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Патент USA US2405334

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AW»
9 1%
w. H. SILVER
AUTOMATIC‘ DEPTH CONTROL‘ FOR AGRICULTURAL IMPLEMENTS
Filed June 19', 1941
-
INVENTQR
I WALTER H. SILV
.
Patented Aug. 6, 1946
2,405,334
UNITED STATES ‘PATENT OFFICE
2,405,334
AUTOMATIC DEPTHCONTROL FOR
AGRICULTURAL IMPLEMENTS
Walter H. Silver, Moline, 111., assignor to Deere &
Company, Molina, 111., a corporation of Illinois.
Application June 19, 1941, Serial No. 398,781
14 Claims. (Cl. 97-50)
1
2
The present invention relates generally to ag
this invention, incorporating a plowing imple
ricultural machines and more particularly to
ment in which the plow beam is connected with
the tractor at a hitch point and is capable of
relatively free floating movement relative to the
tractor.
Referring first to Figure 1, which shows one
ground working implements in which ground
working tools are provided.
The object and general nature of the present
invention is the provision of depth controlling
means deriving operating energy from the trac
tor engine and automatically responsive to
changes in the depth of operation of the tool or
D
form of the present invention, the reference nu- ~
meral I indicates in its entirety a farm tractor
having a motor 2 of conventional construction,
tools, whereby substantially constant depth of 10 the transmission housing of which is connected
operation maybe maintained automatically at
to a rear axle housing 3 carrying axle shafts 4
any desired depth. More speci?cally, it is a fea
on which rear wheels 5 are fixed. The tractor I
ture of this invention to provide an implement
serves as a mobile support or supporting frame
having a movable ground engaging shoe or gauge
for ground working units of various kinds. A
member, movement of which relative to the im
pair of brackets 8 are ‘bolted, as at H, to the
plement automatically controls the application
rear axle housing of the tractor‘ and provide a
of power from the tractor to the depth adjusting
support for a bell crank 9 which is preferably
mechanism so that if it should occur that the
mounted on a pivot shaft I0 supported by the
tools momentarily tend to run deeper or more
brackets B. Secured to the lower portion of
shallow than the desired setting, the mechanism 20 the rear axle housing are a pair of draft angles
is operative to readjust the depth controlling
I'2 between which the front end of a plow beam
means so as to momentarily readjust the depth
[3 is pivoted, the plow beam l3 preferably con
of operation so as to bring the tools back to the
sisting of two forwardly diverging members sim
desired position.
ilar to the lister plow shown in my co-pending
A further important feature of this invention 25 application, Serial No. 314,821, ?led January 20,
is the provision of atomatic depth gauging mech
1940, now U. S. Patent 2,354,886, issued August
anism which includes parts extending through or
1, 1944. The rear end of the plow beam l3 curves
passing near the axis of relative movement be
downwardly and is pivoted, as at IE, to a furrow
tween the implement and the tractor so that the
opener indicated in its entirety by the reference
source of power on the latter may be made ef 30 numeral l6. Preferably, the pivot I5 is formed
fective to control the depth ‘of operation of the
at the lower end of a standard l8 that is ?xedly
implement but without in any way affecting the ‘ secured to the frog of the furrow opener 16. A
freedom of movement of the implement relative
gauge wheel 20 is journaled on an axle 2] that
to the tractor which propels it. It is also a fea
'is carried by a pair of brackets 22 suitably con
ture of this invention to utilize the depth con
’ nected 'with the plow bottom or furrow opener
trolling mechanism which also does not interfere
l 6 and/or its standard 18. The upper end of the
with the freedom of movement of the tool or
latter carries pivot means '25 on which a sleeve
tools relative to the tractor.
26 is carried, and the latter adjustably receives
These and other objects and advantages of the
the rear end of a link 28. The forward end of
present invention will be apparent to those skilled 40 the latter is pivoted, as at 29,. to one of the arms,
in the art after a consideration of the following
indicated at ‘3|, that form the bell crank 9 men
detailed description taken in conjunction with
tioned above.
the accompanying drawing which shows illustra
From the description so far it will be seen that
tive embodiments of this invention.
the furrow opener IB is connected for relatively
In the drawing:
" free ?oating vertical movement with respect to
Figure 1 is a side view of a tractor plow in which
the tractor I since the members [3 and 28 are
the tool means is connected with the tractor by
each pivotally connected to the tractor and to
a pair of vertically spaced links which pivot rel
the standard I-8 at vertically spaced points. In
ative to the tractor so as to permit the tool means
this respect, therefore, the plow beam 13 serves
to ?oat relative thereto, with means on the trac 50 as a link member cooperating with the link mem
tor for adjusting the operating depth and auto
ber 28 and the two link members serve generally
matic gauge means responsive to changes in the
as draft, means or hitch means for connecting
operating depth for controlling the depth ad
the furrow opener l6 and its standard It to the
justing means;
'
tractor. Mechanismcf this kind for ?oatingly
Figure 2 is a side view of a modified form of 56 connecting a furrow opener to a tractor or other
_ 2,405,334
5
moves the lever 5| to its full line position (Figure
1),,which shifts the valve 1I into a position ad
.mitting ?uid to the rear side of the piston 6|,
which causes the piston rod 62 to move to the
right (Figure 1) thus ?rst tipping the point of the
plow bottom I6 upwardly and subsequently rais
6
' wardly and downwardly about its pivotal connec
tion with the angles I2, carrying with - it the
gauge shoe 35 without causing any change in the
linkage between the arm 43 and the hydraulic
unit 60. By virtue of this arrangement, I am en
abled to carry the power actuating depth con
ing the plow I0 bodily into a transport position.
trol on the tractor with the depth responsive
During this movement of the plow bottom the
gauging member on the implement while at the
ground engaging member 35 remains on the
same time permitting the implement to have free
ground, thus moving in a counterclockwise direc 10 vertical ?oating movement with respect to the
tion (Figure 1) relative to the plow beam I3, un
tractor at all times, thus enabling the out?t to ne
til a stop 13 on the arm 45 engages an adjacent
gotiate irregular terrain without in any way los
portion of the tractor, which then limits further
ing the advantages of automatic depth control.
movement of the ground engaging member 35 in
Figure 2 shows another form of the present in
, a counterclockwise direction relative to the plow 15 vention in which the depth responsive means
beam I3. During such movement of the member
serves automatically to maintain the plow bottom
35 relative to'the plow beam I3, the connected
at the desired depth of operation. Referring
.linkage also moves, including the arm 50, but
now to Figure 2, the reference numeral IOI indi
since the detent 52 is out of the notch 53, the
cates a farm tractor of conventional construction.
movement of the arm 50 and associated parts now 20 The tractor includes a motor I02. The imple
has no control of the valve 1I. Hence, as long as
ment is indicatedby the reference numeral I05
thehand lever 5| remains in the position shown
and includes a furrow opener I06 of the mold
in full lines. in Figure l, the plow I0 will be raised,
board type secured to the rear end of a plowbeam
It is desirable, however, to limit the upward move
I01. The plow beam extends forwardly under
_ ment of the tool, and to this end I mount a stop
, neath the rear axle of ‘the tractor IOI and has
lug BI on the rear portion of the piston rod 62,
its forward end pivotally connected to a bell'
and when the plow bottom I6 reaches its upper
crank, indicated in its entirety by the reference
position, the lug 8| comes into contact with
numeral H0. The latter is supported for rock
the arm 5I , moving it to the rightand thus mov
ing movement on a bracket II2 suitably ?xed to
ing the valve 1I to a neutral or piston locking 30 the tractor, and one arm II3 of the bell crank
position.
“When it is desired to lower the plow into an
operating position, the operator moves the hand
lever 5I forwardly, thus actuating the valve H
and introducing pressure onto the forward side
of the piston 6|, which forces the piston rod 62
rearwardly and lowers the plow. As the plow low
ers, the ground engaging member 35 is ?rst low
ered into contact with the ground, and then sub
I I0 extends rearwardly and pivotally receives the
front end of the beam I01. The latter is there
fore capable of rising and falling relative to the
tractor by movement around the pivot axis H4.
The bell crank III], and particularly the arm II3
thereof, serves as hitch means connecting the
front end of the plow beam I01 with the tractor.
A hydraulic power unit 50a, preferably identical
for all practical purposes with the hydraulic unit
sequently moves in a clockwise direction relative 40 00 described above, includes a piston rod 62a
to the plow beam and hence actuates the link
which is connected by a link I I5 to the upper end
age. This motion continues until the correspond
of the arm II1 of the bell crank IIEI so that the
ing movement of the arm 50, which is counter
latter may he rocked by the application of power
clockwise (Figure 1) when the plow bottom is
from said hydraulic unit 50a. Rocking move
lowering and the ground engaging element 35
ment of the bell crank IIO thus serves to raise
moving in a clockwise direction relative thereto,
brings the notch 53 into a position to be reen
gaged with the detent 52. When this occurs the
and lower the front end of the plow beam I01,
causing the furrow opener I05 to operate at an
increased or at a decreased depth of operation.
The valve 1Ia controlling the operation of the
hand lever 5| is then reconnected to the arm 50,
and the next increment of movement of the latter 50 hydraulic unit 50a is connected by means ofa
acts through the arm 5| to move the valve 1I
link I2I to a, hand lever I22, the lower end of
rearwardly from its forward or lowering position
which is pivoted to an arm I23 which, like the arm
to its neutral or holding position. This termi
50 described above, is formed as a sector having a
notch I24 with which detent mechanism on the
nates the lowering movement of the plow bottom
so that subsequent operations take place with
hand lever I22 is adapted to engage so as to lock
the bottom automatically controlled so as to be
the hand lever I22 to the sector I23. This is the
normal position of the hand lever I22 and is
maintained at that depth. It will be noted that
shown in Figure 2 in dotted lines. The lower end
the hand lever 5| is actuable when it is desired
of the arm I23 is connected by a link I26 to a
to raise or lower the plow and that it is unneces
sary to change the adjustment effected by the
position of the adjusting lever 41.
- Reference above was made to the fact that
sector I21 which is pivoted, as at I28, to the plow
beam I01. A ground engaging element I29 is
also pivoted on the plow beam I01 at I28 and has
its upper end formed with or carrying a hand
.the pivot connection between the forward end
lever I30 which is provided with detent mecha- '
of the link 39 and the arm 43, which is mounted
on the tractor, is in substantial alignment with 65 nism I3I adapted to latch the lever I30, and the
ground engaging element I29, to thc sector I 21.
the pivot connection between the forward end
It will be noted that the forward pivotal connec
of the plow beam I3 and the tractor carried angles
I2. This is an important feature of the present
tion of the link I26 with the arm I23 is disposed
invention, inasmuch as it permits the plow bot
not far above the level of the pivot H4 and is
tom I6, including the links I3 and 28, to move up 70 generally adjacent the pivot connection between
wardly and downwardly as the tractor passes
the forward end of the beam I 01 and the tractor,
over irregularities in the ground surface without
whereby when the plow beam I01 Swings upward
in any way interfering with the maintenance of
ly or downwardly there is relatively little pivoting
the desired operating depth by the gauge shoe 35;
in; other words, the plowbeam I3 can swing up 75
of the sector I21 on its pivot I 28.
.
‘The, gauge arm I29 operates to maintain the
i8
'~pl'ow>'1l 06 »‘ atl substantially; a ‘constant depth; and
'- tool ‘and relatively free‘ ?oating movement of-ithe
=-in doingaso functions approximately the-samelas _
’ “implement relative > tosaid' propelling unit; gaug
1 the‘ gauge-v shoe-35 described; above.
If- the plow
.4ing means movably connected with~»'-said--imple
i‘bettom ~ l|l6~should tend-to run- deeper or Jmore
rment and movable [relative thereto-when the-op
‘ shallow than’itheidepth that ‘corresponds to» set .. 5 ~ eratinglidepth or -..said tool» varies, I controllable
--'ti-n‘gofthehand'lever- 1-30 on the sector I21, the
1 latter; acts through the link 125,-the arm ‘I 23, and
vthe-‘lever i22,~which is normally latched- to the
means 'onesaid propelling- unit connected'vwith
‘said implement‘ for tipping the pointof said tool
upwardly ordownwardlyso- as-to tend to decrease
- or increase-the depth of operation; means con
» ‘hydraulic lunitz 60m ‘to’ raise orilower the rear end i 10 nected-with’ said controllable means» for . control
ling - the. latter, and means connecting said con
' v‘of th'eibell" crank arm" H3.
1' arm“ l23,- to cansepthelvawe ‘Ha to readjust the
vln'orderitolift‘ the plow-"I06 to inoperative po
sitiomImeanssuchas-a-‘fleaiible cable 135 having
"afrearise‘cti'on i36,1passing‘over'aY-‘sheave ‘I31 on
lthef "tractor; connects-the upper-armv l l1'~of ' the 1
ilbellcrank'l mwith aibell crank I38~that is mount
ed for: rocking‘ movement on‘ the ‘rear portion‘ of
trolling means with saidgauging means and op
. erable bytmovementof .thelatt'er relative to said
tool
response tocan increase or a decrease in
15: the operatingudepthofsaid tool tooperatesaid
controllablemeansand.tip the point. of said tool .
upwardly orf downwardly, respectively.
'lthe‘ tractor. lTheibelifcranki [>38 includes‘a rear
"2. An . agriculturalimplement adapted:..~to‘;.be
Ja‘rm' ‘I 39~which is connected'lby» a normally slack
connected ' with ; a ‘.tractor having » a iSOHI-CGJ-Of
chain I‘llllidirectlyto the plowibeam Hi1.
iW-hen-it desired to raise the ‘plow into trans
port: position, the operator unlatches the hand
1- _ leveri l2 2' from-the notch~ 124 and moves the lever
'i'l-il'from its'dotted line position‘ '(Figure2) back
Tito itsirfiill line position. “This moves the valve
f'llalinxa position to cause the hydraulic unit 6011
i'tolforce l-thewpist'on‘i?a forwardly. A'This ?rst
‘ rocks'mhekbeu' crank l'l? inla' clockwise direction
_(Figure*l'2);?which has-atheleifectxof causing the
O power; said implement having a front end and
comprising ground working. tool :means - ?xed
thereto so that raising. or lowering'thefronttend
of: said implement serves to‘ adjust the operating
‘position. ofthe toollmeans, movable draft means
25. connecting. said implement with the tractoriand
arranged toaccommodateat least verticalmove
ment of the ‘front. end of said implement relative
to. the tractor, means deriving operating :energy
from such source. of power connected to said; mov
Itpl'ow bottom “16' to momentarily operate at a 30 able draft means for raising and. .loweringhthe
front end of said implement so as to control the
:“more shallow depth. 'As'ithe'iforward movement
depth of operation of said tool means, means for
-~oflthe‘pistoni62a continues'theabell‘ crank I38 is
crooked in a clockwise v‘direction I and eventually
Qtightens the 'chain-l i-MPand lifts the plow bodily
:intoiits ‘transport position. The ‘resulting coun
zter-clock'wise Y‘ rocking of ‘the ' depth - adjusting
controlling said . raising .and lowering means,
ground engaging gauge means-movably connected
with said implement» andtmovab'le relative there
to'iin response to changesin the depth of opera
tion of said ‘tooltmeansgand' means connecting
‘gauge shoe 129 has‘ no effect. on the’ hydraulic
said gauge means with said controlling means for
ivalve‘ mechanism since the hand lever I22 is dis
.operating. said raising and lowering. meansdby
l-c'onne'cted from the arm 1'23. ~=A~ stop Mt of the
:sector. 12‘! .serves to limit the counterclockwise 40 said-source. of power under the-control.‘ of-said
gauge means.
': movement‘iof the‘ gauge shoe ll 29- when the plow
-. 3..
agricultural machine: adapted to beacon
:is'fr'a'ised. Whenit ‘is desired to lower the plow,
.nected-with a tractor-having a-source of power,
‘:the operator- moves" the handllever @122 forwardly,
comprising ground working tool means,‘ a pair or
thuslactu'ating» the hydraulic valvev mechanism to
\ cause the 1 piston-162a to ;be moved rearwardly,
» ‘generally. vertically spaced‘ draft members'con
Qthusiiie'rniitting:thebell crank I38 to rock‘in a
.nected with said tool-means, .ground engaging
counterclockwise direction-and lowering theplow.
gauge means-carriedlby and movable relative to
‘said tool means in response'to changes in the-op
. The :lowering'movement thus; continues until the
. notch‘ I24 reen'gages the detent mechanism of "the
.hand lever: l'22,;whereupon¥the next increment'of
movement-‘shifts the hand lever’ I22 andmoves
‘the :valve. mechanism of ~the’vhydraulic - unit ‘back
'into'fits' ‘holding position. T'I‘his’ is substantially
rthersamelaction as'd'es'cribed ‘above in connection
'- with Figure I andhas all of the advantages there
;of, especially. as regards being able I to ‘raise ‘and
erating depth thereof,rmeans forishiftingone-oi
50 said draft members to control .the depth of. opera
tion of said tool-means; and means controlled‘ by
said. gauge means 1i or‘operatively connecting said
shifting means withsaid-source of power on the
tractor {for automatically -maintaining . saidpto'ol
r means at the desired depth of operation.
*lower the plow‘intoand‘out of its transport vposi
- 4.‘ An agriculturalmachine adapted toibe pro
»pelled by a tractor having a source. of powen'com
ltiori~ .without' losing the ' depth adjustment which
' prising : an : implement unit, ground": working tool
iitzls ‘:de'sired' that the‘ fgauge'ishoe ‘I 29* ‘and associ
' atedpa'rts shall automatically maintain.
While I have ‘shown ‘and-described above the
:preferred means in which the principles “of the
I- present "invention? have . been’ - incorporated; ‘ it is
means .carriedby said implement, unit; bell crank
.means for connecting said unit withv the" tractor
for relatively free ?oating:movement,"movement
:of said ‘bellcrank means in one-direction ori‘the
otherservingto raise 'or' lower thefront end of
said .toolimeansaa memher-pivoted'to said imple
-to'be.;understood thatlmy invention 'is ‘not to be
limited .to the particular-"details! shown andde 55 .ment unitand extending downwardly and rear
scribed” above; but that;'ii1i" fact, lwlidely" di?erent
.means: mayrbe ..'emp'loyed
-wardly...therefrom in’. generally trailingirelation,
‘the-practice bf 'the
ground .. engaging gauge '1 means ~ carried:I at .’. the
{broader aspectsof my'inventicn.
What I claim, therefore;andde'sireto-sseciu'e
lloweriend-l of saidmember .to-?effect‘ movement
thereof relative to. said implement :unit-iiin 're
: by. LettersPatentis :
l- l.
agricultural machine; comprising. a pro
70 sponsetochangesin the-operating depth of said
“tool ‘means, controllable ' means/driven from said
..pelling ¢unit,v.an implement including‘ a‘nioVable
source of power for shifting said- b‘e‘ll1crank means
ground workingtool having suction and a forward
point, means connectingsaidrimplem‘entiwith said
while accommodating said relatively 1free'i?oating
:twvary the operating: depth: of .said .tool means
:propellingmeans to‘. accommodate tipping: oflthe 75 movement: ot the rimplement ‘ unit’ relative to‘ the
2,405,334
a
10
tractor, means for controlling said controllable
means,~and means connected with'said member
and'ext‘e'nding to andj'connected withsaid con- '
pair of links connecting said tool means with said
supporting means for generally vertical ?oating
trolling means for actuating the controllable bell
movement relative thereto, _ ground’ engaging
means carried‘ by said implement and movable
crank Shifting‘ means ‘to maintain the desired
depth of operation of said tool means in any posi
tion of said implement unit relative tojthe tractor
relative to-said tool means in response ‘to changes
in the operating depth thereof, and means'con
trolledby said depth'responsive means for move '
ing,‘ one of said links generally longitudinally for '
adjusting the angle of tilt of said tool means so
tor, a plow beam movably connected therewith at 10 as to maintain substantially uniform penetra
by shifting said bell crank‘means.
'
5.~ An agricultural machine comprising a trac
one end and having a furrow opener at the other
end, controllable means on the tractor for raising
and lowering said one end of the plow beam to
tion thereof.
control the depth of operation of said furrow
power operated unit, said implement comprising
.
10. An agricultural implement adapted to be
connected with a tractor having a controllable
opener, ground engaging gauge means movably 15 tool means, means adapted to be connected with
said unit and deriving operating energy there
connected with said plow beam and movable up
from for adjusting the position of said tool
wardly or downwardly relative thereto in response
to changes in the depth of operation of said fur
means, means movable relative to said tool means
row opener, means for operating said controllable
invresponse to changes in'the position thereof
means for raising and lowering the front end of
said beam, and connections between said gauging
means and the operating means of said control
relative to the ground, means for controlling
said controllable power operated unit means in-,
lable means for causing the latter to raise or lower
movable means with said controlling means for
cluding disconnectible parts for connecting said
the front end of the plow, beam when said gauge
operating the controllable power operated. unit
means moves upwardly or downwardly relative
from said movable means, and means for dis
connecting said parts so as to interrupt the con
to the plow beam.
-
6. In combination, a tractor, ground working
tool means connected with the tractor for gen
erally vertical movement relative thereto into and
out of ground working position, means for ad
justing the operating depth of said tool means,
ground engaging means movably connected with
said tool means, being movable relative to. the
latter in response to changes in the depth of oper
ation of said tool means, disconnectible means *1
connecting said ground engaging means with said
nection between said position responsive means
and said controlling means to provide for rais
ing said tool means independently of said posi
tion responsive means.
11. An agricultural implement adapted to be I
attached to a tractor having an implement-oper
ating power unit and a control valve therefor,
comprising a ground working too1 having suc
tion and including a ground penetrating point,
means for connecting the tool with the tractor for
tilting movement in a generally vertical direc
adjusting means, and means for disconnecting
tion during operation, tilting of said ground I’
said disconnectible means.
'7. An agricultural implement comprising a
working too-l serving to raise or lower the ground
ground working unit including tool means of the 40 ‘penetrating point of the tool so as to cause the
type having suction and tiltable at its front end
tool to run deeper or more shallow, means adapt
ed to be connected with said unit for tilting said
in a generally vertical direction to cause the tool
means to tend to run to a deeper or to a more
tool in one direction or the other, a ground
shallow operating position, ground engaging
engaging member disposed adjacent and movable
means movably connected with said unit and
relative to said tool in response to changes in the I
movable relative to said tool means in response
operating position of said tool, and operating
to changes in the operating depth thereof, con
trollable power operated means for changing the
angular position of said tool means, means for
controlling said controllable means, and means 50
operatively connecting said ground engaging
means adapted to be connected between said
ground engaging member and said control valve
unit.
12. The invention set forth in claim 11, further
characterized by a manual control incorporated
in said operating means for controlling said valve
means with the controlling means of said power
unit independently of said ground engaging
operated means for causing the latter to tilt the
member.
‘
.
tool means and maintain substantially uniform
13. An agricultural implement adapted to be
penetration of said tool means.
55
8. An agricultural machine comprising a sup
attached to a tractor, comprising a generally
porting frame, an implement including ground
working tool means of the type having suction
longitudinally extending tool beam, a ground
working tool having suction connected to the
rear end of said tool beam, a bell crank adapted
cause the tool means to tend to run to a deeper or 60 to be pivotally mounted on the tractor and con
a more shallow operating position, hitch means
nected with the front end of said tool beam,
and tiltable in a generally vertical direction to
connecting the implement with said supporting
frame, ground engaging means carried by said
whereby rocking movement of said bell crank
raises or lowers the front end of said tool beam,
thereby tending to cause the tool to operate
implement and movable relative to said tool
means in response to changes in the operating 65 deeper or more shallow, means disposed adjacent
and movable relative to said tool in response to
depth of the latter, and means controlled by said
changes in the depth of operation of said tool,
controllable mechanism deriving operating en
stantially uniform penetration of said tool means.
ergy from said tractor for shifting said bell crank,
9. An agricultural machine comprising sup 70 means for controlling said mechanism, and means
porting means, an implement including ground
connecting said depth responsive means with said
working tool means of the type having suction
controlling means whereby operation of said
depth responsive means for adjusting the posi;
tion of said hitch means so as to maintain sub
and tiltable in a vertical longitudinal plane to
cause the tool means to tend to run to a deeper
or to a more shallow operating position and a
depth responsive means acts through said con
trolling means and said mechanism for rais
ing or lowering the front end of said tool beam.
2,405,334 a
11 a
14.: In acombination; a :tractom gnoundr-working-i.
121;
means:.connecting saidagmundsengaglngz means»:
tooL-means_-.c0nnected:with ~.thettractor»zfor-,gepen "
with 1 ‘said adjusting g means; means-Jon»: discons; -
allywertical movement irelativev thereto intor-and
nectingt: said ; disconnectible meansp‘ and \ stop‘,~
outz~ oil-ground- working=@position,..-means:101': ad- -
meansaactingf.l between ;sa,id<. > depth. ; responsive 1
meansland. saidtool ‘means for; limiting: the: move- ,
justingv-rthe :operating idepthmf ~t‘said1.11001‘means"; -_-,
gnound engaging (means movably. connected with.- 5
ment rof~ the “depth; responsive means-“relative :
said 2 tool 7‘ ~means,v<.t being ?movable- .vrelative .~;to - the
latter s.- in, .»response r tor changes-‘31in: the »~ depth ‘of 7.
to~saidyitool 11182118:- when' the latter {is :raised- out»
opgration of, saidJada-means,»w disconneetibte .
of its ground working position..
WALTERv H...,SILVER. .>
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