Improvements in Lifting Gear or Hoisting Apparatus.
Year: 1887

page_text: Date of Application, 28th Feb., 1887.
Specification Accepted. 29th Mar., 1887.
COMPLETE SPECIFICATION.
Improvements in Lifting Gear or Hoisting Apparatus.
We, EDWARD POHL of Betjdorf in the Kingdom of Prussia Engineer and JULIUS
JUNGK of the Firm of G. A. Kroll & Co. Manufacturers of Hanover both in the
Empire of Germany 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 improvements in hoisting apparatus or screw lifting gear
in which the screw wheel is formed in two parts being divided down the middle and
is so constructed that the apparatus will not run back when a weight is being hoisted
or is suspended and the apparatus stopped the force of the suspended weight or load
momentum acting in opposite directions as we will now proceed to show with reference
to the accompanying drawings.
Figures I and II of which show the application of the screw wheel with helix in
connection with chain pulleys, as block tackle. Figure I being a sectional front view
of the complete tackle with lower block and chains shown by the dotted lines and
Figure II showing the same (without the two latter parts) in cross section. Figure III
shows the helix on a larger scale, and the arrows marked on it indicate the opposite
directions of the forces of the load momentum transmitted by the teeth of the half
wheels to the screw threads.
The screw wheel is peculiarly constructed of two equal halves A A (see Figure II)
which are fitted loose against each other on the common axis of the lifting gear and
can revolve. Two chain pulleys C and D with different diameters and different
numbers of notches are cast or formed on the outer sides of the half screw wheels A. A.
(see Figure II). The endless load chain is placed in the same way as in "Weston's
differential tackle, in opposite directions over the pulleys C and D, and in one of the
loops a lower block with loose sheave is hung (see Figure 1). A single or double
threaded helix B (see Figures I. II and III) with a fast pitch-connected with a winch
pulley as shown in Figure I or otherwise suitably driven as by a crank or belt and
pulley according as the apparatus is made for a block tackle a windlass or otherwise—
inoves the double screw wheel exactly in the same way as ordinary screw wheels,

page_text: forwards or backwards and when the gear stops the peculiar action of the screw
whcel in two parts comes in as follows:-
The load momentum acting on the load chain has a tendency to turn the chain
pulleys C and D and the respective, half screw wheels A. A. in opposite directions to
each other as indicated by the two arrows in Figure I and thus the teeth of the half
screw wheels exercise opposite pressures on the screw threads whereby the automatic
running back of the helix is prevented without requiring the interposition of a
separate resistance or break and the load is thus held suspended.
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 :-
1. The above described screw wheel in two parts connected directly or indirectly
with chain pulleys or other load carriers and whereof the respective halves A A upon
the stoppage of the gear, exert opposite rotary effects by means of the load momentum
acting on them and thus exercise opposite pressures on the screw threads of the helix
which prevent the helix from running back automatically and thus keep the load
suspended automatically substantially as herein before set forth.
2. The use and application of the screw wheel in two parts to lifting gear or
hoisting apparatus substantially as and for the purposes herein before described and
represented in the accompanying drawings.
3. The improved arrangement and construction of hoisting apparatus substantially
in the manner and for the purposes herein before described and represented in the
accompanying drawings.
البحيم
1005