Year: 1887

page_text: Date of Application, 25th Mar., 1887
Complete Left. 27th Dec., 1887
Complete Accepted, 27th Jan., 1888
THOMAS ARCHER Junior 6. Park Terrace Gateshead on Tyne County of Durham,
Engineer, CHRISTOPHER WATKIN WILSON 55 Leazes Terrace Newcastle upon Tyne
Merchant, do hereby declare the nature of this invention to be as follows:-
Our invention relates to an improved apparaius for relieving the strain upon ropes
and chains subjected to unequal strains more particularly for use in towing vessels
and for vessels riding at anchor.
In its simplest form our invention is operated by making a rope or chain fast to
the rim of a sheave or pulley or disc in such way that when in a medium state of
tension a part of the rope or chain is coiled round the sheave. The centre of the
sheave is liored and screwed and rides upon a screwed shaft keyed into its bearings so
as not to revolve so that on revolution of the sheave in either direction it has a lateral
movement dependent on the pitch of the screw on which it rides. The lateral move-
ment when due to increased tension on the rope or chain compresses laterally a spring
or series of springs which are always more or less in compression and when due to
diminished tension on the rope or chain arises from the expansion of the spring or
springs operating on the inclined planes of the screw.
We are thus enabled to give a large movement of the rope or chain by a small
movement of the springs and thus reduce the size and weight of the apparatus
required and increase its efficiency.
We have for simplicity and clearness described the most simple and easily under-
stood form of apparatus according to our invention with which we are acquainted.
We wish it to be understood however that by variations of details many forms of
apparatus may be used with similar effect.

page_text: We may for instance key the sheave pulley or disc fast on the shaft on which it
riles and make the screw giving the lateral movement on one or both of a pair of
carriages on which the shaft revolves and we can thus produce exactly the same
effect. We may also instead of having part of a turn of rope or chain passed round
a sheave with a straight groove in it have two or more turns passing round the sheave
in a spiral groove.
We wish it to be also understood that although we have used the words lateral
movement the apparatus. may be so placed that the word vertical should be used
instead of lateral and many other changes are possible without departure from the
essential principle of our invention namely to give from the circumference of a sheive
pulley or disc considerable elasticity in the hold of a rope or chain with a much less
movement of the springs brought into play.

page_text: Improved Apparatus for Relieving the Strain upon Ropes
and Chains.
We, THOMAS ARCHER, junior of 6 Park Terrace. Gateshead-on-Tyne, Durham
and CHRISTOPHER WATKIN WILSON of 55 Leazes Terrace, Newcastle-upon-Tyne,
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:
Our invention relates to an improved apparatus for relieving the strain upon ropes
and chains subjected to unequal strains more particularly for use in towing vessels
and for vessels riding at anchor.
In its simplest form our invention is operated by making a rope or chain fast to
the rim of a sheave, or pulley, or disc, in such a way that when in a medium state of
tension a part of the rope or chain is coiled round the sheave. The centre of the
sheave is bored and screwed and rides upon a screwed shaft keyed into its bearings
so that it cannot revolve so that for revolution of the sheave in either directions it
has a lateral movement dependent on the pitch of the screw on which it rides. The
lateral movement when due to increased tension on the rope or chain compresses
laterally a spring or series of springs which are always more or less in compression
and when due to diminished tension on the rope or chain arises from the expansion of
the spring or springs operating on the inclined planes of the screw. This form of
apparatus is illustrated in and by the accompanying drawing in which A. is a section
of the rope. B. is a section of the sheave, pulley or disc. C. is the screwed shaft
shown in full, on which the sheave rides, the thread of the screw upon which the
sheave moves being a double thread of very coarse pitch. D. D. are the bearings or
carriers for this shaft, the key which prevents its revolution being shewn at E, and
the head and nut which prevent its lateral movement being shown at F. and G.
respectively. H. H. are spiral springs shewn in section which are somewhat
compressed when in the position shewn, but which would be still further compressed
if the sheave were revolved on the shaft so as to drive it towards the springs as will
be readily seen. I. 1. are india rubber washers intended to take up shock arising
from sudden release of tension of the rope. J. is a loose ring or washer piece not
revolving with the sheave, the object of which is that the springs may not be moved
out of line when the sheave revolves. It will readily be understood that while the
apparatus is in the condition in which it is shewn in the drawing and with no tension
on the rope the sheave will occupy a position of balance between the pressure of the
springs and the reactionary pressure of the india rubber washers but if a strain
be applied to the rope in the direction of moving the sheave along the shaft in the
direction of the springs there is no longer a balance, and the whole pressure upon the
rope (neglecting friction) rests upon the springs and there is thus formed an elastic
cushion of short compass for the absorption of a varying force of considerable extent

page_text: of range.
We are thus enabled to give a large movement of the rope or chain by a
small movement of the springs and so reduce the size and weight of the apparatus
required for a given efficiency. We have for simplicity and clearness described the
most simple and easily understood form of apparatus according to our invention with
which we are acquainted. We wish it to be understood however, that by variations
of details many forms of apparatus may be used with similar effect. We may for
instance key the sheave, pulley, or disc, fast on the shaft on which it rides and make
the screw giving the lateral movement in one or both of a pair of carriages in which
the shaft revolves and we can thus produce exactly the same effect. We may also
instead of having part of a turn of rope or chain passed round a sheave with a straight
groove in it, have two or more turns passing round the sheave in a spiral groove.
We wish it also to be understood that although we have used the words lateral
movement, the apparatus may be so placed that the word vertical should be used
instead of lateral, and many other changes are possible without departure from the
essential principle of our invention, namely to give from the circumference of a
sheave, pulley, or disc, considerable elasticity in the hold of a rope or chain with a
much less movement of the springs brought into play.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is :
The combination of apparatus for regulating in considerable range varying strains
on ropes or chains by means of springs of short range substantially as described.
Dated this Twenty fourth day of December 1887.