Rapid coupling which is operable even under pressure

The invention relates to a quick coupling which is operable even under pressure, particularly for hydraulic lines, composed of two matable coupling halves in form of a plug and socket valve which can be arrested in the coupled position via a ball-locking arrangement, and which each have a valve body which is biased to closing position by closing springs and in the uncoupled condition of the coupling halves is held in closed condition, being guided in a star body which is mounted in a coupling body, of which one of the coupling halves has a fixed abutment which limits the stroke of the valve body in its open position, whereas the valve body of the other coupling half can perform a stroke equal to double the valve stroke of the other valve body and at the end of the single valve stroke a disengageable and engageable abutment is provided for releasing the double valve stroke respectively arresting this valve body in an open position corresponding to the single valve stroke.

Such a quick coupling is known from U.S. Pat. No. 3,791,411 and also from 
German Allowed Application No. 2,712,117. As a rule it is the valve body 
of the plug-valve which is mounted in the star body for shifting only by 
the single opening stroke, the star body itself forming a fixed abutment 
for the delimitation of the single valve stroke of the valve body. 
According to U.S. Pat. No. 3,791,411 the star body can be adjusted 
relative to the coupling body of the plug valve with the aid of a thread. 
The two socket valves also have a valve body which is biased in closing 
direction via a closing spring, but which as a rule is mounted shiftably 
in the coupling body of the socket valve for displacement by double the 
single valve stroke. 
In the embodiment according to U.S. Pat. No. 3,791,411 the valve body of 
the socket valve is of tubular shape. The coupling body of the socket 
valve is divided and consists of a stationary part and a part movable 
relative to the same which receives the tubular valve body. An arresting 
means is provided within the tubular valve body for arresting the valve 
body of the socket valve in the coupling position between the plug and the 
socket and in the open position of both valve bodies. This arresting means 
consists of an operating bolt mounted in the tubular valve body in which 
in radial arrangement a single locking ball is provided which is spring 
biased. This locking means permits the locking of the operating bolt, the 
valve body and a part of the coupling body. Due to the separated 
construction of the coupling body the seal and the flow guidance in the 
socket valve are difficult and complicated. A plurality of essentially 
radially extending bores and guide channels must be provided in order to 
direct the flow media about the interior arranged locking means through 
the coupling connection. A corresponding pressure drop is among the 
disadvantages of this construction. The major disadvantage, however, is to 
be seen in that the locking means is arranged in the interior of the 
coupling in a very small diameter space, i.e. must be of very small 
construction if the maximum diameter of the socket valve is not to be too 
large. Particularly for small nominal widths, however, this results in a 
coupling which is of relatively large diameter. It is also disadvantageous 
that the drive means for the locking means, namely the spring, must also 
be mounted radially for which again only a very limited amount of space is 
available. Beyond this, this locking for the locking means also acts only 
eccentrically upon the socket valve so that a uniform stress distribution 
over the circumference does not exist. A further disadvantage of this 
construction resides in that it is not possible to determine from outside 
whether the locking means is properly engaged in the locked position or 
whether for example after breakage of the spring the locking function does 
not exist at all any more. Finally, this construction is very complicated. 
Since the single valve stroke of the valve body of the socket valve is not 
adjustable, difficulties may arise on coupling of the socket valve with 
different plug valves. 
In the construction according to German Allowed Application No. 2,712,117 
the flow guidance is solved in a comparatively better manner, so that here 
in particular a comparable pressure drop due to changes in flow direction 
is not to be expected. However, here also the locking means is 
disadvantageously arranged within the flow cross-section of the socket 
valve and arranged and effective between the star body and the valve body. 
This means that here also the locking means due to its radial arrangement 
and mounting engages the valve body eccentrically over a small diameter, 
which is not an optimum solution with respect to the transmission of 
pressure forces from the flow medium to the valve body and with respect to 
the support of these forces. Also, the individual parts of the locking 
means can be only of limited size, which is also disadvantageous. Since 
the star body of the socket valve and the plug valve are not adjustable in 
their relative position, an exceedingly precise tolerance maintenance 
during manufacture of the parts is necessary, in order to obtain a proper 
operation of the locking means, i.e. to engage an abutment even when the 
single valve stroke has reliably been completed. Different plugs with a 
socket respectively vice versa the parts therefore may accidentally be so 
combined in such tolerances that the effect of the locking means does not 
occur at all. In this construction there is also the further disadvantage 
that it is not possible to determine from the exterior whether the locking 
means properly fulfills its function, i.e. whether for example the 
inserted spring of the locking means has not broken. In the case of small 
nominal widths this known coupling also is of relatively large diameter 
because the locking means in the interior requires a certain minimum 
dimension. 
To at least partially counteract the disadvantage of the eccentric force 
transmission of the locking means to the valve body, it is known from 
German Published Application No. 2,715,417 to construct and arrange a part 
of the locking means, namely a cascade, symmetrically with reference to 
the longitudinal axis of the coupling, which then again engages in 
eccentric manner in recesses of the shaft of the valve body. In this 
construction the locking means is arranged immediately between the star 
body and the shaft of the valve body, i.e. in the interior, so that from 
the exterior it cannot be determined whether the locking means in the 
appropriate position is properly locked or not. 
Finally, the German Allowed Application No. 2,724,630 discloses a coupling 
which in contradistinction to the previously described couplings cannot be 
coupled under pressure. In a manner otherwise already known the sliding 
sleeve for operation of the ball-locking arrangement for securing the 
coupled condition respectively release to the uncoupled condition is, 
however, arranged and effective between the coupling valve and the socket 
so as to operate in both directions. Furthermore, here also the coupling 
body is of separated construction, with one part being axially shiftably 
mounted relative to the other. Since the plug valve has no valve body, the 
valve body of the socket valve must be shiftably mounted through a 
corresponding opening stroke. 
The purpose of the invention is to so further develop a quick coupling of 
the type described hereinbefore which can be coupled under pressure, that 
no problems arise with respect to the arrangement of the locking 
means--which is constructed as a disengagable and engagable abutment--for 
locking the valve body capable of performing the double valve stroke in 
the position corresponding to the single stroke. It is to be possible even 
in the case of small nominal widths to maintain the diameter of the 
coupling halves correspondingly small. In a further development of the 
invention it is desired that even at higher and higher operating pressures 
a reliable automatic closing of the second ball-coupling arrangement is 
obtained after closing of the first ball-coupling arrangement. 
According to the invention this is achieved in that the star body of the 
coupling half having the double valve stroke is axially shiftably mounted 
in the coupling body in correspondence with at least the single valve 
stroke, and that the disengagable and engagable abutment is arranged 
between the star body and the coupling body. The new quick coupling thus 
basically departs from the state of the art, in that the locking means is 
not located in the interior, i.e. within the flow cross section, but 
outside the same and thus arranged over a larger diameter. Thus, the 
individual parts of a disengagable and engagable abutment of a 
corresponding locking arrangement can be constructively accommodated in a 
sensible size, and the particular advantage is obtained that a symmetrical 
force engagement respectively force support about the longitudinal axis of 
the coupling halves can be achieved without problems. Since the 
disengagable and engagable abutment is no longer located in the interior, 
but in connection with the coupling body, the further advantage is 
obtained that on appropriate configuration it can be determined from the 
exterior without any difficulty whether a properly locked position after 
coupling of the coupling halves is obtained relative to the engagable and 
disengagable abutment, or not. In the coupled position it is visible at 
the exterior on the coupling that the open position of the valve body, 
which has double the valve stroke, is properly locked. This constitutes a 
significant increase of the safety in use. The new quick coupling has the 
further advantage that after completion of the coupling operation, when 
the sliding sleeve has reached its proper end position, the two valve 
bodies are locked even when two pressure-less lines have been coupled with 
one another; in the state of the art in such a condition the line 
connection can be locked once, during pressure variations i.e. the passage 
may be interrupted, before locking is achieved. Without one-time blocking 
a locking is not obtained. 
The star body may itself and directly be shiftably mounted in the coupling 
body, whereby here at least a stroke corresponding to the single valve 
stroke must be provided. The increase of this stroke is not 
disadvantageous in any case, however, but instead--particularly with 
respect to the combination possibilities with different plug valves--has 
only positive effects. However, it is also possible to provide a separate 
seating sleeve between the star body and coupling body which carries the 
valve seat, against which the star body is supported and between which and 
the coupling body the disengagable and engagable abutment is provided. It 
is also possible that this seating sleeve does not carry the valve seat. 
In all these instances, however, the disengagable and engagable abutment 
respectively the essential blocking part thereof, is arranged over a 
relatively large diameter. 
The star body respectively the seating sleeve is supported against the 
coupling body via a pressure spring acting in closing direction of the 
valve body, the pressure spring being stronger than the closing spring of 
the valve body. The possibility exists to arrange the pressure spring in 
axial direction and thus to depart from the radial constructions known 
from the state of the art. In axial direction an appropriate length is 
available without any problem in a coupling. The coordination of the 
forces between the pressure spring on the one hand and the closing spring 
on the other hand determines the sequence in which the valve body of for 
example the socket valve is opened when the plug valve body is under 
pressure. If the arrangement is so selected as described, then the valve 
body of the socket valve opens initially. In the second part of the valve 
stroke the valve body and the star body move jointly relative to the 
coupling body. In addition, this assures that in a simple manner the valve 
body of the for example socket valve cannot move to a closure position 
relative to the seat during its return movement after the double opening 
stroke to the position of the single opening stroke. 
It is particularly advantageous if the star body with the larger stroke 
than the single valve stroke of its valve body is shiftably mounted in the 
coupling body. This assures that different plug valves can always be 
coupled with one and the same socket valves and vice versa, and that 
tolerance variations in the manufacture of the individual parts have no 
disadvantageous consequences. 
The disengagable and engagable abutment is adjustably constructed, to 
eliminate tolerance variations in axial direction and to permit adjusting 
of the abutment in such a manner that a play-free locking of the two valve 
bodies is possible in the coupled condition. 
The disengagable and engagable abutment for the stroke of the valve body 
advantageously consists of a ball-locking arrangement and a setting screw 
mounted in the star body. For operation of the ball-locking arrangement a 
sliding sleeve may be provided which is shiftably mounted on the 
circumference of the coupling body against spring pressure, and which 
preferably permits in both operating directions a release of the 
ball-locking arrangement. As an example, the construction of the so-called 
sliding sleeve offers itself which is already known in known per se 
so-called push-pull couplings in both directions and provided subsequent 
to a locking cam with shunting grooves. It is also possible to provide a 
common sliding sleeve for the operation of the ball-locking arrangement of 
the engagable and disengagable abutment and the ball-locking arrangement 
for the coupling respectively uncoupling of the two coupling halves, so 
that a simplified operation is obtained. It is then particularly important 
that the locking means is not moved into its disengagable position 
permitting the double valve stroke at the time of uncoupling of the 
coupling halves, but that the disengaging position is released 
simultaneously with the disengaging of the ball-coupling arrangement for 
the coupling halves. To obtain an advantageous locking sequence between 
the two ball-locking arrangements, the common sliding sleeve may have one 
each locking cam and adjacent at least at one side shunting grooves for 
the balls of the two ball-locking arrangements, with the two locking cams 
being coordinated with one another and the locking cam of the 
ball-coupling arrangement of the engagable and disengagable abutment 
having a comparably smaller axial width. This makes it possible for the 
ball-locking arrangement for the two coupling halves to already have 
closed, i.e. to have moved into the locked position, without the other 
ball-coupling arrangement having already being locked. This, however, 
necessarily requires that the sliding sleeve is not yet relative to the 
coupling body in its end position corresponding to proper locking of both 
ball-coupling arrangements. Thus, it is visible from the exterior that 
only one ball-locking arrangement is effective. Only when pressure is 
supplied via the previously pressure-less conduit part, will the 
ball-locking arrangement of the engagable and disengagable abutment also 
move into its locking position, whereby then the sliding sleeve assumes 
its end position. If, however, the two coupling halves are coupled with 
one another without one of the two halves being under pressure, then due 
to appropriate dimensioning of the forces of the pressure spring on the 
one side and the closing spring on the other side such an intermediate 
position can be avoided or deliberately caused. The coupling sleeve may 
have, relative to the sliding sleeve, one or two marks for indicating the 
engaged abutment and/or for indicating the coupled condition. In case of 
construction as a push-pull coupling the number of marks is doubled. 
Even in the case of high and highest operating pressures a reliable 
automatic closing of the second ball-locking arrangement is achieved in 
that the locking cam is axially shiftably mounted on the common sliding 
sleeve and is spring biased to the center position of its stroke. The 
locking cam of the second ball-locking arrangement is thus made movable 
relative to the common sliding sleeve, being mounted for limited axial 
shifting and spring biased in its center position, so that it tends always 
to assume this center position. On the other hand, the locking cam is 
however not prevented from shifting axially sideways if appropriate forces 
act upon it. Since in such couplings on opening after appropriate pressure 
application of the coupling socket it is always the position which is 
reached at which the valve body of the coupling socket which can perform 
the doubled valve stroke is to be fixed on the single valve stroke, the 
spring force and the axially movable locking cam can cleverly be used to 
assure that the same performs a relative movement even if the common 
sliding sleeve is prevented from such a move by the force exerted radially 
by the balls of the first ball-locking arrangement. 
It is particularly advantageous if the locking cam is configurated as a 
ring and axially shiftably mounted for limited displacement in a recess 
formed by the shunting grooves of the common sliding sleeve, with two 
approximately equally strong springs being mounted on the annular locking 
cam to the right and to the left. The springs are advantageously 
appropriately prestressed, with the annular locking cam having the 
possibility of being provided on its inner side with inclined faces for 
the balls. This facilitates the closing of the second ball-locking 
arrangement. 
The two springs are arranged outside the radial path of movement of the 
balls, so that they are not clamped by the balls and can transmit their 
axially directed force to the annular locking cam in any position.

Each quick coupling basically consists of a plug valve 1 and a socket valve 
2. Only a single embodiment is shown of the plug valve 1, whereas the 
socket valve is shown in a first embodiment in the upper half of the 
drawing and in a second embodiment in the lower half of the drawing, in 
all figures. 
The plug valve 1 consists essentially of a coupling body 3 with a seat 4. 
The star body 5, having three arms 6 which are distributed over the 
circumference, is mounted in the coupling body 3 with the aid of the 
safety ring 7. Otherwise, the star body 5 is of sleeve-shaped 
configuration and has centrally a bore 8 in which the shaft 9 of a valve 
body 10 is slidably guided. The valve body 10 forms with the seat 4 of the 
coupling body 3 a check valve 10, 4 which, as shown, closes the 
corresponding line which is connected with the plug valve 1. The valve 
body 10 is pressed against the seat 4 with the aid of a closing spring 11 
which on the other hand holds the star body 5 in abutment against the 
safety ring 7. The valve body 10 extends in closed condition beyond the 
end wall 12 of the plug valve 1 by the dimension a'. Further mounted in 
the bore 8, with the aid of a thread, is a setting screw 13 the front end 
of which constitutes an abutment 14 for the end of the shaft 9 
respectively the valve body. The setting screw 13 is so set in the star 
body 5 with the aid of the thread that the abutment 14 is located spaced 
from the end of the shaft 9 of the valve body 10 by the distance a'. The 
valve body 10 thus can perform between its open position and its closed 
position the valve stroke a'. 
The coupling body 3 has at the illustrated location a circumferential 
locking groove 15 which cooperates with a still to be described 
ball-locking arrangement for locking the plug valve 1 with the socket 
valve 2 in the coupled position and for release of the two parts 1, 2 in 
the uncoupled position. 
Similar to the plug valve 1 the socket valve 2 has a coupling body 16 which 
is threaded onto a connecting part 17, with a seal 18 serving to pressure 
tightly close the interior space. In the respectively proper illustrated 
embodiment a seat sleeve 19 is shiftably mounted in the coupling body 16, 
in which a star body 20 is mounted with the aid of the safety ring 21. The 
seating sleeve 19 carries the seat 22. In the embodiment shown always in 
the lower half of each drawing the separate provision of the seating 
sleeve 19 is omitted. Instead, the star body 20 is directly shiftably 
mounted in the coupling body 16. For this purpose the star body 20 is 
provided in the second embodiment with a gliding sleeve 23. In both cases 
the star body 20 has for example three radially projecting arms 24 between 
which flow can take place as considered over the circumference. In the 
embodiment of the star body 20 with the gliding sleeve 23 the seat 22 is 
formed by the coupling body 16. 
Similarly as in the plug valve 1 the socket valve 2 also has provided 
centrally at the star body 20 a bore 25 which slidably receives the shaft 
26 of the valve body 27. The valve body 27 forms together with the seat 22 
the check valve 22, 27 of the socket valve 2. The front end of the valve 
body 22 extends beyond the end plane 28 by the measure a. A setting screw 
29 is adjustable and settably arranged in the star body 20 with the aid of 
a thread, and its front end constitutes an abutment 30 for the rear end of 
the shaft 26 respectively of the valve body 27. The setting screw 29 is so 
adjusted that on opening the valve body 27 can perform the valve stroke a 
before it engages the abutment 30 with its shaft 26, which abutment is 
also designated as an engagable and disengagable abutment 30. A closing 
spring 31 is interposed between the star body 20 and the valve body 27. 
The valve stroke a of the socket valve 2 corresponds approximately to the 
valve stroke a' of the plug valve 1. Both valve strokes a and a' differ 
only by tolerance variations caused by the manufacture. Basically, the 
same measure is desired and set during the manufacture. 
The star body 20 in the upper embodiment is axially shiftably mounted via 
the seat sleeve 19 respectively with the same, and in the lower embodiment 
it is axially shiftably mounted directly via its glide sleeve 23 in the 
coupling body 16, the two seals 32 and 33 being provided for sealing 
purposes. This achieves in both instances that the star body 20 is axially 
shiftable relative to the coupling body 16 by the dimension b. The 
dimension b is at least equally as large as the valve stroke a' 
(respectively a), but is made larger to obtain simplified manufacture. In 
any case this makes it possible for the valve body 27 of the socket valve 
2 to be shiftably mounted by double the valve stroke 2a, whereas the valve 
body 10 of the plug valve 1 is shiftable only by the single valve stroke 
a'. The star body 20 with its glide sleeve 23 respectively the separate 
seating sleeve 19 are supported via a pressure spring 34 on the connecting 
part 17 or on an abutment of the coupling body 16. The force of the 
pressure spring 34 is selected greater than the force of the closing 
spring 31, so that in this manner a clear time sequence of the relative 
movements is predetermined. 
The coupling body 16 is surrounded by a sliding sleeve 35 which here is 
configurated as a common sliding sleeve and serves for activating two 
different ball-locking arrangements, as will be described subsequently. 
The sliding sleeve is mounted shiftable on the coupling body 16 with the 
aid of the spring 36 in both directions. The complete quick coupling is 
constructed as a so-called pull-push coupling, i.e. the sliding sleeve 35 
can be shifted in both directions relative to the coupling body for the 
purpose of releasing the two ball-locking arrangements. 
Specifically, the sliding sleeve 35 has a locking cam 37 which is 
relatively broad and which is hollowed by two shunting grooves 38 and 39 
in both directions. At the location of the locking cam 37 the coupling 
body 16 has in known manner a series of radial cutouts 40 in which balls 
41 are received. The locking cam 37 forms in conjunction with the shunting 
grooves 38, 39 of the balls 41 and the locking groove 15 of the plug valve 
1 a first ball-type locking arrangement 15, 37, 38, 39, 40, 41 which serve 
to arrest the plug valve 1 and the socket valve 2 in the coupled position 
respectively for release of the two parts in the uncoupled position. Such 
ball-locking arrangements are known per se and therefore require no 
further description. 
For sealing between the plug valve 1 and the socket valve 2 a further seal 
42 is provided on the coupling body 16 of the socket valve 2. 
The common sliding sleeve 35 serves simultaneously for operation of a 
second ball-locking arrangement. For this purpose the sliding sleeve 35 
has a further circumferentially configurated locking cam 43 which is 
comparatively less broad with reference to the locking cam 37. 
In the embodiments of FIGS. 5-8 a circumferentially annular locking cam 43 
is axially shiftably mounted on the sliding sleeve 35 and can be 
comparatively less wide with respect to the locking cam 37. At both sides 
the locking cam 43 is again followed by shunting grooves 44 and 45. 
Associated with these respectively with the locking cam 43, the coupling 
body 16 (FIGS. 1-8) has several cutouts 46 which are distributed over the 
circumference for receiving the balls 47. A circumferential locking groove 
48 is formed exteriorly on the seating sleeve 19 respectively in the glide 
sleeve 23 of the star body 20. The locking cam 43 forms in combination 
with the shunting grooves 44, 45, the cutouts 46 in the coupling body 16, 
the balls 47 and the locking groove 48 the second ball-locking arrangement 
43-48, which serves for locking the star body 20 relative to the coupling 
body 16 respectively for release in its other position. The second 
ball-locking arrangement 43-48 forms in combination with the abutment 30 
on the setting screw 29 of the star body 20 an engagable and disengagable 
abutment for limiting respectively releasing the axial movement of the 
valve body 27. When the second ball-locking arrangement 43-48 is locked, 
as shown in FIG. 1, the abutment 30 is engaged so that the valve body 27 
can perform at maximum the single valve stroke a, if a corresponding force 
is exerted upon the tip of the valve body 27 which serves to overcome the 
force of the closing spring 31. If, however, the second ball-locking 
arrangement 43-48 is disengaged respectively released, as for example 
shown in FIG. 2, then the valve body 27 can perform not only the single 
valve stroke a but can perform relative to the end plane 28 the double 
valve stroke which is composed of the sum of the individual valve strokes 
a+a'2.times.a. 
In the embodiments of FIGS. 5-8 the shunting grooves 44 and 45 form an 
axially continuous recess in which the annular locking cam 43 is mounted 
with relative axial shifting freedom with respect to the common sliding 
sleeve 35 and is spring biased by two springs 54 and 55 in direction 
towards the axial center position of its stroke. 
It is understood that in place of the common sliding sleeve 35 it would 
also be possible to provide a sliding sleeve each for activating the first 
ball-locking arrangement 15, 37-41 and a further sliding sleeve for 
activating the second ball-locking arrangement 43-48. In this case, also, 
the locking cam 43 according to FIGS. 5-8 could be axially shiftably 
mounted in the one sliding sleeve. The common sliding sleeve 35 for 
activating both ball-locking arrangements does, however, significantly 
simplify the operation (FIGS. 1-8). 
With respect to the operation, there will now be first discussed the 
embodiment illustrated in the lower half of the four FIGS.: 
The quick coupling can be coupled even under pressure, i.e. one line of the 
two to be connected line parts can be under pressure. In the embodiment 
illustrated in the drawing it may be assumed that the line which is 
connected to the plug valve 1 is under pressure so that the check valve 4, 
10 is acted upon not only by the pressure of the closing spring 11, but 
also by the pressure of the introduced medium and held in the closing 
position. The line connected to the socket valve 2 is without pressure. On 
insertion of the plug valve 1 into the socket valve 2 the parts can 
initially be inserted into each other as far as indicated in FIG. 1. The 
bevel at the end wall 12 thus abuts against the balls 41 of the first 
ball-locking arrangement 15, 37-41, which is in the locked position. 
Subsequently the sliding sleeve 35 is shifted relative to the coupling 
body 16 in the direction indicated by the arrows 49 in FIG. 2 (or in the 
opposite direction), so that both the first ball-locking arrangement 15, 
37-41 and also the second ball-locking arrangement 43-48 are released 
respectively disengaged. In the embodiments in FIGS. 5-8 the springs 54 
and 55 hold respectively shift the locking cam 43 to its center position. 
In all embodiments the balls 41 can escape into the shunting groove 39 so 
that the plug valve 1 can be further inserted into the socket valve 2. 
Since the check valve 4, 10 is maintained in its closed position by the 
pressure of the enclosed medium, the check valve 22, 27 opens on 
continuation of the insertion movement in that the valve body 27 performs 
the simple valve stroke a and thus moves with its shaft 26 against the 
abutment 30. This intermediate position is shown in FIG. 2. Since the 
closing spring 31 is weaker than the pressure spring 34 the valve body 27 
will first shift relative to the star body 20, as shown in FIG. 2. If, 
however, the closing spring 31 were stronger than the pressure spring 34, 
then initially the star body 20 would shift relative to the coupling body 
16. Since the shifting of the sliding sleeve 35 also has permitted the 
second ball-locking arrangement 43-48 to move to the release position, the 
plug valve 1 can be inserted still further into the socket valve 2 with 
the check valve 10, 4 closed, but now the star body 20 is entrained via 
the abutment 30 so that the dimension b is reduced. The valve body 27 now 
performs in addition to the single valve stroke a a further valve stroke 
a, so that the valve body 27 performs approximately the double valve 
stroke 2a. This position of the parts is shown in FIG. 3. It is understood 
that the balls 47 move out of the locking groove 48 and have been shifted 
into the shunting groove 45. After release of the sliding sleeve 35 the 
same has moved in the direction of the arrows 50 in FIG. 3, so that the 
first ball-locking arrangement 15, 37-41 has already returned into its 
closure position whereas the second ball-locking arrangement 43-48 is 
still open. For the embodiments of FIGS. 5-8 the spring 54 is compressed 
and the spring 55 is partially relieved. This means, as shown in FIGS. 
3-7, that the plug valve 1 is already coupled with the socket valve 2 so 
that the plug can no longer be pulled or pushed out of the socket valve 2. 
A mark 51 provided on the outer circumference of the coupling body 16, for 
example in form of a circumferential kerf, overlaps in this position with 
the end wall of the sliding sleeve 35 (FIG. 3), so that it can be seen 
from the exterior of the quick coupling that the first ball-locking 
arrangement 15, 37-41 is already in the locked position and with respect 
to FIGS. 1-4 that the second ball-locking arrangement 43-48 is not yet 
locked. 
If pressure is now supplied to the line which is connected with the socket 
valve 2, for example by switching on the pressure medium source, then the 
pressure medium flows via the intermediate spaces between the arms 24 and 
the opened check valve 22, 27 against the valve body 10 and thus biases 
the same counter to the force of the closing spring 11 and of the pressure 
there entrapped. In addition, the pressure of the pressure spring 34 acts 
upon the valve body 10 via the valve body 27, so that altogether or at 
appropriate pressure level in any case an opening movement of the check 
valve 10, 4 takes place, so that the pressure compensation occurs. Because 
of the flow of the pressure medium from the line connected with the socket 
valve 2 in the direction towards the line of the plug valve 1, this 
pressure also acts upon the rear side of the valve body 27 whereby this 
movement is aided by the force of the pressure spring 34. In this manner 
the valve body 27 again moves through the single valve stroke a' towards 
the right, taking the valve body 10 along and of course also performing 
the single valve stroke a' until its shaft 9 engages the fixed abutment 
14. This position of the parts is shown in FIG. 4. During this movement, 
which the valve body 27 carries out jointly with the star body 20, without 
the shaft 26 becoming disengaged from the abutment 30, the sliding sleeve 
23 of the star body also shifts so far towards the right that the locking 
groove 48 moves into the range of the balls 47 so that in addition to the 
first ball-locking arrangement the second ball-locking arrangement 43-48 
can now also close. This closing position is made possible in the 
embodiments of FIGS. 5-8 by the axially shiftable mounting of the locking 
cam 43 and the force of the spring 54. Both of the first ball-locking 
arrangement 15, 37-41 and also the second ball-locking arrangement 43-48 
are then in the locked position, as shown in FIGS. 4 respectively 8. A 
further mark 52 (FIG. 4) on the outer circumference of the coupling body 
16 thus becomes visible relative to the end of the sliding sleeve 35 when 
the same has been shifted in accordance with the arrow 53 into the end 
position shown in FIG. 4. The outer circumference of the sliding sleeve 35 
in combination with a recess 56 indicates that the locking cam 43 has 
shifted according to arrow 53 into the end position shown in FIG. 8. The 
marks 51 and 52 reliably indicate that both ball-locking arrangements are 
locked. This means that the abutment 30 is also again engaged, i.e. 
effective. The two valve bodies 10 and 27 are thus in fixedly arrested 
position between the abutments 14 and 30, so that even pressure 
fluctuations of the pressure medium cannot lead to any significant 
shifting of the valve bodies 10, 27 in the parts 1, 2 of the quick 
coupling. This consideration presupposes that the end face 12 of the plug 
valve 1 and the end of the socket valve 2 are located in a common end 
plane in the coupled position, as shown in FIG. 4. 
For uncoupling the sliding sleeve 35 is moved from the position of FIG. 4-8 
either in direction of the arrows 49 or in the opposite direction, so that 
the two ball-locking arrangements 15, 37-41 and 43-48 are unlocked. 
Depending upon the prevailing pressure conditions the plug valve 1 is 
pushed out of the socket valve 2, and both check valves 10, 4 and 22, 27 
move to closed position as shown in FIGS. 1 respectively 5. 
The embodiment shown in the upper halves of FIGS. 1-4 respectively 5-8 has 
an analogous effect, but here the star body 20 is shifted jointly with the 
seat sleeve 19. The drawings show the various intermediate positions under 
the precondition that the pressure spring 34 is stronger than the closing 
spring 31. If, on the other hand, one makes the closing spring 31 stronger 
than the pressure spring 34, then this would have a somewhat different 
effect. In the intermediate position according to FIGS. 2 respectively 6 
the possibly desired advantage would then be obtained that both the check 
valves 4, 10 and 22, 27 would be closed in this intermediate position. If 
one then additionally selects the dimension b at least twice as large as 
the single valve stroke a', such a coupling could be completely closed 
with respect to its first ball-locking arrangement, and in this closing 
position both check valves 10, 4 and 22, 27 would still be in the locking 
position. However, by appropriate pressure build up respectively pressure 
decrease or in other manner it would then have to be achieved that both 
check valves can reach an open position according to FIGS. 4 respectively 
8 and that an appropriate locking of this position is effected. 
It is understood that in the illustrated embodiments the quick coupling 
naturally can be coupled and uncoupled even if none of the two lines 
connected respectively to the plug valve 2 and to the socket valve 2 are 
under pressure during the coupling respectively uncoupling operation. In 
such a case, depending upon the coordination of the springs 11, 31, 34 
with reference to one another, a different sequence of movements of the 
individual valve bodies relative to the coupling bodies 3 respectively 16 
will then occur. If, for example, the pressure spring 34 is stronger than 
the closing spring 31 and the closing spring 11, with the closing spring 
11 and the closing spring 31 being approximately of the same strength, 
then during the coupling without pressure the valve body 10 will perform 
the single valve stroke a', whereas the valve body 27 will perform the 
single valve stroke a, so that immediately the opening position of the two 
check valves 4, 10 and 22, 27 according to FIG. 4 will be reached. 
However, even in this case the locking position will immediately be 
reached when the coupling operation is completed and the sliding sleeve 
has reached its end position. The passage through the quick coupling is 
opened and remains opened because the valve bodies have been locked even 
prior to switching-on of the pressure source. A one-time closing operation 
in the sense of a double stroke movement is no longer necessary for 
achieving the locking position.