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Патент USA US2405377

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Aug; & 1946.
J. STURGE'SS ET AL
-
'
2,405,377
CABLE TENSION REGULATOR
Filed Aug. 2, 1945
4 Sheets-Shee£ 1
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INVENTORS
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Aug. 6, 1946.
.LsTuRsEss ETAL
CABLE TENSION REGULATOR
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Filed Aug.. 2, 1943
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Aug, 6, 1946.
J. STURGESS ET AL
4 2,405,377
CABLE. TENS ION REGULATOR
Filed Aug. 2, v19,43
4 Sheets-Sheet 4
.
JOHN
JOHN
INVENTORS
STURGESS
m 0405
EXI/EISTIAN
w. \ AVITZ
ATTORNEY
"
Patented Aug. 6, i946
2,405,377
UNITED STATES PATENT OFFICE
2,405,377
CABLE TENSION REGULATOR
John Sturgess and John W. Cade, LaCanada, and
Christian W. Savitz, Norwalk, Calif., assignor's
to Sturgess, Inc, Glendale, Calif., a corpora
tion of California
Application August 2, 1943, Serial No. 497,028
16 Claims.
1 .
I
This invention relates to devices for automati
cally regulating or maintaining the desired ten
sion in a work cable, rope, or wire, or a pair of
such cables or wires which are required to be
free from slack at all times or kept under a
minimum operating tension, yet subject to greatly
increased tension when the work load is applied,
as in the operation of remote controls, signal,
arms, etc.
(01. 74-501)
'
The principal object of the present invention
is to provide an improved cable tension control
ling device particularly adapt-ed for use with the
rudder, elevators, ailerons, and other movable
2
intervals to a greatly increased tension when a
working pull is applied to it to accomplish the
work to be done, and after the working pull is
removed the cable is slacked off below its prede
, termined tension.
The function of the regulator is to take up»
(through its spring) any slack in the cable to
maintain the cable taut at the said predetermined
tension when not being subject to the extra work
ing pull, and to lock out the spring during such
time as the working pull is applied, so that the
working pull will be transmitted direct without
passing through the spring.
parts of aircraft which are situated a consider
The looking out of the spring during the Work
able distance from the point where the control 15 ing pull is accomplished ‘through bodily move
ling force is applied to the cables.
ment of the regulator with respect to an adjacent
A feature of importance is that the improved
relatively ?xed tripping device past which the
construction adapts the tension regulator to be
regulator moves, and the unlocking of the spring
used in any type of cable control system, and
similarly taking eifect upon reverse bodily move
for any kind of movable control surface or device. 20 ment of the regulator relative to‘ the tripping
Particular advantages and features of the im
device.
proved construction Will appear in the following
In its preferred form the regulator comprises
description and accompanying drawings.
a hydraulic cylinder with a slidable piston inside
‘ In the drawings-—
,
having a piston rod extended from one end of
Fig. 1 is a side elevation of our improved cable
the cylinder, and with a spring tending to force
tension regulator as applied to the ends of a
the piston toward the opposite end of the cyl
work cable at an intermediate point in the run
inder.
_
of the cable.
The rope or cable to be tensioned is cut and
Fig. 2 is an end elevation of the device of 30 the regulator interposed between the ends by
Fig. 1.
securing them respectively to the cylinder‘ and to
Fig. 3 is a View similar to that of Fig. 1 but
the piston rod with the spring tensioned to yield
showing the device in longitudinal cross section.
the minimum cable tension desired to be main
Fig. 4 is a sectional detail of the by-pass valve
tained. The cylinder is ?lled with a hydraulic
liquid,
preferably oil, and a valved by-pass pas
of the device.
35
sage extending from opposite ends of the cylin- .
Fig. 5 is a sectional view similar to that of Fig.
der around the piston, provides when its valve is
3 but showing a modi?cation of the construction.
closed for stopping the piston from movement
Fig. 6 is a bottom plan view of the track and
cam of Fig. 5.
within the cylinder under a working pull, thus
Fig. 7 is a side elevation of a modifiedform of 4-0 effectively looking out the spring and transmit
cam.
Fig. 8 is a perspective sketch showing a typical
aircraft rudder control system with our tension
regulator applied at an intermediate point in the
run of one of the control cables. -
Fig. 9 is a perspective sketch of an aircraft
rudder control showing one‘way of using our
tension regulator in the so-called dead end cable‘
system.
Before describing the drawings in detail it
may be stated that broadly the regulator com
prises a spring compensator adapted to be in
ting the pull direct, whereas upon opening the
by-pass valve the liquid is free to surge back and
forth from either end’ of the cylinder so that
the spring tension is always maintained on the
45 rope when not subjected to a working pull. The
by-pass valve is arranged to be normally closed
except when tripped to open position by a cam.
device or its equivalent which is relatively ?xed
with respect to the bodily movement of the regu
50 "lator with the movement of the cable in which
it is interposed.
In ordinary aircraft controls having two cables
terposed as a link in an operating cable desired
to be maintained. taut at allitimes'with a prede
either side from a central position there may be
termined tension, but which cable is subject at
one of the regulators for each cable, and the valve
for forcibly pulling the rudder, elevator, etc., to
2,405,377
4
3
trip set to open the by-pass only along the cen
tral position of the rudder or other control sur
face, while for signal or other purposes where
a pivoted device is moved the entire distance
either way respectively, each time either cable
is pulled, the valve trip is set to open the by
pass only at the» ?nal end of the movement of
the non-pulling ca‘ble.
Various novel and important features are in
corporated in the above general structure as will
appear later.
‘
'
'
force to open or stretch it to hold the piston in
about the center of the cylinder with a tension of
about sixty pounds on the cable (depending on
the size and service to which it is put).
The spring is mounted at opposite ends upon
two flanged disks, 3i and 32 spirally grooved or
“threaded” as indicated at 33 to tightly receive the
ends of the closed coil of wire which is forcibly
, screwed upon it and preferably welded at the end
‘of the wire to prevent unscrewing.
Disk 3| is
provided with a central hub to slidably fit over the
outer end of the piston rod and also over the
With respect to the design shown in. Figs. 1 to
3, the cylinder is designated I, the piston body 2,
projecting ends ‘of key 25. Disk 32 is revolvably
tion as an oil displacement and make-up reser
ring 49 in a Wide recess 59 below the cap insures
carried over the end of the cylinder i ‘as by a
piston rod secured thereto 3, closed head of the
cylinder 4, ends of cable between which the 15 cup-shaped metal stamping 34 which is secured
to the end of the cylinder as by cap screws 35
regulator is interposed are designated 5 and 5’
which also hold a cup-leather packing 36 for the
respectively secured to the closed end of the cyl
piston rod in place and also hold an inner tubular
inder and the outer end of the piston rod.
collar 3? in position within the cylinder to pro
In use the regulator isrollably suspended on a
fixed track 6 by means of grooved idlers 1 car 20 vide a limit stop for the piston movement and
protection for the cup-leather.
ried by'a bracket 8 in turn secured to the cylin
The cylinder is ?lled on both sides of the piston
der, or rather to end bolting flange 9 of the cyl
with a suitable hydraulic liquid able to stand low
inder to which the closing head 4 is secured as by
temperatures without freezing, as is also the dis
bolts l0.
Bolts It! also secure the arms of a, spider H to 25 placement space within the hollow piston rod un
til its spring 28 is compressed about half way,
the head 4 and ?ange 9 of the cylinder, and which
the by-pass passage 38—38' is here indicated as
spider revolvably supports a cable connecting
extended in tubes 39, 39’ through a shut-off or
draft rod IE-provided with a flattened apertured
by-pass valve 40, and which passage opens at its
head I 3. The rest of the rod is round and formed
with a portion of reduced diameter embraced 30' ends to opposite ends of the cylinder.
The by-pass valve t!) is shown in section in
within the two halves of a split bushing collar
Fig. 4 and wherein the by-pass passages con
it which rotatably fits within a, central hole in
nect respectively to the lower and upper portions
the spider, and which split bushing is held in
of a vertically disposed plunger valve chamber 42
place bya solid locking ring 11 engaging over the
neck of the split bushing and urged against the 35' in which is slidably positioned a plunger valve 43
normally forced outward by a'spring 44 to close
spider by a, small compression spring l8 reacting
off passage 38' as shown, but which when de
at its outer end against a shoulder 19 formed on
pressed open "both passages 38 and 38' through
rod 12. . This construction makes it easyto dis
the bore 45 and side ports E6 of the plunger. A
connect the draft rod l5 and its cable' 5 from
the cylinder by backing off the locking ring ll 40 cap 47 at the upper end of the valve body I30
?ts over the reduced upper end $3 or stem of the
against spring 18 and slipping out the halves of
valve which projects for operating the valve,
the split bushing 16.
while suitable packing, such as a rolling Thiokol
The piston rod 3 is here shown hollow to func
voir, and it is formed with a head 20 at its inner
end against which the piston body 2 of the piston
bears and is clamped thereagainst by a nut 2i
screwed on the rod against a washer 22 and also
clamping a conventional cup-leather packing 23
in place.
.
>
’
Hollow piston rod 3 is closed at its outer end
by a draft‘ rod 24 which is keyed through the tube
by a key 25, and the outer end of the rod is'
flattened as at 26 and apertured to'receive the
cable 5' ‘like the end l3 of the opposite draft rod
described Within the hollow piston rod is a
small ?oating suitably packed thimble-like piston
21 normally urged toward the cylinder l by a
against liquid leakage around the stem.’
The track 6 upon which the regulator rolls is
of a length great enough to support the regu
lator for the full distance the cable must move,
as well as to allow for some longitudinal adjust
ment if required. The track is preferably of T
form in cross section as shown in Fig. 2 and with
the cross bar of the T extending vertically with
the grooved rollers l engaging it from above and
below so that the regulator cannot become de
tached.
Attached to the horizontally extending central
leg 6’ of the track is a valve tripping cam 51
bolted or otherwise secured thereto in a position
to depress or trip the stem 48 of by-pass valve
at its outer end against the inner end of draft 60 46 as the regulator is moved longitudinally along
the track and hold the by-pass passage open as
rod 24. A small vent 29 in hollow rod 3 provides
long as the regulator is in valve tripping position.
for air circulation at the outer side of piston 21,
The exact position of tripping the valve may
while at the inner end is a small disk screen I30
be determined by longitudinal adjustment of
crimped in place.
While a coiled compression spring may be used 65 the track at its end supports 53 to which it may
be adjustably secured as by bolts 54 passing
within the cylinder to urge the piston one way
through slots 55 formed adjacent the ends of
for tensioning the cable, and as shown in the de
the track after cutting away some of the central
sign of Fig. 5 to be later described, in Figs. 1 to' 3
‘
leg 6' of the track as indicated in Fig. 1 or in any
a relatively large diameter coiled tension spring
30 is used at the outer end of the cylinder as 70' other suitable manner.
In some installations the regulators are in
such a spring has advantages not found in a
stalled
on a pair of cables as used for aircraft
compression spring, particularly‘ in operating
controls in a position to trip or open the by-pass
over a greater range and not requiring support
valves when the control surfaces are in neutral
against inward collapse; This spring is initally
very tightly wound so as to require considerable 75 or central position, whereas for the other kinds of
light wire compression spring 28'which is seated
5
2,40,51,37?
service, it, may be desirableto hold the valves.
open. on the. slack cable. at theextremev endsof
been included to indicate two modes of installing
the regulator in the rudder control system of an
the non-pulling movementor “stroke,” while
airplane.
instill others the. valve may be kept open. for
In the ?guresa rudder is. indicated at 15,-.tho.
half; of the stroke. Such variations of setting. 5 this is for illustrationonly as. the pivoted. control
my. be secured. through. the original setting or
surface or other device to be operated may be
installing, or to a limited exentby shifting the
anything which it is desired to swing by cable,
tracks longitudinally and/or the position or. the
rope, or Wire pull from a remote point, such as
tripping cam Si, or by the. use of special cams
from the pilots position on the plane. At 16 and
512.. 6.7- shqwn. atFies-?. and 7. to. bedescribed.
‘I1; respectively is the pedal operated control.
Alecia some. service requirements. a one way
light spring. loaded check. valve may he placed
inithghead of. the. piston as. shown at 56 in. Fig.
3 (and Fig. 5)v wherein the passage is normally,
closed, This insures the freedom\ of the spring
to exert itsnliniitof pull; atv alltimeson the. cable
evlengthe the wqrkinepull should iallbelow it at
times when‘ the by-pas's valve is closed.
Inv thesmodi?ed form. Qfthe regulator. shown.
shafts geared or linked together as at ‘I8 for
reverse rotation and provided with two pairs of:
pedals 19 with the control cables 5, 5" either
connected at their forward ends directly to»
15 cranks 80 and at their rearward ends to the;
rocker arm 8| secured to the rudder shaft 82,. and
the cables suitably guided by idler pulleys 83
as may be required, all as shown in Fig.8 and‘
which is a conventional system, or as shown in;
in Fig. 5' theparts which operate the same as 20 Fig. 9 the cables 5, 5" from the rudder may pass
those in. the. preceding figures have been given,
over pulleys 84 carried on a crank arm 85 on one
the same numerals so as to, avoid the necessity
of the control shafts and then extend to a ?xed
of. 'redescr-ibing them. The same features differ
ing. slightly from the preceding are in the use
anchor plate 86.
or a cast cylinder body I Witha cast head 4 with
the cable. connection I3 cast integrally with it.
Also. cast. channel 39 for the by-pass passage 38
and the use of two brackets 8 for two grooved
rollers ‘I. each, embracing the track 6.
In this ?gure the spring 30’ is an open coil
compression spring instead of a tension‘ spring
and is placed within the cylinder I which is made
longer. for this, purpose, whilea tubular stop 60'
surrounds the piston'rod' to limit the piston travel
in compressing the spring.
Thejrod. packing. box is indicated at 36’, and
the oil displacement and make-up» chamber in
stead‘ of being within a hollow, piston rod, is‘
vertically positioned at 6_l at one» end vof the
Similarly at the rudder the
cables pass over pulleys 81, and returntoa ?xed
anchor plate 88 secured to a convenient part of;
the plane fuselage. Besides, any number of
guide pulleys or idlers 83 used to lead the cables
around obstacles to their desired destinations.
This latter arrangement is known as the “dead
30
end control system.”
'
'
In the conventional systemas, shown in Fig‘. 8
our regulator I is shown interposed in one cable
only, and rollably supported onits track 6; as ex—
plained previously in detail, tho as stated, prefer
35 ably there is one in each of the cables.
Since
any bodily movement. of the regulator from cen-.
tral position of’ the rudder, trips the by-pass valve.
it is desirable that the body of the regulator.
or cylinder I should, only move as the control:
regulator andprovided with a screw ?lling cap 62‘.
40 pedals are moved and not from relative elonga
In this. showing a. ball. type by-pass valve 43'
tion or contraction of the cables with respect to:
isused, and the body 40 is cast integral, and the;
the airplane structure lying between the pilot
stem d8is. tripped by the track cam. as before,
and the rudder, it is therefore preferable that
but. the cam 52 is shown as formed by bending
the regulator be mounted as near the pilot end.
a ?at strip- of metal 63in turn bolted as at 64 45 of the system as practicable and. that the short
tothe- track through slots 65 cut in the track
piece of cable fromv the control crank be. secured.
forv longitudinal adjustment (see Fig. 6).,
to the cylinder portion of the regulator. Also suit
InFig. 7 is shownin- side elevation a form of.
able turnbuckles are provided in the cables as at.
elongated cam 66 to holdtheby-pass valve open
89 to provide for proper setting of. the regulator
during any desired part of. the travel of theregu 50 piston at mean temperature.
lator, and close it when the valve stem passes
In the “dead end” type of installation, Since the
the slanted end 61.
cylinder I is anchored and cannot move back and
As the position of the piston of this form
forth to trip the by-pass valve, the track with its
should be. about. one third from the closed end
tripping cam is moved instead. This is accom
of. the cylinder’ when the pull on the cables is
plished by pivotally connecting one end of a short
under spring control only (with by-pass open) 55 piece
of track 6v or otherrod to the operating
and at. mean temperature of the locality in which
crank 85 of the control shaft as at 9!) and extend
ing the free end of vthe track over the cylinder I
embraced by its grooved rollers ‘I and with the
This: gage may take the form of a rod 68 pro
tripping cam 5| carried by the track, all so that
60
J'ectingfrom the body of the cylinder parallel to
as the cable is moved back and forth from central
the piston rod and adjacent which rod a thin
rudder position in operating the control shaft it
disk. 69. secured to the piston‘rod travels. The
will trip the by-pass valve as previously described.
rod 68 being. marked at 10 for the proper posie
From the above description of the operation of
tion for the piston, and also colored or marked
at ‘Hand projecting to 12, to show opposite ex 651 our cable tension regulatinggapparatus it is evi
dent that while we show it interposed in the
the installation is. being used, a suitable gage
is provided to' facilitate
accomplishing this.
tremes ofv travel.
From the above descriptionand explanation
cables of a manually controlled system, it will
operatejust as well in any automatic control sys
tem in maintaining, a predetermined minimum
of. the functioning of the various parts, the op»
eration-of the tension regulator should be clear, 70 tension on the control cables.
howevenas there are various. ways of installing
the regulator, depending on the service to which
the. cable or. cables are put, aswell as the par
ticlllar, arrangementv and relation of the operat
Having thus described‘ our invention and its
mode of operation, it will be obvious to those
skilled in the art that various changes in detail of
construction maybe madev within the spirit of.
ing to-the. operated Ilarts, Figs. Sand: .(Lhaye 75 the ,inventionassoughtto be coveredin our. ap.-.
2,405,377.
8
pended claimsand our use of the words “cable”
said regulator and a relatively ?xed track ‘along
or “cables” herein is intended to cover the equiv
alent for some installations where ropes, wires,
chains, or ‘rods, under tension, : are commonly
,which said regulator moves as the>control cable
is operated, and tripping means carried ‘by'said
track arranged to operate said locking means
as the regulator moves relatively therealong, said»
employed to operate from-a distance a pivotally
movable member backand forth. Weclaim:
.
-
'
5
a
T
tripping means being set tounlock said spring
-
- l. Ina control cable tension regulatorof the
meansat a minor portion of the travel of said
regulator along said track and to lock it at the
major portion of its travel.
I
type adapted to be interposed in a run of control
6. Ina control cable tension regulator of the
cable with the ends of the cable secured thereto so 10
type adapted to be interposed in a run of con
as to form a link in said run and said regulator
trol cable with the ends of the cable secured
including! tensioning means for maintaining a
thereto so as to form a link insaid run movable
tension on said cable: the. improvement which
longitudinally back and forth therewith as the
comprises locking means for looking out said ten
sio'ning means whereby the cable pull‘ is rendered 15 cable is moved longitudinally and said regulator
including spring-means for maintaining a ten
direct through said regulator and means extra
sion on said cable; the improvement which com
neous to and movable with respect to said regu
prises locking means for locking out said'spring
lator adapted to lock and unlock said locking
means whereby the cable pull is rendered direct
means as the regulator moves bodily with the
20 through said regulator and a relatively ?xed track
control
cable.
'
'
‘I
a
-
a
2. In a control cable tension regulator of the
‘along which said regulator moves as the control
cable is operated, and=tripping means carried by~
said track arranged to operate said locking means
as the regulator moves relatively therealong, said
so as to form a link in said run and said regu
lator including tensioning meansvfor maintaining 25 tripping means being set to unlock said‘ spring-'
means at the central portion of the travel of said
a tension on said cable: the improvement which
cable and to lock it out for the remainder of its‘
compriseslocking means for looking out said ten
travel.
,
sioning means whereby the cable pull-is rendered
7. In a control cable tension regulator asset
direct through said regulator, an elongated
member along which said regulator moves rela 30 out in claim 4, means for adjustably securing said
tripping means relative to said regulator and
tively as the control cable is operated, and means
along the path of travel thereof.
carried by said member for operating said look
type adapted to be interposed in a run of control
cable with the ends of the cable secured thereto
8. In a control cable tension regulator as set
ing means as the regulator moves relatively.
out in claim 4, said track being T shaped in cross
3. In a control cable. tension regulator of the
type adapted to be interposed in a run of control 35 section with the leg of the T carrying said trip
cable with the ends of the cable secured thereto
ping means, and rollers engaging the edges of
so as to form a link in said run and said regu
the cross arm of the T rollably supporting the
lator including tensioning means for maintaining
regulator thereon.
a tension on said cable: the improvement which
‘
‘
9. In a control cable tension regulator of the
comprises locking means for looking out said ten 40 character described having a hydraulic cylinderv
with a piston slidable therein and piston rod ex
sioning means whereby the cable pull is rendered
tending therefrom and means for securing the
direct through said regulator, including a mem
ends of a-cable respectively to the outer end of
ber along which said regulator moves relatively
said piston rod and to the remote end of said‘
as the control cable is operated, and means car
ried by said member for operating said‘ locking 45 cylinder and spring-means urging said piston to
ward one end of the cylinder and a liquid by,»v
means as the regulator moves relatively, a mov
pass passage extending from the cylinder spaces
able control element for pulling said cable, said
at opposite sides of the piston: the improvement
member linked for movement by said control ele
which comprises a valve on said passage, and a
ment to move said member relative to said regu
50 relatively ?xed valve tripping device arranged
lator as the cable is pulled.
adjacent said cylinder adapted'to trip said valve
4. In a control cable tension regulator of the
as the cylinder is moved longitudinally upon op
type adapted to be interposed in a run of control
erating the control cable.
‘
'
cable with the ends of the cable secured thereto
10. In a control cable tension regulator of the
so as to form a link in said run movable longi
tudinally back and forth therewith as the cable 55 character described having a hydraulic cylinder‘
with a piston slidable therein and piston rod
is moved longitudinally and said regulator includ
extending therefrom and means for securing the
ing spring-means for maintaining a tension on
ends of a cable respectively to the outer end of
said cable; the improvement which comprises
saidpistonrod and to the remote end of said
locking means for locking out said spring-means
whereby the cable pull is rendered direct through 60 cylinder and spring-means urging said piston to
ward one end of the cylinder and a liquid by-pass
said regulator and a relatively ?xed track along
passage extending from the cylinder spaces at
which said regulator moves as the control cable
opposite sides of the piston: the improvement
is operated, and tripping means carried by said
which comprises a valve on said passage, and a
track arranged to operate said locking means as
65 relatively ?xed'valve tripping device arranged
the regulator moves relativelytherealong.
adjacent said cylinder adapted to trip said valve
5. In a control cable tension regulator of the
as the cylinder is moved longitudinally upon
type adapted to be interposed in a run of control
operating the control cable, a track supporting
cable with the ends of the cable secured thereto so
said cylinder for relative movement therealong,‘
as to form a link in said run movable longi~
tudinally back and forth therewith as the cable 70 and said tripping device carried by said track. 11. In a control cable tension regulator of the
is moved longitudinally and said regulator in
character described having a hydraulic cylinder
cluding spring-means for maintaining a tension
with a piston slidable therein andpiston rod-ex
on said cable; the improvement Whichcomprises
tending therefrom and means for securing the
locking means for looking out said spring-means
whereby the cable pull is rendered direct through 7.5: ends‘of a cable respectively to the outer end of >
2,405,377
10
said piston rod and to the remote end of said
reservoir extending upwardly from the rear end
of said cylinder serving also as an air trap,
cylinder and spring-means urging said piston to
ward one end of the cylinder and a liquid by
pass passage extending from the cylinder spaces
14. In a control cable tension regulator of the
type adapted to be interposed in a run of control
cable with the ends of :the cable secured thereto
at opposite sides of the piston: the improvement
which comprises a valve on said passage, said pis
ton rod being hollow with its inner end open to
the cylinder space at one side of the piston only,
so as to form a link in said run to move longi
tudinally back and forth with the cable as the
cable is moved longitudinally and said regulator
including spring-means for maintaining a ten
and a piston slidably positioned within the bore
of the hollow piston rod urged inwardly by a light 10 sion on said cable: the improvement which com
spring to afford a liquid displacement and loss
prises locking means for locking out said spring
make-up chamber.
means whereby the cable pull is rendered direct
12. In a control cable tension regulator of the
through said regulator and means for operating
character described having a hydraulic cylinder
said locking means from a point extraneous to
with a piston slidable therein and piston rod ex
I’ said regulator as the regulator moves longitudi
tending therefrom and means for securing the
ends of a cable respectively to the outer end of
said piston rod and to the remote end of said
cylinder and spring-means urging said piston to
ward one end of the cylinder and a liquid by-pass
passage extending from the cylinder spaces at op
posite sides of the piston: the improvement which
comprises a valve on said passage, and a check
valved passage extending directly through the
piston to permit ?ow of liquid in opposite direc
tion to movement of the piston by said spring
nally with the cable.
15. In a structure as set out in claim 9, said
valve comprising a piston-type plunger slidably
arranged to shut o? or open the by-pass passage
and normally held in close position by a spring
and with the end of the plunger extending for
operation by said tripping device.
16. In a structure as set out in claim 9, gage
means carried by said piston rod, and cooperat
ing gage means carried by said cylinder denot
ing the position of said piston in said cylinder.
means.
13. In a structure as set out in claim 9, means
supporting said cylinder substantially horizon
tally, and a liquid displacement and make-up 30
JOHN STURGESS.
JOHN W. CADE.
CHRISTIAN W. SAVITZ.
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