IMPROVEMENTS IN APPARATUS OR "BAG-SKIPS FOR DEPOSITING MATERIALS, SUCH AS CONCRETE, IN DEEP WATER OR OTHER PLACES
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Robert Aytoun at the Office of the
Commissioners of Patents on the 12th August 1881.
"
_ROBERT AYTOUN, of Fraserburgh, in the County of Aberdeen, North Britain.
"IMPROVEMENTS IN APPARATUS OR "BAG-SKIPS FOR DEPOSITING MATERIALS,
SUCH AS CONCRETE, IN DEEP WATER OR OTHER PLACES."
This apparatus refers, as hereafter described, to apparatus or bag skips made, say,
of stout canvas or other suitable material. If canvas be employed it may be
rendered waterproof if desirable by any of the usual methods.
Along the sides of the bag on its outside and in the direction of its length ropes
are fastened securely; for example, a convenient arrangement is to use a strip of
canvas strongly stitched first to the rope and then to the bag on each side of the
rope, or by any other mode of stitching which may be found preferable. Each of
these strengthening ropes begins at the mouth of the bag and traverses its entire
length; it then takes a turn round an iron eye at the bottom of the bag, and
returns to the mouth of the bag on the opposite side to that on which it came up.
Where each rope begins and terminates at the mouth of the bag, a "stopper knot "
is formed out of the strands of the rope itself. A small part of each rope next to
the mouth of the bag, and also next to the iron eye at the bottom, is not secured by
means of the covering strip above mentioned, but is simply stitched strongly to the
material of the bag itself.
All along the sides of the bag the ropes run parallel to each other, and are
equidistant from each other.
The number and size of these ropes is proportioned to the carrying capacity of
the bag.
"
Where the ropes turn round the iron eye at the bottom of the bag, they are
fastened together by being strongly "served" with a smaller rope; the "serving'
is also carried round the neck where the ropes begin to diverge from the eye.
If it is found necessary for larger sizes of bags the canvas (or bag material) may
be doubled or trebled over the whole or a portion of the bag; also the bag may be
strengthened by ropes girding it round its breadth in addition to those already
specified in the direction of its length.

page_text: When the bag has been filled with concrete, it is then lifted by means of a sling
chain having at one end a hook which is inserted in a shackle passing through the
eye at the bottom of the bag, and at the other a clip which at one and the same
time closes and carries the mouth of the bag.
This clip which may be of wrought iron, steel, or any preferable material, works
on the same principle as an ordinary stone mason's clip, which utilises the weight
of the stone to tighten the grasp of the instrument. Instead however of holding
the weight with the point of the claws, the points are allowed to pass each other so
that the claws form themselves into a ring which grasps the neck of the bag as
soon as a lifting strain comes upon the chain and completely closes the bag, while
from the arrangement of ropes the bag is sufficiently strong to admit of its being
lifted by the clip at its mouth and the hook at its other end, and carried to the
required place of deposit.
To empty the bag all that is necessary is to lower it gently to the ground, when
the clip opens of its own accord by the action of return springs, say, of india-
rubber or metal, spiral for example (as soon as the lifting strain ceases), and the
clip springs clear of the bag altogether. Upon now hauling on the sling the bag is
lifted by the bottom end only, and its mouth being open it is at once emptied.
The clip need not necessarily be opened by springs. A tripping rope attached
to the claws may be used to drag it clear of the mouth of the bag as soon as the
lifting strain is taken off.
In working the spring clips I sometimes provide an arrangement by means of a
temporary small chain or rope to keep the clips closed around the bag until the
lifting strain comes fairly upon it to be then removed.
The hook which holds the tail of the bag should be furnished with a guard, so
that it may not slip out of the shackle during the emptying process.
When very
small bags are used ropes may not be a necessary part of the apparatus.
The clips may be kept temporally closed while under lifting strain by means of
a light chain provided with pins, which carry the upper ends of the india-rubber or
other springs slightly lengthened for the purpose; or it may be a pair of studs
placed somewhere near the end of the upper arms; the light chain aforesaid is
made fast to one stud, and is of such a length that a ring at its end will just slip
over the other stud when the clips are closed.