Note: Descriptions are shown in the official language in which they were submitted.
The invention relates to overload couplings.
According to one aspect of the present invention, there is provided
an overload coupling comprising two coupling members rotatable about a
common axis, a first of said members having displaceable frangible means and
the second member having abutment means, said frangible means normally
engaging said abutment means to establish rotational movement of said
members together in at least one direction of rotation, said frallgible means
being fracturable upon overload whereby one o~ said members is rotatable
relative to the ot~-~er member, advancement means cooperating with said
frangible means and automatically urging the latter into re-engagement
with said abutment means to re-establish normal rotational movement of
both coupling m.embers in common, said second coupling member compris:ing
release means for releasing a fractured :Eragment of said frangible means
from thc abutment means.
For a better understanding of the present invention and to show
how the same may be carried in~o effect, reference will now be made, by
way of example only, to the accornpanying drawings, in which: :
Figure 1 is a side elevation of an argicultural machine attached
to a tractor and including an overload coupling;
Figure 2 is a sectional view of the overload coupling of
Figure l;
Pigure 3 is an elevational v:iew of the over-
5~L
l.oad coup].ing taken in the dlrectlon of the ar.row III
in Figure 2,
Figure 4 is a ~;ectional view o:~ a ~econd
embodiment of an overload coupling;
Figure 5 i~ a view taken in tha directlon
o~ the arrow V in Figwre 4~
Figure 6 is a ~ec-tional view taken on the
lines VI-VI in Figure 5 9
Figure 7 is a sactional view o:E a third
embodiment of axl overload coupling~
Figure 8 shows an al ternative COLlS truction
~or part of the co-upllng sllown in ~igure ~,
Figure 9 i8 a sectiorlal view taken OIl the
l.ines IX~IX in Flgure 8,
Figure 10 is an elevcttiorlal view of a fourth
embodiment of an overload coupling.
Figure 11 is an elevational view taken:in the
diraction of the arrow XI in ~i.gure 10,
Figure 12 is a ,sectionctl view taken on the
line XII~II in Figure 11,
Fi~ure 13 is a sectional ~iew of a fi~'th
embodi~nent of an overload coupling,
Figure 14 i~ an elevational view taken in
the direction of the arroT~ XIV in Fig~re 13,
Figure 15 is a sec tional view tQken on the ~.
line~ XV ~V in ~igure 14~
3 ~ 5 ~
Figure 16 is an elevati.onal ~iew taken on the
lines ~VI-~VI i.n Figure 13,
Figure 17 ~how~ sepera^t~ly a component ~uitable
for use in the coupling of ~igu~es 13 to 16;
Figure ~8 shows an altern~i.ve construction
for part of the overload couplin~ o~ Figure 1~3
~ igure 1g is a sectio~a:L view of a ~ixth
embodime~t of an overload coupling;
Figure 20 ls a sec~i~nal viaw taken ~ t-he
lines XX~XX in ~igure 191
Figure 21 is an elsvational view of pa:rt o~ ;
the coupling of ~igure 19,
Fi~ure 22 is a ~3ec-tional view taken on the
lines XXII~XXII in Fig1lre 21;
Figure 23 is a ~ectional view of part of a
seventh embodiment of an overload coupling;
~ igure 24 is a sectional view taken on the
lines XXIV-XXIV in Figure 23,
Fi~lre 25 is a s~ctional view oP an ei~hth
embodiment of an overload coupling;
Figure 26 is an elevational vi.ew taken in the
directio~ of the arrow XXVI in Figure 25;
~ igure 27 i.s a sec-tional view o~ a I~inth
e~bodiment of an overload oouplin~ g
Figure 28 is an elevational vi.ew taken in the
direction of -the arrow XX~III in Fi~ure 27
3~
Fig~ure c9 is a sectional of part of a ten-th
embodiment of an overload coupling3
Figure 30 is a sectional view t~ken on the
line3 X~X~XX in Figure 29; and
~ igure 31 is a ~ecbi.onal view of part of an
eleventh embodiment of an overload coupling.
An agricultural implement 1 shown in ~igure 1
to be a rotary harrow is attached by an intermediate frame
2 to the three-point liftin~ device 3 of a tractor 4.
Viewed in the normal directio~ of operative travel
indi.cated by an arrow A~ -the ~ront of the intermedia-te
frarne 2 is provided wi-th a hitch 5~ which is connected at
the top with upwardly extending plates ~ and at the bottom
with s-trips 7. The plates ~ have aligned holes for re-
ceivin~ a pin 8, which forms a connecting means f`or a
top rod 9 of the thre.e~point- lif-t 3J In a similar manner
the ~ 7 have bores for receiving pins 10 for attaching
the hitch 5 t~ the lower arms 11 of the three-point lift
3~ ~he rear :end parts of the supporklng strips 7 are
secured to a gear casing 12 clcsed a-t lts top by a cover
13. Near the top of the hitch 5 are provided two downwardly
diverging struts 14~ which are ~ec~lred near the rear o~
the casing 12 to the cover 130 ~he gear casi.ng 12
ex~ends for so~e distance transversely of the direction
o~ ~ovement A and is connected near the centre with a
gear box '15~ above which is disposed ano-ther g~ar box 16,
. . ~ . . , ,
. .
l`he gear box 1b is provided on its rear side wi.th a
change-speed gear tran~mission 17~ ~he pinions in the
gear box 1~ are drivably in engagement wlth a stu.b shaft
18 extending in the direction of movement A and being
located at the front oY the gear box 16~ ~he stub shaft
18 is coupled b~ an au~iliary or unlversal ~haft 19
with a rearwardly extending po,~er take-off shaft 20
of the -tractor 4~
FroTn the bot-tom of the hollow gear casing 12
project a plurality of shaf'ts 21~ At the lower end these
shafts 21 are connected with rotors 22, which penetrate,
at least i.n normal operation, for some distance below
the ground surf'ace.
The auxiliary s~laft 19 include~ two universal
couplings ~3, which are interconnected by a telescopically
extensible main part 24~ Ihe auxiliar~ shaft 19 is coupled
by one end portion 25 with the power take-o~ shaPt 20
and by another end portion 26 with the stub shaft 18.
The end por-ti.on 26 includes an overload coupli.ng 27 shown
in Figure 2. ~he overload coupling 27 comprises a coupling
memb~r 28, which is connected by a hollow shaf-t 29 with
the end portion 26~ The shaf't 29 is rigidly connected
near its end. remote ~rom the couplirlg 23 to a coupling
plate 30 extending f'or some distance iII a radial direction~
T~e pla~e 30 extends outwardly in the shape of' a tag9 as
shown in the elevational view of' ~igure 29 a~d near it~
-- 6
,. , , . .
:; .
end remote from -the shaft 29 it has a width substan-tially
corresponding to one third o~ the diameter of the shaft
29, '~o the e:nd of the coupling plate 30 remote from t:he
shaft 29 is we].ded a f ing 31 extending axially of the
rot~ry axis 29A of the sha~t 29 away from the plate 300
The face of the ring 31 remote :from the rotary axis 29A
is provided with a connecting arrangement comprising a
holder 32 containing a fr.an~ible connecting element 33~
~he holder 32 extends away fron~ the ring 31 in a radial
direction and comprises a cylindrical sleeve. Tlhe
:Erangible element 3 3 comprises a shear pin enclosed at
its outermost end in an anmllar seat 34 havin~, at the
side remote from the shear pin, an abut~lent surface for
a helical compression spring 35 extendln~ f:rom the seat
34 to near the outermost end of the holder 321 ~he
outermost end o.f the spri.ng 35 eng~ages a circular plate
36~ which abuts a guard pin 37 to prevent outward radial
movement of the spring,. ~he guard pin 37 has a pivotable
locking rl~g 38 so that the pin 37 can be fixed in place
on the holder 32~
Inside the ring 3'1 ls fitted a sleeve 39 which
ext^ends awa~ from the holder 32 towards the ro-tary axis
29A and serves to absorb torque transferred by -the shear :
pin 330 q`o this end, the sleeve 39 i.s a close fit around
the shear pin 330 ~he sleeve 39 may be made f`rom hardened
material~
The shear pin ~3 normally connects the coupling
member 28 with another coupling member 40. ~he coupling
member 40 comprises a coupli.ng plate 41 loca-ted coaxialy
with the rotar~ axis 29A and extencLing over 80me distance
in an axia] direction. It has near the rotary axis 29A
a cylindrical cavity~ The coup].ing p'late 41 is provided
with a sleeve 42 for receiving one end of the shear pin.
~he sleeve 42 is preferably made from hardened material
and is arranged replaceabl~ in the coupling plate 410 ~'
The sleeve 42 has an opening 43 for receiving the end of
the shear pin, -t'his opening being cylindrica]. in this
embodiment and havi.ng a diameter slightly exceedi.ng the
di.ameter of the shear pin 33. ~his diameter i.s critical
as will be apparent later in this descriptionO '~he
openin~ 43 extends radially for about one quarter of the
~ radial length of the sleev~ 42. The opening 43 ls blind
and its bottom is at the radially inrler end for co-
operation with the end of the shear pin 33~ The wall of
the opening 43 acts as an abutment for .the shear pin 330
r~he coupling plate 41 and the ~leeve 42 define a cylindrical
outer surfacs which meets the edge of the opening 43.
The coupling member 40 comprises a hollow shaft
por-tion 44 which is rigidly connected with the coupling
plate 41 and is ~astenedt coaxial with ths axis 29A,
in the c~lindrical opening in the coupling plate 410
The shaft portio~ 44 ex-tends inwardl~ from the coupling
8 ~
., . . ~, : - , ,
38~
plate 41 ~or sGme distance towards the rotary axis 29A~
~he shaft ~ortion 44, as shown in the elevational ~iew
of ~igure 3, is provided with serrations or k~ ways
for transferrin~ a high torque to the stub ~haft 18.
I~ide the shaft 29 the shaft portion 44 i~ received in
a sleeve 46, which is pressed into the shaft 29, the
material of this sleeve 46 being appropriate to the
intermittent function of the sleave 4~ as a sliding
bearin~ for the shaft portion 44. ~he sleeve 46 and the
shaft portion 29 are fixed again~t an axial displacement
by a key formed by a bolt 47 which is held in place b~
a nut. ~he sleeve 46 and the shaft portion 44 have for
this purpose corresponding annular openings 48 which are
coaxial with the rotary a~is 29A.
- In operation the overload coupling ~ shown in
~igures 2 and 3 is emplo~ed to protect the machine
components and the shafts against overloading. ~or
thi~ purpose the shear pin 33 is adapted to transmit
a predetermined maximum torque. If this maximum torgue
is exceeded, the portion of the shear pin 33 engaging the
wall of the opening 43, whlch acts as an abutment, will
break offO After this portion of the pin has broken off, ~,
t~e coupling members rotate about the rotar~ axis 29A
relatively to each other although they are still axiall~
fixed together by the bolt 47~ ~he shear pin 33 will abut -~
the cylindrical outer surface o~ the coupling plate 41
3~
When the connection between the two couplin~ members is
bro~.en, tthe driving coupling member 28 wlll contlrlue
to .rotate, but the driven coupllngr member 40 will very
soon or a~ter a short time come to a s-tandstill i.n
dependence upon the magnitude of the overload, Since the
coupling member.28 contlnues to rotate9 the hol.der 32 and
the associated shear pin 33 also continu~ to rotate. As
a resul-t, centrlfugal force will bias the shear pin
outwardly against the pressure of' the spring 35O '~he
width of the opening 43 is dependent on the characteristlc
of` the spring 35 and the irlertla of the shear pin~ Owlng
to the balance between the cen-trif`ugal. forc,e acting on
tne mass of' the shear pin 33 and -the force of the spring
35, the shear pin 33 will be urged with only very slight
pressure against the supporting surface formed by the
radially outer wall of the plate 41 and towards the
opening 43 during the continued rotation of the coupling
member 280 ~hus under these conditions the shear pln 33
is not capable of re-establishing tthe connection between
the coupling members. 'r.he connection between the two
coupling members will not; be established u~til tne speed
of rotation o~ the coupling member 28 has been appreciably
reduced b~ intentionally uncoupling the drive of the power
take~off shaft 20, when the spring 35 wlll act a~ advance
ment means f'or advancing t,he pin 33 into re-erlgagement
with the opening 430 '~his can be achleved by matchlng
; . . : .
the cIrcum~renti~al extent o$ the opening 43 to the
diameter o~ the pin 33, the inertia force of the pin, and
the characteris~*ic o~ the spring 35. The circumferential
extent Ge the opening 43 is a function o~ the factor T
in the formula S = 1~2 ~ T2, in which S is the distanre to
be covered by the pin towards the bottom of the opening
43 in order to re~establish a connection between the two
coupling members. The factor A is a function of the force
of the spring 35 and the mass of the pin 33.
In order to keep the factor A constant however ~;
many times the pin 33 has been fractured, the reduction
of the spring force due to the radial inward shift of the
pin 33 after racture should be proportional to the red~ced
mass o~ the pin.
The c~rcum~erential extent o~ ~he opening 43
may be about twice the diameter of the shear pin. The
speed at which the pin re-establishes the connection is
pre~erably chosen to ~e lower than the mini~um possible
sel:f-sustaining speed of the driven engine. In this way
the pin cannot prematurely re-establish the connection
while the engine is still running at a speed reduced by
the overload and while the drive is still in engagement.
It shauld be noted that the radial orientation
of the pin 33 in this embodiment means that the tension
of the spring 35 may~be coordinated with the inertia of
the pin 33 ~y~invert~ng the coupllng so that the coupling
member 4~ is~driven ~y~t~e po~er ~ake-off shaft and the
coupling mem~er 28 ~s connected ~ith the implement. As
a result of th~s adaption t~e pin 33 can be urged ~y a
very light pressure towards the opening 43, wh~lst the
coupling mem~er continues rotating normally~ whilst upon
reduction of the speed of the drive the spring force be-
comes dominant owing to the reduced inertia of the pin
33 so that it can move the pin into the opening 43 in
the same manner as descri~ed above.
It s~ould ~e noted that since the opening 43
extends radially, the ~r~ken-off fragment of the shear
pin 33 is automatically thrown out oE the opening 43,
and a flrther portion of the shear pin 33 automatically
re-establishes the connection ~nce the speed ls reduced.
The opening 4~ thus acts as release means or as an
ejectGr for the Broken-off fragment. Since, after over-
load, t~e operator can re-esta~lish the connection
between the two coupling members only when he has inten-
tionally reduced the drivlng speed by an appreciable
~Q amoun~, inadvertent continuous repeated fracture of the
pin ~ill be avoided.
Figures 4, 5 and 6 show a second embodiment
of an ~verload coupling ~h~ch is also suitable for use
in the auxiliar~ shaft 19. This coupling comprlses a
coupling memfier 49 on ~hich a plurality o~ shear pins
50 are arranged, c~ntained in individual holders 51
3~
similar to the holder 32~ ~'he pins 50 occupy a radial
position with respect to the rotar~ axis 49A of the
coupling member 4~ ancl a.re p:rovided wi.th g:rooves 50Ao
In normal operation one of the shea:r pins 50 es^tablishes
a connection bet-ween the coupling members 49 and 52
ln order to urge the shear pin towards the coupli.ng
member 52~ a torsion spring 53 is a:rrarlged orl-the circular
coupling member 499 viewed i.n a dlrec-tion parallel to tile
rotary axis 49Ag one limb o:E this spring acting UpOII the
radially outer end of the pin 50 and belng movable in
an arcuate slot in the holder 51~ The operatl.o:n of the
torsion spring 53 i9 f(~ comparable w.ith that of the
spri.I1g 35 in the f.i:rst embodi.ment. 'rhe coupli.ng me~ber
52 has an opaning 5IL in a circul.ar flarlge 55 associated
with the coupling r~ember 52~ 'rhe opening 54 has~ viewed
in the direction of the rotar~ axis 49A1 a minimum
radial dimenslon which corresponds to the distance
between the various grooves 50A in the pi.n 50~ he
opening 54 is bounded partl~ oy a supporting me:mber
constituted by a hard metal i~lsert or disc 56 exteflding
radially away f-rom the circumference of the flange 55O
r~`he centre line of the in~ert 56 is preferabl.y parallel
to the centre line of the respective shear pin~ '~he insert
56 has an abutment for the shear pln 50, constituted by
a recess surrol.~ding the opening 54 over an arc o~ abo1l-t
'100 (see :Fig-ure 6). '~he open:ing~las an eJecting or
~ 13 ~
~3~5~
release means formed by a charlllel 57 for thrusting
the broken fragment of the shear pin ~rom the openingO
rrhe channel 57 has a wall 57.A~ which i.s curved 'rhe
wall subtends an angle o~ about 90 and extend.s 9 near
the i.nsert~ parallel to the centre ~ ne of the pin 50,
whereas 9 awa~ from the insert 9 it is at an angle to the
centre 1ine~ ~he wall e~tends -to the side of the coupling
member 52 remote from the coupllng member ~90 Ap~rt ~rom
the hard. steel insert 56 in the coupli.ng portion 52 9 a
hard stee'l. ring 58 is provided on -the coupling mem`ber 49
~ e ring 58 co~stitutes a ~'astening area for 6 to 10
breaklng pins 509 in th:is embodlment ei.ght, one o~ them
being irl the ~erat:ive pos.i-tion l.n the open1.rlg 54 i~l t'he
m~nner desc:r:ibed above~ A plllral.l.ty of openings 5l~.rnay be
provided fOI' co--operation with a mlm'ber of the s'hear pins
for transferring a higher torque~
~ wring operatlon the coupling s'hown in Figures
-to 5 establishes the connection between a drl.ving par-t an~
a driven,part o~ a sh~t and/or machine part and l-t rotates
in the direction of the arrow B (Figures 5 and 6)o
In -this em'bodimen-t, OWiIlg to the use o~ a plura~
lity of shear pins 50 t-'he collpling as a whole is balancedO
~he coupling can be employed for a ver-~ long tlme witho~lt
the Ileed to replace the shear pins~
In the embodlmeIlt shown in Figures 7 and 89
a coupling member 59 is connected~ in normal operation9
~ 14 -
,, , ~. . ~
3~ ~ ~
b-y means o~ a shear pin 60 with a coup:Ling member 610
~he coupllng member 59 comprises a ~l.ange 62 and the
coupling member 6~ comprises a f'la.rlge 639 both o~ these
flan~es bslng generally ci.rcular about the ro-tary axis 6L~o
.A key member i8 provided~ as in the preceding etn'bodiments~
to prevent an axial movement o:~ the two members~
'~he shear pln ~0 extends parallel to the rota:ry ,.,
axis 64 and i.s located in an axially extending hol,der ;,
659 which is similar to the holder 32 of -the first
embodiment so as to form a housing for a re-taining pin 9 ~'
a compressi.on spring 67 and the shear pin ~0O r~'he
operative portion of the shear pin 59 ls 1.ocated ln a
bli.nd openirlg ~8 to l.lmit the travel of the s:hear pin~
~.his opening has e~ecti.ng or releasing mean~ c~onstituted
by a channel ~9 extending radially outwardly from the
opening~ ~he channel 79 has a c~lindrical or paraLlel- :
sided cross~sec-tion ln this embodiment~ b-ut i-t may
alterna-tively ~lare outward:L~ he opening 62 may be
bounded a-t least partl~ 'b~ hardened rna-te.rial t as in :the
preceding embodi~ents, in a manner not shown. Figure 7
shows that fou.r equispaced shear pins are provi~ledO
'.~hree shear pins ~0 are spare and only one is operatlve
at any one timeO
Fi~Jres 8 and 9 show an alternatl~e ~orm o~
opening and the associated e~ec-tlng means suitable .~or
use in the cons-tructions shown v~ the preceding embodiments
~ ~5 -
~ 3 ~ ~ ~
and that of ~lgure 7~ An ~butment member fo~med by a
rotatable ClI'CUlar disc 70 is recei.ved .in -the flange 62
and can be set in any one o.f' a plw~all.ty of posit.-lorls
with the ai.d of a bolt 7'1 hav.ing a countersunk haad 7
a nut 72 and a dished plate spring 7~0 The periphery of'
-the disc 70 has semi~circular recesses 74 opening out
on the outer sicde of the disc. ~our recesses 74 are
provided in the dLsc althollg~ other numbers of recesses
could be provided. Depending on the size of' the di.sc
and the size of the recesses 74 more recesses, for
example~ six ~ay be provided~ One of the rèces~es 74 ~:
opens (see ~igllre 8) into an ejec-ting channel '75 extendlng
rearwardly and outwardl,y away f'rom the disc '70 with
respect to -the direc tion of rotat-ion B o~'-the coupling~
rr~he ]ongitudinal centre li.ne of this ~haQnel 75 is a-t
an angle o~ about 50 to a radlal line going th:rough
-the reGesS 74~ By turning c~f the disc, another recess
74 ca.n 'be positioned -to open into the channel 75~
In the event of d.amage of a recess '74 a new recess 74
can be set to open into the channel 750
Figures 10 to 12 show a fourth e-mbodiment
of an over'load couplin~, T I:i9 COUpliIlg comprises9 as
in the preceding em'bodiment, coupl.ing members 7~ and 77~
l'he coupllng member 77 is provided near part of its outer
edge with a fastening par-t 78 extending axially for some
distance away f'rom the coupling member 7~. Viewed in a
~irection parallel to the ro-tary axis 7t3, this part,7
coincides at its outer circumfcrence with part o~ -the
circu~ference of the coup'lirlg member 779 In the embod:1merlt
shown the faste~ing part 78 subtends an al1~'le o,f abou-t
80 at the centre of the member 77~ '~he fastening part
78 comprises furthermole two supporting parts 80
extending radiall~ i.nwardly towards the rotary axis 79~
In the rliche bounded. by -the supporting parts 80 and the
fastening part 78 i9 secured an arcuate holder or casse-tte
81, which can be ~astened to the fastening part 78 by :
means of a qulck release connector 82. '~h0 ~uick.-relea~-3e
connector 8~ comprises a torsioIl spri~g 83 operating to :
turn a retaining member towards the cou~ ing mern'ber '7~.
~rhe ho'lder '78 accornodates several (in the embocli.ment
shown~ fi.ve) shear pins bO si.de by sideO Ea~h shear pin
~0 is recei~ed in a '~.ole of the holder and this hol.e has
a narrow portion adJacent -the cvupling member r76= '~'his .'
portion serves as a s-top f`or a shoulde.r 7~ a-t t'he end
o:f the sheaI pi.n 60~ 'rhe top ~ide o~ the shoulder ;.s
engaged by one end o~' the helical compress.i.on spring 67
the other end/which engages a ring 86 held irl plaee
by a retaining pin 87c Each of the shear pi.ns 81 passes
as a close fit into a respect;ive aperture 88 in -the
coupling mem~er 770 In normal operatlon9 one of' the shear
pins is located i~l the opening 68 communi.cating with tha
ejecting channe]. 69~ e coupling plate 74 has Eurthermore
~ 17 ~
3~
two tapped holes 90 for receiving fastening means of a
balancing unit (not shown) for balancirlg the mass of
the holder 780 Alternati-vely~ a second hold~r may be
provided diametri.cally opposite the first one~
In ope.ration the coupli.ng shown in E'igures 10
-to 12 constitutes an overload safet;~ unit as in the
preceding embodiments~ ~he holcler or casse-tte 81 can be
readily replaced by a fresh holder, wi.th new pins~ -
By omi-ttlng the shoulder 60A the holder 81 ma~ also be
primaril~ used as a pressure means for a plurality of
shear pins, in which ~h~ case first the pi.ns 60 are
sli.pped in-to the recesses 8~, after which the holder
15 slipped onto the pins and :El~ed ;.n place b~ ~tneans
of the quick release connector.
In the embodiment shown in Figures 13 to 17 the
overload coupling is substantially s~mmetrical to a pLane
of symmetr~ going through -the centre line 90 of -the
coupling. The coupling comprises as a unit -the end por-tion
26 of Figure 1 and is connected with a fork par-ts 91 of the
universal coupling 230 ~he coupling compr~ises a coupling
member 9~ connected with the fork parts 91 and a coupLi.ng
member 93 co-operating wlth the member 92 and being
connectable wi-th the stub shaft 18~ ~he co~pling member
93 comprises a hub 94 having a radial bore 95 holding ..
a ball 96, which, in normal operation, lies in an annuLar
groove of the stub shaft 18 and is fi:xed i.n place in a -~
~8 - :
.. ,., , j, :., - .
., . .. " ; , ., .
radial. directioIl with the aid. of` a retainin~ bol-t 96A~
~he couplingr member 93 comprises furtheImore a radi.al1.~
extending fla.nge ~8~ whi.ch i.9 r-l~idl~ secured to the hub
94. '~he coupli~lg member 92 comprise~ a carrier 999 w~ich
i~ substantiall.y concentric wi.th the hub 94, on which i-t
is journalled by means of ~ needle bearing 100~ The
carrier 99 is locked i.n p1.~ce a~ially with respect to the
hub 94 by a pre~sure ring 101 and a reta1ning ring 102O
Four bolts 103 es-tablish a connection between the fork
parts 919 the carrier 99 and a circular cu-tting ri.ng 1049
whi.ch is at least par-tly i.n contact with the flange 9~0
~`he cutt;ing ring 104 hac; a centering pla-te 105 haviIlg R
portion 106 bent over at ri~ht angle~ and extendin~
towards -the universal coupli.ng 23~ By means oP the bolts
103 and a second cente:ring pla-te 107 with a portion 108
bent over at right ang:les exterlding towards the coupling
member 9~ is fi~ed in place. ~y means of the bent-o~er
portions 106 an~. 1089 which form retaining rims, two holders
109 are fixed in place9 each of which accomodates a
plurality of shear pins 110. On the ~ide of -the uni.ver~a:l.
coupling, the holders 109 have an edge 1'1, which can be
clamped beneath -the portion 108~ ~he shear plns 110 are
each urged hy a respec-ti.~e spring 112 towards the ~la~ge
98~ In order to gui.de the shear pi.rls 110 the holder is
provided with sleeves 11~9 whilst the cutting ring 104
and the centeri.ng plate 105 have recesses closeLy flt-ting
~ 19 ~
3 ~ ~ ~
arpund the sh~ar pins 1'iO~ ~ach sprin~ 112 has~ where it
engages its pin 110 a number of turns of smaller diameter
than th~ r~st o~ the spring~ l~e shear pins 110 and thb
sprin~s 112co:nstitu-te together coupling means with an
axial dimension corresponding sub~t~mtially to the
fastening portion of the stub sha~t 18.
~ he flange 98 has an openirlg 114 having a
substantiall~ radially extending cha~rAel 115 opening at the
outcr circumference of the flange 115. r~he circumfer0ntial
width of the openirg 114 is about 10 to 20 mm~ dependlng
upor~ the diameter of the shear pin. With r~spect to the
pos~ibility of e~tablishing the cormecti.on of the two
coupling portions onl~ at a reduced speed~ thc distance
b2tween the shear pin 110 in the opening 114 and the wall
of the opening 114 opposite the pln i~ this embodiment is
about 50 to 70% o~ the di.ameter of -th~ shear pin. ~he ~:
pin is support2d in ~An axial direction by a bottom part
1160 At the side of the opening 114 there is provi~ed a
substantially circular cutting P1~Ate 117 0~ AhardOned ;~
material like the ring 104 ha~ing a diameter o~ about 20
to 30 ~ms. The functiorl of this cutting plat~ is comparabl.
with that of the cutti.ng plPAte 70 in Figu:re 9. It has
three openin~s 118 at its circumference and b~ means of ;~
a locating pin 119 the cutting plat~ Carl be fixed in
placeO '~he shear pins can be fixed in th~ manner shGwn
in Figure 17 în the holder 109 b~ means of ~ locking
,. ~ ~ . . .. .
member form~d by a common r~taining pin 120~ When the
hold~r is put in place, the r.etaini.:ng pin 120 can b~
removed from the holder 9 aft~r which the pins move into
th~ir positions~ Owing to the provisiorl of the c~nt~ring
plate 105 the pins slid~, after the removal o the guard
pi.n 120, without further manipulation, into the recesses
ln the cuttin~ rin~ 1040 ~y the guick-release connectors
formed b~ the retaining rims 106 and 108 the holders
are simpl~ locked in place and the sleeves 113 prevent
the shear pins from tipping overO If during operation
by overload a portion of the connecting shear pin 110
breaks off 9 the fragment is rapidly conducted away through
the channel 115a Since the opening 114, as in the precedi.ng
embodiments 9 has a critical width, shear pin 110 can slip
into the opening 114 only a~ter a reduction of the sp~ed ;.
o~ the power taka~off sha~t 20~ As in the emb~diment
shown in Figures 8 and 99 the cutting plate carl be set in
a dif`fere~t position~ should an opening 118 be d~ma~ed~
q'he variant shown in ~igure 18 comprises a holder
dif~ering from the foregoing structure. 'rhis holder 121 i5
closed on top by means of a cap 122. '~he holder 121 i5
pre~erably made from synthetic resinO 'nhe cap 122 has a
cavity ~or accomodating the end portion of a compressio~
spring 123, the other end of which is located in a cavity
i:n a presswre pin 1240 ~he pressure pin 124 presses the
shear pin 110 home. ~he pressure pin 124 has a shoulder 125
- 21 ~
in sliding engagement with the .inner wall of the holder 12~1"
~he pressure pin 124 may also be made from s~nthetlc resin,
~le holder ca~ thus be manufactured at low cost without
detracting from its effectiveness~
In the embodiment shown in :Figures 19 to 22 the
coupling is constructed diff`erentl~ ~rom that of ~i.gure 130
The coupling member 93 is substantially identical to that
shown in Figure 13 but it i~ connected by the pin 110 w;.th
a coupling member 126 differing from -the coupling member 9Z.~ ~.
m e coupling member 126 is fastened b~ mearls of a pluralit~
of bolts 127 to a fastening portion 128 having a
substantially circular circumference and ser~ing to receive
the Pork parts 91~ ~o the fastening part 128 is secured
a carrier 129, the function of which is comparable with
that of the carrier 99 and which is located be-tween the
fastenin~ part 128 and the cutting ring 104~ ~he carrier
129 has two ca~ities or recesses 131 disposed diametrically
opposite each other about a centre line 130. ~hese cavities
131 receive a plurality oP shear pin holders. Each cavity
receives~ for example, five cylindrical holders 132 each
containing a shear pin 1100 Each holder 132 comprises a
sleeve of synthetic resin, Por example~ a plastic tube.
~he holder covers th0 whole space between the fastenin~
part 128 and the cutting ring 1040 ~ear the cutting ri~
104 the holder is provided on lts inside with a t~eri~.
i~ner ring 133 constituting both a guide for ~he ~lear pi.
- 22 ~
3~
110 arld ~ stop fo~ a widanet1 pa.rt of a pre~ure pln 13
F c~r:r~p(~ d.~ W~ h~ r~ Jl 24 ~ clo~
of the holder (`J~l the s i de o:f the end porti o~l of the spri rl~
~1~3 .I.s si~lLa:~ to tl~at; o:~ Figu~e 180 ~h e cap i.S :I~LXed
in place by ma~7ls of a re tai n.lng pl~ e ho1~lers 1~2
~re enc1osed in th~ ca~r:it~ '131 b~ means o~ a cove.r 13~i9
which i s co:ncentric wl th the centre li.ne 130 an~l t;he
side~ o~` which are bFtnt over to iEo:rm luæs 137O ~he lugs
137 co~operate with clampincP spri~gs 1~85 ha~ g a num~ctr
of turns which surrourld the ~o:L-t 127 and press the co~el:
13~ towards the ce.ntre linLt 130,3 In or~Ler I;o a~roid movs-Lnent
of the cover wi~h re~3pect tc) th~t ~pring 138 each l.~ 37
has ridges 139.,
l~ thi~ embodi.DIe:rlt the pi.n 110 is iII i.ts cormec-
~ting position located in the openin~5 9~l4 reIer:red tc i.n th~t
prec~din~s ~tmboaim~tnt ~ this openi:~g belng bourlded at onc
end9 wi-th resp~ct i~o the dlrect1o~ of rotati.on B~ b~J
~he cut~ing plate or d.LSC 70 of F1g,l1re~ ~ ~nd 9 ~see ~i.gurè
21)~ At the end o:f t;he ope:~:i.ngl~ 114 remote .from the~ cuLtl~l.n~; -
pla-te '70 a fi1li~æ~ p:Late 'l40 i s coIlnec ted wi th the coup]..ing
meIQber 93 b~ nu.t and holii; c,o:rlnectio:n" r~lhe dimen~io~
o:E ~igu:re ~ pre~erabl;y l6 1~15 ~ and on thls basi`s the
fi:l.li-ng p~ at~ 140 ha~ l,he follow:L7lg ~11memsio.rls 141a a:nd
'141b:
3~
Sheer ~i~ diameter 141a 141b
7 mms 20~0 mm~ 28~0 mms
8 mms 1~.5 ~ms ~6~ mm~
10 mms 15~5 mms 2305 mm~ ~
The operation of the coupling shown in ~igures -;
19 to 22 largely corresporltls with that of the precading
embodimen-tsO ~he couplin~ can be readily ~illed with shear
pin holders 1329 which can be easi.ly fixed irl place b~
-the cover 136 a~d the springs 138~ With dif~aren-t pin
tli.~meters the factor.~:in the f'ormula S 1- ~- Aq12 ~-the
~actor T being es~en-ti,all~ cLetermined b~ th~ pi.n di.~meter
and the assoc~ated c:ire,um~ereIltial width 'l41 af the ope~lln~
114) can be kept cons-tant iXI this embodime~t ~i~ce the
~illing plate 140 carl be exchanged9
~ igures 23 and 24 show an alternative embodi~ent
of a breaklng coupli:tlgg in which a shear pin 142 largely
~imilar to the shear pin 110 is provided with a groove 143
ex-tending parallel to its longi.tudinal centre line through~
out or substantiall~ throughout t;he lengt;h~ .his ~roove
co~operates witth a corresponding ke~ 144 provided on the
pin guide mean~ for ex~mple, the sleeve 113, the centering
platte 105 and the cutt.-ing ring 104 of Figure 13, '~he ke~
144 prevents the breaking pin from tu.rning with respsc-t
to the rest o:~ the coupling.
'~he overload couplin~ ShOWII in ~1igures 25 and
~ 24 - ....
3 ~
26 comprises 9 as i~l the embodime:nt o~ Figure 13, ma~ y ~he
end portioa 26 of the a~xlllar~ sh~f-t 1~o A coupli~ ~nem~er
145 is connected w:i~th fork parks 146 a:rld. a coupling
porti.on 147 is connected with a s-tub shaft 18 as i.n the
embodime~t of Flgure 13~ ~.he coupli.ng member 147 CO~lpriSeS
a hub 14~ and a flarlge 150 extendi~g radiall~ ou~wardl.~ ~
of a centre line 149~ '~he hu~ 148 exte~ds a~ to
each side of the flangs 150 and the side of th~ .~lan~e 150
remote ~rom the coupling memb~:r 145 ls provided with
pressure mealls preferably formed b~ ~ spiral blade spring
151~ surrounding the hub ~.i1ih9 for example9 five turns~
'~he format ratio o~ the blade sprlng 151 is at le~s-t 1:10
~ e .in:ner end o:E -the sprin~; 151 .ls :r.3..g:idly sec~ ed to the
hub, whereas the outer end of the spri.ng is c,onnected. w.)t~:
a co~re:r plate 15~ by a ri~ret or bolt ~oint~ he plate 152
is rigidly connected nea~ the circumference of the breaki~lg
coupli.ng by a plurall~y of ~bol~s 153 with a~ annular wall
154 havlng a sub~tarltlall,y cylilldrical shape alld be~ g
provlded on its outside with url~vennesses :I.n the for~n o:f
knurls 155, On the in~ide~ the wall 154 is provld~d with
at least one spring pawl 1~ ure 26)~ but preferably
with threeO '~he spring pawls extend i-nwarcll.y from -the :~
wall 154 :in a directio.~ i~dl~ated b~ the arrow B 1n ~igu:re
26 and ara intallded to co~oparate wi~h tha ou~er pe.rlpherst
of a ri~g or ratche-t dr~ '157 having9 viewed along the
centre line ~499 a ~awtooth shape for unldirectlonall~
lockin~ a~ainst the spring pawls 1~6* 'rhe spring~ 1519 tha
r
.. ~ ;;,
3B~4
wall 154 and the xatchet drum 157 co:nsti.tute iIl commor
advancement means for a .franglble el~merlt const~ ttsd b~
a length of ~teel band 1590 The rat;chet drum 157 an~ th~
steel band 159 ha~e a width9 mea~uretl axiall~ o~ the
centre line 14~ 9 which corresponds to the a~lal dimenslon
of the wall 154~ ~he st~el band 1~9 ma~ have about te~
coils and be accomodated in the spac~ bo~ndecl b~ the
inner wall of the ra~chet drum 157. ~he steel band
preferably has a thickne~s o.~ about 1 ~m ~nd a width o~
4 to 7 cms, and in thi~ embodiment about 6 cm9, The end
portion 160 of tho steel ba~d 159 remote fro~ the ratchet
drum 157 is ben~ over from ~ub~tantiall~ clrc1lm.~erential
alignmcnt towards the centre l.ine 149~ The end portior~
pa~ses between two cuttln~ ~loclcs '16'1 and 1~.',, whi.ch are
bolted to the flange 1500 ~etween the block~ 161 aIld 162 ~-~
i8 a gap 1~4 con.~titutinæ a ~lide pa~sage~ ~he g~p 1~4
~uiac~ the ~nd portion 163 ~o that this end portion has
locall~ a sha~per curva~ure than the rest c~ the ~teel
band 159~ The length o~ the gap 164 i~ preferabl~ abollt
~ c:ms9 ~he free cnd of ~he e.nd portlon 1~3 lies in an
opexllng 165 in a c-~lindrical carriflr 1~6, which i~ axia.ll~
~ixed in place in ~ manner ~imllar to lihe carrle:r 99 in
re 13 with r~pect to the hub 1~87 a~d is àournall~
c~ee~
o~ the hub b~ mean~ of a needle bearing 157~ ~he
~ bolted to the fork part~ 14 b~ and con~t.ii-tutes the
main part of the coupli.n.g m~mbe:r 145.~ ~h~ ca~rier 1~6 ha~
~ ?~ :
, . . , ... . ' ~
~3~5~L
an ax:~.al dimen~lon whlch subs tantlall~r correspond~ wi th
that OI the ba:nd 15~ he s~pa,e bound0d b~ the band 1i9
and the carrier 1~6 can collect brok:en-o:E~ fra~m~nts from
the band,. '~he ope~ g ' ~ ; bolmdecl i.n operati on i~ the
direction of the arrow :B correspondln~s with the dlrection
of rotatio;n of the auxiliarclr shaft 19 by a cu.l;tlng plate
~168, which en~age~- ~he eIId port;lon ~ b;y a slanting slde
joi~ing the ~;ap 1~4. As i.n l;he precedl.ng emb~d.iments and
particularl~ ure 21 the circ~m~erantial w;.dth o~
the openi~g 165 ma~ be vRried by using cu.tti.ng plate~ 168
of dif'fererlt circumfer~ntial dime~5ionsO ln t;his em~odlment
the circ~mf'erential dimension o.~ the ope~i.rl~ 165 is
~referabl~ ~bout ~hree time6 the thi.cknsss o~ th~ steel.
band 159~
'~he embodiment of the coup:Li~g show~ ures ::
25 and 26 operates as fol 10~8:
~ he band 159 i~ delivered to the user in the form
of a reelO '~he diamete~ of the reel ma-~ be chos~n in
accordance with ~he outsr d.iamete:r of the rest of the
au~ iary sh~'t 19 so that the reel can be sli.pped .i:nto t;he
coupling without the need for removin~ the auxllia~ shaf't
and the ~ree e:nd portion 163 is inser-ted into the gap 164
The other end ~ortion ~60 wil~ enga~e one o~' the internal
saw~toot~ everle~se~on the in~e.r ~ide o~ the ratchet
drum '1570 ~herlthe feeder sprin~ 151 is wound up `~ rotat~
the ~rum ~ormed by the wall 154 in the d:L~eckion opposite
~ 27 ~
,, , ~:
- . . : .
3~
, .
~he arrow B ln Flgure 26~ ~le spring pawl 156 prevenl,s
an undesirable reverse rotat;ion of the WR~ 4 " After
the sp.ring 154 is ~ul:Ly wound9 Lt ur~;es t;he {;teel band 159
towards the car:ri.er '1660 A.~ter relative rotati.orl between
the two coupling membe:rs ~ -the end portiorl 163 will be
pressed i.nto the ope.ning 16S 30 that t;he band 1$g lS in a ~;
position in which i~ interconnects the two coupling m~mbers~
In the event of overload, as in the preceding embodiment
the portion of t:he steel band 159 loca-ted i~ ~he openlng
l65 will break off~
~ i~;ures 27 and ~8 show a f1lrther variaIIt of o~rer-
load coupling co~prlsing a feeder~ d~ice arld further par-ts
whi.ch lar~el~ correspo~d with those oE F;gures 25 ~nd 2~
~he pawl sprin~s 156 co^-op~3rat~3 with a drum ~16(3~ which i~-;
adapt;ea to co~operate with a l.a:rge number of radi.ally
disposed shear p:ins 1709 arranged in a pin ring 171
The pin ring 171 is connec-ted b~ fit~ing pi~s wit~lthe fl~uîge
150, ~he pi.ns 170 are cla~ped slightl~ in hardened sleeves
172, which are pres~ed into the pin ring 170~ ~h~
radiall~ lnner side of tho pin ring 171 is adjacent a
cutting rin~ '1739 which forms part of the second couplin~
member of` the b~eakl~.g coupling an~ has a r~di.al op~nlng
174 f'or receiving one of the shear pins to interconne~-t
the two coupll.~g ~e.mbers~ ~he circumf~r~rltial dlmensio~
of the openi~g~, as in the preceding embodiments 9 ls
cri-ticalO ~he cuttl.rl~ rin~ 17~ is ri.Kidl-~ fastened by
-.. .. . .
3~
two bolts 175 to its coup~inæ memberO X'he drum 169 has
an lnner pro:Eile ~`or supporting the shear pirls 1700 rl~`his
pro~ile comprlses a ~irst suppo.rt-Lng surf'ace 17~9 whi.ch
ligh-tL~y supports thc? shear pi;lS 17() not ~c? t moved into a
f:irst connectlng posit;ion6, Viewc?d i:tl a dlrection opposi.te
the arrow .139 the f.-L.rs-t supporti.ng sllr:~ace 176 ~xtends to
a fl:rs t lug '177 hav~Lng an o~Liquel~ ascend-LIlg connecting
ramp s~Lrlace which ls at ~n anglt? of about; 20 to 50 9 pre--
ferabl~ 30 ~ to a tangent passing through i~ a:nd whlch leads
on to a SeCOnt:l supporting sllrface 17~39 which is neare:r t:he
cent:re :line "149 t:ha~ t;he fir8t supportlng sur.face '176, '.r:he pi.
are provided w.ith rou.lldc?d end. portions to enable t:tlam to
slide up the :Lu~ 177~ As is shown i~l P`i.gure 28 the lug 17'7
exerts pressurc on a shear pin 179 by the action of the
spring '151, which pin is not yet in a connecti.on pOsition0
At the same time, a shear pin 180 lies at lea~;t part;ly
in the ope:ning ~174 and establi~3hes a connection betweer
the two c~pllng :membersD 'rhe erld port:ion of the shear
pln 180 engages part of` the second supportin~; sur~ace 178
ad~acent the lug 177~ ~ th.ird brea:king p-ln '181~ h~:in~;
b:roken o~':f already once subsequent to an overlo~d~ is
located between the s~cDnd supporting surface 17~3 and ths
inter:Eace between the pin rin~s '17'1 aIld ~he cuttlng ring
1730 qhe second supporting surface 178 is coaxi.Al w:Lth
the centre line 14g and ex-ten.ds from -the ~ '177 :lfl ;9
d.irec tion opposi~e the arrow :B throllgh ~n arc o:E 170~ 3
~ ~g ~ ~ .
. .
~ ~ 3 ~
s~id sacond supporting surface 178 then leads OIl to a
second lug 182 havi.ng a slopin~ ~ace corresponding wi.th
that o~ the first lug ~7~O A thlrd ~3upporting surface 18-
~e~tends OVeI` a fairly short distance adaacent the lug 'l82)
-the circ~mferential extent o~ that sur~ace `belng such t;hat
it can aust support one shear pin 170. In a direction
opposite the arrow B the third supportîng surface 18~
leads back on to the first supporting surface 176~ In
operation3 the coupling ~hown in Flgures 27 and 28 is
provided with a series of breaki.ng pins 170 arranged along
an arc o~ about 1~0 on the rin~ 171, in thi~ e~bodiment
eleven pins are ~hown~ 'rhe pin 181 of .Fi~ure ~8 m~ t
initiall~ be positioned i.n front o~' the lug 177, vi.ewed ln
the direc-tion o~ the arrow B~ In this s-tate ~lll the plns
are located between the ~ir~t ~upporting sur~ace 176 and
the interface between th~ pi.n ring 171 and the c;utting
ring 17~ After the .spring 151 has been wound in the man~er
described with reference to the preceding embodimentg it
will cause a radial pressure to be exerted on the pin 180
under the ac tion of the sloping connec tion ramp surface
on the lug 177~ Relative rotation between the two coupl;.ng
members results in the pin 181 being slipped into the
opening 1743 At the same time the d~m 1~9 rotates in the
direc-tio~ o~ the arrow B until the lug 177 reaches the
next- followin~ shear pin 1803 ~he coupling i9 th0Il -read~ i
for normal operation~ In the even^t o~ overload the
~ 30 ~
3~il5~
portion of the shear pin 181 in its connecting poslkior
in the opening 174 will break off so that the coupli.ng
member connec-ted with -the implement of the harrow (see
~igure 1) will come to a standstillO '.l~a drum 169 rotate~
through a small angle in the direction o~ the arrow B
thus shifting the ~hear pin 180 into a connecting po-
sition. ~he drum then occupies a positlon a6 ShOWrl
in Figure 28, in which the lug 177 bears on the shear
pin 179. Fracture of a shear pin followed b~ rotation of
the drum 169 and the positioning of a f'ollowing shear pin
are repeated until all the shear pins have b~okan off once~
In this state the shear pin 181 engages the second lug
182, which pushes the pin 181 for the second time in a
radial direc~tion in-to the opening 174~ Thus by means of the
second lug 182 all the shear pins can again be used~
By providing further lugs, further fracture of the pin
a~ter leavin~ the lug 182 may be repeated several times.
the resultant bre~k.ing coupling has a compact structure,
but it can neverthel.ess transfer a very high torqu~.
Figures 29 and 30 show a variant o~ the breaklng
coupling shown in Figures 27 and 28. In this embodiment a
wall portion 184 is bolted to an inner part 185 and is
provlded on the inner side with pawl springs 186 co-operating
with a drum 187~ .Apart from -the first drum 187 a second
drum 188 is provided which is i~ engagement with the wall
184. Like the drum 157 of the preceding embodiment the
~ 31 ~
~ 33~5'~
drums ~87 and 188 co~operate with pin ri~gs 189 and 190
respectively9 each pin ring co~oper~tln~ with an vpening ;;
:;n the cutting ri~g 1730 ~he flrst drum 187 has a groove
191 extending coaxially wi.th ~he c~.ntre line 149 a:nd is
pro~ided with a lug or pawl 192. ~h.e second druTn 188 is
pro~ided with a catch 19~ w:hi.ch e-xtends axially and is
located i~ tho groove 19'l~ In operation the drum 187
co operates with the wall and the pl~ rin~ 189 in the same
manner a~s in the precedil~g embodimentD After the pins
of the ~irat pin ring 189 are consumed9 the second pin
.ring 190 is ~ade op~rative by contact betw~e~ the catch
193 and the pawl 192~ ~hus the pins o~ the ,second ring
190 are used in order -~ successlon, so that the C~pACi ty
.~,~
of the coupl.ing is dJubledO In a similar mann~r several
piII rings ma~ be arranæed orle b~hind the other.
Figure 31 shows a fu:rther embodlment o~ -the
coupling shown in ~igures 27 a~d 28~ in which the outer
wall is formed by a wall 194, which is coaxial with the
centre li~e 149 and extends away from the plate 152 and is .
provided near the :~langre 150 with a pluralit~ of pawl springs
1959 whlch can co-operate ~with a drum 1960 Ihe drum 19~
is provided with a lug 197 which has an upwardly slan-ting
ramp ~ur~ace 198 and is remote Prom the flange 1509 this
~ur~ace being at~an acu-te angle to a plane perpen~iculaI
to the centre ll~e 1499 t~is angle pr~f`erably bei.ng about
30. r.rhrough the lug 197 9 -the drum 196 co=~operates wi-th a -;
~3~
pin ring 199 having a plurality of breaking pins 200
extending parallel to the centre line 149. ~he other
coupling member comprises a disc 201 which extends
transversely of the centre line 149 and is connected with
the fork parts 146. The coupling shown in Figure 31 operates
basically in substantially the same way as those shown in
any one of the Figures 27 to 30, the pins 200 being,
however, orientated axially~ whilst the lug 197 moves the
respective pins 200 into a connecting position. In this
way one lug will suffice and the possibility, which may -;
be advantageous, is available of disposing the pins very near
thc circumference oE the coupling, so that the coupling is
capable of transferring a vcry high torque. The coupling,
as described in any one of the preceding embodiments can
be placed in a flywheel very effectively since the shearing
pin can be completely disposed within the outer periphery
of the flywheel and may even be arranged inside the fly-
wheel.
It should be noted that the positions of the
coupling members in these embodiments with respect to the
driving shaft and the driven shaft may be inverted.
- 33 -
