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Патент USA US2408171

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Sept_.'24, 1946.
'
-
‘
J‘. F. HOFFER
2,408,169
LEVEL WORK SUIV’PORTING STRUCTURE
‘Filed Feb; 12, 1944
:5 sheets-sheet 1
IH Q
Iwani)l.r-|
_
,
INVENTOR.
James ?/yaffér
_
BY
‘
‘
gw'éyvf'
irromwrs
Q Sept. 24, 1946. Y
J. FIHOFFER -
2,408,169
LEVEL WORK SUPIfORTING STRUCTURE '_
Filed Feb. 12, '1944
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2,408,169
Patented Sept. 24, 1946
UNITED STATES PATENT; lorries '
James F. v,Ho'?er, -Detroit, Mich, assignor _ to" .811
a perdraulic Corporation, De'ai'born, Mich., "a
corporation 'of‘Michigan
.
,
'
~ >. _.:Applicati0niFebruary 12; 19.44,-ISe1-'ial'No.>522;063
- 4 ‘Claims.
'
‘ (c1. 1:21-41)
, The vpresent invention relatesto a work sup
According to the present invention, .a-s'tructure '
porting structure and particularlyrelates to such
is provided by which a workpiece may be sup
ported-and (maintained ‘lever-regardless of irregu
a structure in which the work support is auto
matically maintained level.
necessary
lar-i-ties
inwthe
and~desirablein
ground-or ?oor
-many
support.
?elds, for ex?
ample, in the airplaneassembly ?eld.~- .Thereitis
desirable to hold large subassemblies. absolutely
*"Onejof‘ the primary objects of the-present in- ,~
vention is’ to automatically maintain a work: sup
port level-,with extreme ;accuracy regardless of
any variations, in level in the ?ooror ground
Support
p
..
‘
.
leve1 during the entire vprocedure'of-assembling ~
the individual parts. The: structure of the pres
10' ent invention may-be either mounteddirectlyon
.
{Another object ‘of. the-ninventionqis to-auto
matically maintain a work-support level through
the-?oor, or it "may becarried on trucksalong
trackways, or. supported merely by trucks; or ,the
like. In any case, variations inthe levelof the
the action ofanovel ,?oat'controlled, ?uid actu- '
atedservo-mechanism.
,
,~
I
,
,
_
'
~
A 'further'obi'ect of theinvention is to provide
ground supporting surfaceor trackways would 7
animproved valve mechanism associated with the 15 tend to disturb‘ the ‘level support-of the .WOl'k
servo-mechanism.
'
-
i
‘
piece, which is necessarily supported at numerous
points-so that under those circumstances it would
not, remain inaccurate alignment during assem
,
A further object of the invention is to provide
an improved valve mechanism having a shiftable
valve element in which .the efriction is reduced-be
bly. With ajstructure ctr-the present invention, '
tween the valve element and the valve housing by 20 all of the supporting points of the workpiecewill
effecting continuous rrela'tive rotation‘ therebe
remain in .accurate relation ‘:regard-lessf-o-f any"
tween, thereby providing a sensitive and accu
variations in levelness of the ‘supporting ground
rately responsive servo-mechanism. "
'
A further object of theinvention is‘to 'provid
a-vvisual signal which indicates the relative rota
tionzabove
mentioned.‘
'
=
'
'
,
-
ortrack.
Referring to the
- drawings,
‘
»~
/ a ?at
> > table
->
member
_
25 I0 is mounted on a frame [2 and interconnected
thereto-through servo-mechanisms generally in
I
Other objects and advantages of theainvention
dicated'at ‘l4. Intheembodiment illustrated, the
table “Land frame-'1 2 aretriangular in shape with
will _ become xclearly apparent ‘from the following
speci?cation, thee-drawings relating thereto, and
fromthe claims hereinafter set forth. 7
three-:servo-mechanisms Myone located at each
.30. corner and ?xed to plate‘members 1.6, which are
' a
- .In thedrawings, in which like “numerals refer ’
' mounted'on the frame 42 at-the corners thereof.
to like partslin the several viewsthroughout:
Through the actionlof the servo-mechanisms“,
. Figurelis atop plan view of a work. supporting
to be described in detail hereinafter, the table
II] is maintained absolutely-level regardless of
structure embodying features of the present in
vention;
.
'_
r
v
35
'
Fig. 2 .is a front elevational view of the struc
_ j
~ .
‘Each servo-mechanism includes a ‘base 18
‘
forming a receptacle for a ‘bath of liquid, such
Fig.3 is adiagrammatic-view orthe hydraulic
as oil. The base I8 is secured to a plate lliby
means o'fybolts or‘ the like. An upper housing
40 member 2!] is removably secured to the top edge
ture shqwn'inFig. 1;
_
circuit and its relationship to the servo-mecha
niSm.
1
_
'
I
'
‘
.Fig. 4is~ a vertical, cross-sectional-viewthrough
one of the servo-mechanisms of the :present in
' of the base 18 andris formed to provide an vup-v
vention .and showing suchmechanism in its re
pending central portion 24 is formed, integral
lationship tothe supporting surface;
.»
..'Fig.; 5 is a cross-sectional view taken substan
tiallyalong the. line-1555101‘ Fig. 4;
wardly directed :cylinder chamber 22.» A de
with the housing :20 centrally thereofan'dwisv
45 forced 'withva vertical central bore 26. The upper
' end of bore “opens into the chamber Hand
M Fig; 6 .l-is~an'"enlarged,cross-sectional view-of
the lower end opens into the space ‘above re
that portion within the circle 6 of Fig. 4;
“Fig. 7 is a cross-sectional,viewtakensubstan
within chamber 22 :and is formed with an an
tially along theline 1—-'~7of.1i‘ig.;4;
,
any ti'ltingof the frame 12.
ceptacle +8. -Ar-pis_ton 28 .is'slidably :disposed
50 nular recess ‘30 -_on the periphery thereof within ‘,
-8 :is a .fragmentary, cross-sectional view
' which anannular synthetic rubber ring 321s
taken substantiallyalong the .line .8--.8 of. Fig,
disposed. .:Such vring 3,2 is circular incross-sec-k
tion and sealably engages ‘the wall of chamber
‘hand
7
.
'
.';Fig'.19 is ,a vertical, cross-sectional view of a 7
'22 as the piston 28 slides therein.
7
_
‘
'
portion of'ihas‘tructure showniniFigAand taken.
~ The integral'upper
I
I end 34 ‘of piston 2 8 extends]
at substantially 90° therearound.
through a ‘sealed opening in'an end cap‘ 36 which
,
2,408,169
4.
3
purpose of clear illustration. The valve element
96 is formed with reduced annular portions 98
and I00. Stem 54 is providedwith an enlarged
recess forming an annular chamber I02, such
annular chamber being located below passage
way 82, above passageway 60, and in direct com
munication with passageway ‘I4. The valve ele
is secured to the upper end of housing 20. The
upwardly projecting end 34 has an axial open
ing 38 formed therein which receives a pilot stem
40 of an adapter 42. The axial opening 38 may
be tapped to receive another type of adapter
which may be desirable for adjustability. The
adapter 42 has a dish-shaped recess 44 formed
ment 96 is formed with a pair of annular valve
portions I04 and I06. The shoulders formed
in the top surface thereof with an upstanding
integral pin 46 in the center thereof. The pin
46 is received through an opening 48 in table I0.
and the undersurface of table I0 rests upon a
top ?at surface of a supporting member 50;
Such supporting member 50 is formed with a
central opening therethrough' through which the '
pin 46 passes with a loose ?t. The undersurface
52 of member 50 is formed complementary in
shape to the shape of the dished recess .44 sov
by the chamber I02 de?ne annular valve sur
faces I08 and H0. The diameter of valve por
tion I04 is such that the lower annular edge
H2 thereof will seat against valve surface I08
to prevent the, passage of ?uid thereacross when
in its ‘seated position. The diameter of valve
portion I06 is smaller than that of valve portion
I04'and'the upper annular edge H4 thereof is _
disposed so that it will not entirely out off the
?ow of ?uid past valve'surface I ID in any of its
to piston portion 34 for properly supporting the
positions,
but will vary the resistance to ?ow past
20
table I0.
>
that the member 50 may tilt slightly with respect
the valve‘ surface I08 as'the relative positions
of the valve surface H0 and valve portion I06
The piston 28 is also formed with a] depending
stem 54, which is slidably received within bore
26; r The stem 54 is formed with chambers, ports
vary with respect to each other.
'
The passageway 58 is connected to a- source 'of
?uid under pressure in a manner that will be
?xed in position adjacent the "enlarged recess
I20 to limit relative movement inone direction
while the adjacent shoulder of the-‘recess limits
movement in the opposite direction. The lower
end of valve element 96 is ?xed to "the ?oat H6
The lower end of valve element 96- extends
and passageways for the ?ow of ?uid there
through and for the reception of a valve element 25 downwardlythrough the lower end ofbore ‘I0
and is connected to a ?oat H6. In order to limit
to‘ control the flow therethrough. A reduced
the relative movement between valve element
annular portion 56 is formed on stem 54 to pro
96 and bore 10, the valve element has an en
vide an inlet chamber which receives ?uid
larged annular shoulder H8 which is received
through passageway 58 and port 60 formed in
housing 20. A ?lter 62 is disposed in passage 30 within an annular recess I20 formed adjacent
the lower end of bore 12. v A stop ring I22 is
way 58 to ?lter the oil passed therethrough.
described hereinafter.
'
‘
A vertical passageway 64 is formed in stem
5.4 and communicates through passageway 66
with the annular chamber 56. A passageway
68 communicates with passageway 64 andalso
communicates with central bore ‘I0 formedv in
.stem 54.
so that it occupies the same vertical position
as the ?oat and so that it will rotate as the ?oat
rotates.
The ?oat H6 is supported in a bath
40 of ?uid, such as oil, the level of which is indi
cated generally at ‘I24. All of the receptacles
Anotherlvertical passageway ‘I2 is formed in
I8 are in open communication’ ‘with each other
stem 54 and communicates with bore ‘I0 through
through interconnecting pipes I26, one of the
passageway ‘I4 and also communicateswith'an
pipes'l26 having a tank or reservoir I 28 con
annular chamber "I6, formed by reduced portion
‘I8. of stem 54, through passageway 80. The 45 nected therein and in open communication with
that particular pipe I 26. The level‘of the ?uid
chamber ‘I6 communicates with the cylinder
in all of the receptacles I8‘ will thus always be
chamber 22 on the underside of piston 28.
Another passageway 82 is formed in stem 54'
the same so that the ?oats H6 may be consid
and communicates with another passageway '84 ,. ._ ered as being disposed in a common bath of ?uid.
formed on stem 54, which passageway 84 also‘ a. So as to effect an accurate and sensitive action
communicates through opening 86 with the in
of the valve elementv96 to control the ?ow of
?uid, friction between the valve element 96- and
terior of a tubular jet member 88. Such tubular
the wall of bore ‘I0 is reduced by rotating the
member 88 is ?tted to the lower end of stem
valve element 96 with respect to bore 10. Such
54 and the outer end thereof is formed to pro
rotation is effected by rotating the ?oat H6. An
vide a tangential jet outlet 90, as best shown
upwardly'extending skirt I28 is secured to the
in Fig. 8. The purpose of the tubular member
?oat H6 around the peripheral edge thereof and
88 and the jet outlet will be described herein
extends above the top surface thereof. A ring
after.
h
member I30 is also'connected to member I28 and
The outer ends of passageways 64,68, ‘I2,- 82
and 84 may be closed by ball plugs 92, with ‘the "601 ?oat H6 andis formed with in-struck tabs I32
adjacent surfaces of stem 54 peened thereover.
therearound which form rotor or turbine blades
against which the ?uid from jet 90 impinges to
The chamber 56 is sealed with respect to bore
cause rotation of "the ?oat H6 and, therefore,‘
26 by means of upper and lower sealing rings
rotation of the valve element 96. Drain openings
94 which are disposed in annular grooves formed
in stem ‘54. The arrangement of passageways e I34‘ are formed through members I28 and I30 at
spaced intervals the'rearound so that the ?uid di
68, ‘I4 and 82' with respect to each other‘ is as
rected against the vanes I32 may drain back to
shown and a control of the ?ow of ?uid there--v
between is e?ected by means of a valve element
generally'indicated at 96. Such‘ valve element
96 is slidably disposed within bore ‘I0 and is'
formed at its upper and lower ends with land‘
surfaces Which slidably engage the sides of the
bore ‘I0. Certain portions of thevalve element,
96 are shown in enlarged form in Fig. 6 and cer
the receptacle.
'
f
'
In‘ order thatan' attendant may be instantly
apprized of the fact that the valve element 96 is
rotating, a visual‘ signal is provided which will
indicate such rotation and will indicate whether
such rotation has stopped. Such means are |best
, shown in Figs. 4, v, and 9 and include an electric,
tain of the dimensions are exaggerated for the' 75. lamp I40 disposed in‘ each of the housings 20 and’
amazes
with suitable electricconnections tor I lately leach Themanneninwhich. eachof the
of; the bulbs_-..
polars-so. located-aside
serve-1nechanisms;v It acts. or operates. to. main»
directhehnaeainsttheiacingendlit-eia?ui
tain the lerei, condition is.» the Same’ for 311cm
ales: on-Luoiterod. I144”. SucheBlex-iglas. and-Lucite
such.- mecnanismsand a description for one will
are well known’.
of. thermoplastic?‘ material 5- be; sumcient; for an understanding; of all.v It will
which transmit. light. rays and.
be
5.0
be appreciatedthat. all of the floats. I-I-B are dis
thattherodextends upwarmythrouehcpening.
posed in a common; bath so that theyare; all
[.46 pnovidcd; in. housing; 2.0; ‘and; then: extends
maintainedat the,- same: level, thus. maintaining
completely around the housingwithinsanannulas
the-@valve;elementsfa?.atthe same level. Hydraulic
grooveiorrnedtherein>.on<.the.outside.. Theiouter 1.0 ?uidnnder’pressure,issuppliedpassageway 58am].
edgernay thenbe» ggtoundr?at asshownat; I48. It
chamber; 22 under piston 28;- wilL be ?lled withoil
intone-oi the, properties. of thismateriakthanlight
witl-rtheg» pistongin. the- approximate position- in.
reefs.impinging;against,surtaceg I:.42.'wil1:be~.visible
on». the roughened. surface I.4;8-.. A shutter? 01:
dicated in Fig. 4.. Ati-lting down of; one of the
corners of the-rfra-meewouldgeausea corresponding
screen L50.informed.withiamupstanding,central. 15' downward ,movementof receptacle.~ I8 and house
portion having cutawaysections. I52- betweenthe /
ing; 20;; and-,gwhile the, absolute level. of. theliquid
upstanding; screen-sections- I50.. Sucnupstande
remainasubstantiallythe same, the-depth ofthe
ing; sections. are.- disnosed. tonnes. betweensuriace
liqnidin'receptacle I8; is increased. This increase
I42: andbulb. Mil-as, the-?oat H6 rotatesrsottha't
in- depthpcauses the.v ?oat to rise.- with-therresult,
sections. I50=will-. intermittently blankthe direce zo thatthevalvesurface I08;mo.ves, away fromvalve
tion oLlig-ht. rays. against surf-ace I42- This will
edge [ill-so; that; the-?uid-under pressu-rerwollld
be indicated: by a blinking/onsurface: I48. In the
' pass from passageway 58, through passageway”,
eyentthat the. blinking stops. it will anonce be
‘intochamber 56,,through.passageways66;_64, and
apparent .thatthe rotation» of» the valve-element.
68,, past valveasurfacee II;2,, into- passageways. ‘[4,
has stoppedindicating; excessive-friction invalve, 2,5 1.2-,‘ 80.- a-ndinto, chamber; 16. and from: there into
failurezof hydraulicvpressureg etc. Accesstdthe ‘chamber: 22 under piston. 2-8, thus raising; the
interior ofthereceptacle I-8maybe-had-thmugh
piston.- 2-8. At thesametime, ?uidisrpassin'g from
an opening I54 having a transparent-removable
chamber I<0.2~.past valvesurface I.I-0_-into passage
windowtliliiassociated therewith.
waxt82. The. ?uid from- such. passageway. then
A source of ?uid under pressure is constantly 3,0 passesthrongh passage 8.4»into.and-.through tubue
supplied each of the passageways 58 of each of
lar jet member 88 and through the jet opening
the mechanisms I4.
Such source comprises a
‘ '90 so that it impinges against the vanes I32 to
pump I60 having the inlet end thereof communicating with tank I28 and having the outlet end
cause the valve 96 to rotate. The passage of ?uid
‘into chamber 22 would cause the piston 28 to
thereof communicate through a pressure relief 35 raise so that the valve surface I08 would move
valve I62 with each of three‘ branch lines I64.
Each of the branch lines I64 is attached to the
opening into passageway 58. The pump is driven
to a position adjacent valve surface I I2 to shut
off the ?ow of ?uid from passageway 68. .Any
tendency on the part of the table I0 to lower
by a suitable prime mover such as an electric
would cause piston 28 to move downwardly so that
motor I66. The relief valve I62 communicates 40 ?uid from chamber 22 would pass into chamber
back to the tank through a return conduit I68, as
‘I6 and through passageways 80, ‘I2, and ‘I4 into
is usual in hydraulic circuits. Suitable means
chamber I02 and past valve surface IIO through
‘may be provided within tank I28 to prevent tur-‘
passageway 82. The ?uid from the passageway
bulence therein, and also suitable means may be
82 then passes through the jet against the smooth
provided to ?lter the oil to the inlet to the pump. 45 annular surface above the blades I32 to cause the
Housing 20 is formed with a vertical passagevalve to rotate as mentioned above. By directing
way "0 which communicates at its lower end
the stream against the smooth surface itis spread
with the space above receptacle I8 and commu-
' over a relatively large area and ?ows down
nicates at its upper end through a passageway
against the blades in a tangential direction so
"2 with the chamber 22 above piston 28 so as to 50 that a smooth rotative action is attained. The
vent or return any ?uid which may have leaked
valve edge II2 may be considered as'the control
past piston 28 to the reservoir.
edge and, in a balanced condition, it will be very
In the embodiment illustrated, the frame - I2 is
slightly removed from seating contact with valve '
shown as being supported upon the ground or
seat I08. The relative linear movement between
?oor surface. In order to effect an approximate 55 valve 06 and piston stem 54 is very slight, in the
leveling of the device, screw jacks I80 are disneighborhood of a few thousandths of an inch,
posed adjacent each corner of the frame.
While }
so that the control is very accurate with a con
in the embodiment illlustrated, three jacks are
stant ?ow of ?uid past valve surface IIO either
shown, any number may be used, if desired.
from port 68 or port ‘I4. The slightest variations
However, it is to be understood that such frame 60 in levels at the corners of the frame will thus be
I2 might just as well be supported on trucks
instantly re?ected in any of the servo-mechan
running on a trackway or on trucks having
isms which instantly act to compensate for such
ground-engaging wheels. As mentioned above,
variations in tilting of the frame.
if there is any unevenness in the ground 01‘ ?OOr '
It is to :be understood that within the broader
surface or in the trackways Causing a tilting of 65 aspects of the present invention a single'servo
frame I2, the servo-mechanisms I4 automatimechanism Ii4 could be employed in which event
cally act to maintain the support I0 level
the projecting end of the plunger 3-4 would serve
In the operation of the device above described,
as a supporting member_
the work article is supported upon the table I0.
whatis claimedis;
The frame '2, which may be Supported as de- 70 1. A device of‘the type described comprising a
scribed above, may not be level so that each of
supporting member’ a ?oat disposed in a bath
the three corners of the frame may be diSDOSBd
of liquid, and a ?uid servo-mechanism intercon
at different levels. In that event. the SerVOnecting said ?oat with said member, said mech
mechanisms of each of the corners will autoanism including a cylinder, a piston disposed
matically act to maintain the Support “I abSO- 75 therein and connected to said supporting mem
2,408,169
7
her, a pair of cooperating and relatively shift
able valve elements, one of said valve elements
being connected to saidpiston and the other to
said ?oat, and means to supply ?uid under pres
sure past said valve elements, said valve elements
being so constructed and arranged thatv ?uid'is
continuously passed to atmosphere.
'
_
8
one of said valve elementsbeingconnected to said
piston and the other-"t0 said ?oat, means to sup
ply'?ui‘d under pressure past said valve elements,
said'valve elements being so constructed and ar
ranged'th‘at ?uid is continuously passed to at
mosphere, and means disposed in the path of the
fluid passed-to atmosphere and connected to one
of said valve elements to continuously rotate said
,2. A device of the type described comprising a
one of said valve elements.
‘
supporting member, a ?oat disposed in a bath of
‘4. A device of the type described comprising a
liquid, and a ?uid servo-mechanism interconnect
supporting member, a ?oat disposed in a bath of
me; said ?oat with said member, said mechanism
liquid, and a ?uid servo-mechanism interconnect
including a cylinder, a piston disposed therein
ing said ?oat with said member, said mechanism
and connected to said supporting member, a pair
including a cylinder, a piston disposed therein
of cooperating and relatively shiftable valve ele
and connected to said supporting member, a pair
15
ments, one of said valve elementsbeing connected
of cooperating valve elements shiftable relative
to said piston and the other to said ?oat, and
to each other in a linear direction, one of said
means to supply ?uid under pressure past said
valve elements being connected to said piston and
valve elements, said valve elements being so con
structed and arranged that ?uid is continuously
the other to said ?oat, means to supply ?uid un
passed to atmosphere and 'for certain positions 20 der pressure past said valve elements, said valve
elements being so'constructed and arranged that
of said valve a portion of said fluid is passed to
said cylinder.
'
.
?uid is continuously passed to atmosphere and
for certain positions of said valve a portion of
3. A device of the type described comprising a
said ?uid is passed to said cylinder,‘ and means
supporting member, a ?oat disposed in a ‘bath of
liquid, and a ?uid servo-mechanism intercon 25 disposed in the path of the ?uid passed to at
mosphere and connected to one of said valve ele
necting said ?oat with said member,’ said mech
ments to ' continuously rotate said one of said
anism including a cylinder, a piston disposed
valve elements.
_
I
therein and connected to said supporting mem
"JAMES F. HOFFER.
ber, a pair of cooperating valve elements shift
able relative to each other in 'a linear direction,
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