill when at work. Springs have been tried for the purpose of preventing
such working loose but they are objectionable on account of their liability to break
and because they are in the way. The cup-leather system of packing frequently
adopted in rock drills worked by compressed air is objectionable because the cup
leather acts as a brake on the piston rod during the return stroke and so retards
the speed of the drill. It moreover wears out very quickly and the cylinder head.
requires to be taken to pieces to replace the packing which is inconvenient.
According to my invention provide in the end of the cylinder and surrounding
the piston rod a metallic packing composed of a metal the nature of which is softer
than cast or wrought iron. Such packing may be made of an alloy of lead,
antimony, tiu, and a small proportion of copper and arsenic. I have found that the
following proportions are very suitable, viz., lead 84-6 parts; antimony 4 parts;
tin 9-5 parts; copper and arsenic 7 parts. place above the said packing and.
between it and the piston a ring or washer of steel or other suitable hard metal,
and in some instances I place below the metallic packing and between it and the
cylinder head or cover a suitable soft packing, one for example having a rubber
core. The metallic packing can however be used without the aforesaid ring or
washer, in which case the piston will strike the metallic packing direct. It can
also be used without the soft packing.
The aforesaid packing is maintained tight by its own elasticity. Should it
become slack and leaky by reason of wear, all that it is necessary to do in order to
tighten it is to allow the piston to strike a few blows on the hard metal washer or
ring aforesaid and thereby compress the metallic packing axially thus ensuring
the tightening of the packing around the piston and within the part of the cylinder
which contains it.
The part of the cylinder in which the packing is placed is open to the cylinder
proper at the inner end so that the packing can be operated on by the piston in the
manner bereinabove indicated.
The metallic packing may be used in the form of complete rings or in segments
of rings.

page_text: I, JAMES MCCULLOCH, of Bella "Vista," Portreath Cornwall, 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 packing for the spindles or piston-rods of rock drills..
The methods of packing heretofore adopted for firmly supporting the piston rod
or spindle and preventing leakage around said rod have been faulty and a source of
great trouble and inconvenience, some of them chiefly owing to the difficulty of
keeping the packing tight and others of them by reason of the excessive friction
set up by them. For example the gland method of packing whether the gland is
screwed into the stuffing-box or adjusted by means of bolts or studs and lock nuts,
is unsatisfactory owing to its tendency to work loose, such tendency being due to
the vibrations caused by the drill when at work. Springs have been tried for the
purpose of obviating this defect but they are objectionable on account of their
liability to break. The cup-leather system of packing frequently adopted in rock
drills worked by compressed air is objectionable because the cup leather acts as a
brake on the piston rod or spindle during the return stroke and so retards the
speed of the drill. It moreover wears out very quickly and the inconvenient
operation of taking the cylinder head to pieces. to replace the packing becomes
necessary.
According to my invention I provide in the end of the cylinder and surrounding
the piston rod a metallic packing composed of a metal the nature of which is softer
than cast or wrought iron. Such packing may be made of an alloy of lead,
antimony, tin, and a small proportion of copper and arsenic.
I have found that the
following proportions are very suitable, viz. lead 84-6 parts; antimony 4 parts;
tin 9.5 parts; copper 07 parts and arsenic 0-7 parts. I place between the said
packing and the piston a ring or washer of steel or other suitable hard metal, aud
in some instances I place on the other side of the metallic packing i.e. between
it and the cylinder head or cover a suitable soft packing, one for example having a
rubber core.
In order that my invention may be more clearly understood I will now describe
it with reference to the accompanying drawing which illustrates in longitudinal
central section a stuffing-box packed in accordance with my invention.
A indicates part of the cylinder of a rock drill the piston rod or spindle B of
which is provided with a packing ring C formed of metal of the kind above
specified. The said ring C is placed between two other rings, i.e. one ring D
of iron or steel and another ring E of softer material; the ring D is placed
at the inner end of the stuffing-box and serves as a seat for the fore end of the
piston F; the ring E is of soft or compressible material and is interposed between
the inner side of the cover G and the ring C.
The aforesaid packing is kept tight by its own elasticity. Should it become
slack and leaky by reason of wear, all that is necessary in order to tighten it is
to allow the piston to strike a few blows on the hard metal washer or ring D, and
thereby compress the metallic packing C axially, thus ensuring the tightening of
the packing around the piston rod or spindle, and within the stuffing-box.. The
stuffing box or part of the cylinder in which the packing is placed is open to the
cylinder proper at the inner end so that the pistou can act on the packing in
the manner hereinabove indicated.
The metallic packing can be used without the aforesaid inner ring or washer, in

page_text: which case the piston will act directly on the metallic packing. The said packing-
may also be used without the soft packing and may be made in the form of complete
or undivided rings or in segments.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is :-
1. A packing consisting of a ring formed of an alloy of lead, antimony, tin and a
small quantity of copper and arsenic in approximately the proportions set forth.
for the purposes specified..
2. A packing consisting of a ring formed of a soft metallic alloy combined with
a ring of hard metal such as iron or steel or with a ring of soft packing, or with
both, substantially as described and for the purposes specified.
3. In a rock drill the combination with the piston and piston rod or spindle of
the packing formed of the materials specified and arranged substantially as described
with reference to the accompanying drawing.
Dated this 23rd day of November 1896
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.