Improvements in and relating to Cramp-keys or Wedges for Securing Wheels, Pulleys, Levers, and like objects.
Year: 1891

page_text: Date of Application, 1st Jan., 1891-Accepted, 7th Feb., 1891
COMPLETE SPECIFICATION.
Improvements in and relating to Cramp-keys or Wedges for
Securing Wheels, Pulleys, Levers, and like objects.
I, RUDOLF HORNSTEINER, of Zizkov, Prague, in the Kingdom of Bohemia,
Manufacturer, 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 :-
My invention consists in the use of keys or wedges of prismatical shape of
constant section, in substitution of keys or wedges of increasing section previously
made. These keys or wedges may be inserted in the usual rectangular groove or
space in the shaft, to which wheels, pulleys, and like objects are desired to be
secured. In some cases, the base of the key is made hollow, and used without the
groove or space in the shaft. In such cases, the key or wedge, when cramped,
will penetrate the plain surface of the shaft, and thus secure the object placed
upon it.
The wheels, pulleys and like objects to be secured may be divided by a split or
splits and the parts drawn together by bolts, so as to repose against the two inclined
sides of the prismatical key.
By this arrangement of fastening, the wheels, pulleys, levers or like objects are
secured to their respective shafts with accuracy and precision; whilst by the usual
method a displacement of the parts is a natural result of forcing the wedge-key into
its seat by strokes or strong pressure.
In the accompanying drawings, Fig. 1 is a front view, and Fig. 2 a horizontal
view of the hub of a wheel, split between two arms, and fastened by one of my
improved cramp keys to its shaft; and Figs. 3, 4, 5 and 6 shew the same method of
securing a lever to its shaft. Figs. 7 and 8 represent two views of a pulley in two
equal parts or halves secured together by bolts, with the cramp key reposing in
the split. Figs. 9 and 10 represent a single pulley in two views partly in section,
shewing an artificial split between two arms with the cramp key in place. Fig. 11
is a detailed sectional view of Figs. 7 and 8 of the cramp key and its arrangement
with the other parts. Figs. 12, 13 and 14 are enlarged sectional views of the
cramp keys; Fig. 12 being a cramp key with plain basis for key seat, and the
others are cramp keys with hollow bases; and finally Fig. 15 is a cramp bolt in
an enlarged view and transverse section.
a,
My improved keys, as represented on the drawings, are perfect prisms possessing
two symetrically inclined flanks a and b, against which repose the two inclined
portions of the split parts of the hub A and B, which are drawn together by the
bolt S, so as to exercise a strong pressure against the flanks
b. This pressure is
transmitted on to the basis m n, through the object or key K. The key seat may
be either sunk in the shaft W as seen in Fig. 12; or the key may be made hollow
as seen in Figs. 13 and 14, in which case the seat is not required to be sunk in the
shaft W, as the edges of the key m and n, when cramped, will penetrate the surface
of the shaft W and fasten together the parts A, B and W more securely than by
the ordinary methods of key fastenings.
The key K may be cramped by screwing together the split parts A and B by
means of screw bolts S, seen in Figs. 3, 4, 5 and 6, or of several such bolts, as for
example longer and shorter bolts may be combined, as seen in remaining views, for
securing the parts together. In case of a pulley wheel or piece A B being already
divided, no artificial split p is needed to produce cramping, as seen in Figs. 7 and 8.
In cases where the wheels, pulleys and like objects are not already divided in
the casting, such objects must be provided with an artificial split p, perpendicular
to the basis m n, as seen in Figs. 3, 4, 5 and 6.

page_text: Fig. 15 represents a symetrical cramp screw with left and right threads at its
ends; and a polygonal head F in the middle is used in cases where the nut
cannot be turned, as shewn in Fig. 1.
When pulleys or wheels are near a wall or any other object, which does not
allow of a symetrical hub, shown in Figs. 7 and 8, a one sided box is applied with
two shorter cramp screws S in the hub, and two longer ones S₁ through the arms,
as shewn in Figs. 1, 2, 9 and 10.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The method of cramping wheels, pulleys, and similar objects upon a key,
having flanks a and b, symetrically inclined to the basis m, n, substantially as
described.
2. The cramp key of a constant section, its flanks a b being symetrically
inclined to the basis m n, which may be either plain or hollow, substantially as
described and illustrated.
Dated this 31st day of December 1890.
THOS. RICHMOND,
Agent.