Note: Descriptions are shown in the official language in which they were submitted.
~ )42~33
ISRAEL AIRCRAFT INDUSTRIES LTD.
MINE-FIELD CLEARING APPARATUS ~lOUNTABLE ON A VEHICLE
FIELD OF THE IN~ENTION
The present in~ention relates to apparatus for
clearing mines, and more particularly to mine clearing
apparatus mountable on an armoured vehicle such as a tank.
BACKGROUND OF THE INVENTION
ij It is known in tank warfare to employ mine
clearing apparatus mounted on a vehicle for clearing a
path through a mine-field. Conventional mine clearing
apparatus which is mounted on armoured vehicles is
relatively cumbersome and often interferes with the
fighting ability of the vehicle. This is due to a number
of disadvantages. Firstly, once it is desired to pass
through a mine field, lowering the mine clearing apparatus
into ground engaging ~osition requires a manual operation
from outside the tank. Raising of the mine clearing apparatus
-' out of ground engaging position is sometimes done manuatly
and sometimes done by means of a hydraulic or elcctrical
lifter. The hydraulic or electric lifter is extremely
susceptible to failure and may be disabled even by small-
weapons fire. In such a case, the vehicle may be totally
. . .
- disabled in its mobility. Another difficulty with
conventional mine clearing apparatus is that in its raised
position, it interferes with the field of vision of the driver
of the vehicle and may also interfere with the positioning
of the cannon of an armoured vehicle such as a tank.
~ZO~Z83
-3-
SU~RY OF THE IN~ENTION
The present invention seeks to overcome
disadvantages and limitations of prior art mine clearing
apparatus and proYides mine clearing apparatus for
attachment to a vehicle comprising a Frame mountable onto a
vehicle for selectable positioning in a raised or lo~ered
orientation; apparatus for raising and shunting aside mines
mounted onto the frame, and apparatus for selectably
retaining the frame in a raised orientation and comprising
control apparatus operable from inside the vehicle for
releasing the frame from the raised orientation and allowing
it to assume the lowered orientation.
Further in accordance with an embodiment of the
invention, there is provided mine ~learing apparatus for
attachment to a vehicle comprising a frarne mountable onto a
vehicle for selectable positioning in a raised or lowered
orientation; apparatus for raising and shunting aside mines
mounted onto the frame; and apparatus for automatically
raising the frame from its lowered orientation to its raised
orientation in response to backwards motion of the vehicle.
Additionally in accordance with an embodiment of
the invention, the apparatus for raising and shunting aside
mines comprises a plurality of plow teeth which, in operation,
extend below the ground surface and first and second plo~l
sections, disposed one above another in hing~d engagement and
operative to lie in the same plane during operation and in
folded en~agement when the frame is in its raised orienta.ion,
so as not to interfere with normal tank operation.
2~33
-4-
Further in accordance with an embodiment of the
present invention, the raising and shunting apparatus also
comprises a gliding surface which supports the frame in its
lowered orientation. The gliding surface is provided with a
- front mine deflector ptate for deflecting mines in the path
thereof. The gliding surface may be provided with a retaining
member so as to prevent inadvertent engagement of the gliding
surface with treads of its supporting vehicle under certain
conditions of terrain.
1~l There is also proYided in accordance with an
embodiment of the present invention apparatus for clearir.g
mines comprising a frame mounta~le or,to a vehiclc for selec~J~le
positioning in a raised or lowered orientation, plow apparatus
for raising and shunting aside mines mounted onto the fra~e and
i- apparatus for automatically raising the plow from its lowered
orientation to its raised orientation in response to backwards
motion of the vehicle and including mounting apparatus rotatably
mounted onto the Yehicle, spring supporting apparatus mounted
onto the mounting apparatus and attached to the plow apparatus,
and tooth apparatus fixed onto the mounting apparatus and
arranged for selectable engagement with a vehicl~ tread, the
spring supporting apparatus being operative when the plow is in
its lowered orientation to urge ~he tooth apparatus into driven
ergagement with the vehicle tread whereby during backwards
-'; movement of the vehicle the mounting apparatus rotates in a
first direction, thereby extending the length of the spring
supporting apparatus, and increasing the spring force thereof
until a spring force is reached at a first position of the
mounting apparatus sufficient to raise the plow to its raised
~ 4Z~3
--5--
orientation. Continued rotation oF the mounting apparatus
raises the plow until it engayes a retaininy hook, and is
held stationary. Continued backwards movement of ~he vehicle
treads causes the mounting apparatus to continue to rotate in
the first direction increasing the length and spr~nq force
of the spring support until it passes a second position
defining a first dead point at which the longitudinal axis of
the spring supporting apparatus intersects the axis of rotation
of the mounting apparatus. After it passes the second position
1~ the mounting apparatus reaches a third position at which the
teeth are disengaged from the treads for free forward movement
driven by the spring ~orce of the spring supporting apparatus.
The mounting apparatus then rotates under the force of the
spring supporting apparatus for a fourth position at which
I; the teeth are totally disengaged ~rom the treads, and the
spring supporting apparatus is at a minimum length and spring
force.
Further in accordance with an embodiment of the
invention, the spring supporting apparatus comprises first and
second springs having different spring constants arranged in a
series arrangement.
Additionally in accordance with an embodiment of the
present invention, at least one of the springs comprises a disk
or belleville spring.
Further in accordance with an embodiment of the present
invent;on, the tcoth apparatus comprises two tee~h, one of which
engages the vehicle treads when the frame is in the lowered
orientation upon the onset of backwards motion and the other of
~04Z~3
-6--
l which becomes disengaged from the vehicle treads upon traversal
of the third position, in order to permit spring driven
rotation of mounting apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be more fully understood
and appreciated from the following detailed description taken
in conjunction with the drawings in which:
Fi 9 . 1 i s a top view illustration of mine clearing
- lO apparatus constructed and operative in accordance with an
embodiment of the present invention;
Fig. 2 is a side view illustration of t~e apparatus
of Fig. l in a lowered orientation;
Fig. 3 is a side view illustration of the apparatus
of Figs. l and 2 in a partially lowered orientation;
Figs. 4A and 4B are respective views of a locking
mechanism forming part of the apparatus of Figs. 1, 2 and 3
in respective locked and unlocked orientationsi
Fig. 5 is a top ~iew illustration of an alternate
embodiment of mine clearing apparatus constructed and operative
in accordance with the present invention;
Fig. 6 is a side view illustration of the apparatus
of Fig. 5 in a lowered orientation;
Fig. 7 is a side Yiew illustration of the apparatus
of Figs. 5 and 6 in a partially raised orientation;
Fig. 8 is a side view illustration of the apparatus
of Figs. 5-7 in a raised orientation with the sprin~ support
apparatus at a first dead point orientation; and
Fig. 9 is a side view illustration of the apparatus
of Figs. 5-8 in a raised orientation.
~4~3
--7--
DETAILED DESC~IPTIO~ OF THE INVENrION
Reference i5 now made to Figs. 1 - 3 which illuctrate
mine clearing apparatus constructed and operatiYe in accordance
with an embodiment of the present invention. The present
description is presented with particular reference to mine
clearing apparatus which ;s mountable onto a particular type
of tank, the M-60 Patton. It is appreciated that this is
entirely for the purpose of illustration and that the ir,vention
is applicable to sLmilar types of vehi.cle.
As seen in the illustrations, the mine clearing
apparatus comprises a frame 10 including a pair of identical
side portions 12 which are joined at their front end by a cross
bar 14 and at their rear end support an axle 16. Frame lQ
is rigidly mounted onto an armoured vehicle such as a M-60 tank
in the illustrated embodiment by engagement of pins 17 located
at side portions 12 with towline lugs fixed onto the tank.
Ridigity of mounting is provided by bolts 18 which engage the
underside of the tank and force mounting plates 20, fixedly
mounted onto side portions 12 on the opposite side of pins 17,
into tight engagement with the underside hull of the tank.
First and second arms 22 and 24 are independently
rotatably mo~nted onto axle 16 and extend forwardly thereof
in generally parallel planes. Arms 22 and 24 are strengthened
by reinforcing elements 26 and 28 respectively which are
fixed at one end thereof to the respective arms and are
rotatably mounted by means of clamps 30 and 32 onto axle 16.
~204Z~3
-8-
Rigidly mounted onto each of arms 22 and 24 is a
mine plowing assembly 3~. Mine plowing assembly 34 comprises
main plow portion 36, of generally elongate configuration and
concave cross section.
The general configuration of main plow portion 36
may be similar to that of an ordinary vehicle powered sn~w
plow. Disposed above main plow portion 36 and hinged
thereonto is an auxiliary plow portion 38. Auxiliary plo~
portion 38 has two positions, a lowered position in which it
u extends forwardly of the surface of main plow portion 36 and
a raised position in which it defines an upper continuation
of the surface of the main plow portion 36. This hinged
construction is to obviate the problem of interference with
a driver's field of vision or with the range of operation
Ir, of the armament on a tank. Towards this end, the hinged
auxiliary plow portion 38 may be lowered when the plowin~
assembly 34 is in its raised orientation.
Disposed below main plow portion 36 there are
provided a plurality of vertically disposed planar blades 40,
2(; whieh during operation are disposed below the ground surface.
The horizontal spacing between adjacent vertical~blades is
selected to be such that anti-vehicle mines will of necessity
be engaged thereby. The blades are provided with an inclined
forward surface, so as to raise mines located under the ground
~: surfaoe into engagement with main ~low portion 36, so that
they may be plowed aside.
42~3
g
I A desired depth of operation for blades 40 is
determined by means of a gliding surface assembly 42 which
is articulatedly mounted onto each of arms 22 and 24~
The gliding surface assembly 42 comprises a sled 44 which is
- arranged to slide on the ground surface and is formed at its
front with a vertical blade 47 for deflecting mines to the
side thereof. Sled 44 is rotatably mounted onto a cam slot
of a mounting plate 46. Mounting plate 46 is mounted in turn
onto a mounting element 48. It is appreciated tha.t sled 44
( is permitted to undergo a somewhat complex articulated
motion in a single plane within limits defined by the
respective cam paths. This mounting arrangement permits
selectable adjustment of the penetration depth of the plowing
assembly 34 and also permits the sled 44 to be folded when
the plowing assembly is in its raised orientation to eliminate
interference with operation of the tank.
A chain 50 e~tends from each auxiliary plow portion 38
to a location on the tank hull or onto frame 10. The length
of the chain 50 is selected such that it is slack when the
plowing assembly is in its raised orientation but becomes tight
when the plowing assembly is lowered, thus pulling on
auxiliary plow portion 38 and orienting it towards a generally
vertical orientation. The full raised orientation of the
auxiliary plow portion 38 is reached only when soil being plowed
'j is forced thereagainst~
Reference is now made additionally to Figs. 4A and 4B
which together with Figs. 1 - 3 illustrate apparatus for
retaining the arms in their raised orientation and for
:~XQ42~33
-10-
selectable release thereof. A hook member 60, is pi~otably
mounted about an axis 62 onto each side portion 12 and
comprises a socket portion 64 located at one end thereof
and a roller portion 66 at another end thereof and ha~ing
~- mounted thereon a roller 68. A selectable release lever 7Q
is pivotably mounted onto each side portion 12 about an
axis 72 and defines first and second roller su~por' shoulders
74 and 76. A spring 78 joins hook member 60 and release
lever 70, urging lever 70 into seating engagement with roller
l'~ 68 at one of shoulders 74 and 76. A cab1e connection 80
is pro~ided to the interior of the vehicle, such that pulling
on the cable is operative to provide counter-clockwise
mo~ement of lever 70 about its pivot axis 72 (as seen in
Figs. 4A and 4~).
lL The operation of the apparatus described hereinabove
will be understood from a consideration of Figs. 4A and 4B.
Fig. 4B shows a retainer roller 82 which is fixedly mounted
onto each of arms 22 and 24 about to engage socket portion 64
and moving in an arc illustrated by an arrow 84. Engagement
7G of roller 82 with a surface 86 of the socket portion forces
the hook member to pi~ot in a clockwise direction about its
pi~ot axis 62 (in the sense of Figs. 4A and 4B). Due to the
action of roller 68 against hook member 60, and the subsequent
tendency of hook member 60 to rotate in a counterclockwise
direction in response to the effect of gravity on roller 82
and the massive plowing assembly attached thereto, roller 68
seats on shoulder 76 and is thus prevented from further
counterclockwise rotation into an upen orientation.
~2~Z~3
-11 -
Roller 82 is thus securely engaged by hook member 60 and arms
22 and 24 are maintained in their respective raised
orientation, provided that lever 70 remains in the seated
position (Fig. 4A).
When it is desired to lower arms 22 and 24 to ~heir
respective lowered, ground engaging orientations, it is
sufficient to pull on respective cables ~0 from the safety
of the driver's compartment. Pulling of cables 80 causes
the lever 70 to pivot in a counterclockwise direction and
out of supporting engagement with roller 68. Hook member 60
is then free to rotate in a counterclockwise direction about
its pivot such that pin 82 is released, thus allowing arm 22
or 24 as the case may be and the associated mine plowing
assembly 34 to fall by gravity into their respective lowered
orientations ln engagement with the ground. Meanwhile, under
the influence of spring 78, roller 68 seats on support
shoulder 74. It is appreciated that the particular cons~ruction
of the hook member 60 and of the lever 70 enable the release
of the mine plowing assembly to be achieved with relatively
little pull force on cable connection 80.
Reference is now made once again to Figs. 1, 2 and 3
which also illustrate apparatus for automatically lifting the
mine plowlng assembly. There are provided two installations
of such apparatus, corresponding to the two mine plowing
assemblies. The apparatus for automatically lifting the mine
plowing assembly cbmprises a freely rotatable d;sk 90 which is
bearing mounted onto a mounting member 92 which is bolted
onto a tension wheel 94 of a tank. Tension wheel 94 engages
.
1~042~
-12-
the tread of.the tank and maintains it at a desired tension.
Mounted on an outer facing surface of disk 90 are three
outer pins 95, 96 and 97 and an inner disposed pin 98.
Mounted on an inner facing surface of disk 90 is a tooth 100
'i which is disposed ordinarily out of engagement with corresponding
interstices defined between pla~es of the tank trea(l.
Mounted on pin 95 is a lifting chain 99 which is
attached at its other end to a location 102 fixed onto main plow
portion 36. Mounted on pin 98 is a spring 104 which is attached
i at its other end to main plow portion 36. Spring 104 is
operative when in the orientation illustrated in Fig. 2 to urge
disk to rotate about its axis 91 in a clockwise direction
(in the sense of Fig. 2). This rotation brings tooth 100 into
driven engagement with corresponding interstices between plates
l~ of the tank tread. As soon as the tank is moving forward,
this engagement produces only a clicking action as engagement
with the interstices between the plates of the tank tread tend
to move the tooth 100 in a counterclockwise direction, while
the spring 104 snaps the tooth back in a clockwise direction.
; The apparatus for automatically lifting the mine
plowing assembly described above is operative upon reYerse
motion of the tank wi~h the mine plowing assembly in a lowered
orientation. As the tank treads move in a backwards direction
tooth 100 engages one of the interstices between adjacent plates
- thereof and is driven together.. with disk 90 in a clockwise
direct.ion thereby causing chain 99 to wind about pins 96 and 97,
with the result that the chain pulls the plowing assenlbly 34
upwardly until roller 82 engages hook member 60 in locked
engagement for retaining the arm and associated plowing
assembly in a raised orientation.
~2Q~Z~3
-13-
Continued backwards motion of the tank tends to
continue to drive tooth 100 and disk 90 in a clockwise motion.
Once plowing assembly 34 is locked by hook member 60, chain 99
cannot move forward in the clockwise direction and thus disk 90
is prevented from progressing in this direc~ion. As a result,
toulh 100 repeatedly engages one of the interstices of the
tread plates and is pulled forward, only to be snapped back
by the action of chain 99. This iifts the tread plate slightly
and bangs it down, producing a significant noise which signals
!~ to the operator to terminate backwards motion.
Once forwards motion is commenced, tooth 100 enga~es
one of the interstices of the tread plates and is mK)ved in a
counterclockwise direction until it reaches a location at which
the treads tend to disengage therewith. Since the orientation
i of spring 104 has passed its dead spot due to the raised
orientation of plowing assembly 34, spring 104 is operative to
urge the tooth 100 and disk 90 to undertake further counter-
clockwise motion until tooth 100 is totally disengacled from the
tank treads. This orientation remains until the plowing
2b assembly is lowered, at which time, spring 104 is again
reoriented and urges the disk 90 into the orientation shown in
Fig. 2.
A limit chain 110 is provided for attachment between
frame 10 and each of arms 22 and 24 to prevent arms 22 and 24
.,
from falling beyond a certain limit in the event that a sudden
drop in the ground level is encountered, as such a drop could
otherwise bring the plowing assembly into engagement with the
tank treads.
283
-14-
It is noted that the plowing assembly enga~es the
ground surface in the Yicinity of the treads and outwardly
thereof. In order to protect the intermediate portion of the
tank from mine damage, a weighted chain 120 is mount:ed between
... the two plowing assemblies to engage and detonate any mines
that are encountered at a safe distance from the tank.
Reference is now made to Figs. 5 - 9 which
illustrate an alternate embodiment of the mine clearing
apparatus constructed and operative in accordance with the
1~ present invention. Like numerals in Figs. 5 ~ g ancl Figs. 1 -4
indicate 1ike elemen~s.
The mine clcaring apparatus of Figs. 5 - 9 also
comprises a frame 10 including a pair of identical side portions
12 which are Joined at their front end by a cross bar 14 and
t at their rear end support an axle 16. Frame 10 is rigidly
mounted onto an armoured vehicle such as an M-60 tank in the
illustrated embodiment by engagement of pins 17 located at
side portions 12 with towline lugs fixed onto the tank.
Rigidity of mounting is provided by bolts 18 which engaae
'~' the und~rside of the tank and force mounting plates 20, fixedly
.mounted onto side portions 12 on the opposite side of pins 17,
into tight engagement with the underside hull of the ~ank.
First and second arms 22 and 24 are independently
rotatably mounted onto axle 16 and extend forwardly thereof
~`' in generally parallel planesO Arms 22 and 24 are strengthened
by reinforcing elements 26 and 28 respectively which.are
fixed at one end thereof to the respective arms and are
rotatably mounted by means of clamps 30 and 32 onto axle 16.
~2~4Z,~3
-15-
Rigldly mounted onto each of arms 22 and 24 is
a mine plowing assembly 34. Mine plowing assembly 34 comprises
main plow portion 36 which is substantially identical to
that described in connection with Figs. 1 - 4. Disposed
i above main plow portion 36 and hînged thereonto is an
auxiliary plow portion 38, substantia71y identical with that
described hereinabove.
Disposed below main plow portion 36 there are
provided a plurality of vertically disposed planar blades 40,
which during operation are disposed below the ground surface.
The horizontal spacing between adjacent ver~ical blades is
selected to be such that anti-Yehicle mines will, of neoessity,
be engaged thereby. The blades are provided with an inclined
forward surface, so as to raise mines located under the ground
l~ surface into engagement with main p~ow portion 36~ so that
they may be ptowed aside.
A desired depth of operation for blades 40 is
determined by means of a gliding surface assembly 42 which
is articulatedly mounted onto each of arms 22 and 24. The
;' gliding surface assembly 42 comprises a sled 44 whioh is
arranged to slide on the ground surface and is formed at its `
front with a vertical blade 45 for deflecting mines to the
side thereof. Sled 44 is rotatably mounted onto a cam slot
of a mounting plate 46. Mounting plate 46 ~s mounted in turn
onto a mounting element 48. It is appreciated that sled 44
is permitted to undergo a somewhat complex articulated motion
in a single plane within limits defined by the respective
cam paths. This mounting arrangement permits selectable
~2()4Z~3
-16-
adjustment of the penetration depth of the plowing assembly 34
and also permits the sled 44 to be folded when the plowing
assembly is in its raised orientation to eliminate inte~ference
with operation of the tank.
A chain 50 extends from each auxiliary plow portion 38
to a location on the tank hull. The length of the chain 50
is selected such that it is slack when the plowing assembly is
in its raised orientation but becomes tight when the plowing
assembly is lowered, thus pulling on auxiliary plow portion 38
lu and orienting it towards a generally vertical orientation.
The full raised orientation of the auxiliary plow portion 38
is reached only when soil being plowed is forced therea~ainst.
The locking mechanism of Figs. 4A and 4B also act
as described hereinabove with the apparatus of Fj95Q 5 - 9
l~ to retain the arms in their'rais~d orientation and to
selectably release them.
Reference is now made again to Figs. 5 - 9 which
illustrite an apparatus for automatical'ly lifting the mine
plowing assembly. ~here are provided two installations of
2fi such apparatus, corresponding to the two mine plowing
assemblies. The apparatus for automatically lifting the mine
plowing assembly comprises a freely rotatable disk segment l90
which is bearing mounted onto a mounting member 192 which is
bolted onto a tension wheel 194 of a tank. Tension wheel 194
engages the tread of the tank and maintains it as a desired
tension,. Mnunted on an outer facing surface of disk segment l90
at a first radius from the pi~ot,location 193 about which the
disk segment rotates, is a mounting pin 195. Mounted on an
12~2~3
-17-
edge surface of disk segment 190 are first and second spaced
teeth 196 and 198 which selectably engage the interstices
defined between plates of the tank tread in accordance with
an embodiment of the invention.
,Spring supporting apparatus 199 comprises a spring
housing 200 which is rotatably mounted at a first end thereof
onto mounting pin 195.and a spring compressing rod 205 which
is connected at an exterior end thereof to a location 202 fixed
onto the main plow portion 36. Spring supporting apparatus
i' 199 may be generally described as comprising a spring loaded
extensible support member formed of elemen~s 200 and 205
and comprising first and second springs 201 and 203 arranged
in a series arrangement. Springs 201 and 203 preferably have
greatly di~ferent spring forces. Typically, spring 201 is
l'~ an ordinary hea~y duty co;l spring while spring 203 comprises
a series of independent disk or belleville springs which are
characterized in that they undergo complete compression at a
compressive force of about 7 ton. It is appreciated that any
other suitable spring arrangement may be employed alternatiYely
, . . .
and that the arrangement of apparatus 199 is such that
extension of apparatus 199 produces compression of springs 201
and 203.
The operation of spring supporting apparatus 199 and
of the entire apparatus for aùtomatically lifting the mine
plowing assembly will now be described with reference to
Figs. 5 - 9.
~ 4Z~3
-18-
In order to understand the operation of the
automatic lifting apparatus, it is necessary to appreciate
the details of construction of disk segment 190 and the
relati~e positions of teeth 196 and 198 and pin 195 thereon
As seen in the drawings, the direction of motion of the tank
treads during reverse motion of the tank is indicated by an
arrow 204. Upon engagement of at least one teeth 196 and 198
with the tank treads, the disk segment 190 is caused to rotate
in a clockwise direction, indicated by an arrow 206 about pivot
location 193. ~ith respect to this direction of rotation,
indicated by an arrow 207, pin 195 leads tooth 196 by about
20 and tooth 196 leads tooth 198 by about 90.
Fig. 6 shows the plowing assembly in a fully
lowered plowing orientation prior to enga~ement of tooth 196
with the tank treads. In this orientation, spring 201 is
compressed to about one-half of its maximum length. This is
the orientation during forward mine clearing operation of
the tank.
When it is desired to raise the mine clearing
apparatus to a raised orientatlon, the tank simply shifts to
reverse motion. Due to the position of tooth 196 which is
pressed against the tank tread during motion in a forward
direction as illustrated in Fig. 6, reverse motion of the tank
tread in a direction indicated by arrow 204, tends to draw
tooth 196 into driven engagement therewith, causing clockwise
rotation of ~isk segment 190 in a direction indicated by
arrow 207. An initial backwards movement of the tank causes the
blades 40 to lie on the ground surface instead of being buried
partially therebelow.
~Z(~2~33
-19-
Continued backward motion of the tank and consequent
clockwise rotation of disk segment 190 causes the length of
supporting apparatus 199 to increase until sprina 201 is fully
compressed, as seen in Fig. 7. It is a particular feature of
the invention that the force required to fully connpress
spring 203 is greater than the force required to lift the
plowing apparatus. Consequently9 further backwards n~tion
of the tank and clockwise rotation of disk se~ment 190 causes
lifting of the plowing apparatus to a fully raised orientation.
At the fully raised orientation roller 82 engages hook
member 80 in locked engagement for retainîng the arm and
associated plowing assembly in the raised orientation and
preventing further upward movement thereof.
It may ~e apprecia~ed that a series combination of
a relatively weak spring 201 and a relativeiy stronn spring 203
are employed in spring support apparatus 199 for a number of
reasons. One reason is to present a relatively weak spring
force during plowing operation so as not to force tooth 196
against the tank tread with excessive force during plowing
,........ .
operations which could cause excessive wear of tooth 196.
A second reason is not to cause inadvertent disengagement of
the plowing apparatus from the soil due to the force of spring
support apparatus 199. The strong spring 203 is, however,
predominant during the lifting operation. As seen in Fig. 7,
the weak spring 201 is quickly fully compressed at the
beginning of the lifting operation and this is neutralized,
allowing the spring force of the strong spring 203 to
predominate.
12~4283
-20-
It is also appreciated that the provision of a
spring element such as spring 203 is very desirable in the
apparatus since it provides the needed flexibility in the
couplin~ apparatus to enable locking of the plowing apparatus
in its raised position under different conditions, such as
different positions of the tank tension wheel and thus of
pivot location 193 during operation.
With continued backwards movement of the tank
treads, the disk segment 190 continues to rotate due to ~he
engagement of tooth 198 with the treads, even after tooth 196
becomes dlisengaged therefrom. This continued rotation
combined with the immobility of the plowing assembly due to
its raised locked orientation cuases spring 203 to become
compressed. Maximum compression occurs at an orientation
iliustndted in Fig. 8, wherein the longitudinal axis of spring
supporting apparatus l99 intersects the axis of rotation of
disk segment l90 at pivot location l93. The orientation
illustrated in Fig. 8 represents a dead point at which the
spring supporting apparatus does not urge rotation of the
disk segment l90 in either direction. Once disk segment l90
moves even slightly oYer the dead point orientation of Fig. 8,
the spring force of the spring supporting apparatus 199 urges
clockwise rotation of the disk segment l90. Further rotation
of the disk segment l90 in response to further movement of
the tank tread in a backwards direction is operative to permit
disengagement of tooth 198 from the tread. The spring force
of springs 201 and 203 is then operative to snap the disk
segment l90 in further clockwise motion to a final orientation,
-
4Z83
-21-
illustrated in Fig. 9, wherein the spring force of t;he sprins
supporting apparatus 199 is at a minimum and the teeth 196
and 198 are fully disengaged from the tank tread. Rod 205
defines the minimum length of apparatus 199.
The click of decompression of the springs 2Ql
and 203 provides a noise sensible to the driver of t;he tank,
indicating to him that he can commence forward motion of the
tank with the plowing assembly in a raised orientation.
A limit chain is provided for attachment between
frame 10 and each of arms 22 and 24 to prevent arms 22 and
24 from falling beyond a certain limit in the event that a
sudden drop in the ground level is encountered, as such a
drop could otherwise bring the plowing assembly in~o
engagement with the tank treads.-
It is noted that the plowing assembly engagesthe ground surface in the vicinity of the treads and
outwardly thereof. In order to protect the intermediate
portion of the tank from mine damage, a weighted chain 120
is mounted between the two plowing assemblies to engage
and detonate any mines that are encountered at a safe
distance from the tank.
It will be appreciated by persons skilled in the
art th~t the invention is not limited to what has been
particularly shown and described hereinaboYe. Rather, the
scope of the invention is defined only by the claims which
follow:
