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Патент USA US3033395

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May 8, 1962
A. l.. zANow ETAL
3,033,384
HYDRAULIC DRAFT GEAR
Filed Dec. 7. 1959
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2 Sheets-Sheet 1
May 8, 1962
A. l.. zANow ErAL
3,033,384
HYDRAULIC DRAFT GEAR
Filed Dec, 7, 1959
2 Sheets-Sheet 2
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v3,033,384
Patented May 8, Y1962
2
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FIG. 4 is a cross section taken along line 4-4 of
3,033,3�
HYDRAULIC DRAFT GEAR
Andrey L. Zanow, Cleveland, Ohio, and .lohn W. Uver
beke, deceased, late of La Jolla, Calif., by Catherine
A. (lverbelre, administratrix, La Jolla, Calif., assignors
to National Castings Company, a corporation of Ohio
Filed Dec. ?7, 1959, Ser. No. 357,615
7 Claims. (Cl. 213-43)
FIG. 2.
'
FIG. 5 is a perspective of the draft gear metering de
vice.
f
.
The improved hydraulic draft gear comprises an outer
container 2 and an inner container 4, both containing a
fluid. The outer container encloses the inner container
and is connected thereto at its open end by means of a
duid-tight seal. Slidably dispose-d within the inner con
This invention relates to an improved railway draft 10 tainer is a piston member 6 that is reciprocable from an
extended position of the gear to a compressed position.
gear. In particular, it is a draft gear that relies on the
The travel of the piston member is from the extended po
energy-absorbing attributes of a hydraulic mechanism to
sition of the gear, shown in FIG. 1, to the compressed
cushion the greater-than-average impacts delivered to the
position, shown in FIG. `2. It is during this travel that
mechanism during railroad switching and humping opera
energy absorption by the gear is effected.
tions.
Referring to FIG. 1, outer container 2 serves as the
Currently employed resilient type draft gears function
reservoir and overflow chamber for the fluid in inner
adequately under the compressive forces induced by im
container 4. Movement of the iluid from the outer con
pacts, but they have little capacity for energy absorp
tainer to the inner container may be effected by any suita
tion. The resilient type of railway draft gear is charac
terized, in operation by its recoil after compression. A 20 ble pressure producing means. In the embodiment illus
trated, kgravity is relied upon as the pressure producing
major part of the kinetic energy initially applied to this
means to move the fluid to the inner container. The
type of draft gear during the compressive stroke is stored
inner container functions as a cylinder in which piston
by the gear in the form of potential energy. This energy
member 6 is, as aforementioned, reciprocable from the
is then returned to the train in the form of a jolting re
coil during the expansion stroke of the draft gear. This 25 extended position or? the mechanism to the compressed
position thereof.
'
recoil is responsible for much of the damage done to
The outer container 2 comprises a cylindrically shaped
lading carried by the railroads.
side wall S having an opening litt and screw cap l2 there
The friction-type draft gears extensively employed by
for providing means for the easy addition of iiuid to the
American railroads have a greater energy absorption
level than the resilient type, but they, too, are character 30 reservoir chamber. Container 2 has a flat end wall 14
provided with inwardly facing, reinforcing ribs 16 so lo
ized by a pronounced recoil. The jolting recoil that is
cated as to strengthen end wall 13 of inner container 4
present in the aforementioned types of railway draft
as well as to firmly stabilize the inner container within the
gears is one that is generally inherentin any draft gear
outer container. Each reinforcing rib 16 has an open
means. The friction-type draft gear, however, does have 35 ing 29 permitting fluid to pass readily from the reservoir
chamber through a hollow fluted tube ?22a into the piston
4an advantage over the resilient type in that it is able to
relying upon spring means to serve as the force cushioning
and ultimately into the inner container.
As aforementioned, inner container 4 is located with
in the outer container and engages ribs 16 on the llat
the form of recoil, but it has not solved the problem en
40 end wall y14 at the forward end of the outer container.
tirely.
At the other end, the inner container is tightly encircled
The ideal draft gear would be one having the ability to
by the outer Ycontainer and a substantially fluid-tight seal
absorb all the compressive forces to which it is likely to be
is provided by >sealing element 17. Flat end-wall >18 of
subjected, coupled with the ability to restore the draft
籺he forward end of the inner container has a centrally
gear to its extended uncompressed position without any
45 located circular aperture 24 which receives an end of
recoil.
the metering device 22, comprising the hollow 駏ted
vlt is the primary object of this invention to provide a
tube 22a. The fit of tube 22a in the aperture 24 is sub
hydraulic energy-absorbing device adapted for use as a
stantially fluid-tight, and the tube is held in a 馲ed posi- railway draft gear that is capable of sustaining high energy
level impacts as well as being capable of automatic re
tion within aperture 24 by snap-rings 26. The forward
covery with a minimum of recoil.
50 end of tube 22a is spaced from the opposing wall4 14
A specilic object of this invention is to provide a hy
to allow 駉w of 駏id between the tube and outer con-V
dissipate a substantial portion of the compressive forces
as frictional energy which is not returned to the train in
draulic energy-absorbing device adapted for use as a
tainer 2.
Extending into the open end of the inner con
tainer 4 is the hollow piston member 6, which is cylin
ing the other with a piston disposed in the inner container,
drically shaped and is the movable element ofthe draft
the piston having a reservoir to receive 駏id upon com 55 gear mechanism. The piston member may be squareor
pression of the mechanism, and means to restore the pis
rectangular in cross-section. The only restriction on its
railway draft gear comprising two containers, one enclos
ton to its extended position with a minimum of recoil.
A more specific object of this invention is to provide a
metering device for use in a hydraulic railway draft gear
shape is that it must be complemental to the inner con
tainer. However, in the preferred embodiment of the
invention, Ias shown in the drawing, the piston member t
comprising a hollow tube having an exteriorly disposed 60 is cylindrical 玦n shape. At its forward end piston 6 has
flute of varying cross-section adapted for slidable inser
an end wall 28 provided with centrally disposed circular
tion in an opening with a fixed perimeter during operation.
opening 30 kthat slidably receives hollow fluted tube 22a.
Other objects and advantages of the invention will be
Preferably, 羇 snug lit exists between tube 22aand open
apparent from the following description taken in con
ing 3i). ln addition to circular opening 30, openings 32
junction with the accompanying drawings.
65 of any suitable shape are provided in end-wall 28 to per
Referring to the drawings:
mit 駏id to pass, either during the `compression stroke
FIG. l is a longitudinal section illustrating the draft
of the mechanism, or `during the expansion stroke, or
gear in its fully extended uncompressed position.
both. The embodiment illustrated in FIGS. 1 and 2 per
FIG. 2 is a longitudinal section illustrating the draft
mits iiuid to 駉w through openings 32 during the ex
gear in a compressed position.
70 pansion stroke only. Washer 34, mounted on tube 22a,
FIG. 3 is a cross section taken along line 3_3 of
is adapted to engage front face 2SC of wall 28 to close
FIG. l.
the openings 32 during the compression` stroke while
3,033,384.
9
@al
snap-ringv 36 secured to the forward 馻nge 28a on wall
28 limits washer 34 in its movement away from the
openings during the expansion stroke.
Within the piston the rearward end of the metering
device 22 is formed with a cap member 38 which is inl
iiow from the inner container is through the orifice
formed by flutes 50 and opening 30 into the piston,
籺hence into tube 22a via opening 44 and out into the
the reservoir 2. The fluid-flow, as is indicated in FIG.
2, is due to a reduction in'thefavailable space within the
inner container 4 caused by the movement of the piston
walls into container 4. The volume of 駏idzdisplaced
is equal, approximately, to the volume of the piston walls
not pass, 玜nd secondly, it serves as a stabilizing member
for `tube 22a and the piston. An oil ring 40 is placed
entering the inner container. During the extension or
-around the outer periphery o?f cap 38 to form a fluid 10 restoring stroke, fluid Vmoves from reservoir 2_into inner
container 4 via the iluted tube and piston, as is shown
tight seal between the cap and the inner surface 6a of
by the arrows in FIG. l. Reservoir capacity is greater
the piston. Within the piston member is oil sump 42
than the needs imposed by the changing inner container
which provides lubrication to thecap. The sump ex
volume; tlie? excess capacity being available to replace
tends from cap 38 to transverse wall y54 which is aihxed
any fluid loss that may result due to protracted periods of
to the piston by snap rings 56 and 58. Cap 38 is pro
use without preventive maintenance;
vided with a forwardly extending projection 38a having
Although this invention is described in an Vembodiment
openings ?communicating with the opening 23 in tube
calling for a cylindrically shaped inner and outer con
22a, thus permitting 駏id in the-piston to move to and
tainer, the only limitation as to shape is that the piston
fromV the reservoir, as indicated by the arrows in FIGS.
must be complemental to the inner container 4.
1 and 2.
n
The rearward end of piston 6 is closed by an end plate
The terms and expressions which havebeen employed
tegral with tube 22a. This cap -serves'a two-fold pur
pose: first, it forms a wall beyond which the fluid may
48 which is secured to the piston walls. Plate 48 is
provided with lateral shoulders 48a which are in abut
ting relationship with the rearward end of coil spring 46.
The spring surrounds portions of the?piston 6 and outer
container 2wat its forward end and abuts against the
shoulders 2a onvthe outer container; It is this spring
are used as terms of'description and not of limitation,
and there is no intention of excluding su'ch equivalents
of the invention described or of the portions thereof as
fall within the purview of the claims.
What is claimed is:
,
`
_
l. A hydraulic shock absorbing mechanism comprising
an outer container and an inner container joined together
at their open ends, fluid disposed in at least one of said
In FIG. l the draft gear mechanism is illustrated? in its 30 containers, said outer container providing a fluid reser
that furnishes the'force to'restore the draft gear mech
anism to its extended position after compression.
uncompressed position. IUpon compression of the mech
voir about?said inner container, pressure means to move
said fluid from the outer> to the 'inner container, a hollow
anism, in response to draft or bui� forces applied there
to, piston Vmember 6 moves into inner container 4. As
piston member reciprocable within said inner container,
the mechanism Vis compressed, washer 34 on tube`22 is
forced Vagainst `flat surface 28e on end-wall 28 of the
tainer and said piston member, said device comprising
piston by the fluid in inner container 4, thereby closing
openings 32. By thus closing openings 32, 駏id in the
inner container is necessarily forced through the orifice
tainer and slidably extending through an opening in the
formed by a pair of flutes 50 provided on the outer side
a fluid metering device extending within'said inner con
a longitudinal hollow tube secured to said'inner con-V
head of said piston, one end of said tube extending into
said reservoir, said tube having in its sides a longitudinal
flute of varying cross-section, said 駏te in conjunction'
of. tube 22a and circular opening 30 in> end-wall 28 of 40
with said opening in the? piston head forming an orificev
the piston. It is to be understood that iiutes are formed
of decreasing cross-sectional area as said piston member
inthe outer side of the tube and ?are of -a depth less than
moves into said inner container during compression of
the- thickness of the tube wall. The outerV surface of
said mechanism.
. l
tube 22d is in` slidable contact� withthe inner surface of
The~駏tes are so shaped as -to form an
2. A hydraulic shock absorbing mechanism compris
-orifice that is larger in cross-section at the beginning of
thecompression stroke thanat the end of the stroke;
ing an outer container and an inner container oriented
opening 30'.
in the same direction, fluid disposed in at least one of
Each flute commences at a point on tube 22d Where end
said containers, said containers being sealed together at'
vva11`28'- of the piston is positioned when the mechanism
their open ends, said? outer container providing a 駏id
is fully extended,?as in FIG;v l.l At this point, the cross 50 reservoir, pressure means to move said fluid from the
outer to the inner container, a longitudinal hollow tube
sectional larea of the -駏'te is greatest and likewise the
member within said inner container and secured there
aforementioned orifice formed by the'駏tes and opening
to, one end of said tube extending into said reservoir,
30 is fa maximum.- The flute decreases in cross-sectional
said tube member having an exterior-ly disposed flute of
area. in a. forward direction until it reaches the point
along the tube where end-wall?28 is positioned when 55 varying cross-section, a piston member reciprocable within
the' mechanism is fully compressed. At the latter point,
the orifice formed is `a minimum inA-cross-sectional area.
By ythus changing the orifice size, the mechanism closes
said inner container from an extended position to a com
pressed position of said mechanism, said piston member
projecting longitudinally outward through the open end
of said inner container, said piston member comprising
60 a hollow cylinder closed at both ends, one of said ends
having an opening to slidably receive said rod member
mechanism is restored to its'fully extended position by
during compression of the mechanism, said opening and
spring 46.
_
said ilute forming an> orifice of variable cross-sectional
Dining the restoration stroke; washer 34 moves for
area upon compression or extension of the mechanism,
wardly-away fromopenings 32 into contact with ,ring 36
of thepiston, thus enabling a rapid flow of fluid from 65 and resilient means disposed in abutting relationship to
said piston and said >outer container to maintain the
the piston through openings 32 into the inner container
mechanism in an extended position.
?
4 as the piston 'moves outwardly from the inner con
3. A hydraulic shock-absorbing mechanism compris
tainer. The maximum distance _of extension of the gear
with ever-decreasing speed during the compression stroke,
Up'on cessation of lthe compressive force, thedraft gear
isdetermined by abutment surfacefSZron projections 38a
ing an outer container and an inner container oriented
pocket in a railway car before end-wall 28 ever abuts
posed within saidA containers, pressure means vto move
of the tube capwhich engages the rearward surface 28b 70 in the same direction, said outer container enclosing
said inner container and spaced therefrom, said contain
of piston end-wall 28.VA However, the limitation could
ers being sealed together at their open ends, a 駏id dis
just yas well Vbe imposed by `the size of the draft'gear
against surface 52A..
j
During the energy-absorbing compression stroke, Huid 75
said fluid from the outer to the inner container, a piston
member reciprocable from an extended to a compressed
3,033,384
5
position of said mechanism disposed in said inner con
member reciprocable from an extended position to a
tainer and projecting longitudinally outward through the
compressed position of said mechanism disposed in said
inner container and projecting longitudinally outward
open end of said inner container, said piston member
comprising a cylinder closed at both ends, one of said
ends having an opening therein, a hollow rod member
secured within said inner container and having an end
extending into said outer container, said rod member
projecting through the opening in the piston member
throng-'.1 the open end of said inner container, said piston
member comprising a cylinder closed at both ends, one
of said ends havin." a circular opening therein, a hollow
rod member disposed within said circular aperture and
connected to the end-wall of said inner container, theV
opening and said flute forming an orifice of varying cross
other end projecting through the opening in the piston
member, said rod member having an exteriorly disposed
flute of varying cross-section extending the length of the
rod, said piston opening and said flute forming an ori馽e
sectional area upon compression or extension of said
through which said iluid may pass upon compression or
mechanism, and resilient means disposed in abutting
relationship to said piston and said containers to main
extension of said mechanism, an annular collar disposed
tain the mechanism in an extended position.
posed in abutting relationship to said collar. and said
to permit the latter to slidably receive the rod, said rod
member having an exteriorly disposed ilute of varying
cross-section extending lengthwise of the rod, stiel piston
4. A hydraulic shock-absorbing mechanism comprising
on the outward end of said piston, resilient means dis
onter container to maintain the mechanism in an extended
an outer container and an inner container oriented in
position.
the same direction, fluid disposed in at least one of said
6. The hydraulic shock-absorbing mechanism of claim
4 further characterized by said other end of the rod
member having disposed thereon an annular cap, said
cap sealing said hollow rod, an opening in said rod ad
jacent said cap allowing iluid to pass therethrough, the
outer perimeter' of said cap in slidable abutting relation
ship with the inner surface of said piston member.
7. A hydraulic shock absorbing mechanism comprising
containers, said outer container enclosing said inner
container and spaced therefrom, said containers being
sealed together at their open ends, pressure means to
move said lluid from the outer to the inner container,
a piston member reciprocable within said inner container
from an extended position to a compressed position of
said mechanism and projecting longitudinally outward
through the open end of said inner container, said piston
a lltu'd reservoir container and a second container ad
member comprising a cylinder closed at both ends, one
jacent said reservoir container, 駏id disposed in at least
or? said cylinder ends having a circular opening therein,
one of said containers, pressure means to move said
a longitudinal hollow rod member disposed within said 30 iluid 韗orn the reservoir container to the second container,
a hollow piston member reciprocable within the second
inner container and being secured thereto, one end of
container, said piston member having an opening in the
said rod member extending into said outer container,
the other end of said rod member projecting through the
head thereof, a fluid metering device disposed within
opening in the piston member and having disposed there
the second container and piston member, said metering
on an annular cap, said cap sealing said hollow rod, an 35 device comprising a hollow tube~like rod secured to
opening in said rod adjacent said cap and connecting
with the opening in said rod member, the outer side sur
face of said cap being in slidable relationship with the
interior surface of said piston member, said rod member
having an exteriorly disposed flute of varying cross-sec 40
tion extending lengthwise of the rod, said piston opening
said second container and slidably extending through said
opening, means on said rod cooperating with said open
ingl to form a fluid metering orii'ice varying in cross-sec
tion as said piston moves into said second container,
said rod connecting said reservoir container to said piston
member to allow fluid to pass therebetween.
and said ilute forming an orifice through which said
fluid may pass upon compression or extension of said
mechanism, and resilient means disposed in abutting rela
tionship to said piston and said containers to maintain 45
the mechanism in an extended position.
5. A hydraulic shock-absorbing mechanism compris
ing an outer container and an inner container oriented
in the same direction, said outer container enclosing said
inner container and spaced therefrom, said containers
being sealed together at their open ends, a fluid disposed
References Cited in the iile of this patent
UNITED STATES PATENTS
770,128
770,537
782,964
1,378,281
Teal ________________ __
Raders _____________ ___
Hopkinson ___________ __
Ross ________________ -_
2,726,773
Fitz-lohn ____________ __Dec. 13, 1955
366,156
Italy _______________ __ Dec. 20, 1938
within said containers, pressure means to move said fluid
from the outer to the inner container, the end-wall of
said inner container having a circular aperture, a piston
Sept.
Sept.
Feb.
May
13,
20,
21,
17,
1904
1904
1905
1921
FOREIGN PATENTS
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