Note: Descriptions are shown in the official language in which they were submitted.
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Description
universa] Coupling Spider Bearin~ and Yoke
Technical Field
This invention relates to a uni~ersal coupl-
ing construction and, more particularly, to an improvedspider bearing and yoke assembly.
Background Art
Articulated coup~ings for conne¢ting a pair
of rotatable shafts set at an angle to one another are
generally well-known. one type of articulated coupling
is a universal joint which allows for rotatiorl in three
planes similar to that commonly ~nown as a ~ooke's
joint. Such a joint permits one shaft to be rotatively
driven by a second shaft through the universal coupling
even though the shafts are not co-linearly arranged or
even though the angle between the respective rotational
; axes of the shafts may change as the shafts are rotated.
A universal coupling of the above-mentioned
type includes a multi-legged spider. The ~ree ends of
the spider legs are journaled within yokes carried by
each of the rotatable shafts at their respective oppos-
ed ends. Typically, spider caps are anchored to the
yoke and carry bearings or bushings to reduce rotation-
al friction between the spider and the yoke. In conven-
tional spider and yoke couplings, the spider caps areattached to the yoke by a plurali-ty of bolts. Since the
number and size of the securing bolts are usually not
great enough to produce a large clamping force, driving
keys are required to transmit driving torque between
the rotating shafts. In the prior art, a spider cap
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is constructed with a single square driving key which is
fitted into a slot defined in the yoke.
In applications where torque reversals do not
occur, this construction is sufficient. I~owever, in those
applications where ~orque reversals do occur, relative
motion may take place between the spider cap and the yoke
to which it is anchored because of clearances between the
driving key and the slot. This relative motion can cause
fretting between the mating surfaces of the parts thereby
resulting first in bolt loosening due to loss of preload
and then in the ultimate failure of the spider cap
connection and of the coupling itself.
Disclosure of Invention
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In accordance with one aspect of the invention,
there is provided a spider bearing and yoke assembly for
use as a universal coupling for interconnecting ~wo
opposed rotatable shafts, said assembly comprising: a
spider element with plural legs; a pair of yokes for
mounting on opposed ends of the respective shafts, such
yokes having spaced parts; a spider cap located on each of
said yoke parts providing a journal for each leg of the
spider element; one of said spider caps and yoke parts
having a tapered key extending axially outward toward the
mating one of the spider cap and yoke part; and said
mating one of the spider cap and yoke part defining a
tapered keyway for cooperation with said key, said tapered
keyway being smaller than said tapered key to prevent said
key from moving completely into said keyway; said tapered
key and keyway lying parallel to an axis of the related
3Q leg of the spider element and being displaced radially
outward from said axis, and securing means for moving each
of said spider caps toward its respective yoke part to
draw the spider cap and yoke part together into fixed
axial relation, the tapers of said key and keyway being
frictionally engaged to pre- vent relative radial and
axial movement between the spider cap and yoke part.
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In another aspect of the invention, there is
provided a spider bearing and yoke assembly for use as a
universal coupling for interconnec~ing two rotatable shafts
having opposed ends, said assembly comprising: a multi-
legged spider element; a pair of yokes for mounting on theopposed ends of the respective shafts, each such yoke
having spaced parts with mounting flanges extending
laterally from the rotational axis of its respective shaft,
said mounting flanges each having a pair of bolt-mounting
bores, each bore disposed generally along a centerline
spaced from the rotational axis of the respective shaft; a
spider cap located on each mounting flange and each pro-
viding a journal for one leq of the spider element and
having two bolt-receiving bores, saia bolt receiving holes
being on either side of the spider journal, and disposed
generally along a centerline spaced from the spider journal
and aligned with said bolt-mounting bores; a plurality of
;` bolts extending respectively through the bolt-mounting
bores and into the bolt-receiving bores; a pair of tapered
keys extending axially outward from and aligned one along
the centerline of each respective bolt-receiving bore;
said pair of tapered keys aligning with each other along
an axis radially spaced outward from the rotational axes
of said shafts; and a pair of tapered keyways defined in
each mounting flange aligned one along the centerline of
each respective bolt-mounting bore and having a cross-
sectional size smaller than that of said tapered keys, said
pair of tapered keyways aligning with each other along an
axis radially spaced outward from the rotational axes of
said shafts, whereby tightening of the bolts aligns and
secures the spider caps to the respective yoke-mounting
flanges with the keys frictionally seating partially
within their respective keyways for transmission of
rotational torque between the shafts.
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Brief Description of Drawing_
Fig. 1 is an elevatîonal view of a spider and
yoke coupling constructed in accordance with the prior art;
Fig. 2 is an elevational view of a spider and
yoke coupling constructed in accordance with the present
invention; and
Fig. 3 is a plan view of the face of one of the
yokes looking in the direction of the arrows 3-3 of Fig. 2
Best ~ode for Carrying Out the Invention
10Referring to Fig. 1, a coupling, broadly
: designated 10, utilizing a prior art method of construction
is illustrated~ Therein, two rotatable shafts 12 and 13
have opposed Y-shaped yoke members 15 and 16, respectively.
The yoke members 15 and 16, which are oriented 90 relative
to one another, are drivingly
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interconnected by means of a multi.-legged spider element
18. The yoke members 15 and 16 and the cross-shaped
spider element 18 thereby define a universal coupling
joint somewhat simiLar to a ~Iooke~s joint.
The yoke members 15 and 16 are similarly con-
structed and each supports a pair of spider caps 20.
As seen with respect to the right-hand yoke member 15,
one spider cap 20 is secured to each yoke mounting por-
tion 22 and 23 at oppositely spaced ends of the yoke
body portion 25. The mounting portions 22 and 23 extend
radially outward relative to the rotational axis of the
shaft 12. The spider caps 20, each having a bearing or
bushing (not shown) for journaling one leg of the spider
element 18, are fixed by conventional mea~, such as
bolts 27, to the mounting portions 22 and 23.
As seen with reference to the spider cap 20
attached to the yolce member 16 of the left-hand shaft
13, each spider cap 20 has a hub portion 29 and a pair
of laterally opposed flange portions 30 extending out-
ward from the hub portion 29. For each spider cap 20,
two bolts 27 extend through the mounting portion 22 and
23 and are threaded one into each spider cap flange
portion 30 at opposite sides of each hub portion 29.
Each spider cap 20 also includes a single squared or
rectangulax driving key 32 extending axially from the
hub portion 29. The driving key 32, when the spider
cap 20 is properly bolted to the yoke member 15 or 16
protrudes into a slot or keyway 33 of squared or rec-
tangular configuration defined along the centerline of
the yoke member 15 or 16.
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Referring to Figs. 2 and 3, a coupling, broad-
ly designated 40, incorporating the spider bearing and
yoke assembly of the present invention is illustra-ted.
As with the prior art construction shown in Fig. 1, two
rotatable shafts 42 and 43 have opposed ends 45 and 46
carrying Y-shaped yoke members 48 and 49, respectively.
The yoke members 48 and 49 are interconnected through
a multi-legged spider element 51 in a manner described
hereafter.
Since each of the yoke mem~ers 48 and 49 is
similarl~ constructed, for purposes of brevity and
clarity, only one yoke member will be described in de-
tail. The yoke member 48, see Figs. 2 and 3, has a bod~
portion 53 secured by suitable means (not shown) co-
linearly with the shaft 42 and has laterally extending
leg portions, each designated 54 and including a moun-t-
ing flange 56. Each of the mounting flanges 56 has an
axially outward flat mounting surface 57 which is per-
pendicular to the rotational axis of the shaft 42 and
terminates in an outer abutment 59
Four spider bearing caps, all of which are
designated 60 and are of similar construction, i~clude
bearings or bushings (not shown) which journal the re-
specti~e end of one of the four legs of the cross-shaped
spider element 51, all of the spider legs being desig-
nated 52. oppositely disposed legs 52 of the spider
element 51 extend across each yoke member 48 or 49 and
are journaled by the spider caps 60 for rotation along
an axis extending therebetween. Each of the spider caps
30 60 has a body portion 61 with a flat bottom face 62
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which will be located in fronting relation with themounting surface 57 of the yoke mounting flange 56.
As seen with reference to the yoke member and
spider cap associated with the rotatable shaft 43, bol-t
receiving bores 64 are defined in the spider cap 60 and
extend axially inward from the bottom face 62. One bore
64 is located on each lateral side of the journaling
portion of the spider cap 60. Bolt-mounting bores 65
are defined through each of the mounting flanges 56 of
the yoke member 49 and are spaced from the rotational
axis of the sha~t 43 along a lateral line across the
flange. The bolt-mounting bores 65 permit the threaded
shanks of bolts 67 to be inserted through the mounting
flange 56 and threaded into the spider cap 60.
A pair of tapered driving keys 70 are carried
integrally by each of the spider caps 60 and extend
axially outward from the bottom face 62. Each key 70
tapers axially outward and thus is wider at the base
adjacent the bottom face 62 than at the outward end.
The tapered keys 70 are respectively aligned along the
centerline of the bolt-receiving bores 64 spaced from
the spider journal.
A pair of tapered slots or keyways 71 are de-
fined in the axial outward mounting surfaces 57 of the
mounting flange 56 and are aligned along the centerline
of the bolt-mounting bores 65. The keyways 71 taper
axially inward and thus are wider across their opening
at the axial face than at their bottom. Although the
keys 70 and keyways 71 are generally of similar cross~
sectional configuration and are adapted for cooperative
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engagement with one another, tha ke~ways 71 have a
cross-sectional siæe which is slightly smaller than the
cross-sectional size of the keys 70.
During assembly of the universal coupling 40,
a spider cap 60 will be positioned on the end of each
of the spider legs 52. The spider caps 60 can then be
located adjacent the yoke-mounting flanges 56 with the
bottom face 62 of the spider cap 60 in face-to-face
relationship with the mounting surface 57 of the mount-
ing flange 56 and the spider cap 60 and mounting flange56 being aligned. In this position, the keys 70 and
keyways 71 will also be placed in axial alignment with
the keys 70 extending axially toward the keyways 71.
Thereafter, the bolts 67 are inserted through the bolt-
mounting bores 65 of the yoke member 48 or 49 and
screwed into the bolt-receiving bores 64 in the spider
cap 60. As the bolts 67 are tightened, the spider cap
60 will be moved toward the yoke member 48 or 49 to
draw the key and keyway combination to~ether in fixed
relation.
When the bolts 67 are tightened to attain a
predetermined pre]oad, the keys 70 will frictionally
seat within the keyways 71~ Since the keys 70 and key-
ways 71 do not interfit completely, there will be a gap
73 defined between the axial mounting surface 57 of the
mounting flange 56 and the bottom face 62 of the spider
cap 60. The gap 73 does not adversely affect the struc-
tural integrity of the connection between the yoke mem-
ber and the spider cap.
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The tensile force o~ the bolts 67 is trans-
mitted to the parts so that a ~orce is exerted between
the respective mating tapered surfaces of the key 70
and the keyway 71, thereby resulting ln a substantial
frictional force. Since the spider cap 60 is fixed to
the yoke member 48 or 49 against relative movement,
torque is transmitted from one shaft through the key
70 and keyway 71 to the other shaft to effect rotation
thereof.
Industrial Applicability
It can be appreciated that the above-clescribed
couplin~ having a spider-type connection may be employed
in line with drive shafts, steering columns and the like,
with advantageous results. The tapered design allows
a full seat and thus eliminates relative motion between
parts and the resultant loosening of the connection
b~tween parts. The placement of the key and keyway
along the bolt centerlines allows the bolts to be
tightened to any desired preload without distortion of
the bolts of the joined parts.
Thus, the problem o~ maintaining clearance or
low tolerances is avoided. In addition, high torque
and shear stresses are distributed over a-t least two
key and keyway combinations rather than one.
other aspects, objects and advantages of this
invention can be obtained ~rom a study o~ the drawings,
the disclosure and the appended claims.
