IMPROVEMENTS IN HYDRAULIC CRANES
Year: 1875

page_text: LETTERS PATENT to John Frederick Boetius, of Plaistow, in the
County of Essex, for the Invention of "IMPROVEMENTS IN HYDRAULIC
CRANES."
Sealed the 6th October 1875, and dated the 5th May 1875.
PROVISIONAL SPECIFICATION left by the said John Frederick Boetius
at the Office of the Commissioners of Patents, with his Petition,
on the 5th May 1875.
I, JOHN FREDERICK BOETIUS, of Plaistow, in the County of Essex, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
HYDRAULIC CRANES," to be as follows:-
Heretofore in hydraulic cranes it has been usual to fix one end of the
lifting chain to the hydraulic cylinder or to some other fixed portion of
the crane, and after leading the chain over pulleys carried on the head
of the ram and below the cylinder to lead it over guide pulleys to a
pulley at the end of the jib or arm of the crane, and the load to be
raised has been connected to the end of. the chain which hangs down
from this pulley. In place of thus fixing one end of the chain to the

page_text: cylinder or frame I lead this end of the chain over guide pulleys and
over a second pulley at the head of the jib or arm in a similar manner
to the other end of the chain.
When the crane is required to exert its full power both ends of the
chain are connected to the load to be raised, but if the cranc is only
required to exert half its power one end only of the chain is connected
to the load, whilst the other end of the chain is attached to a fixed eye
situated vertically under the upright beam or pivot of the crane arm or
jib, and at a convenient height from the ground. Thus the man who
has to connect the lifting chain or chains to the load to be raised can
himself determine whether the half or full power of the crane shall be
exerted.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Frederick Boetius in the Great Scal Patent
Office on the 5th November 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
FREDERICK BOETIUS, of Plaistow, in the County of Essex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifth day of May, in the year of
our Lord One thousand eight hundred and seventy-five, in the thirty-
eighth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Frederick Boetius, Her special
license that I, the said John Frederick Boetius, my executors, adminis-
trators, and assigns, or such others as I, the said John Frederick
Boetius, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make
use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention
for "IMPROVEMENTS IN HYDRAULIC CRANES," upon the condition (amongst
others) that I, the said John Frederick Boetius, my executors or
administrators, by an instrument in writing under my, or their, or
one of their hands and seals, should particularly describe and ascertain
the nature of the said Invention, and in what manner the same was
to be performed, and cause the same to be filed in the Great Scal

page_text: Patent Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said John Frederick Boetius, do hereby
declare the nature of the said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement thereof, that is to say :-
Heretofore in hydraulic cranes it has been usual to fix one end of the
lifting chain to the hydraulic cylinder or to some other fixed portion of
the crane, and after leading the chain over pulleys carried on the head
of the ram and below the cylinder to lead it over guide pulleys to a
pulley at the end of the jib or arm of the crane, and the load to be raised
has been connected to the end of the chain which hangs down from this
pulley. In place of thus fixing one end of the chain to the cylinder or
frame I lead this end of the chain over guide pulleys and over a second
pulley at the head of the jib or arm in a similar manner to the other end
of the chain, thereby obtaining variable power.
When the crane is required to exert its full power both ends of the
chain are connected to the load to be raised, but if the crane is only
required to exert half its power one end only of the chain is connected
to the load, whilst the other end of the chain is attached to a fixed eye.
The Drawing hereunto annexed shows a hydraulic crane constructed
as above described.
Figure 1 shows a side view of the crane, and Figure 2 a plan view.
A is the hydraulic cylinder; B, the ram; C, C', sheaves mounted on
the top of ram and bottom of cylinder, as usual; D is the lifting
chain.
Instead of securing one end of this lifting chain to the body of the
lifting cylinder, as is usually done, and passing only the other end över
a set of guide pulleys and over the end of the crane down to the ground,
pass
both ends by means of guide pulleys d, d, d, over the end of the
jib or arm of the crane down to the ground, thereby obtaining variable
power.
I
When the maximum power which the ram is capable of exerting is to
be applied I hook the end e¹ of the chain in the ring i situated just above
the counterbalance weight g of the other end e of the chain, and attach
this end e to the load that has to be raised. If the lesser power is to
be applied I unhook the end e' of the chain from the ring i, and secure

page_text: it to the staple or eye f situated by preference vertically under the
pillar of the crane, and at such a hight from the ground that a man
can easily reach it with his hands.
When the maximum power of the crane is required the ram B has to
make its full stroke in order to raise the weight through the entire lift,
that is, from the ground to the end of the jib of crane, but when the one
end e¹ is secured to the ring or staple f, as it is shown in the Drawing,
the ram B will only make half its full stroke to effect the entire lift, but
it will only be able to lift half the maximum weight, thereby requiring
just half the quantity of water required to raise the maximum weight.
The arrangement for turning the crane is carried out in the usual
manner by means of two small hydraulic cylinders and rams J.
It is not absolutely necessary to secure the end e¹ of the chain at the
point. Any other convenient place will do, as for example, the end e¹
can be secured to the jib of the crane. In this case the man who receives
the goods has the means of altering the power of the crane, instead of
the man who attaches the chains to them below; neither need the
chain be led over the guide pulleys d, d, d, in precisely the same manner
as shown in the Drawing.
Having thus described the nature of my Invention, and the manner of
performing the same, I would have understood that I do not confine
myself to the precise details herein described and represented in the
Drawing but what I claim is, the construction of hydraulic cranes
substantially as herein-before described, with both ends of the lifting
chain passed over guide pulleys to the ground, so that either both ends
of the chain may be attached to the load to be raised, or one end to the
load and the other to some fixed point, thereby obtaining variable
power.
In witness whereof, I, the said John Frederick Boetius, have
hereunto set my hand and seal, this Fifth day of November, in
the year of our Lord One thousand eight hundred and seventy-