Note: Descriptions are shown in the official language in which they were submitted.
33
CI.UTCI-I ~n~JCMANIS~I FOR llOISTING APPARATUSES
. .
The present invention relates to a clutch mech-
anism for hoistirLg apparatuses. It is particularly
useful with cranes, winches~ shifting crabs and the
like.
Clutches are, of course,very well known in the
art. They normally comprise two coaxially mounted
plates which are urged into engagement under spring
pressure and disengaged by cam action.
In accordance with the present invention there
is disclosed a positively activated clutch mechanism
which does not rely on spring pressure for actuation.
The clutch mechanism is characterized by its reliabil-
ity and simplicity~ the combination of which give quick
and safe operation
In accordance with the applicant's invention,
two coaxially mounted discs are e~nployed. Each disc
has at least three holes therein on the face which faces
the other disc. The holes are characterized by belng
elongated with at least a portion of the sidewall
being essentially oblique to the surface of the disc
and in the opposed sidewall being preferably substan-
i
` ~44~93
tially perpendicular to the surface of the disc.
Preferably each of the holes form an oblong re,-
cess with downwardly dec~easing cross-sectional area
ending in a generally spherically concave portion of
predetermined radius of curvature. The perpendicular
sidewall is also preferable a semi-cylindrical sidewall
with predetermined radius of curvature and the.axis
of the semi-cylindrical portion bein~ parallel,to the
axis of rotation of the disc.
' The holes of each of the opposed discs are juxta-
posed in opposition to one another and a dowel or such
like is disposed Ln each pair of opposing holes.
The dowel preferably has rounded ends which ends
are generally hemispherical having a radius of cur- '
vature corresponding to that of the generally spherical
concave portion of the bottom of.the holes.- The rounded
ends of the dowel rest in the corresponding bottoms of
the opposing holes. The radius of a cross section of
the dowel may be less than the radius of curvature
of the perpendicular semi-cylindrical sidewall,
however, it is preferable that the radius of each
dowel be such as to provide-a close fit against the
perpendicular sidewall of the hole.
, ~ ,
, -2-
. . .
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11444~3
In the non-activated position the dowel lies along
the oblique sidewalLs of the opposed holes. When
it is desired to activate the clutch mechanism,
one of the discs is rotated with respect to the
other to move the dowel from the oblique sidewalls
to the perpendicular sidewalls. Since the dowels
have a length which is less than or equal to the
combined lengths of the oblique sidewalls but
greater than the combined length of the perpendicular
sidewalls, the dowels will cause positive separation
of t~e two disc elements when they are moved from
the oblique sidewalls to the perpendicular sidewalls.
This motion, can, in turn, be transferred to a drum
which has a plate which bears against a moving clutch
plate when the clutch mechanism is in the engaged
position. Counter-rotation of the two discs returns
the dowels to their original position against the
oblique sidewalls thereby disengaging the clutch
plate fro~ the drum plate~ ~
In order to limit the rotation between the two
discs, a positive stop may be introduced to prevent
over travel. According to the invention, however,
over travel is preferably prevented by the close
fit of the dowel against the pPrpendicular sidewalls
of the opposing holes when the two discs are separated.
These and oLher aspects of the present invention
may be more fully understood with reference to
the drawings wherein:
Fig. 1 is a sctlema~ic view of the clutch mechanism
according to the present invention in a disengated po-
s ition:
Fig. 2 is a clutch mechanism according to the
present invention in an engaged position; and
Fig. 3 is a front view of one of the discs making
up the clutch mechanism showing the holes therein.
Referring first to Fig. 1, there is shown a
drum 10 having side plates lZa and 12b. Wîre cables
or ~he like may suitable be wound on the drum. Side
plate 12a is translatable towards and away from en-
gagemen~ with drive plate 14 affixed to driven chain
wheel 16, the drive mechanism not being shown.
Abutting against the outside of plate 12b is a
bearing 18 (details not shown) to permit free rotation
of the drum L0 with respect to discs 20 and 22 of the
clutch actuation mechan;sm. While discs 20 and 22
are preferably circular, they need not be. Disc 22
is axially fixed while disc 20 is axially moveabIe
toward and away from chain wheel 16. Components 10,
18, 20 and 22 are coaxially mounted on a spindle
(not shown).
~a
33
Discs 20 and 22 are provided with holes 24 and 26,
respecti~ely. In conjunction with -Fig. 3, it can be
seen that these holes have sidewalls 28 and 30 re-
specti~ely, which are formed as generally semi-cylin-
drical por~ions having an axis o sy~metry generally
perpendicular ~o the opposed faces of the disc and
sidewalls 32 and 34 respectively which are oblique ~o
the opposed faces of the discs. The angle which the
oblique s;dewall makes with respect to the surface
is not critical but is suitably at most about 80.
Each hole is a generally oblong slot having downwardLy
decreasing cross-sectional area ending in a generally
spherical concave portion.
As can ble seen in Fig. 3, the holes are aligned on
the disc 20 SID that the opposed oblique and perpendicular
sidewalls of ,each hole intersect an arc concentric with
the axis of the disc. However~ i~ will be appreciated
that all holes need not intersect the same arc. Further-
more it can be seen that all oblique sidewalls are
aligned in the same direction on one d;sc and it wilt
be appreciated that they are aligned in the opposite
direction on the other disc.
As shown especially in Fig~ 3, there are employed
at least three holes in each disc. More may be em-
ployed if desired but three has been found to be the
preferable number.
The holes arR pre:Eerably substantiall y equi-
dis~an~ly spaced. While this is not absolutely ne~
cessary, the radial angular distance ~ from the
center line of one hole to the center line o~ the
next adjacent hole in either direction should never
exceed about 170 and should be about 150 or less.
Postioned in each of the holes is a dowel 36.
Each dowel has a length which is greater than the
leng~h of the opposed perpendicular sidewalls 28
and 30. Furthermore, the distance 38 between the out-
side of the plate 12a and the facing side of drîve
plate 14 is less ~han the distance by which the length
of the dowel ex~eeds the length of the two perpendicular
sidewalls of the holes. The upper limit of the length
of the dowel îs not critical. However, for practical
reasons it should not be substantially greater (e.g. no
more than about 25%3 than the combined length of the
opposed oblique sidewalls 32 and 3~-r ~ and it is preferably
equal to or less than that combined length.
Fîg. 2 shows the device of Fig. 1 in the engaged
position. Disc 20 has been rotated with respec~ to
disc 22. This can suitably be accomplished by arm 40
which may be manually operated or may be connec~ed
through appropriate linkage to a drive mechanism (not
shown). As the disc 20 rotates the sidewalls of the
1~4~93
dowels are moved from the oblique sidewalls of the
holes towards the perpendicular sidewalls o the
holes. This positively moves the plate 20 and
thus the drum 10 axially moves towards the chain
wheel 16 and drive plate 14 and this motion con-
tinues until plate 12a of drum 10 engages drive
plate 14. As can be seen, a substantial gap 42
existæ between the opposed faces of discs 20 and
22 in the engaged position.
Further rotation of the disc 20 past the deadpoint
(i.e. where the dowels are parallel to the axis of
rotation) can be prevented by a stop (not shown) to
inhibit further movement of arm 40. Additionally,
according to the invention, further rotatîon is pre-
vented by the novel relationship of the dowels and
holes as shown in the f~gures. The rounded ends of
the d~wels 36 conform substantially to the bottom
portion of the holes 24 and 26. The radius of the
cylindrical portion of each dowel 36 also closely
conform to the radius of curvature of the perpendicular
sidewalls 28 and 30 of the ~orresponding holes. Thus:
when the dowels abut the perpendicular sidewalls 28
and 30, they are essentially captured by the semi-
cylindrical sidewalls and prevent the disc 20 from
rotating past this point.
r;~
As can be seen especially in Fig. 33 the
direction of ~he holes makes a sma11 angle with
respect to an imagînary line through the hole per-
pendicular ~o the radius. That ;s, the axis G~
symmetry of each of the holes lies at a small
angle with respect to a tangent of a radial line
through the axis of symmetry of the semi-cylindr~a~..
sidewall of the hole.
Counter-rotation of the discs 20 and ~2 will
again shorten the efecti~e length of the dowels 36
as they approach the oblique sidewalls 32 and 34.
This will in turn disengage the plate 12a of the - .
drum 10 rom the drîve plate 14~
Pre-erably, the direction of rotatîon of dîsc
20 requîred to bring the drum 10 în contact wîth
chain wheel 16 should be opposite the directîon of
rotation of the chaîn wheel 16. Accordingly then,
the friction of the system will cause the disc 20
to automatically return to the disengaged position
when ~he arm 40 is released.
It will be understood that the claims are in-
tended to cover all changes~and modîfications of the
preferred embodiments of the invention hereîn chosen
for the purpose of illustration~ which do not con-
stitute departures from the spirît and scope of the
inventîon.
