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Jani 20, 1948.
B. w. sNoDGRAss
2,434,725 ~
Filed March l, 1946
3 Sheets-Sheet l
Ärraëms Y
Jam 20, 1948l
Filed March l, 1946
3 Sheets-Sheet 2
Jan. 20, 1948.
B. w. sNoDGRAsS
>Filed March l, 1946
3 Sheets-Sheet 3
5 ¿NJA/WN h( Ö/voßáeqss
Á’ Troef/Ey
Patented Jan. 20, 1948
Benjamin W. Snodgrass, Úënver,f(lolo¿,_ äs’siigiiioi'
of one-half to Benjamin F. Englandèrà'ßènver,
Appiicsfiofi March 1, 194e,seriäiiîibftsin‘äà
e claims. (ci. ess-e6)
scale as rigùie ‘taken jgmrtiiexiniiic‘atee une ’lr-¿44
` This `_in`v‘ention relates to powered hammer de
vices adapted to Agenerate rapidly successive im
pacts applicable Afor work eiîect and t'o direct ysaid
impacts to the effective actuation of drills,vchisels,
of Figure 1.A F‘ijgureñfis across section/pri the
'saine scale fais,y Figure 3,.,_ta‘ken Aon thein'dicate'd
tamps, and analogous tools susceptible of inter
changeable association therewith, and more par
ticularlyto electrically-driven such hammer de
ti‘ongon the same scalïe as Figureß, taken on the
indicated line Sri-6 of Figure 1. Figure 'i kis _a
cross section, ,on the same scale as >Figure 3, taken
gouine iiiciiòate‘d _iiiife 1+i ‘of 4Figure 1. ` AFigure s
vices, and has as an object to provide an improved
construction‘anvd cooperative arrangement of ele
'isjafeross se tion, 'on-the `same scale as Figure
nifentfs constituting 'an improved hammer of high io -atak’en 'ont è indid line ses 'of Figure 1. s
eñi'ciency and "wide utility.
` The noveltiesjof `th
an improvedconstrl'iction and'oper’ative mount
ing for >a reciprocatory impact member in an elec
trically-driven hammer.
><"`e`s"`er'1’t invention are de
velopments _fromlari‘djimprove??ients over certain
AT_further `object of the inventionv is to provide
[email protected] th‘e‘disclò' res "of my United States‘Patent No.
12,353,[email protected] domizil», A1944, and `are applicable
j15 to use with îand _to enh «"ce the pra'cticability and
`eiîlieienoy of electrically-driven >ita'ower hañiin'ers
A ïfurtherfobject oi the invention is to provide
jimproved impactgtrans'mitting tool mounting
‘in 'an electrically-driven hammer.
"of the type s`
" n 'in A’sèiiíl patenti, particularly
when such’h rneí‘sar'e employed iïn the drilling
ï¿if rieles incident tö -infiniiig 'and blasting opera
` AA further object `of the invention is to provide
an ‘improved construction and arrangement of
ì'?ipaot ii'i‘eh’lb'er aotüàtíon to rotate the tool
_ As Shown rthe d?aw'iñgsfa cylindrical casing
vitl 'opera'ííívely‘Íiiiòì-ìnts, houses, and protects the
rnea'n's automatically operable -as an incident of
mounting andgassociated tool of an electrically
driven hammer.
‘in 'aïíçi'al -coincidence "with said casing. Fixed to
and 'for 'rotation v’with one end of the shaft Il,
disc-like ‘drive ,iplatè ’I2 is operatively housed
'somewhat iiivvaiaiy from 'one end of the casing
means automatically eiîective as an incident of
hammer "actuation to pressure feed liquid to and
'through thelwork 'end of a t'oòl associated 'with
an eiec'tncaiiy-driven liiaiiiiiiei.
A further object of the invention is to provide
{iïniproved operative driving connections between
"an -impact member r’eciprooably responsive to
rotation 'and a powered shaft in a-Xial alignment
y `
after s'etrforth, pointed out in my claims, and
illustrated by the accompanying drawings, in
ärouate outer margins f5 _adapted to 'Conform tO
'to engage the vlatter'ïin constantèdriven relation
fvith said plate y"and shaft Il in a manner permit
'as assembled ready for 'practicall use-` Figure 2
tiï g ofv'sieparàtion and 'i‘appro'chment of "the shoe
an exterior elevation of the assembly accord
elements¿aiaiiieiificaiiy bf js‘àid ‘plate within said u
ing to Figure l takenat arright angle and on a
jatfan opposite 'extreme of their range _of actua
and engage at times' against the inner ‘cylindrical
’wail ò'f the ksaid ‘reces-s, and pins it nxediy pro
ïjec'ting 'a-iàial y fr‘on'i the 'outer "face of the plate
il’. are received
tangentially-‘elongate slots l1
formed in and adjacent the ends of said shoes
` Figure lisa view, largely in longitudinal, axial
section, of a typical embodiment of the invention
reduced -Scale rfr'elative~ to said latter figure. Fi`g~
ure 3 is a fragmentary, detail, axial section, on
rxan enlarged scale, through tool mounting and
'actuating elements of the assembly according to
Íajn‘d substantiallyon the indicated line 3_3 of
Figure 1 depicting 4said elements on >a plane 15er
Ípendicular to thelshowingwof said latter 'ñgure and
@lowly-adjacent, independently-rotatable,
‘hovering relation with thel axially and cylindri
"c'alïly recessed end "of a clutch member I3 carried
`'iîit'e'riorly of said casing end for rotation about
an ‘airis 'aligned
that 'óf the _shaft ll`. The
recess of the 'irn‘embe'r l`3ß‘cover‘e`d by the plate I2
cojo ratively receives fa -pair’of complementary,
i4 having' manica-lagged,
With the foregoing and other objects in view,
'my invention consists in the construction, ar
rangement, and combination of elements herein
lfilature oi‘d?iven shaft "H Vis suitably jòur?äled
¿A `fu~rtherobjeot of the invention is to provide
an improved construction and arrangement of
with Asaid member.
` R
tensile resi
e _coil springs T8 of suitable
_ e -`'oper tively engage between >in
né margins df trie Sintes r4 and iena to honi said
shoes in end abutment the inner limit of their
out of margin löen'g‘age
the Inbe'r `i`-3_ recess inner cylindrical
wail; _iii [email protected] @utp saidnshqe's are free to rp
¿I2 _interfi'orly of and Without
tion. Figure 4 is a cross section, von the `'same 55 driving 'eiîect ‘on the vrecess and member until such
a speed of rotation is attained as will generate
through a plurality of posts 21 fixedly outstand
centrifugal forces acting on the mass of said
ing from the member I3 web in uniformly-spaced
shoes suñicient to induce outward separation of
angular relation inwardly adjacent and axially
paralleling the annular ilange surrounding the
the shoe elements such as will overcome the ten
sion of the springs I8 and frictionally engage
the shoe margins I5 against the recess wall and in
driving relation with the member I3. Wedge
blocks I9, having each an outwardly-directed
point disposed for Wedging engagement between
abutted ends of the shoe I4 elements, are asso
drive disc 211, which posts register with and slid
ably engage through corresponding marginal
notches or apertures intersecting said disc 2li,
thereby locking said drive disc to and for rotation
~ with the clutch member in a manner to accom
10 modate limited reciprocation of said drive disc
'ciated with and interiorly of said shoes for lim
and its associated elements axially of and rela
ited travel radially of the assembly and for out
ward shifting in response to speed-generated cen
trifugal forces, said blocks I9 functioning in an
tive to the clutch and casing members.
viously, whenever the speed-responsive clutch
reacts during operation of the shaft II to fric
obvious manner to enhance and maintain the fric 15 tionaliy engage and drive the clutch member I3,
tional grip of the margins I5 against the member
the stem 22 is correspondingly rotated by means
I3 recess wall, at proper rotative speeds, and to
of the drive disc 24 and posts 21 to rotate the
thereby minimize vagrant fluctuations in the so
cam block 25 relative to the followers 26 and
thereby simultaneously reciprocate said stem and
established frictional driving relation. The
speed-responsive clutch just described is func 20 its attached elements repetitiously through a
tionally identical With and structurally very simi
vcycle determined by the lobe arrangement and
lar to that shown in my‘earlier patent and in and
contour of the block cam faces; the illustrated
of itself forms no part of the instant invention,
construction being designed to eiîect two com
being herein illustrated and described merely to
plete reciprocatory cycles for each revolution of
facilitate understanding of the structural and 25 the stem 22 and to free the reciprocatory as
operative relationships of a complete hammer
sembly from every mechanical actuating force or
restraint at each limit of its reciprocatory travel,
The clutch member I3 is formed with a trans
in the manner and for the purposes set forth in
verse web closing the end of its shoe-containing
my above-identiiied, previous patent.
recess remote from the plate I2 and an annular 30
The end of the casing member 20 remote from
flange outstanding axially from said web to define
the casing I0 ñxedly engages and cooperates with
a cylindrical cup concentric with the plate I2
one end of a tubular sleeve 28 thereby mounted
and opening outwardly of the casing I9 there
from; said annular ñange projecting axially be
yond the adjacent end of the casing I3 for
journaled reception within the cylindrically
and supported in axial alignment with and as
an extension outwardly beyond said casing mem
ber end, said sleeve having a straight, axial bore
of a »diameter somewhat less than that of and
communicating at its inner end with the larger
portion of the two-diameter chamber housing
recessed end of a tubular casing member 23
ñxedly end-engaged with and forming an axially
aligned extension of said casing I0. The casing
the impact head 23, so that the sleeve 28 inner
member 23 is axially traversed by a straight, 40 end serves to partially obstruct and limit the
axial length of said chamber. A tool mounting
cylindrical bore opening at one end into the cup
unit is formed with a straight, tubular end por
defined by the member I3 annular flange and at
tion 29 of a length slightly greater than that of
its other end into a radially-enlarged, concentric,
the sleeve 28 and an external diameter en
two-diameter, cylindrical chamber whereof the
lesser portion is adjacent and communicates 45 gageable Within the sleeve bore to rotatably and
through an abrupt angular shoulder 2I with said
reciprocably mount said portion 29 within and
bore and the greater portion is adjacent and ar
through said sleeve with its inner end projecting
ranged to open outwardly through the casing
into the greater portion of the two-diameter
chamber for engagement at times by the impact
member 20 end remote from the clutch member
I3. A suitably-worked, straight stern 22 is dis-ç 50 head 23.
An annular, radially-outstanding
posed axially of and to extend entirely through
collar 33 formed integrally about a midportion
the straight bore portion of the casing member
of the tool mounting unit determines the ex
20 in adjustable, interconnecting relation be
terior length of the tubular portion 29 and is t
adapted to engage at times against the outer end
tween a double-cone impact head 23 housed with
of the sleeve 28 and thereby limit projection of
in the two-diameter chamber at one end of said
said portion 29 inwardly beyond the adjacent
bore and a drive disc ‘Ztl housed within the cylin
sleeve end, and a cylindrical extension 3I of said
drical cup of the clutch member I3 at the other
unit axially and outwardly beyond the said collar
end of said bore, said stern, impact head, and
drive disc constituting a unitary assembly rotat
3l] is formed with an end-opening, concentric,
able and reciprocable relative to the casing mem 60 inwardly-tapered socket 32 separated `from the
ber 2B. Work-effecting reciprocation of the
bore of the tubular portion 29 by a solid trans
verse web 33 and adapted to telescopically re
stem 22, head 23, and disc 2li assembly is de
veloped as a consequence of assembly power rota
tion through the agency of a double-faced, suit
ceive, seat, and frictionally grip the correspond
ingly-tapered end of a tool stock 34.
The tool
ably-contoured cam block 25 adjustably ñxed to 65 mounting unit is held against separation from
and limited in its range of reciprocation out
an intermediate portion of the stem 22 within
wardly‘of the sleeve 2li by an annulus 35 rotat
the casing member 2D bore between and f or reac
ably and reciprocably embracing the extension
tion against independently-rotatable cam fol
3l adjacent the collar 30, said annulus being
lowers 26 radially overhanging the block 25 cam
margins from their diametrically-oppose'd, 70 equipped with fixed, radially-outstanding ears 33
adapted to register with and end-abut against
corresponding ears 31 fixedly carried by the
sleeve '28 outer end and be clamped thereto by
means of bolts 38 engaged through registered
patent, and power to rotate said assembly is
transmitted thereto from the clutch member I3 75 holes intersecting said ears in parallelism with
axially-spaced, paired mountings in the casing
member 20 wall, in much the same manner and
with the same effect described in my earlier
the longitudinal axis of‘the tool assembly, adjust
tubular yportion bore. With the arrangement of
ment in the spacing between >the sleeve 28 outer
elements shown and described, rotation-induced
reciprocation-of‘the impact membercarrying the
end land the annulus 35, and hence in the re
ciprocatory range _ofthe tool `mounting unit as
determined -by engagemen-t of the collar Sûwithin
such space, being conveniently >had -in a usual
head 23 is reflected without impairment or re
striction by a corresponding axial play of the
tongue 4l longitudinally vwithin andbetween the
manner through the use of shims or spacers be
tween adjacent ends of the ears 36 and 31.
«shoes 39'; the powered rotation of said impact
Vmember operating, -by virtue of -the interengaged
As should be manifest from the drawings and
tongue and shoe bore cross-sectional outlines, to
Yforegoing description, axial 4reciprocation of the "10 rotate «the shoe assembly and to simultaneously
stem `22 deriving from actuation of the shaft Il
is reflected adjacent t-he limit of stem Vtravel re
-mote -fromthe casing 'lû as impact engagement
of the head 23 against the inner end of ^the tool
mounting 'unit Atubular portion v2-9, and through
`the elements of said tool mounting unit to’ and
ifor -work effect >through the stock 34 and tool
associated therewith, weight or feed pressure of
the -tool assembly applied 4to the stock 34 serving
to normally vurge the tool mounting unit to vmaxi
mum inward projection of >its tubular portion 29
yfor maintenance of said tubular portion in posi
«tion for repetitious impact engagement by said
head 23. Stem 22 travel Itoward. the casing I ll
is arrested by engagement of the impact head
inner >cone base against the annular shoulder 2l,
and the range of stem travel, normal position of
»the -tool'mounting unit tubular portion inner end,
:urge ‘said> shoes ‘radially apart and l‘into 4such fric
»tional `engagement of their 'lagged surfaces
:against the tubular portion 29 inner Wall as will
rotate the tool mounting and the tool therewith
associated. 'While the centrifugal forces of rota
tion and the wedgingaction of the tongue 4I com
bine to‘establish and maintain a strong Vfrictiona’l
Àgrip of the shoe surfaces 40 against `the tubular
portion 29 and correspondingly effective rotation
of »the tool stock 34 during hammer assembly ac
tuation, `it is to -be noted that such frictional grip
is the only linkage rotatably interconnecting the
tool »mounting with the positively-driven impact
member, so that anysevere resistance to rotation
Iencountered by the tool may instantly be accom
modated through slippage between the shoe `sur
faces 49 and tubular portion 29 without undue
‘strain on, damage to, or interruption in the opera
land clearances between cam surfaces of the
tion of the hammer assembly elements.
lblock 25 and the followers '26, are so correlated 30
In rock, coal, concrete, and like drilling opera
with other pertinent operative factors and with
each other as to synchronously utilize rebound
of the head Z3 and associated elements _for
initiation of travel in a direction adapted for ’
smooth subsequent acceleration by means of the 35
tions to which the improved hammer is effectively
applicable, it is a highly desirable common prac
tice to continuously supply liquid, such as Water,
to the working face of the drill for cooling -eifect
on the latter and to free the working area of dust
Lpowered associations iprovided.
and chips which `impair drilling eñiciency, it be
Certain operations to Awhich the improved ham
>mer is applicable are facilitated and expedited by
providing for rotation of the working tool, to
-which end means and operative associations ef 40
ing usualand convenient to form the tool stock 34
with an axial bore or channel 42 wherethrough
such liquid-may Vbe fed to and outwardly from the
tool Working end, and >a further novelty of the in
stant invention resides in the provision of means
automatically operable .as an incident of hammer
actuation to pressure-supply liquid to and
fective for such purpose are `incorporated in and
with the elements hereinabove described. The
tool mounting unit of the improvement being ro
tatably, as well as reciprocably, carried by the
through the tool stock. Conveniently adapting
sleeve 28 and annulus 3‘5, and arranged for fric 45 the improved hammer for liquid supply to the
tional, rotation-imparting grip with the associat
tool actuated thereby, the driven shaft ll of the
ed end of the tool stock 34, it is convenient and
hammer motor is extended, through suitable
wholly feasible to apply the powered rotation of
packing glands (not shown), axially and out
the stem 22 and head `23 to eifect tool mounting
wardly beyond its'supporting bearing remote from
unit rotation in a practical manner free from dis 50 the drive plate `l2 and 'into an end-opening com
astrous consequences occasioned by sticking tools.
partment formed in the casing l0 free end, where
As shown, a pair of complementary, semi-cylin
said shaft engages in driving relation with a gear
43, rotatably housed in said compartment.
drical shoes 39, of suitable rigid material, have
their exterior, cylindrical "surfaces suitably fric
Radia‘lly--offset from and in-meshing relation with
tion-lagged, as at 40, and are sized to slip axially 55 the gear 43, a second gear 44 is housed and mount
within and cooperate to substantially ñll the bore
ed for rotation about its axis within said casing
in the tubular portion 29 of the tool mounting
end compartment, and the inner walls of said
unit; the lengths of said shoes 39 being slightly
compartment are formed and contoured to pro
less than that of the tubular portion bore, so as
vide chambers on each side of the diametric
to clear said shoe ends from any possible driv 60 plane containing the axes of the gears 43 and 44
ing engagement with the impact head 23. The
and inwardly-extending abutments closely coop
plane, diametric faces of the shoes 39 interen
erating with the outer opposite arcs of said gears
gageable to complete a shoe cylinder housable
in separating relation between said chambers. A
within the tubular portion 29 are centrally and
cap 45 removably and replaceably cooperates
longitudinally grooved or routed to form ~corre 65 with the free end of the casing l0 to operatively
sponding transversely-arcuate, relatively wide,
confine the gears 43 and 44 and to complete the
shallow channels cooperable when the said shoes
chambers oppositely adjacent thereto, said cap
.are assembled as shown to denne a transversely
being apertured to provide access to the casing
oval bore extending axially of and entirely
chambers covered thereby and supporting iiow
through the cylinder comprised from the shoes; 70 lines 46 and 41 communicating through the cap
apertures and with the respective chamber in
the so-iormed oval bore being adapted to ñt
snugly about and :slidably accommodate a similar
teriors. The meshed gears 43 and 44 constitute
ly transversely-oval tongue 4l ñxedly projecting
a pump operable to draw liquid through one of
axially and outwardly from the impact head 23 a
the flow lines and into the chamber served there
distance slightly less than the axial depth of the 75 by, to transfer the incoming liquid from the in
ñow chamber to the other chamber of the casing
compartment, and to deliver the liquid under
pressure as outflow through the other of the flow
lines, according to the direction of gear rotation,
the line 46 in Figure 1 accommodating liquid in
flow and the line 41 functioning as a conduit for
pressure outflow when the gear 43 of Figure 6 is
rotated in a clockwise direction. The gear pump
being productive of operatively adequate suction
of said impact member, a head on the other end
of said impact member for repetitious work-ef
fecting engagement against the tool mounting
unit adjacent end, cooperating impact member
cam and casing assembly follower means eifec
tive to reciprocate said impact member as an
incident of its rotation, a tongue ñxedly project
ing axially from said impact member head in
slidably-supported association with said tool
eifect, the inñow line 45 may connect with any 10 mounting unit, and means reactive to rotation of
said tongue for frictional engagement with and
consequent rotation of said tool mounting unit.
sump, tank, reservoir, or the like, and need not be
2. Apparatus as Set forth in claim 1, wherein
pressure served. The pressure outiiow line 41,
the rotational driving connection between the
which may be either a flexible conduit or a rigid
pipe assembly, is led exteriorly of and along the 15 clutch driven member and the impact member
comprises a plurality of studs iixedly projecting
hammer assembly to connection of its delivery
convenient source or supply of liquid, such as a
end with and radially through the annulus 35,
said latter element advantageously being formed
toward the adjacent impact member end from,
in axial parallelism with, and in angularly
spaced relation on said clutch driven-member, a
with an annular groove 48 shallowly intersecting
its inner face and arranged to receive and dis 20 disc radially of and ñxed to said impact member
adjacent end, and holes in said disc in registra
tribute liquid inflow circumferentially about the
f tion with and to telescopically receive said studs.
adjacent exterior area of the tool mounting ex
3. Apparatus as set forth in claim 1, wherein
tension 3|, and with annular marginal shoulders
said tool mounting unit comprises a generally
cooperating with complementary elements on the
collar 30 and extension 3l to minimize liquid 25 cylindrical body formed with a radially-project
ing annular collar intermediate its ends, an ax
leakage therebetween. A plurality of flow chan
ially-bored tubular portion on one side of said
nels 49 is formed radially of the extension 3| in
collar for journaled reception through the casing
communicating relation between the inner end of
assembly end and impact-receiving cooperation
the socket 32 and the outer surface portion of said
extension underlying the groove 48, so that the 30 with the impact member of the hammer, and a
cylindric extension on the other side of said col
flow delivered to said groove from the line 41 may
lar formed with an end-opening tool-receiving
freely enter the inner socket end and the bore 42
socket and adapted for journaled cooperation
of the tool stock 34 engaged in said socket and be
with an annulus ñxedly supported from and in
thence pressure-impelled through and outwardly
of the tool working face. Thus, actuation of the 35 axial alignment with said casing assembly,
4. Apparatus as set forth in claim 1, wherein
hammer power unit may be directly and auto
the impact member comprises a stem disposable
matically applied to maintain a liquid iiow to and
axially of the casing assembly, a disc radially of
through the tool actuated thereby, whenever and
and threadedly fixed to `one end of said stem for
wherever liquid serving of the tool is desired.
The improved hammer assembly may be 40 driven association with a rotatable hammer
clutch member, a spool-like, double-cone head
equipped with manipulating and operating han
concentric with and threadedly fixed to the other
dles and switch in such speciiic construction and
end of said stem for impact engagement against
arrangement as may be deemed to be practical,
work-transmitting elements of the hammer, a
such features being conventional in association
with hammers of the type disclosed herein, and " slide tongue projecting iixedly and axially from
said head, a tubular cam block on and threadedly
suitable lugs and brackets for operative engage
fixed to said stem between said disc and head,
ment with manual or powered feeding mecha
and cam faces formed on the ends of said block
nisms and supports may be provided in fixed re
for member-reciprocating cooperation incident
lation with the casing l!) and casing member 2i),
to member rotation with followers supported by
as is customary in the application of powered
and in radially-inward projection from said cas
hammers to particular uses.
ing assembly.
Since many changes, variations, and modifica
5. Apparatus as set forth in claim 1, wherein
tions in the specific form, construction, and ar
the tool mounting unit rotating means reactive
rangement of the elements shown and described
to rotation of the impact member tongue com
may be had without departing from the spirit
prises a tool mounting unit tubular portion ax
of my invention, I wish to be understood as being
ially aligned with and opening toward the im
limited solely by the scope of the appended
pact member in telescoping relation over the im
claims, rather than by any details of the illus
pact member tongue, a pair of semi-cylindrical
trative showing and foregoing description.
I claim as my invention:
1. In an electric hammer of the character de
scribed having a tubular casing assembly, an
60 shoes nested within and substantially filling the
bore of said tubular portion, complementary,
transverseiy-arcuate grooves axially of the juxta
posed shoe diametric faces to define an axially
straight, transversely-oval throat, and a throat
power shaft axially of said assembly, and a speed
responsive clutch including a shaft-concentric 65 conforming, exterior contour on the impact mem
ber tongue,
driven member `operatively associated with the
6. In a hammer of the character described
motor power shaft inner end interiorly of said
having a casing assembly, an impact member
assembly, a tool mounting unit rotatably and re
power-rotatable within and reciprocable as an
ciprocably carried in the end of said assembly
remote from said motor, an impact member ro 70 incident of its rotation axially of said assembly,
and a tool mounting unit journaled in an end
tatable and reciprocable axially within said as
of said assemblyk in axial alignment' with said
sembly between said clutch driven member and
impact member to receive and transmit impacts
tool mounting unit, an axially-slidable, angu
therefrom, means responsive to impact member
larly-fixed, rotational driving connection be..
tween said clutch driven member and one end 75 rotation for frictionally engaging and yieldably
electric motor housed in one end and with its
rotating said tool mounting unit, said means com..
prising a tubular unit end portion aligned with
The following references are of record in the
and opposed to said impact member, a pair of
ñle of this patent:
semi~cylindrica1 shoes nested within and sub
stantially filling the bore of said tubular portion,
friction lagging on the shoe cylindrical surfaces,
complementary, transversely-arcuate grooves ax
Snodgrass ________ __ July 11, 1944
ially of the juxtaposed shoe diametric surfaces to
Demo ____________ __ Oct. 27, 1942
define an axially-straight, transversely-oval
throat, and an axially-straight, transversely-oval 10
tongue projecting ñxedly and axially from the
adjacent impact member end for slidable, non
rotatable engagement within said throat.
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