Improvements in Friction Ratchet Mechanism.
Year: 1897

page_text: Date of Application, 9th Jan., 1897-Accepted, 3rd Apr., 1897
COMPLETE SPECIFICATION.
Improvements in Friction Ratchet Mechanism.
I, KARL MARTIN BERNHARD ERIKSSON, of Ljusne Mek. Verkstad, Ljusne, in
the Kingdom of Sweden, Engineer, 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 such friction ratchet mechanisms, as consist of two
concentrically rotating parts, viz. a shaft or spindle and a box shaped centre or
nave, and of ratchet blocks, situated between the shaft and the box shaped nave
and having such a form, that when one of the rotating parts turns in the one
direction, it will cause the other part to turn in the same direction in consequence
of the friction between them and the nave.
:
If, on the contrary, the one part turns in the opposite direction, the other part is
not acted upon by the blocks and consequently it does not partake in the rotation of
the first part.
The blocks are usually triangular in section, perpendicular to the axis of the
shaft. Two of the corners of a block are situated close to the inside of the box
shaped nave, the third corner being situated in a recess or groove in the shaft. In
ratchet mechanisms of this kind as heretofore constructed the first mentioned
corners are on the same side of a line passing through the centre of the shaft and
the third corner, wherefore it has been necessary to employ a spring for each block,
this spring serving to press the side of the block, situated between the outer
corners, against the inside of the nave.
In order to avoid the employment of springs and the inconveniences caused
thereby, and for making the mechanism as simple as possible the blocks are,
according to this invention, so arranged, that the two corners which are placed
close to the inside of the nave, are on each side of the line, passing through the
centre of the shaft and the third corner, but at different distances from said line
in such a manner, that a locking between the rotating parts can take place only
when one of them rotates in the one direction.
In the accompanying drawing
Figures 1 and 2 show the invention adapted to a ratchet mechanism, in which
nave or box B, surrounding the shaft A, which is to be rotated by the box, is
provided with an arm D, by means of which the motive power is transmitted to
the box B.
Figure 1 shows a side view of the ratchet mechanism; the cover B', belonging
to the box B, being removed.
Figure 2 shows a section of the box.
The inner corners a of the blocks C are situated in the longitudinal grooves E,
made in the shaft A.
Figures 3 and 4 show two sections (perpendicular to each other) of a ratchet
mechanism, in which the grooves E of the shaft A approach the centre line of the
shaft, in consequence of which no locking of the parts A and B will occur, if one
of said parts is displaced in the longitudinal direction of the shaft, as will easily
be understood. In Figure 4 is indicated in dotted lines, the position of the box
when displaced to the right.
From Figures 1 and 3 it will be seen, that the two outer corners b and c of the
blocks C, which corners are placed close to the cylindrical inside of the box B and

page_text: between which the sides of the blocks may have the same curvature as the inside
of the box or any other form, are at different distances from the line 1-1, running
through the centre of the shaft and the third corner. The corners are so near
to the line 1-1 that, when the box B turns in the direction of the arrow or when
the shaft A turns in the opposite direction, they will come to press against the
inside of the box, whereby the shaft or the box is caused to partake in the motion
of the box or the shaft, while the corners c are so far from the line 1-1, that they
slide on the inside of the box, when the box or the shaft turns in a direction,
opposite to that above referred to, in consequence whereof the shaft or the box is
not acted upon.
If the blocks are turned upside down from the position (Figures 1 and 3) the
locking of the parts A and B is reversed.
Figure 5 shows a cross section of a modification of the described mechanism.
The modification consists therein, that the inner corners a of the blocks C are not
placed in recesses or grooves in the shaft, as above mentioned, but on the
circumference of the shaft, besides which they are enlarged on the one side of the
surface a-b in order to obtain a fourth corner d. Also these corners d are situated
on the circumference of the shaft for aiding the corners a to support the blocks C.
The mode of operation of this construction is similar to that of the described
construction that is to say, locking takes place, when the box turns in the direction
of the arrow or when the shaft turns in the opposite direction.
Ratchet mechanisms, arranged according to this invention, work safely,
instantaneously and silently.
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. In friction ratchet mechanisms which consist of a box shaped centre or nave,
surrounding a spindle or shaft and between which and the spindle or shaft are
placed triangular blocks, one corner of each of which enters a recess or groove in
the spindle or shaft, the arrangement that the two other corners of each block are
situated on each side of the line, running through the centre of the shaft and the
corner, situated in the shaft, with the object of dispensing with the springs, which
otherwise are required for the locking of the parts.
2. In ratchet mechanism, as specified in Claim 1: the arrangement that the
grooves in the shaft, in which the corners of the blocks are placed, approach the
centre line of the shaft, with the object of preventing locking between the nave
and the shaft by displacing one of these parts in the longitudinal direction of the
shaft.
3. A modification of the mechanism, specified in Claim 1: consisting therein, that
the corners of the blocks, instead of being situated in recesses or grooves in the
shaft, are situated on the circumference of the same, and that the blocks are
provided with one more corner, also situated on the circumference of the shaft and
aiding the first mentioned corner to support the blocks.
Dated the 0th T
1007
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.