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Патент USA US3046750

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July 31, 1962
3,046,744
K. RITTER
HYDRAULIC CONTROL APPARATUS
Filed March 29, 1961
5 Sheets-Sheet l
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July 31, 1962
3,046,744
K. RITTER
HYDRAULIC CONTROL APPARATUS
Filed March 29, 1961
3 Sheets-Sheet 2
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INVENTOR
Karper Rz'zlÍe/f'
BY 'MQ/Lul É „mk
/1/-3' ATroRNEY
July 31, 1962 '
K. RITTER
3,046’744
HYDRAULIC CONTROL APPARATUS
Filed March 29, 1961
3 Sheets-Sheet 3
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INVENTOR
/f I'J ATTORNEY
United s States
1
3,046,744
KasparyHYDRAULIC
Ritter, Kirchheim,
CGNTROL
Teck, Germany, assigner t0
. AllgaierfWerke G.m.b.H., Uhingen, Wurttemberg, Ger
man
y Filed Mar. Z9, 1961, Ser. No. 99,173
2t) Claims. (Cl. ‘S0-_53)
- «Patented J'uly' s1, 19erV
`
a
duit means, is subjected to the pressure of the main con- -
duit means and holds the first control valve inthe open»
position. However, when the shiftable valve memberY l’
connects the control conduit means with the-discharge’
opening, the pressure acting on the control piston is re-.r
‘ duced,- and the control piston eiïects closing of the'iìrst
control valve. ` As soon as the ñrst control valve isl
closed, the pressure iluid in the inner conduit builds up
the pressure until it is great enough to open the second
The present invention relates to a hydraulic control
apparatus for varying the transmission ratio of a hy 10 high pressure control valve which opens and permits dis-v
draulic transmission, for example a transmission in which
charge of the pressure fluid through the outletz SinceV
`
a wobble plate pump drives a wobble plate motor. In
the shiftable valve member in its connecting position con
transmissions of this type, a pump is provided for pump
nects the inlet conduit with one end of the operating cyl
ing liquid under pressure into the -transmission. The
inder, and the‘discharge opening ‘with the other end of .
pressure of this pump can be used to drive a servo piston
the operating cylinder, the operating piston is moved -by
which operates the means by which the transmission ratio
pressure ñuid under the high pressure, and effects adjust--
is adjusted.
' Known control arrangements serving this purpose have
ment of a controlled element connected thereto.
Y
The control apparatus of the invention advantageously
the disadvantage that the comparatively low pressure re
forms part of a novel combination with a hydraulic trans
quired for the transmission and supplied by the pump, 20 mission whose ratio is to be .adjusted by the control appa-f
necessitates the provision of a servo piston having an ex
ratus. In this arrangement, the above-described main
. tremely great cross-section since only in this manner the
great forces for the adjustment of the transmission can be
produced. The great cross-section of the servo piston and
the corresponding cylinder, results in a very slow motion
of the piston and of the means `which adjust the ratio of
conduit> means is a part of a pressure conduit by which a
pump is connected to the hydraulic transmission to supply l
the liquid thereto so that the necessary pressure is main->
tained in the transmission. The operating piston Vof the
control apparatus is connected to the operating means by
the transmission. Moreover, in the control arrangement
which the transmission ratio is adjusted, and actuates the>
Saule.
of the prior art, the supply of the pressure liquid to the
transmission is interrupted during the adjustment of the
ln a preferred embodiment of the invention, a sliiftable`
ratio of the transmission, resulting in an interruption of 30 member, for example a lever, is articulated to the operat
ing piston which controls the operating means of the
the torque transmitted by the transmission, which is par
ticularly undesirable when the transmission is used for
transmission .and also to the shiftable valve member. The
driving the wheels of a vehicle.
It is one object of the present invention to overcome
the disadvantages of the prior art constructions providing
a servo motor for adjusting a hydraulic transmission, and
to provide a hydraulic control apparatus permitting a
lever is also connected to a manually operated means by
which the operation is started since a shifting of the
lever will result in shifting of the valve member. When
rapid adjustment of a control element by a comparatively
sure and has adjusted the transmission, it has also moved
the shiftable valve member to its closing position, rein
small piston.
stating the initial position of all elements.
Another object of the present invention is to provide a '
hydraulic control apparatus in `which the pressure of a
supplied operating liquid is increased when an adjusting
operation is required.
Another object of the present invention is to provide
.
the operating piston is displaced by the increased pres
-
In one embodiment of the invention, the first control
valve is a slide v_alve'movable transverse to the direction
of the conduit in which it is located. In another em-`
bodiment, a valve seat is provided in the respective con
duit, and the control valveis seated on this valve seat,
a hydraulic control apparatus for a hydraulic transmission 45 when in its closed position. vIn both embodiments'fof
the invention, it is advantageous to provide a throttlein which the comparatively low pressure of a liquid sup
intermediate the main conduit means and the controlï
plied by a pump is increased in the control apparatus to
conduit means the pressure of which effects operation ofÍ
effect a rapid operation of .a servo piston >under manual
the ñrst control valve. The throttle has the eifect that
control, so that the transmission can be rapidly adjusted
without a reduction of the pressure of the fluid supplied 50 the movement of thel operating piston is somewhat
dampened so that too rapid changes of the transmissionby the pump to the transmission.
ratio are reliably prevented.
With these objects in View, the present invention re- l
'I'he novel `features which are considered as characterise
lates to a hydraulic control apparatus which comprises
tic for the invention are set forth in particular in thef
main conduit means including an inlet conduit for a pres
appended claims. The invention itself, however, both as
sure tluid and íirst and second parallel outlet conduits
to its construction and its method of operation, together
connected to the inlet conduit; a normally opened first
with additional objects and >advantages thereof, .will -be
control valve in the Íirst outlet conduit; a normally closed
»best understood from the following description of spe
second high pressure control valve in the second outlet
cific embodiments when read in connection with the ac
- conduit; control conduit means connected to the main
A
conduit means and having a discharge opening; a hy» 60 companying drawings, in which: `
FIG. l is a schematic longitudinal sectional view of anY
draulic control member operated by the pressure of the
apparat-us according to the present invention for driving.
control conduit means to operate the ñrst control valve; a a vehicle,
’ cylinder communicating with the control conduit means,
_ _ for example a tractor, and including a hydraulic.
transmlsslon, and a hydraulic control apparatus in accord-`
and a piston in the cylinder; and an operating valve means
in the control conduit means including a shiftable valve 65 ance with the present invention for varying lthe transmis-1V
member having a closing position closing the cylinder,
sion ratio under manual control;
p
f
FIG. 2 is a fragmentary axial sectional view illustrating
and a connecting position connecting the control conduit
the hydraulic control apparatus according to the present
means with the discharge opening.
invention lon an enlarged scale in a first operationalvposi-V.
When the valve member is in the position closing the
tion;
cylinder, the hydraulic control member, for example> a 70
control piston in a cylinder chamber of the control con
FIG. 3 is a longitudinal sectional view illustrating the~>
control apparatus shown in FIG. 2 in a different oper
speer/4.4.
3
ational position in which the transmission ratio of the
transmission is adjusted; and
FIG. 4 is a longitudinal sectional view of the control
apparatus in accordance with a modified embodiment of
the present invention.
Referring now to the drawings, and particularly to
FIG. 1, a hydraulic control apparatus 50 according to the
present invention, which is actually located within the
(l,
mission so that losses of‘liquid taking place during the
inner circulation of the liquid between the pump and the
motor of hydraulic transmission are replaced. Further
more, additional liquid is required when certain changes
of the transmission ratio take place.
In accordance with the present invention, the pressure
ñuid of pump 80 which mainly serves the purpose of
replacing fluid losses in the transmission, is used for
operating a servo motor arrangement including the oper
housing 70, is illustrated in a position turned through an
angle of 90° and located outside of the housing 70 in l0 ating piston 2 by which the transmission ratio is adjusted.
However, since the pressure produced by pump 80 is com»
order to facilitate the understanding of the operation. A
paratively small and determined by the construction of the
hydraulic transmission 62 is located in housing 70 and
hydraulic transmission 62, a very large cross-section of
has tiltable members 51 and 52 to which cam follower
operating piston 2 would be required for producing the
levers 51’ and 52’ are secured. A sleeve 78 is shiftable
great forces necessary for the adjustment of the trans
in axial direction of the transmission 62, and has a slot
mission. For example, the pressure produced by the
with two portions 76 and 77 receiving cam follower por
pump may be approximately 65 to 100 lbs./inch2, which
tions of cam follower levers 51’ and 52’ so that axial shift
would require a very large piston 2, but in accordance
ing of sleeve 7S will effect relative turning of the tiltablc
with the present invention the fluid pressure is increased
members 51 and 52 whereby the wobble plate pump on
the left side of transmission 62, and the wobble plate 20 for the operation of piston 2, and may be, for example,
between 600 tand 1,000 lbs./inch2, resulting in a small
motor on the right side of transmission 62 are adjusted
so that the transmission ratio is varied.
The motor of the transmission is connected by a gear
54 to another gear 55 which drives through a gear 56
another gear 57 which is connected to a bevel pinion 58
driving a bevel gear 59 which is connected to the shafts
operating piston and cylinder.
However, as soon as the adjustment of the transmission
ratio has been completed, the normal low pressure of the
liquid is automatically re-established. One embodiment
of the hydraulic control apparatus 50 of the present inven
tion is illustrated in FIGS. 2 and 3, and another embodi
60, 61 of the tractor Wheels.
ment 56’ is illustrated in FIG. 4. FIGS. 2 and 4 illustrate
The wobble plate pump is driven through a shaft from
the respective control arrangement in the normal inopera
a motor 53 and the variable hydraulic transmission 62
permits an adjustment of the rotary speed of the wheels. 30 tive position corresponding to the neutral position of
handle 65 in FIG. 1. The embodiments 50 and 50' shown
Such adjustment is carried out under control of the
in FIGS. 2 and 4 correspond to the apparatus 50 shown
manually operated handle 65 which can be moved in the
in FIG. l.
directions of the arrows 63 and 64 from its normal posi
In both embodiments of the control apparatus, an op
tion of rest to two end positions. Handle 65 is connected
erating piston 2 is located in an operating cylinder and has
by Bowden cable 66 to a lever 7 so that the position of
a piston rod 3 projecting from opposite sides of the hous
lever 7 can be adjusted by manual operation, as will be
explained hereinafter in greater detail. Such adjustment
ing 4 through end plates 5 and 6. As described with
effects displacement of an operating piston 2 in the con
trol apparatus 50. Operating piston 2 has a piston rod 3
projecting out of the housing, and having at the end there
of a pair of pins 67 located in slots of a bifurcated end
portion 68 of a lever 71. Lever 711 is turnably mounted
in housing 70 by means of stud shafts 69 and 69', and
has a pair of arms 72 and 72’ embracing sleeve 78 and
reference to FIG. 1, one end of the piston rod 3 is con
nected to lever 71, while the other end of piston rod 3 is
articulated by a pair of pins 9 to the bifurcated slotted end
portion 10 of a shiftable lever 7 whose end is connected
to Bowden cable 66 to be moved in the direction of the
arrow S in FIG. 2 when the handle 65 is operated. Lever
being connected by pivot pins 73, 73' to slide members
which has circular control portions 11, 12 and 34, 35, an
inner longitudinal conduit 44, two transverse conduits 43
and 45 and is formed with annular chambers 40, 38 and
42. The cylinder in which operating piston 2 is located is
74, 74' which are secured to a bearing ring 75 connected
to sleeve 7S. Consequently, shifting of operating piston
2 will effect turning of lever 71, 72, and displacement
of sleeve 78 yon the rotating housing 79 of the transmis
sion so that the relative angular position of the tiltable
members 51 and 52 is changed, and the transmission ratio
is varied. In this manner, the transmission ratio can be
adjusted between a reduction ratio of one to infinity and
7 is articulated to the end of a shiftable valve member 1
divided into cylinder portions 15 and 16 which are con
nected to conduits 13 and 14, respectively, which are
closed in the position of valve member 1 shown in FIGS. 2
and 4 by the control faces 11 and 12. However, if valve
member 1 is shifted to the left to the position shown in
FIG. 3, conduit >13 connects the annular chamber 36 with
the maximum ratio determined by the construction and
the cylinder portion 15, while conduit 14 connects the
dimensions of the axial pistons of the pump and motor,
and by the relative angular position of the tiltable mem
annular chamber 42 with the cylinder portion 16. Of
bers 51 and 52. It will be understood that shifting of
course, if valve member lis shifted to the right contrary as
sleeve 78 in one direction will result in rotation of the
viewed in FIG. 2, cylinder portion 15 will be connected
to annular chamber 40, and cylinder portion 16 will be
output shaft in forward direction, and shifting of the
sleeve 78 in the other direction to its end position will ` connected to annular chamber 38.
result in reversing of the direction of rotation of the out
Since in the position of FIGS. 2 and 4, the valve mem
put shaft, and consequently in a rearward motion of the
ber 1 closes all conduits connected to cylinder 15, 16,
tractor. It is necessary to `supply an operating liquid into
piston 2 cannot move, and if lever 7 is actuated by cable
66, the valve member 1 will be shifted while the pivot
the hydraulic transmission 62, and a pump 80 is mounted
on the shaft of prime mover 53, and pumps the operating (if connection 9, 10 will momentarily be the fulcrum of
lever '7.
liquid, for example oil, from the oil sump of housing 70
through pipe 81. The pressure outlet of pump 80 is
An inlet conduit 17 is connected to the pressure conduit
connected to a pressure conduit 82 which supplies ñuid
82 of pump 80 and is connected by a conduit 25 to a
to a conduit means in the control apparatus 50.
’I‘he
pressure Huid flows from control apparatus 50 into the
second portion of the pressure conduit 83 which is con
nected by a manually operated valve to a third portion
84 of the pressure conduit which communicates with an
first outlet conduit 20 which includes a chamber 19 and
a valve seat for a spring-loaded first control valve 18. Inlet
conduit 17, 25 also communicates with a second outlet
conduit 29, 21 in which a second high-pressure control
valve 30 is located. Control Valve 3_0 is urged by a spring
axial bore in the output shaft of the hydraulic transmis
31 against its seat, and normally closed. The end of the
sion and supplies the pressure ñuid to the hydraulic trans 75 first outlet conduit 20 opens into the end of the second
l
.
5
,
_
outlet conduit 21 which ís connected to the pressure con
'I'he movement of piston 2 to the lright in thedirec
tion of the arrow 46 displaces the pivot means 9, 10 so
that, if the pivot connection 48 between lever 7 and Bow
den cable 66 is rigidly held by Ihandle 65, valve member 1
duit 83. Consequently, the outlet conduits 19, 2t) and
29, 21 are connected in parallel between the inlet conduit
17, 25 and the outlet 83. .
Conduit V25' is connected through a throttle 39 to the
annular chamber 38 formed by valve member 1. Another
will be shifted/,to the right by the moving piston 2 and
its piston rod 3, until valve member 1 is again in its
initial position shown in FIG. 2. lIn this position, all
conduit 26 is connected to inletconduit 17, 25 and con
nected by a throttle ZSto a conduit `27 one end of which
conduits connected to the ‘cylinder 15, 16 are closed so
is closed in the position of FIG. 2 by the control face 34.'
The other end of conduit 27 opens into a cylinder 24 in
which a control piston 22 is slidably arranged. A spring
that piston 2 is stopped, while conduit 17 is disconnected
from the discharge outlet 36 and supplied with pressure
fluid through throttle 28 so that the pressure in the cyl
23 urges control piston 22 to the right into a position
abutting control valve 18 to hold the same in the illustrated
open position. Since control valve 18 is open, the pressure
inder chamber 24 increases and is soon suñicient to bal
ance the pressure of cylinder chamber 19, so that spring
23 urges control member 22 to the right and eiîects shift
of the inlet conduit 17 prevails in the cylinder chamber 19,
and when pressure iluid is supplied through conduit 26,
ing of control valve 18 to the right so that control valve
18 opens and permits the passage of pressure fluid into
the outlet conduit 20. The pressure in conduit 29 is im
throttle 28, and conduit 27 to the cylinder chamber por
tion 24, the force of spring 23 is su?cient to hold control
mediately reduced, so that spring 31 closes the high-pres
valve 18 in the open position.
sure valve 30. ~
`
Conduits 17, 25, 20, 29 and 21 may be considered as 20
If handle 65 is shifted in the other direction, the pres
the main conduit means of the control apparatus, since
sure fluid entering annular chamber 38 is supplied through
they connect the inlet pipe 82 with the outlet pipe 83.
conduit 14 to cylinder chamber 16, while cylinder cham
All other conduits of the apparatus may be considered as
ber 15 is connected b_y conduit 13 and annular chamber
control conduit means which are connected to the inlet
40 to discharge outlet 36. Consequently, piston 2 moves
conduit. The control conduit means further include a 25 to the lett and shifts lever 71 in the opposite direction so
conduit 32 connecting conduit 27 with a port 33 closed by .
that the transmission 62 is adjusted in the opposite sense.
control face 35 in the position of FIG. 2. Furthermore,
Piston 2, moving to the left, takes along valve member 1
aconduit 36 Iopens into a discharge opening, yand is nor
so that the same is `returned to the left to its initial posi
mally closed by the control face 34, while another conduit
tion shown in FIG. 2. In the position of the valve mem
37 opens into a discharge opening and is normally closed ‘ 30 ber 1 displaced to the right, the liquid in cylinder cham
by control face 35 of valve member I1.
ber 24 is discharged through conduit 17, conduit 32,'an-V
In the normal position of the control apparatus shown
nular chamber 42 and discharge conduit 37.
in FIG. 2, the liquid enters inlet conduit 17 at the normal
Since the operating piston 2 is shifted in opposite di
low pressure required for supplying the liquid to the trans
mission, passes through the open control valve 18 into the
outlet conduit 2G and through the end portion of Outlet
conduit .21 into the portion 83 of the pressure conduit
which is connected by conduit 84 to the transmission.
When an adjustment of the ratio of the transmission is
rections by shifting of handle 65, sleeve 7S is shifted in
one or the other direction and the relative angular posi
tion of members 51 and 52 will be changed under con
trol ot cam followers 51’ and 52’ moving in slots 76V
and 77. Thereby, the transmission ratio will be gradual
ly varied during forward or rearward drive of thenp'laptor.
desired, handle 63 is operated so that Bowden cable 66 40
The embodiment of FIG. 4 corresponds in its construc
shifts the upper end of lever 7 to the left as viewed in
tion and operation substantially to the embodiment `of
FIG. 2. Since Iall conduits leading to the cylinder 15, 16
are closed by valve member 1, pivot means 9, 10 provide a
FIGS. 2 and 3. However, instead of valve 18, a slide
valve 49 is provided, which is located in Ia cylindrical
chamber extending transverse to an extension of inlet
conduit 17 by which conduit 17 is connected to the out
momentary ñxed fulcrum about which lever 7 turns, so
that valve member 1 is displaced to the left ask Viewed in
FIG. 2 and assumes the position shown in FIG. 3. `As
soon as Valve member .1 starts moving, the control faces
11, 12, 34 and 35 of valve member 1 begin to open the
correlated conduits. The annular chamber 46 connects
conduit 17 to the discharge conduit 36 so that the pressure
let conduit 2i). A control piston 22 is again provided
in -a cylinder 24 and is urged by spring 23 to moveto the
right to abut on valve 49, and to shift the same to the
right as viewed in FIG. 4 against the action of the weaker
spring Sil. The outlet conduit 20 is connected through a
throttle 28a to the cylinder chamber portion on the left,
side of control piston 22, while the outlet conduit20~ is di
rectly connected to the cylinder chamber portion 19 on
the other side of control piston 22. As compared to the
embodiment of FIG. 2, this arrangement substantially re
in the cylinder chamber portion 24 is immediately relieved,
and the pressure in chamber 19 is suihcient to shift control
piston to the left into the position shown in FIG. 3 so that
the projection of control piston 22 no longer abuts the
corresponding projection on control valve 18, and spring
41 urges control valve 18 to a closed position. The first
outlet conduit 20 is consequently closed by control valve
18, and the pressure fluid supplied through inlet conduit
17 increases the pressure in conduits 25 and 29 until the
pressure is increased to such an extent as to open the high
duces the amount of operating liquid ñowing through
, conduit 27 and discharge conduit 36 when valve mem
ber 1 is shifted to the position shown in FIG. 3.
It is necessary that ‘spring 23 is so strong as to be
60
capable of shifting slide valve 49 through control piston
pressure control valve 30 which,'in open position, permits
22 to the right against the action of spring 50, although Y
discharge of pressure fluid through the second outlet
the chamber portions 19 and 24 have -.the same duid pres
conduit 21.
sure.
However, before the valve 30 opens, the pressure in
In the position illustrated in FIG. 4, the pressure ñuid
conduit 25 is substantially increased, and pressure Huid 65 passes through inlet conduit 17, outlet conduit 20 .and
passes through throttle 39 into the annular chamber 38,
through the end of outlet conduit 21 into pipe 83. When
and from there through conduit 13 into cylinder chamber
valve member 1 is shifted to the left or to the right, as .
15 urging piston 2 to the right. At the same time, the
explained with reference »to FIG. 3, liquidy is discharged
annul-ar chamber 42 is connected through conduit 14 to
from cylinder chamber portion 24 through conduit 27
the cylinder chamber 16, so that during movement of pis 70 and conduit 36 so -that the pressure in cylinder chamber
ton 2 to the right, iluid is discharged from cylinder cham
portion 19 urges ’control piston 22 to the left against thel
ber 16 into the annular chamber 42 and fromV there
action of spring 23, permitting spring 50 to push slide
through the transverse conduit 43 and the longitudinal
valve 49 to the left so that outlet conduit Ztl is cut off
conduit 44 into the transverse conduit 45 and through the
from inlet conduit 17, and also from cylinder chamber 19.
annular chamber 40 into the `discharge conduit 36.
75 The pressure fluid supplied into inlet conduit 17 builds up
antena-a
SÉ
pressure until the high pressure valve 35i opens and per
scribed above, or two or more together, may also íind a
mits discharge through conduit 21. 'Fluid under the
higher pressure passes through throttle 39, annular charn
useful application in other types of hydraulic apparatus
differing from the types described above.
ber 38, and conduit 13 or 14 to cylinder chamber 15 or
16, while the respective other cylinder chamber 16 or 15
as embodied in a hydraulic control apparatus for tempo
While the invention has been illustrated and described
rarily producing a high fluid pressure for operating a
servo piston controlling the ratio of a hydraulic trans
mission, it is not intended to be limited to the details
discharges through conduit 14, 44 and 36, or through con
duits 13, 44 and 37, respectively.
In both embodiments of the invention, the high pres
shown, since various modifications and structural changes
sure valve 30 is constructed to open at a pressure of 600
to 1060 lbs/inchz, while the normal pressure in pipe 82, l0 may be made without departing in any way from the
spirit of the present invention.
33, produced by pump 80, may be 65 to 100 lbs/inch?.
Without further analysis, the foregoing will so fully
The pressure is automatically increased when the manual
reveal the gist of the present invention that others can by
ly operated means 65 is shifted, and the operating7 means
applying current knowledge readily adapt it for various
including lever 72 and sleeve 7S adjust the transmission
applications without omitting features that, from the
to a different ratio, whereupon the control apparatus
standpoint of prior art, fairly constitute essential charac
automatically returns to its initial position.
teristics of the generic or speciñc aspects of this inven
Since the pressure used for shifting the operating piston
tion and, therefore, such adaptations should and are in
2 is ten times as high as the normal pressure, piston 2 and
tended to be comprehended within the meaning and range
cylinder 15, 16 have a comparatively small cross section,
of equivalence of the following claims.
and piston 2 moves rapidly to carry out the adjustment.
What is claimed as new and desired to be secured by
Furthermore, the small cross section of cylinder 15, 16
Letters Patent is:
reduces the size of the control apparatus so that it can
l. A hydraulic control apparatus comprising, in corn
be disposed within the housing 70 in which the transmis
bination, main conduit means including an inlet conduit
sion is located. FIG. l shows the control apparatus 50
for a pressure ñuid and first yand second parallel outlet
outside of housing 79, but this illustration has only been
conduits connected to said inlet conduit; a normally open
chosen for the sake of clarity and simplicity, while ac
tirst control valve in said iirst outlet conduit; a normally
tually the apparatus, together with lever 7 and the pipe
closed second high pressure control valve in said second
connections 82, 83 are completely enveloped by hous
outlet conduit adapted to open when the pressure in said
ing 70.
Another advantage of the increased pressure of the 30 second outlet conduit increases due to closing of said ñrst
control valve; control conduit means connected to said
iluid, and the reduced cross section of the operating cylin
main conduit means and having a discharge opening; a
der and piston, resides in the small amount of pressure
hydraulic control member operated by the pressure in
ñuid necessary for eiiecting displacement of the operating
piston 2. Consequently, the amount of iluid supplied by
said control conduit means to operate said tirst control
pump 80 to the hydraulic transmission is reduced very
little by the use of the pump 80 for operating the means
valve; an operating cylinder communicating with said
for adjusting the transmission. This is very important,
since otherwise an insuiiicient amount of iluid may be
supplied by pump `81) to the transmission 62, which may
cause an interruption of the hydraulic coupling between
the pump and the motor of the transmission. At the
same time, the power required for driving pump Sli is
substantially reduced, since the same mainly operates
under the low normal pressure required for the transmis
sion, which results in an improvement of the etiiciency of
the transmission, and moreover increases the span of life
of pump 80 during which the pump reliably operates.
The throttle 39 through which the inlet conduit 17 is
connected to the control conduits of the operating cylin
der 15, 16, dampens the movement of piston 2 so that
too sudden changes of the transmission ratio are pre
vented.
"
Cylinder chamber 19 is directly connected to a pres
sure conduit so that control piston 22 can rapidly move
to the left to effect closing of the valve 18 or 49. On
the other hand, cylinder chamber 24 is connected to a
pressure conduit by a throttle 2S or 23a, so that the
certain time is required until the full pressure is reestab
lished in cylinder chamber 24 after the same has been
connected to a discharge opening by shifting of valve
member 1. A comparatively small >cross section of cylin
der 24 and control piston 22 is required so that the size
of the apparatus is further reduced as compared with
>known constructions.
The embodiment of FIG. 4 provides the throttle 28a
between the outlet conduit 20 and the cylinder chamber
portion 24 which is particularly advantageous, since it
further reduces the amount of liquid lost through a dis
charge opening during operation of valve 1 and adjust
ment of the transmission ratio. Another advantage of
the embodiment of FIG. 4 resides in the fact that the
slide valve 49 does not have to overcome iiuid pressure
during shifting, so that it can be operated by a compara
tively small force.
It will be understood that each of the elements de
control conduit means, and an operating piston in said
operating cylinder adapted to be connected to a con
trolled element for shifting the same; and an operating
valve means in said control conduit means including a
shiftable valve member having a closing position closing
said operating cylinder, and a connecting position con
necting said control conduit means with said discharge
opening to effect closing of said ñrst control valve by
said hydraulic control member and thereby a pressure
increase in said inlet conduit until said second high pres
sure control valve opens, and connecting said inlet con
duit with one end of said operating cylinder and said
discharge opening with the other end of said operating
cylinder so that said operating piston is moved by the
pressure fluid under said high pressure.
2. A hydraulic control apparatus comprising, in com
bination, main conduit means including an inlet conduit
for a pressure fluid and iirst and second parallel outlet
conduits connected to said inlet conduit; a normally open
first control valve in said first outlet conduit; a normally
closed second high pressure control valve in said second
outlet conduit adapted to open when the pressure in said
second outlet conduit increases due to closing of said
Íirst control valve; control conduit means connected to
said inlet conduit, having a discharge opening, and in
cluding a cylinder chamber; a control piston in said cylin
der chamber for operating said first control valve and
dividing said cylinder chamber into two chamber por»
tions, said chamber portions communicating with said
main conduit means; an operating cylinder communicat
ing with said control conduit means, and an operating
piston in said operating cylinder adapted to be connected
to a controlled element for shifting the same; and an
operating valve means in said control conduit means in
cluding a shiftable valve member having a closing posi
tion disconnecting said operating cylinder from said inlet
conduit, from said cylinder chamber, and lfrom said dis
charge opening, and a connecting position connecting one
of said chamber portions of said cylinder chamber with
f said discharge opening to effect closing of said ñrst con
3,046,744
l@
trol valve and thereby a pressure increase in said inlet
conduit until said second high pressure control valve
opens, and connecting said inlet conduit with one end of
said operating cylinder and said discharge opening with
the other end of said operating cylinder so that said oper
ating piston is moved by the pressure ñuid under said
high pressure.
3. -A hydraulic control apparatus comprising, in com«
bination, main conduit means including an inlet conduit
for a pressure fluid and first and second parallel outlet
conduits connected to said inlet conduit; a normally open
ñrst control valve in said iirst outlet conduit; a normally
closed second high pressure control valve in said second
outlet conduit adapted to open when the pressure in said>
second outlet conduit increases due to closing of said
lirst control valve; control conduit means connected to
said inlet conduit, having a discharge opening, and in~
cluding a cylinder chamber; a control piston in said cylin~
der chamber for operating said first control valve and
dividing said cylinder chamber into two chamber por
tions, one of said chamber portions communicating with
said inlet conduit, and the other chamber portion com
municating with at least one of said outlet conduits; an
operating cylinder communicating with said control con
duit means, and an operating piston in said operating
cylinder adapted to be connected to a controlled element
for shifting the same; and an operating valve means in
said control conduit means including a shiftable valve
member having a closing position disconnecting „said
operating cylinder from said inlet conduit, from said
cylinder chamber, and from said discharge opening, and
a connecting position connecting said one chamber por
tion of said cylinder chamber with said discharge open
ing to eifect closing of said lirst control valve and thereby
,
.
,
5. A hydraulic control apparatus comprising, in corn
bination, main conduit means including an inlet conduit
for a pressure iiuid and iirst and second‘ parallel outlet
conduits connected to said inlet conduit; a normally open
ñrst control valve in said first outlet conduit; a normally
closed second high pressure control valve in said second
outlet conduit adapted to open when the pressure in said
second outlet conduit increases due to closing of said ñrst _
control valve; control conduit means connected to said
inlet conduit, having a discharge opening, and including
a cylinder chamber; a control piston in said cylinder
chamber for operating said'tìrst control valve and divid
ing said cylinder chamber into two chamber portions,
said chamber portions communicating with atleast one
of said outlet conduits; a throttle intermediate one of
said chamber portions and said outlet conduit; an operat
ing lcylinder communicating with said control conduit
means, and an operating piston in said operating cylinder
adapted to be connected to a controlled element for
shifting the same; and an operating valve means in said
control conduit means including a shiftable valve mem
ber having a closing position disconnectingsaid operating
cylinder from said inlet conduit, from said cylinder cham
er, and from said discharge opening, and a connecting
position connecting said one chamber portion of said
cylinder chamber with said discharge opening to effect
closing of said iirst control valve and thereby a pressure
increase in said inlet conduit until said second high
pressure control valve opens, and connecting said inlet
conduit with onerend of said operating cylinder and said
discharge opening with the other end of said operating
cylinder so that said operating piston is moved by the
pressure Huid under said high pressure.
'
6. A hydraulic control apparatus comprising, in com
a pressure increase in said inlet conduit until said second
bination, main conduit means including an inlet conduit
high pressure control valve opens, and connecting said
-fOr a pressure iiuid and iirst «and second parallel outlet
inlet conduit with one end of said operating cylinder and
conduits connected to said inlet conduit; a normally open
said discharge opening with the other end of said operat
first control Va‘lve in said »ñrst outlet conduit; a normally
ing cylinder so that said operating piston is moved by the
closed second high pressure control valve in said second
40 outlet conduit adapted to open when the pressure in said
pressure fluid under said high pressure.
4. A hydraulic control apparatus comprising, in com~
vsecond outlet `conduit increases due to closing of said
bination, main conduit means including an inlet conduit
iirst control valve; control conduit means connected to
for a pressure fluid and lirst and second parallel outlet
said inlet conduit, «having a discharge open-ing, «and in
conduits connected to said inlet conduit; a normally open
cluding a cylinder chamber; »a -control piston in said cyl
iirst control valve in said first outlet conduit; a normally 45 inder chamber `for operating said ñrst control valve and
closed second high pressure control valve in'lsaid second
dividing said cylinder chamber into two chamber portions,
outlet conduit adapted to open when the pressure in said
said chamber portions communicating with said main
second outlet conduit increases duc to closing of said
conduit means; a throttle intermediate one of said cham
iirst control valve; control conduit means connected to
ber portions «and said main conduit means; an openating
said inlet conduit, having a discharge opening, and in 50 cylinder communicating lwith said control conduit means,
cluding a cylinder chamber; a control piston in said cylin
and an `operating piston in said operating cylinder adapted
der chamber for operating said ñrst control valve and
dividing said cylinder chamber into two chamber por~
tions, one of said chamber portions communicating with
said inlet conduit, and the other chamber portion com
municating with at least one of said outlet conduits; a
throttle intermediate said one chamber portion and said
inlet conduit; an operating cylinder communicating with
to be connected -to a controlled element for shifting the
same; and an operating valve means in said control con
duit meansl including a shiftable valve member having a
closing position disconnecting said operating cylinder
from said inlet conduit, from said cylinder chamber, and
from said discharge opening, yand a 'connecting position
connecting said one chamber portion of said cylinder
chamber with said discharge opening to effect closing of
said control conduit means, and an operating piston in
said operating cylinder adapted to be connected to a 60 said first control valve 'and thereby a pressure increase in
controlled element for shifting the same; and an operat
said inlet conduit until said second high pressure control
ing valve means in said control conduit means including
valve opens, and connecting said inlet conduit with one
a shiftable valve member having a closing position dis
end of said operating cylinder .and said disch-arge open
connecting said operating cylinder from said inlet con
ing with the other _end of said operating cylinder so that
duit, from said cylinder chamber, and ‘from said dis
said operating piston is moved by the pressure fluid under
charge opening, and a connecting position connecting
said high pressure.
_
said one chamber portion of said cylinder chamber with
'7. ’A hydraulic control apparatus comprising, in com
said discharge opening to eiîect closing` of said íirst con
bination, marin conduit means including »an inlet conduit
-trol valve and thereby a pressure increase in said inlet
for a pressure iiuid `and iirst and second parallel outlet
conduit until said second high pressure control valve 70 conduits connected to said inlet conduit; a normally open'
opens, and connecting said inlet conduit with one end of
first control valve in said first outlet conduit; a spring
said operating cylinder and said discharge opening with
biasing said Íirst control valve to close; a normally closed
the other end of said operating cylinder so that said
second high pressure control valve in said second outlet
operating piston is moved by the pressure liuid under said
conduit adapted to open when the pressure in said second
high pressure.
outlet conduit increases due to closing of said íirst con
andere@
1l
trol valve; control conduit means connected to said inlet
transmission for maintaining a selected íluid pressure in
conduit, having a discharge opening, and including a cylin
der chamber; a control piston in said cylinder chamber
the same; operating means for adjusting said hydraulic
transmission to vary the transmission ratio thereof a hy
draulic control apparatus comprising a main conduit
means connected into said pressure conduit means and
including an inlet conduit for the pressure tiuid pumped
portions, said chamber portions communicating with said
by said pump through said pressure conduit means, and
main conduit means; spring means in said cylinder cham
iirst and second parallel outlet conduits connected to `said
ber for urging said control piston and thereby said first
inlet conduit and opening into said pressure conduit
control valve against the action of said spring to a posi
tion in which said iirst control valve is closed; an operating 10 means, a normally open ñrst control valve in said ñrst
outlet conduit; a normally closed second high pressure
cylinder communicating with said control conduit means,
`and an operating piston in said operating cylinder adapted
control valve in said second outlet conduit adapted to open
when the pressure in said second outlet conduit increases
to be connected to a controlled element for shifting the
due to closing of said lirst control Valve; control conduit
same; and an operating valve means in said control con
duit means including a shiftable v-alve member having
means connected to said inlet conduit, having `a discharge
for operating said first control valve abutting the same
and dividing said cylinder chamber into two chamber
a closing position disconnecting said operating cylinder
opening, and including a cylinder chamber; a control pis
from said inlet conduit, from said cylinder chamber, and
from said discharge opening, and a connecting position
connecting one of said chamber portions of said cylinder
chamber with said discharge opening to eiîect closing of
ton in said cylinder chamber for operating said first con
trol valve and dividing said cylinder chamber into two
said ñrst control valve and thereby `a pressure increase in
said inlet conduit until said second high pressure control
valve opens, and connecting said inlet conduit with one
chamber portions, said chamber portions communicating
with said main conduit means; an operating cylinder com
municating with said control conduit means, and an oper
ating piston in said operating cylinder, connected to said
end of said operating cylinder ‘and said discharge opening
operating means and `an operating valve means in said
control conduit means including a shiftable valve member
with the other end of said operating cylinder so that said
having a closing position disconnecting said operating
operating piston is moved by »the pressure fluid under
said high pressure.
cylinder from said inlet conduit, from said cylnder cham
ber, and from said discharge opening, `and a connecting
position connecting one of said chamber portions of said
cylinder chamber with said discharge opening to effect
closing of said first control valve and thereby a pressure
increase in said inlet conduit until said second high pres
8. A hydraulic apparatus las set forth in claim 7 wherein
said first control valve is a slide valve moving transverse
to said first outlet conduit.
9. A hydraulic l'apparatus as set forth in claim 7 Where
in said ñrst outlet conduit has a valve seat, said ñrst
control valve being seated on said valve seat.
l0. In hydraulic apparatus of the type described, in
combination, ‘a hydraulic transmission; a pump; a pres
sure conduit means for connecting said pump with said
transmission for maintaining a selected iiuid pressure in
sure control valve opens, `»and connecting said inlet con
duit with one end of said operating cylinder yand said
discharge opening with the other end of said operating
cylinder so that said operating piston is moved by the
pressure ñuid under said high pressure; shifting member
the same; operating means for adjusting said hydraulic
connected to said valve member and to said operating pis
ton; and manually operated means connected to said shift
transmission to vary the transmission ratio thereof and a
ing ‘member for shifting the s-ame so that said valve mem
hydraulic control apparatus comprising a main conduit
ber is shifted from said closing position to said connect
means connected into said pressure conduit means and
ing position whereby said operating piston is moved and
including an inlet conduit for the pressure fluid pumped
by said pump through said pressure conduit means, and
ñrst and second parallel outlet conduits connected to said
inlet conduit and opening into said pressure conduit
means, a normally open iirst control valve in said iirst
outlet conduit; a normally closed second high pressure
control valve in said second outlet conduit adapted to
open when the pressure in said second outlet conduit in
creases due to closing of said iirst control valve; control
conduit means connected to said inlet conduit, having a
shifts through said shifting member said valve member
back to said closing position.
l2. In hydraulic apparatus of the type described, in
combination, a hydraulic transmission; a pump; a pres
sure conduit means for connecting said pump with said
transmission for maintaining a selected ñuid pressure
in the same; operating means for adjusting said hydraulic
ltransmission to vary the transmission ratio thereof and
a hydraulic control apparatus comprising a main conduit
means connected into said pressure conduit means and
discharge opening, and including a cylinder chamber; a
control piston in said cylinder chamber for operating said
first control valve and dividing said cylinder chamber into
two chamber portions, said chamber portions communi
including an inlet conduit for the pressure ñuid pumped
by said pump through said pressure conduit means, and
tirst and second parallel outlet conduits connected to
said inlet conduit and opening into said pressure con
cating with said main conduit means; an operating cylin
der communicating with said control conduit means, and
duit means, a normally open iirst control valve in said
tirst outlet conduit; a normally closed second high pres
sure control valve in said second outlet conduit adapted
to open when the pressure in said second outlet conduit
to said operating means for shifting the same; Aand an oper
ating valve means in said control conduit means including 60 increases due to closing of said ñrst control valve; control
conduit means connected to said inlet conduit, having a
a shiftable valve member -having a closing position dis
discharge opening, and including a cylinder chamber; a
connecting said operating cylinder from said inlet con
an operating piston in said operating cylinder connected
duit, from said cylinder chamber, and from said disch-arge
opening, and a connecting position connecting one of said
chamber portions of said cylinder chamber with said
discharge opening to effect closing of said iirst control
valve and thereby a pressure increase in said inlet conduit
until said second high pressure control valve opens, and
connecting said inlet conduit with one end of said operat
control piston in said cylinder chamber for operating said
first control valve and dividing said cylinder chamber
into two chamber portions, said chamber portions com
municating with said main conduit means; an operating
cylinder communicating with said control conduit means,
and an operating piston in said operating cylinder, con
nected to said operating means and an operating valve
ing cylinder and said discharge opening with the other 70 means in said control conduit -rneans including a shiftable
valve member `having a closing position disconnecting said
operating cylinder from said inlet conduit, from said cyl
índer chamber, and `from said discharge opening, and a
connecting position connecting one of said chamber por
combination, a hydraulic transmission; a pump; a pres~
sure conduit means for connecting said pump with said
tions of said cylinder chamber with said discharge open
end of said operating cylinder so that said operating pis
ton is moved by the pressure fluid under said high pressure.
ll. In hydraulic apparatus of the type described, in
A)
3,046,744
13
l »4
ing to effect closing of said iirst control valve and thereby
connecting position whereby said operating piston is
a pressure increase in said inlet conduit until said second
moved and shifts through said shifting member s-aid valve
Ymember back to said closing position.
16. In hydraulic apparatus of „the type described, in
high pressure control valve opens, and connecting said
inlet conduit with one end of said operating cylinder and
said discharge opening with the other end of said operat
ing cylinder so that said operating piston is movedv by
the pressure fluid under said high pressure; a lever means
articulated to said valve member `for shitting the same,
and articulated to said operating piston to be shifted
bythe same; and manually operated means connected to
said lever means for shifting the same so that said valve
member is shifted from said closing position to said con
nesting position whereby said operating piston is moved
Ul
combination, a hydraulic transmission including a wobble
plate pump and a wobble plate motor; a pump; a pressure
conduit means for connecting said pump with said trans
mission for maintaining la selected iluid pressure in the
same; operating means for adjusting said hydraulic trans
mission to vary the transmission ratio thereof and a hy
draulic control apparatus comprising `a main conduity
means connected into said pressure conduit means and
including an inlet conduit for the pressure ñuid pumped
by said pump through said pressure conduit means, and
iback to said closing position.
15 tirst'and second parallel outlet conduits connected to
13. A hydraulic control apparatus as set forth in claim
said inlet conduit and opening into said pressure conduit
and shifts through said lever means said valve member
12 wherein said manually operated means includes aV
handle, and a Bowden cable connecting said handle with
said lever means.
means, `a normally open first control valve in said first
outlet conduit; a normally closed second high pressure
control valve in said second outlet conduit ladapted to
14. A hydraulic control `apparatus as set forth in claim 20 open when the pressure in said second outlet conduit in
12 wherein said hydraulic transmission includes a wobble
creases due to closing of said first control valve; control
plate pump and a wobble plate motor; and wherein said
conduit means connected to said main conduit means and
operating means include -a forked lever connected to
having a discharge opening; Ka hydraulic control member
said operating piston, a sleeve shiftably mounted in said
operated by the pressure in said control conduit means
hydraulic transmission and being partly embraced by said
forked llever to be shifted by the same, said lever having
a cam slot, and cam lfollower means located in said cam
25 Íto operate said ñrst control valve; an operating cylinder
communicating with said control conduit means, and an
operating piston in said operating cylinder connected to
slot and operatively connected to said wobble plate pump
said operating means for shifting the same; and an openat
and wobble plate motor to vary the transmission ratio
ing valve means in said control conduit means including a
of said hydraulic transmission.
l30 shiftable valve member having a closing position closingl
l5. in hydraulic apparatus of the type described, in
said operating cylinder, and a connecting position con
combination, a hydraulic transmission including a wobble
necting said control conduit means with said discharge
plate pump and a wobble plate motor; a pump; a pressure
opening to effect closing of said first control valve by
conduit means for connecting said pump with said trans
said hydraulic control member and thereby a pressure
mission for maintaining a selected Huid pressure in the 35
increase in said inlet conduit until said second high pres
same; operating means for adjusting said hydraulic trans
sure control valve opens, and connecting said inlet con
mission to vary the transmission ratio thereof; a hydraulic
duit with one end of said operating cylinder |and said
control apparatus comprising a main conduit means con
discharge opening with the other end of said operating
nected into said pressure conduit means and including an
cylinder so that said operating piston is moved by the
inlet conduit for the pressure fluid pumped by said pump 40 pressure iiuid under said high pressure.
through said pressure conduit means, and lirst and second
17. In hydraulic apparatus of the type described, in
parallel outlet conduits connected to said inlet conduit and
combination, a hydraulic transmission including a wob
opening into» -said pressure conduit means, a normally open
ble plate pump and a wobble plate motor a pump; a pres
Íi-rst control valve in said first outlet conduit; a normally
sure conduit means for connecting said pump with said
closed second high pressure control valve in said second 45 transmission for maintaining a selected iluid pressure
outlet conduit adapted to open when the pressure in said
in the same; operating means for adjusting said hydraulic
second outlet conduit increases due to closing of said
transmission to vary the transmission ratio thereof and
iirst control valve; control conduit means connected to
a hydraulic control apparatus comprising a main conduit
said inlet conduit, having a discharge opening, and in
means connected into said pressure'conduit means and
cluding a cylinder chamber; a control piston in said cylin 50 including an inlet conduit for the pressure fluid pumped
der chamber for operating said -iirst control valve and
by said pump through said pressure conduit means, and
dividing said cylinder chamber into- two chamber por
ñrst and second parallel outlet conduits connected to said
tions, said chamber portions communicating with said
inlet conduit and opening into said pressure conduit
main conduit means; a throttle intermediate one of said
means, a normally open first control valve in said iirst
chamber portions and said main conduit means; -an operat
outlet conduit; a normally closed second high pressure
ing cylinder communicating with said `control conduit
means, and -an operating piston in »said operating cylinder,
connected to said operating means andan operating valve
means in said control conduit means including a shiftable
control val-ve in said second outlet conduit adapted to
open when the pressure in said second youtlet conduit in
creases due to closing of said first control valve; control
conduit means connected to said main conduit means and
valve member having a closing position disconnecting 60 having a discharge opening; a throttle intermediate said
said operating cylinder from said inlet conduit, from said
main conduit means and said control conduit means; a
cylinder chamber, and from said discharge opening, and
hydraulic control member operated by the pressure in
a connecting position connecting said one chamber por
said control conduit means to operate said first control
tion of said cylinder chamber with said discharge open
valve; an operating cylinder communicating with said
ing to eiîect closing 'of said first control valve yand thereby 65 control conduit means, and an operating piston in said
a pressure increase in said inlet conduit until said second
operating cylinder connected to said operating means
high pressure control valve opens, and connecting said
for shifting the same; and an operating valve means in
inlet conduit with one end of said opera-ting cylinder and
said control conduit means including a shiftab‘le valve
said discharge opening with the other end of said operat- Y i member having a closing position closing said operating
ing cylinder so that said operating piston is moved by the 70 cylinder, and a connecting position connecting said con
pressure fluid under said high pressure; shifting member
trol conduit means with said discharge opening to eiîect
connected to said valve member and to said operating
closing of said iirst control valve by said hydraulic con
piston; and manually operated means connected to said
trol member and thereby a pressure increase in said
shifting member for shifting the same so that said valve
inlet conduit until said second high pressure control valve
member is >Áshifted from said closing position to said 75 opens, and connecting said inlet conduit with one end
of said operating cylinder and said discharge opening
whereby said operating piston is moved and shiftsy
with the other end of said operating cylinder so that
through said shifting member said valve member back
to said closing position.
said operating piston is moved by the pressure fluid
under said high pressure.
18. In hydraulic apparatus of the type described, in
i9. A hydraulic control apparatus as set forth in
claim 18 wherein said hydraulic transmission includes
sure conduit means for connecting said pump with said
a wobble plate pump and a wobble plate motor; and
wherein said operating means include a forked lever
transmission for maintaining a selected fluid pressure in
the same; operating means for adjusting said hydraulic
connected to said operating piston, a sleeve shiftably
mounted in said hydraulic transmission and being partly
transmission to vary the transmission ratio thereof; a
embraced by said forked lever to Ibe shifted by the same,
combination, a hydraulic transmission; a pump; a pres
hydraulic control apparatus comprising a main conduit
said sleeve having a cam slot, and cam follower means
means connected into said pressure conduit means and
located in said cam slot and operatively connected to
said wobble plate pump and wobble plate motor to vary
including an inlet conduit for the pressure ñuid pumped
by said pump through said pressure conduit means, and
first and second parallel outlet conduits connected to said
inlet conduit and opening into said pressure conduit
means, a normally open iirst control valve in said first out
et conduit; a normally closed second high pressure con
trol val‘ve in said second outlet conduit adapted to open
when the pressure in said second outlet conduit increases
due to closing of said Iirst control valve; control conduit
means connected to said main conduit means and hav
ing a discharge opening; a hydraulic control member
operated by the pressure in said control conduit means
to operate said iirst control valve; an operating cylinder
communicating with said control conduit means, and an
operating piston in said operating cylinder, connected
to said operating means and an operating valve means
in said control conduit means including a shiftable valve
member having a closing position closing said operating
cylinder, and a connecting position connecting said control
conduit means with said discharge opening to effect
closing of said ñ-rst control valve by said hydraulic con
trol member and thereby a pressure increase in said inlet
conduit until said second high pressure control valve ,~
opens, and connecting said inlet conduit with one end
of said operating cylinder and said discharge opening
with the other end of said operating cylinder so that said
operating piston is moved by the pressure ñuid under
said high pressure; shifting member connected to said
valve member and to said operating piston; and manually
operated means connected to said shifting member for
the transmission ratio of said hydraulic transmission.
20. A hydraulic control apparatus comprising, in com
bination, main conduit means including an inlet conduit
for a pressure iluid and lirst and second parallel outlet
conduits connected to «said inlet conduit; a normally open
first control valve in said lirst outlet conduit; a normally
closed second high pressure control valve in said second
outlet conduit adapted to open when the pressure in said
second outlet conduit increases due to closing of said
Íirst control valve; control conduit means connected to
said `main conduit means and having a discharge open
ing; a throttle intermediate said main conduit means and
said control conduit means; a hydraulic control member
operated by .the pressure in said control conduit means
to operate said first control valve; an operating cylinder
communicating with said control conduit means, and an
operating piston in said operating cylinder adapted to be
connected to a controlled element for shifting the same;
and an operating valve means in said control conduit
means including a shiftable valve member having a clos
ing position closing said operating cylinder, and a con
necting position connecting said control conduit means
with said discharge opening to eíiect closing of said first
control valve by said hydraulic control member and
thereby a pressure increase in said inlet conduit until
said second high pressure control valve opens, and con
necting said inlet conduit with one end of said operating
shifting the same so that said valve member is shifted
cylinder and said discharge opening with the other end
of said operating cylinder so that said operating piston
is moved by .the pressure fluid under said high pressure.
from said closing position to said connecting position
No references cited.
.mi‘.
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