Note: Descriptions are shown in the official language in which they were submitted.
35~7
Saw Chain for a Motor riven Chain Say
Field of the Invention
The invention relates to a saw chain for a motor-driven
chain saw. The saw chain includes a safety link having an
approximately rectangular, plate-like body. The plate-like
body has at least one safety projection which projects out
beyond the plane of the body and which defines a bearing
surface for bearing against a wall of the kern in the wood cut
by the saw chain.
Background of the Invention
Saw chains are guided around the free end of a guide bar
of the motor-driven chain saw through a small arc of 180. In
plunge-cutting operations in which the motor-driven chain saw
plunges with the free end of its guide bar into the wood to be
cut with the saw chain rotating, the cutting links can
penetrate the wood too deeply in spite of the depth limiters
provided on the cutting links. If this situation occurs, the
motor-driven chain saw experiences a sudden rearward and
upward thrust known as the kickback effect. To avoid such a
I kickback condition, safety links are provided which take
support upon the kern bottom when moving over the rounded nose
end of the guide bar and limit the depth of penetration of the
cutting links.
In a known safety link of the type described in German
I published patent application DEMOS 3,145,672, the safety
projection lies in the plane of the plate-like body over which
it projects at its longitudinal edge facing toward the kern
bottom. the safety projection is configured in the same
manner as a depth limiter of the cutting link. When viewed in
the direction of rotation of the saw chain, the safety link is
., 1 ,
~ZZ3S07
located adjacent to the cutting link so that -the depth limiter
and the safety projection are side by side. As a result,
these two parts are supported together upon the kern bottom.
The objective of this arrangement is to increase the effective
width of the depth limiter in order to reduce the penetration
of the depth limiter into the wood in the presence of a
kickback condition. This safety link can only be arranged
laterally adjacent to the cutting link and provides merely an
increased width of the bearing surface of the depth limiter.
However, this increase in width necessitates two saw chain
links, that is, the cutting link with its depth limiter and
the safety link.
Moreover, it has been shown that, while such a safety
link is in a position to reduce the risk of chain saw
kickback, this risk cannot be avoided satisfactorily. It has
been shown further that the relevant saw chain cannot ensure a
sufficiently smooth running condition and clean cut because
the depth of penetration of the cutting link is solely
determined by the depth limiter.
Summary of the Invention
It is an object of the invention to provide a saw chain
having a safety link providing a large bearing surface for
coming into contact engagement with the kern bottom, whereby
an improved cutting quality of the saw chain is obtained.
The saw chain of the invention is for a motor-driven
chain saw. The saw chain cuts a kern into wood during
operational use thereof. The saw chain includes: a plurality
of cutting links, a plurality of safety links, a plurality of
side connecting links, and a plurality of driving links, the
links being pivotal interconnected by rivets or the like to
~35~7
define the saw chain, said driving links defining a mid plane of
the saw chain with said safety links disposed on alternating sides
of said plane along the length of said saw chain and said cutting
links likewise being disposed on alternating sides of said plane
along the length of said saw chain;
each one of the cutting links including: a flat body
having an upwardly extending rearward bent-over top portion
defining the cutting tooth of the cutting link, a forward upwardly
extending portion defining the depth limiter of the cutting link;
and, said cutting tooth having a cutting edge at an elevation
above said depth limiter; and,
each one of said safety links having a plate-like body
of approximately rectangular shape and having a side surface
facing said plane, said plate-like body defining a plane parallel
to said mid plane and having two bores formed therein and arranged
one behind the other in the longitudinal direction thereof for
accommodating respective ones of two of said rivets, said safety
link having a safety projection extending out beyond said
plate-like body and in said plane of the latter, said safety
projection having an upwardly directed edge facing the bottom of
the kern, said edge defining a bearing surface for bearing against
the bottom wall surface of the kern, said safety link further
having an L-shaped cross section along at least a portion of its
length so as to define a widening formed thereon, said widening
extending out beyond said one side surface and toward said mid
plane so as to define an ancillary bearing surface for further
supporting said safety link against the bottom wall surface of the
Jo
` - ~2235~)7
kern whereby the cutting links are prevented from penetrating the
wood too deeply so as to reduce kickback of the chain saw during
operational use thereof.
The safety link ox the invention includes a widened
portion ensuring that a large surface area of the safety link
bears against the kern bottom. This enables the shape of the
safety link, particularly of its safety projection, to be
independent of the shape of the depth limiter of the cutting links
of a saw chain, thus permitting simple and low-cost manufacture.
I The safety link limits the depth of penetration of the cutting
link in addition to that of the depth limiter, thereby reducing
the risk of unwanted kickback of the motor-driven chain saw to a
minimum. The safety link may be
`~`
- pa -
223~7
disposed preferably ahead of the cutting link when viewed in
the direction of saw chain movement so that, as a result of
its cooperation with the cutting link, kickback of the chain
saw can be essentially avoided and a substantial improvement
in cutting capacity and cutting quality can be obtained.
Further features of the invention will become apparent
from the following description, the drawing and the appended
claims.
Brief Description of the Drawing
The invention will now be described with reference to the
drawing wherein:
FIG 1 is a side elevation view of a portion of a saw
chain of the invention;
FIG 2 shows the saw chain of FIG 1 as it moves over the
rounded nose of a guide bar of a motor-driven chain saw;
FIG 3 is a side elevation view of the safety link of the
saw chain of the invention;
FIG 4 is a rear elevation view of the safety link of
FIG 3 seen in the direction of arrow IV of FIG 3;
I FIG 5 is a side elevation view of a second embodiment of
the safety link of the invention;
FIG. 6 is a top plan view of the safety link of FIG 5
seen in the direction of arrow VI of FIG. 5;
FIG 7 is a side elevation view of another embodiment of
the safety link of the invention;
FIG 8 is a rear elevation view of the safety link of
FIG 7 seen in the direction of arrow VIII of FIG 7;
Figs 9 to 14 are top plan views of further embodiments
- of safety links of the invention;
FIG 15 is a side elevation view of another embodiment of
~Z~356)~
the safety link of the invention,
FIG. 16 is a top plan view of the safety link of FIG. 15
seen in the direction of arrow XVI of FIG. 15;
FIG. 17 is a view of a portion of the safety link of
FIGS. 15 and 16 within a kern;
FIG. 18 is a side elevation view of another embodiment ox
the safety link of the invention;
FIG. 19 is a top plan view of the safety link of FIG. 18
seen in the direction of arrow XIX of FIG. 18;
FIG. 20 is a top plan view of another embodiment of the
safety link of the invention;
FIGS. 21 to 23 are front elevation views of further
embodiments of safety links of the invention;
FIG. 24 is a top plan view of a portion of a saw chain of
the invention wherein a further arrangement of safety links is
illustrated; and,
FIG. 25 is a schematic of the arrangement of the safety
links of a saw chain as they engage a kern.
Description of the Preferred Embodiments of the Invention
I The saw chain is provided for use in motor-driven chain
saws and includes cutting links 1, 1' positioned on the sides
Jo the saw chain such that a right-hand cutting link
alternates with a left-hand cutting link. Each cutting link
has a cutting edge I 2' and a depth limiter 3, 3'. To one
US side of each cutting link 1, 1', there is connected a
strap-like side connecting link 4, 4'. The cutting
links 1, 1' and connecting links 4, 4' are connected to center
driving links 5, 5' as shown. Individual ones of the
connecting links are replaced by safety links 6, 6'
alternating on either side of the saw chain and disposed ahead
235~)7
of their respective cutting links when viewed in the direction
of movement 7 of the saw chain. The safety links 6, 6'
interconnect mutually adjacent driving links 5, 5'. All links
of the saw chain are pivotal interconnected by rivets 8. It
is not necessary for the safety links to be disposed on the
sides of the saw chain; instead, they may also be center
links. In the nose region of the guide bar for the saw chain,
the driving links 5, 5' engage the nose sprocket (not shown).
In the straight part of the guide bar (no-t shown) of the
motor-driven chain saw, the driving links 5, 5' engage the
guide groove of the guide bar.
At the nose region 9 of the saw chain (FIG. 2), the
safety links 6, 6' bear against the bottom 10 of the kern 11.
In plunge-cutting operations, this prevents the cutting
links 1, 1' from cutting into the wood too deeply.
The safety link 12 of FIG. 3 has an approximately
rectangular plate-like body 13 which, in its longitudinal
direction, has mutually spaced bores 14, 15 for receiving the
rivets 8. The bores are arranged one behind the other and
20 have their axes 16, 17 in a common plane B. Safety link 12
further includes a nose-shaped safety projection 18 projecting
rearwardly over and beyond the body 13 in the direction
opposite to the direction 7 of movement of the saw chain. The
sides 47, 47' of the projection 18 are in respective common
planes with the sides I 49' of the body 13 (FIG. 4).
Longitudinal edge 19 of body 13 which is close to the
kern bottom 10 with the saw chain in operation (FIG. 2) and
the adjacent edge portion 19' of the safety projection 18 are
bent outwardly at right angles extending over and beyond the
30 one side 47, 49 of the safety link (FIG. 4) so as to be
~235()7
directed towards the center of the saw chain. Edges 19, 19'
define a flange or widening 20 extending over the entire
length of the body 13 and the safety projection 18.
Widening 20 protrudes over the one side 47, I of safety
link 12 by an amount corresponding approximately to the
thickness of the body 13. As a result, the outer surface 21
of widening 20 provides a large bearing surface for -the safety
link 12 to take support on the kern bottom 10 during the
operation of the saw chain. This configuration has the added
beneficial effect of providing a higher pressure in the
direction of movement 7 and of thereby reducing the danger of
kickback. In particular, smooth running of the saw chain and
thus its cutting behavior are thereby substantially improved
At its forward end when viewed in the direction of
rotation 7, longitudinal edge 19 of body 13 becomes a narrow
edge 22 which is initially downwardly inclined and then
describes a portion 22' of a circle curving approximately
about axis 17 of bore 15. As a result of this steady and
smooth transition, the safety link cannot become caught as the
I saw chain moves through the kern.
he rearward end of edge portion 19' of safety
projection 18 becomes a curved edge 23 of approximately
semicircular shape, yet of a substantially smaller radius of
curvature. There then follows a transition to a concave edge
US portion 24 having a large radius of curvature and lying above
plane B thereafter edge 23 of body 13 then blends into a lower
edge portion 25 curved about the axis 16 of the bore 14 in the
form of a portion of a circle. Edge portion 25 and curved
portion 22' of opposite edge 22, in combination with
connecting end portions 26, 26', respectively, of the lower
31 ;~;~35~7
longitudinal edge 27 ox body 13, form approximately
quarter-circular curved edges of the lower corner regions of
the plate like body. These corner regions reach about as far
as to the vertical planes 28 and 28' which extend tangentially
to the bores 14 and 15 and contact said bores at respective
contact points on the bore edges which lie opposite each other
as shown.
End portions 26, 26' are connected with each other via a
slightly concave edge center portion 26".
lo The spacing 30 between the vertical planes 28, 28' is
about three to four times the maximum extension 31 of the
lower corner region of body 13, when measured parallel to
plane B.
In the rounded nose end 9 of the guide bar of the
motor-driven chain saw, the safety link 12 prevents the
cutting link which follows there behind from cutting into the
wood too deeply. In plunge-cutting where the motor-driven
chain saw plunges into the wood with the free nose end of its
guide bar, kickback of the chain saw is thus prevented or at
I least substantially reduced, so that the risk of an accident
is avoided.
In operation, the widening 20 serves to support the
safety link 12 as it bears against the kern bottom 10 in the
rounded end area thereby limiting the depth of penetration of
I the hollowing cutting link and also preventing kickback of the
motor-driven chain saw.
The safety link aye of FIGS. 5 and 6 differs from the
above-described safety link 12 only in that its upper
longitudinal edge lea, lea' is widened in a mid-region between
the vertical planes aye, aye'. As in the widening 20 of
~2~Z35~
FIGS. 3 and 4, this widening aye is formed by an edge piece
bent outwardly at right angles, thereby protruding over the
one side aye (FIG. 6). Widening aye is also of the same width
as widening 20 of FIG. thereby similarly providing the
safety link aye with a relatively large bearing surface aye
projecting over the side of the body aye. The provision of
such a large bearing surface for taking support upon the kern
bottom prevents the cutting link from plunging too deeply into
the wood, which avoids kickback and ensures smooth running and
perfect cutting conditions of the motor-driven chain saw. The
widening 20 and aye of the safety links 12 and aye,
respectively, may also be formed by forming the respective
edges 19 and lea.
Since widening aye extends only to the position of the
rearward bore aye, a recess 38 is formed between the latter
and the upper rearward body portion 37 incorporating the
safety projection aye. In the top plan view of FIG. 6,
recess 38 is dimensioned to receive the depth limiter of the
following cutting link with clearance as the saw chain is
propelled around the free nose end of the guide bar thereby
ensuring free clearance of motion of the links of the chain.
In this arrangement, the rearward edge 32 of widening aye may
serve as bearing surface for the depth limiter.
In the embodiment ox FIGS. 7 and 8, the upper
I longitudinal edge lob of body 13b extends somewhat more
steeply than the longitudinal edges 19 and lea ox safety
links 12 and aye, respectively. In addition, when viewed in
the direction of movement of the saw chain, the rearward
portion 33 of the longitudinal edge lob and of edge lob' of
safety projection 18b have a slightly convex curvature.
3~2~3S~)7
Portion 33 extends roughly from a vertical plan 28b
tangentially to the rearward bore 14b of body 13b up to a
rearward tip 35 of safety projection 18b. Widening 20b is
likewise formed by bending at longitudinal edge l9bl, the bent
portion extending from the tip 35 of safety projection 18b to
about the position of the vertical plane 28b tangential to
bore 14b on the side thereof closest to bore 15b.
Widening 20b extends at a right angle outwardly over the
sides 47b and 49b, 49b' of the safety projection and the
body 13b, respectively This provides a large bearing
surface 21b FIG. 8) for abutment with the kern bottom. In
plunge-cutting, this safety link prevents the cutting link
following directly there behind from penetrating the wood too
deeply and preventing kickback of the chain saw. In addition,
a saw chain equipped with these safety links runs very
smoothly and ensures a high cutting quality.
The safety links 12c and 12d of FIGS. 9 and 10 correspond
substantially to the safety link 12b of FIGS. 7 and 8. us in
the safety link aye, they have widening 20c and 20d provided
with recesses 41 and 42, respectively, to receive the depth
limiters of the following cutting links when these links are
at the rounded nose end 9 of the guide bar.
In the embodiment of FIG. 9, recess 41 is a rectangular
aperture cut through the widening 20c of body 13c, whereas
I recess 42 of FIG. 10 is open at the edge such that a recess
lies in the edge 43 of widening 20d, the edge 43 being
parallel to the sides 47d, 49d of the safety link 12d.
The recess 41 extends slightly beyond the bore axis 16c,
preferably up to vertical plane 28c tangential to the bore
lying closest to the safety projection 18c. Recess 42 extends
235~)7
up to bore axis 16d of the bore lying closest to the safety
projections 18d.
Recesses 41 and 42 ensure that, in the operation of the
saw chain, the cutting links are pivot able about their
respective rivet axes, so that freedom of movement of the saw
chain in the rounded region defined by the nose of the guide
bar is not impaired. Recesses 41 and 42 are configured such
that in the rounded end region, the depth limiter which
follows behind the safety link is allowed to project with
clearance into the recesses by such an amount that an
uninterrupted transition is formed between the depth limiter
and the safety projection. Abnormal wear of the depth limiter
and excessive cutting depth can thereby be avoided.
It is also possible to provide an embodiment wherein the
cutting and safety links of FIGS. 7 to 10 partially overlap
one another when viewing the saw chain from the side, and
wherein the depth limiter is bent in the direction of the
center of the saw chain, so that it extends into the
respective recess 41 and 42 thereby surrounding the depth
I limiter.
FIGS. 11 to 14 illustrate further embodiments of safety
links which basically may be configured as any one of the
safety links of FIGS. 3 to 10. They differ from these safety
links by a widening formed by bending the safety projection
I and a forward end portion of the body. Safety link eye of
FIG. 11 includes a safety projection eye and a forward end
portion 44 of body eye. The end portion 44 is disposed at the
forward end of the safety links eye when viewed with respect
to the direction 7 of movement of the saw chain and is
disposed above the forward bore eye. The safety
35~3~
projection eye and the end portion 44 are bent in the same
direction, so that the safety projection eye and the end
portion 44, when viewed in top plan view, are on the same side
next to body eye of the safety link and form respective
widening eye and eye'. The outer sides eye, eye'
and eye, eye' of safety projection eye and end portion 44,
respectively, blend in a continuous curve into the parallel
outer sides eye, eye' of the body eye.
As shown in FIG. 11, body eye is not bent in its center
portion 45. The outer sides eye, eye' of the safety
projection eye blend in a continuous curve into the outer
sides eye, eye' of the body eye not only in the vertical, but
also in the longitudinal direction of the safety link eye. In
the longitudinal direction of the safety link eye, the outer
sides eye, eye' of the end portion 44 likewise blend in a
continuous curvature into the outer sides of the unbent center
portion 45 of the safety link. While the outer
sides eye, eye' of the safety projection eye have a continuous
curvature over their entire length, the outer sides eye, eye'
I of the end portion 44 are initially curved from the center
portion 45 of the body eye and then extend parallel to the
outer sides eye, eye' of the body eye up to the free end of
the safety projection eye. It is also possible to have the
cuter sides eye, eye' of the end portion 44 extend in a
I continuous curve. Safety projection eye and end portion 44
may be bent such that the outer sides eye' and eye' lie in a
common plane.
The bent configuration of the safety projection eye and
of the end portion 44 provides the safety link eye with a
bearing surface for abutment against the side walls of the
~35~7
kern 11 (FIG. 2). This results in a high lateral stability
and a smooth running of the saw chain, in particular when
lateral forces act on the saw chain. The safety link eye is
arranged in the saw chain so as to permit the safety
projection eye and the end portion 44 to contact the side wall
of the kern 11. Above all, the bent configuration of the
safety projection eye and of the end portion 44 results in an
enlarged bearing surface of the safety link at the kern
bottom, so that the widening extends in an inclined outward
direction above the body eye. Thus, these embodiments too
keep the depth limiter and consequently the cutting links from
digging into the wood too deeply.
In the embodiment of FIG. 12, the safety projection 18f
and the end portion 44f are bent towards different sides to
form widening 20f and 20f', respectively. This permits the
safety link lo to be disposed on either side of the saw
chain. Depending on the location of the safety link in the
saw chain, it is either the safety projection 18f or the end
portion 44f that comes to bear against the side wall of the
kern 11. Safety projection 18f is bent in the same manner as
in the safety link of FIG. 11. Also the end portion 44f is
Kent in the same manner as in the safety link of FIG. 11, yet
in an opposite direction. As in the embodiment of FIG. 11,
the safety projection and the end portion are bent such as to
I form a bearing surface for abutment with the side walls of the
kern 11, thereby ensuring high lateral stability and a smooth
running of the saw chain.
In the safety link 12g of FIG. 13, the
widening 20g, glue formed by safety projection 18g and end
portion 44g, respectively, are again bent towards the same
So
side of the safety link using, Louvre, the other side of the
safety link when compared to the embodiment of FIG. 11. When
viewed in the direction of rotation 7 of the saw chain, the
safety projection 18g and the end portion 44g axe on the
left-hand side of the body 18g; whereas, in the embodiment of
FIG. 11, they are positioned on the right-hand side of the
body eye. Safety projection 18g and end portion 44g are of
the same configuration as in the embodiment of FIG. 11. This
safety link, too, affords a large bearing surface for abutment
with the kern bottom lo, high lateral stability and smooth
running of the saw chain. Because the safety projection 18g
and the end portion 44g are provided on one side of the
body 13g, mounting of this safety link 12g is restricted to
one side of the saw chain if the safety projection 18g and the
end portion 44g are to contact the side wall of the kern 11.
In the safety link 12h of FIG. 14, safety projection 18h
and end portion 44h forming, respectively, the widening 20h
and 20h' are provided again on opposite sides of the body 13h,
so that the safety link may be mounted on either the
right-hand or the left-hand side of the saw chain. By
contrast with the embodiment of FIG. 12, the bent safety
projection 18h is on the left-hand, and the bent end
portion 44h is on the right-hand side of the body 13h when
viewed in the direction of rotation 7. The bent safety
I projection 18h and the bent end portion 44h are of the same
configuration as in the embodiment of FIG. 12.
As in the embodiments of FIGS 3 to 10, the upper edge of
the safety links of FIGS. 15 to I is bent at least over part
of its length which provides a widening ensuring a relatively
large bearing surface at the kern bottom in the direction of
14
~356~7
movement 7 of the saw chain. This enlarged bearing surface
results in an increased operator thrust pressure and a smooth
running condition of the chain. In addition, the enlarged
bearing surface also reduces the risk of kickback.
IT. 15 shows a safety link 12i which is configured as
one of the safety links of FIGS. 3 to 10. However, the safety
projection 18i is bent in an inclined outward relationship
such that its rearward edge 23i extends parallel to the outer
sides 49i, 49i' of the safety link, that is, parallel to the
direction of movement 7 as shown in FIG. 16. The safety
projection 18i thereby forms a widening 20i providing a large
bearing surface for abutment with the kern bottom, whereby a
substantial reduction in kickback is obtained. The bent
edge 51 of the safety projection 18i extends perpendicularly
to plane B, but may also extend in an inclined relationship
thereto. In addition, the bent edge 51 may be at a smaller or
larger distance from the tip 35i of the safety projection 18i.
With the saw chain in operation, safety link 12i rests with
the edge surface 23i of its bent safety projection 18i against
20 the side wall 52 of the kern 11 (FIG. 17). This also ensures
a high lateral stability and a smooth running condition of the
saw chain.
In the safety link 12j of FIGS. 18 and 19, not only the
safety projection 18j but also the end portion 44j are bent to
25 provide a widening 20j and 20j', respectively. As FIG. 19
shows, safety projection 18j and end portion 44j are bent in
opposite directions such that their edges 23j, 22j are
parallel to each other and to the outer sides 49j, 49j' of the
safety link. Preferably, the safety projection 18j and the
end portion 44j are bent at identical angles so that they are
~35~
parallel to each other. Depending on the location of the
safety link in the saw chain, either the safety projection 18j
or the end portion 44j bears with its respective end surface
against the side wall 52 of the kern 11. In both cases, a
high lateral stability and a smooth running condition of the
saw chain are obtained in addition to an increased thrust
pressure and a reduced risk of kickback.
The bent edge 51j of safety projection 18j may again
extend vertically to plane s or also in an inclined
relationship thereto. Also, the distance between the bent
edge 51j and the tip 35j of the safety projection 18j may be
larger or smaller than in the embodiment of FIG. 18. In the
embodiment shown, the bent edge 54 of the end portion 44j
extends at an acute angle to plane B. The bent edge 54 may
also extend parallel to plane B or at other angles thereto.
The distance between the bent edge 54 and the forward edge of
end portion 44j when viewed in the direction of movement 7 may
also be larger or smaller than in the embodiment of FIG. 18.
depending on its location in the saw chain, it is either
20 the edge 23j or the edge 22j of the safety link 12j that abuts
with its surface against the side wall 52 of the kern 11.
Thus, in addition to reducing the tendency of the saw chain to
produce a kickback condition, the widening 20j and 20j'
formed by the safety projection 18j and the end portion 44j,
I respectively, of this embodiment likewise afford a high
lateral stability and a very smooth running of the saw chain,
in particular in the presence of lateral forces acting on the
safety link or the saw chain.
The safety link ok of FIX. 20 differs from the
30 embodiment of FITS. 18 and 19 only in that the end portion 44k
16
So
is bent towards the same side of the safety link as the safety
projection 18k, each forming a respective widening 20k
and 20k'. The edges 23k and 22k of the safety projection 18k
and of the end portion 44k, respectively, are parallel to each
other and to the side surfaces 49k, 49k' of the safety link.
Preferably, the edges 23k and 22k are in a common plane. As
the saw chain moves around the guide bar, the safety link 12k
is braced with the edges 23k and 22k against the side wall 52
of the kern 11. High lateral stability and smooth running of
the saw chain may also be accomplished by material buildup at
the edge of the safety link.
FIGS. 21 and 22 show a safety link 12p and 12m,
respectively, that it made of a material having a
predetermined profile as shown. In the safety link 12p of
FIG. 21, the safety projection and/or the end portion are
widened at their upper linearly extending edge. The upper
edge is formed by the upper side 55 of a transverse bar 56
which extends at equal lengths over both sides 49p, 49p' of
the safety link 12p, thereby forming a widening 20p. The
I transverse bar 56 has a rectangular profile so that its side
surfaces 57, 58 are parallel to one another and to the outer
sides 4gp, 49p'. With the side surfaces 57, 58 of the safety
link 12p bearing against the side walls 52 of the kern 11, the
safety link is safely secured against the impact of lateral
forces.
The safety link 12m of FIG. 22 has also a transverse
bar 56m forming a widening 20m, with its sides 57m, 58m
blending into the outer sides 49m, 49m' via inclined
surfaces 59, 60. The width of the upper side 55m of
transverse bar 56m is greater than the thickness of the safety
35~7
link Transverse bar 56m, which extends in a straight line
over its entire length, is provided a-t the upper edge of the
safety projection and/or the end portion of the safety
link 12m.
The upper edge of the safety projection and/or of the end
portion of the safety link 12n of FIG. 23 is formed by
squeezing as shown at 61. This provides again a widening 20n
which ensures high lateral stability and smooth running of the
saw chain because the widened edge affords a large bearing
surface at the kern bottom which avoids the danger of
kickback.
As shown in FIG. 1, the safety links illustrated in
FIGS. 3 to 23 may be disposed ahead of cutting link 1, 1' when
viewed in the direction of movement 7 of the saw chain and on
opposite sides of the latter.' As a result, the cutting links
and their respective safety links 6, 6' are alternately on the
left and right sides of the saw chain. The safety links 6, 6'
take the place of connecting links, each interconnecting two
driving links 5, 5'.
However, it is also possible for the safety links 6, 6'
to be arranged on the same side as the cutting links 1, 1'
disposed ahead of the latter when viewed in the direction of
movement 7. The safety links 6, 6' may be configured as the
safety links of FITS. 3 to 23. On the side of the saw chain
US opposite the safety links 6, 6', a strap-like connecting
link 4, 4' is provided which interconnects two adjacent
driving links 5, 5' as does the safety link adjacent thereto.
As shown in FIG. 24, the safety links 6, 6' may also be
arranged in pairs ahead of corresponding ones of cutting
links 1, 1' when viewed in the direction of movement 7 of the
I
~35~7
saw chain. The safety links are located on opposite sides of
the saw chain, each interconnecting again two adjacent driving
links 5, 5'. The safety links 6, 6' of FIG. 24 may be
configured in accordance with the embodiments of FIGS. 3
to 23.
hen using the safety links of FIGS. 15 to 20, they may
be arranged in the saw chain such that their bent safety
projections and/or end portions face each other when viewed in
the longitudinal direction of the saw chain, as illustrated in
FIG. 25. In this arrangement, the safety links may be mounted
in the saw chain in accordance with FIGS. 1 and 24. It is,
however, also possible to mount the safety links according to
FIGS. 1 and 24 in such a manner that the bent portions of the
safety projection and/or of the respective end portion extend
outwardly so that the surfaces of their edges come to bear
against the side wall 52 of the kern 11.
It is also possible to provide a saw chain wherein the
function of the safety link is performed by the depth limiter
of the cutting link. In this embodiment, the depth limiter
has a widening formed thereon. The widening extends out
beyond at least one of the side surfaces of the depth limiter
an defines bearing surface means for supporting the cutting
link in the kern whereby the cutting links are prevented from
penetrating the wood too deeply so as to at least reduce
I kickback of the chain saw during operational use thereof.
accordingly, in this embodiment, it is the cutting link itself
which acts as a safety link.
It is understood that the foregoing description is that
of the preferred embodiments of the invention and that various
other changes and modifications may be made thereto without
19
35~37
departing from the spirit and scope of the invention as
defined in the appended claims.
