JPS6236090B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a quick coupler, and more particularly to a so-called Z-bar having a pair of lift arms spaced apart in the lateral direction and a tilt link positioned between the pair of lift arms in the lateral direction. This invention relates to a quick coupler for detachably connecting a working device to a linkage type (including reverse Z-bar linkage type and forward Z-bar linkage type) earthmoving vehicle.

As a quick coupler for removably connecting a bucket, blade, fork, or other working device to an earthmoving vehicle such as a loader, for example, JP-A-54-
Publication No. 56202, Japanese Patent Application Laid-Open No. 54-56203 or Japanese Patent Application Publication No. 56202
As disclosed in Publication No. 55-65639, etc., a quick coupler consisting of a hitch attached to the front end of an earthmoving vehicle and a hook fixed to the back of a working device to be connected to the earthmoving vehicle has already been proposed and put into practical use. ing.

However, conventional quick couplers have a so-called tilt coupler having a pair of lift arms spaced apart laterally and a pair of tilt links corresponding to the pair of lift arms spaced apart laterally at substantially the same distance. It was developed for 8-bar linkage type earthmoving vehicles, and can be applied as is to Z-bar linkage type earthmoving vehicles in which one (or two) tilt links are located laterally between a pair of lift arms. I can't. To further address this point, the hitch in a conventional quick coupler includes a pair of side members disposed at a distance in the lateral direction corresponding to the lateral distance between the pair of lift arms; The hitch body includes an upper horizontal member disposed between the upper end portions and a lower horizontal member disposed between the lower end portions of the pair of side members, and has a generally rectangular shape as a whole. There is. Upper engaging portions are provided at both end portions of the upper horizontal member, and lower engaging portions are provided at both end portions of the lower lateral member. When such a hit is installed on an 8-bar linkage type earthmoving vehicle, the lower ends of the pair of side members are rotatably connected to the tips of the pair of lift arms, and the upper ends of the pair of side members are connected to the ends of the pair of lift arms. portion is pivotally connected to the tip portions of the pair of tilt links. On the other hand, when the hitch as described above is to be attached to a Z-bar linkage type earthmoving vehicle, it is necessary to attach the hitch not to the lower ends of the pair of side members but to the upper side member (or an additional member fixed thereto). ) is rotatably connected to the tip of one (or two) tilt links. As is well known to those skilled in the art, in a Z-bar linkage type earthmoving vehicle, when the tilt link is placed in the most tilted position, the tip of the tilt link is lower than the upper edge of the pair of lift arms in the vertical direction. It is set to descend downward. Therefore, when the above-mentioned conventional quick coupler is applied as is to a Z-bar linkage type earthmoving vehicle, as is easily understood, when the tilt link is tilted back to a predetermined position before the most tilted back position, the tilt back is adjusted accordingly. Both ends of the upper horizontal member of the hitch then come into contact with the upper edges of the pair of lift arms, making further tiltback impossible. Such a problem can be solved by making the interconnection position of the hitch and the hook offset forward by a required distance with respect to the tip position of the pair of lift arms, and also by setting a position corresponding to the offset distance in the lateral center of the upper horizontal member. This problem can be solved by fixing an additional member extending rearward by the length and pivotally connecting the tip of the tilt link to the rear end of this additional member. However, in this case, the position of the working device with respect to the tip positions of the pair of lift arms is offset forward by the above-mentioned offset distance. (maximum allowable load on the working equipment that allows the working equipment to be tilted back from the lifted position), and chipping load (overturning load; with the pair of lift arms extending substantially horizontally, the rear end of the earthmoving vehicle is The maximum load that can be loaded onto the implement without it floating off the ground) is significantly reduced.

In addition, in the conventional quick coupler, when the pair of lower engaging parts of the hitch are engaged with the corresponding pair of lower receiving parts of the hook fixed to the back surface of the working device, the pair of lower engaging parts of the hitch In contrast, rearward and upward movement of the pair of lower receiving portions of the hook is restricted, but downward movement is not restricted. Therefore, the vertical load of the working equipment and the earth and sand loaded thereon is transmitted to the pair of lift arms from the pair of lower engaging parts of the hitch that engage with the corresponding pair of lower receiving parts of the hook. Rather, it engages with the corresponding pair of upper receiving parts of the hook and restrains the downward movement of the pair of upper receiving parts of the hook from the pair of upper engaging parts of the hitch through the pair of side plates of the hitch main body. It is transmitted to a pair of lift arms. Therefore, the strength of the pair of side plates of the hitch body must be sufficient to withstand the vertical load of the working equipment and the earth and sand loaded thereon. In addition, when a conventional quick coupler is applied to a Z-bar linkage type earthmoving vehicle, the lateral distance between the pair of upper engaging parts of the hitch and the part to which the tip of the tilt link is connected becomes considerably large. Therefore, when the hitch and the hook are connected to each other and the working device is connected to the earthmoving vehicle, it is compared to an upper horizontal member that extends laterally between the pair of upper engaging parts and the part where the tip of the tilt link is connected. A large moment acts on the target. Therefore, the strength of the transverse member must be sufficient to withstand the relatively large moments mentioned above. Because of this, in the conventional quick coupler,
The weight of the hitch itself becomes considerably large, and the manufacturing cost of the hitch becomes considerably high.

The present invention has been made in view of the above facts, and is a quick coupler for a Z-bar linkage type earthmoving vehicle, which is a new and excellent quick coupler that solves the above-mentioned problems related to conventional quick couplers. The goal is to provide the following.

A more detailed explanation will be given below with reference to the accompanying drawings.

A first specific example of a quick coupler constructed in accordance with the present invention will be described with reference to FIG. 1. The illustrated quick coupler consists of a hit generally designated by the number 2 and a hook generally designated by the number 4. .

The hitch 2 has a generally trapezoidal main body having a horizontal member 6 extending laterally and vertical members 8 extending upwardly and laterally inward from both sides of the horizontal member 6. Transverse member 6 in the illustrated embodiment
is formed from a hollow cylindrical tubular member extending laterally substantially horizontally. Further, the vertical member 8 is formed of a pair of parallel outer support plates 8a and inner support plates 8b fixed to both sides of the horizontal member 6 at a distance in the horizontal direction.

Further, the longitudinal member 8 further includes a pair of central support plates 10 and 12 extending upward from a lateral intermediate portion of the transverse member 6. The pair of central support plates 10 and 12 are located at a predetermined distance in the lateral direction, and their lower ends are fixed to the horizontal member 6.

Support disks 14 are fixed to both ends of the horizontal member 6, respectively. Each of the support discs 14 has an inner end of a pin 16 removably mounted in any suitable manner, and an outer end of the pin 16 that projects laterally outwardly beyond the side end of the transverse member 6. An engagement disk 18 constituting a lower engagement portion of the hitch 2 is fixed to the end.

A connecting piece 20 is fixed to the upper ends of the outer support plate 8a and the inner support plate 8b, and the connecting piece 20 connects to the central support plate 10.
(or 12).

A lower end of an auxiliary support plate 24 extending upward parallel to the central support plates 10 and 12 is fixed to the upper end of each of the outer support plates 8a.

At the upper ends of the central support plates 10 and 12 and the auxiliary support plates 24 located on both sides thereof, hollow tube members 2 are provided which extend laterally through the central support plates 10, 12 and 24.
6 is fixed. The pipe member 26 is connected to the hitch 2
constitutes an upper engaging part of.

A hook piece 30 having an engaging recess is rotatably attached to each of the lower ends of the outer support plate 8a and the inner support plate 8b by a pin 28. At the free end of the hook piece 30,
The lower end of a connecting rod 34 extending upwardly through a hole 32 formed in the outer support plate 8a is pivotally connected.

The upper end of the connecting rod 34 is rotatably connected to one end of a link member 40 which is rotatably attached to a support piece 36 fixed to the upper end of the outer support plate 8a by means of a pin 38.

The other end of the link member 40 is rotatably connected to an output rod of a double rod type hydraulic cylinder mechanism (constituting an operating mechanism) (not shown) mounted within the tube member 26. When the fluid pressure cylinder mechanism is in the contracted state, the hook piece 30 is positioned at the unlocked position shown by the solid line,
On the other hand, when the hydraulic cylinder mechanism is extended, the hook piece 30 is pivoted to the lock position shown by the two-dot chain line.

The hitch 2 as described above connects both ends of the horizontal member 6, more specifically, the support disc 14 and the engagement disc 1 of each of the pins 16 located at both ends of the horizontal member 6.
8 is rotatably attached to the tips of a pair of lift arms 42 (indicated by two-dot chain lines) of an earthmoving vehicle, and is also attached to a pair of central support plates 10.
and 12 portions 44 are rotatably attached to the tip of one tilt link 46 (indicated by a two-dot chain line) of an earthmoving vehicle, thereby creating a pair of lift arms that are spaced apart in the lateral direction. 42 and a single tilt link 46 located laterally between the pair of lift arms 42, as required.

Next, the hook 4 which cooperates with the hitch 2 as described above will be explained. The hook 4 fixed to the back of a working device 48 (indicated by a two-dot chain line) such as a bucket bag includes a pair of lower hook parts 50 fixed to the lower part of the back of the working device 48 at a distance in the horizontal direction;
A pair of upper hook parts 5 are fixed at the upper part of the back surface of the working device 48 and between the pair of lower hook parts 42 in the lateral direction with a slight interval in the lateral direction.
2.

Each of the pair of lower hook portions 50 includes an outer plate 54 and an inner plate 56 that are spaced apart from each other in the lateral direction. Outer plate 54
A substantially semicircular lower receiving surface 58 that is open toward the rear is formed in each of the lower receiving surfaces 58 . The lower receiving surfaces 58 formed on each of the outer plates 54 are connected to a pair of lower engaging portions of the hitch 2, that is, of the hook 4 which cooperates with the engaging disc 18, as will become clear from the description below. It constitutes a lower receiving part.

In addition, the outer plate 54 and the inner plate 5
The hook piece 30 of the hitch 2 is located between the rear ends of the hitches 6 and 6.
A pin 60 with which the engaging recess is engaged is fixed, and the pin 60 constitutes an engaged portion for the hook piece.

The upper hook portion 52 has a pair of plates 62 located at intervals in the lateral direction, and a substantially semicircular upper receiver that is open downward is provided at the upper end of each of the pair of plates 62. A surface 64 is formed. As will be clear from the following description, the upper receiving surfaces 64 formed on each of the pair of plates 62 constitute an upper engaging portion of the hitch 2, that is, an upper receiving portion of the tube member 26.

Next, the operation of the quick coupler consisting of the hitch 2 and the hook 4 as described above will be explained.

In order to interconnect the hitch 2 and the hook 4 and thus the working device 48 to the earthmoving vehicle,
The earthmoving vehicle is advanced against the back of the working device 48 placed on a support base such as the ground, and the hitch 2 attached to the front end of the earthmoving vehicle is moved to the hook fixed to the back of the working device 48. Position it opposite to 4. Then, the earthmoving vehicle is further advanced, and both sides of the pipe member 26 of the hitch 2 (namely, the pair of upper engaging portions) are brought into contact with the lower end portions of the pair of plates 62 of the hook 4. Next, lift arm 4
2 is raised, and the both sides of the pipe member 26 of the hitch 2, more specifically, the part of the pipe member 26 between the center support plate 10 and the left auxiliary support plate 24, and the part between the center support plate 12 and the right side The portion between the auxiliary support plate 24 and the upper hook portion 52 of the hook 4 is connected to the pair of plates 6, respectively.
2 is engaged with the upper receiving surface 62 formed on each of the two. In this way, the pair of upper hook portions 52 of the hook 4 are attached to both sides of the pipe member 26 of the hitch 2.
The relative movement of the upper receiving surface 64 in the front-rear direction and downward direction is restricted. After that, lift arm 42
When the hitch 2 and the hook 4 are further raised and the tilt link 46 is tilted back, the hitch 2 and the hook 4 are relatively pivoted about the central axis of the tubular member 26 of the hitch 2 in a direction toward each other. When the hitch 2 rotates in this manner, each of the pair of engagement discs 18 (i.e., lower engagement portions) of the hitch 2 engages with the lower receiving surface 58 (i.e., the lower portion) formed on the outer plate 54 of each of the pair of lower hook portions 50 of the hook 4. The pair of lower receiving surfaces 58 of the hook 4 are engaged with the pair of engagement discs 18 of the hitch 2 from moving rearward and in the vertical direction.

Thereafter, the hydraulic cylinder mechanism (not shown) provided in the pipe member 26 of the hitch 2 is extended to move the pair of hook pieces 30 from the unlocked position shown by the solid line to the locked position shown by the two-dot chain line. Make it rotate. In this way, the engaging recesses of the pair of hook pieces 30 are connected to the pair of lower hook parts 50 of the hook 4.
As can be understood from FIG. 1, the lower receiving surface 58 of the hook 4 is restrained from moving forward with respect to the engagement disc 18 of the hitch 2. In this way, the hitch 2 and the hook 4 are reliably connected, and therefore the working device 48 is reliably connected to the earthmoving vehicle.

In order to disconnect the hitch 2 and the hook 4 and detach the working device 48 from the earthmoving vehicle, the above-described connecting operation may be performed in reverse, and will be briefly described below.

The lift arm 42 is lowered sufficiently to position the working device 48 on a support reference surface such as the ground, and then the hydraulic cylinder mechanism (not shown) of the hitch 2 is moved.
is contracted to pivot the pair of lock pieces 30 from the locked position shown by the two-dot chain line to the unlocked position shown by the solid line, and thus each of the pair of lock pieces 30 is removed from the pin 60 of the pair of lower hook parts 50 of the hook 4. Force them to leave.

After that, the earthmoving vehicle moves backward, tilt link 4
6, the pair of engagement discs 12 of the hitch 2 are separated from the lower receiving surfaces 58 of the pair of lower hook parts 50 of the hook 4, and both ends of the pipe member 26 of the hitch 2 are removed. It is preferable that each of the sections be separated from the upper receiving surface 64 of each of the pair of plates 62 of the upper hook section 52 of the hook 4.

FIG. 2 illustrates a second embodiment of a quick coupler constructed in accordance with the present invention.

In the second embodiment shown in FIG. 2, the actuation mechanism for moving the hook piece 30 is a double rod type hydraulic cylinder mechanism (not shown) provided within the tube member 26 in the first embodiment. Instead, it is composed of a pair of rod-type hydraulic cylinders attached to each of the outer support plates 8a, and the other configurations are substantially the same as the first embodiment. still,
Components that are the same as those shown in FIG. 1 have the same reference numerals.

A fluid pressure cylinder mounting member 80 is fixed to each of the outer support plates 8a, and the mounting member 8
A rod-type hydraulic cylinder 84 is rotatably attached to each of the cylinders 0 and 8 by a pin 82.

A hydraulic cylinder 84 is connected to the outer support plate 8.
The lower end of the output rod 86 of the hydraulic cylinder 84 directly connects to the hook piece 3.
is pivotally connected to the free end of 0. Each of the hook pieces 30 has substantially the same structure as shown in FIG. 1, and is rotatably mounted by a pin 28 between the lower ends of the outer support plate 8a and the inner support plate 8b. . Therefore, when each of the hydraulic cylinder mechanisms 84 is in the retracted state, the hook pieces 30 are positioned in the unlocked position shown in FIG. 2, whereas when the hydraulic cylinder mechanisms 84 are in the extended state, the hook pieces 30 Piece 30 is pivoted into a locking position similar to that in FIG. Therefore, instead of the double rod type hydraulic cylinder shown in FIG. 1, the rod type hydraulic cylinder 84 shown in FIG.
Even if the hook piece 30 is used, the hook piece 30 can be reliably engaged with the engaged portion provided on the hook.

The connection and detachment of the hitch 2 and the hook 4 (shown in FIG. 1) in the specific example shown in FIG. 2 are substantially the same as in the specific example shown in FIG. 1, so a description thereof will be omitted.

In the quick coupler constructed according to the present invention as described above, the main body of the hitch 2 composed of the horizontal member 6 and the vertical member 8 is approximately trapezoidal as a whole, and the horizontal member 6 itself has a pair of lifts. Although it extends in the lateral direction over a length corresponding to the lateral spacing between the arms 42, the lateral width of the trapezoidal vertical member 8 is smaller than the lateral spacing between the pair of lift arms 42. Furthermore, the distance between the outer surfaces of each of the pair of upper hook portions 52 of the hook 4 (in other words,
The entire lateral width of the pair of upper hook portions 52) is also sufficiently smaller than the vertical spacing between the pair of lift arms 36. Therefore, when the tilt link 46 is tilted back the most so that its tip is located below the upper edges of the pair of lift arms 42 in the vertical direction, the vertical member 8 of the hitch 2, the pipe member 26 fixed thereto, and The pair of upper hook parts 52 and the like of the hook 4 can tilt back to a desired position between the pair of lift arms 42 without being obstructed by the tilt back movement due to contact with the upper edges of the pair of lift arms 42. Can be done. Therefore, like the conventional quick coupler mentioned above,
The interconnection position of the hitch and the hook is offset forward by the required distance with respect to the position of the ends of the pair of lift arms, and therefore there is no need to offset the position of the working device with respect to the ends of the pair of lift arms by the required distance. , the position of the working device 48 with respect to the tips of the pair of lift arms 42,
It can be made substantially the same as when directly attached to the distal ends of the pair of lift arms 42 without using a quick coupler, and the above-mentioned decrease in breakout force and chipping load can be avoided.

Also, it should be noted that in the quick coupler constructed according to the present invention, the hitch 2 and the hook 4 are connected to each other, and the pair of engagement discs 18 (i.e., the lower engagement portion) of the hitch 2 are connected to each other. Hook 4
When engaged with the pair of lower receiving surfaces 58 (i.e. lower receiving portions), the pair of lower receiving surfaces 58 of the hook 4 can only move backward and upward relative to the pair of engagement discs 18 of the hitch 2. Also, downward movement is restricted.
Therefore, the vertical load of the working device 48 and the earth and sand loaded thereon is mainly transmitted directly from the pair of lower receiving surfaces 58 of the hook 4 to the pair of engagement discs 18 of the hitch 2. from the pair of upper receiving surfaces 64 of the hook 4 (i.e., the upper receiving surface) to both sides (i.e., the upper engaging portion) of the pipe member 26 of the hitch 2 and the pair of lift arms 42 of the hook 4 via the vertical member 8. Even if there is anything that is transmitted to the arm 42, only a very small portion of it is transmitted. The required strength of the longitudinal member 8 is therefore significantly reduced. In addition, a hitch 2 that is engaged with a pair of upper receiving surfaces 64 (i.e., upper receiving surfaces) of the hook 4 from a portion of the vertical member 8 to which the tip of the tilt link 46 is connected is provided.
The lateral distance to both sides of the tube member 26 (i.e., the upper engaging portion) is relatively short. Therefore, when the tilt link 46 is tilted back or tilted forward to cause the working device 48 to be tilted back or tilted forward, the moment acting on the tubular member 26 and the longitudinal member 8 of the hitch 2 is relatively small, and therefore, such a point is This also reduces the required strength of the pipe member 26 and the vertical member 8 of the hitch 2. In this way, the weight of the hitch 2 itself can be reduced considerably, and the manufacturing cost of the hitch 2 can be reduced considerably.

Although preferred specific examples of the quick coupler configured according to the present invention have been described in detail above, the present invention is not limited to such specific examples, and various modifications and changes can be made without departing from the scope of the present invention. It does not need much to say that this is possible.

For example, the shapes of the lower and upper engaging portions of the hitch 2 and the lower or upper receiving portions of the hook 4 that cooperate with these can be modified as appropriate.

Further, although the hitch 2 in the illustrated embodiment is mounted on a Z-bar linkage type earthmoving vehicle in which a single tilt link 46 is disposed between a pair of lift arms 42 in the lateral direction, the hitch 2 is mounted on a Z-bar linkage type earthmoving vehicle in which a single tilt link 46 is disposed between a pair of lift arms 42 in the lateral direction. The quick coupler configured as shown in FIG. To do this, the form of the vertical member 8 of the hitch 2 is modified or modified as necessary, and the tips of the two or more tilt links described above are attached to the vertical member 8 of the hitch 2.
What is necessary is just to connect it to the appropriate part so that it can rotate freely.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a first specific example of a quick coupler constructed according to the present invention. Figure 2 shows
FIG. 6 is a perspective view showing a second specific example of the quick coupler hitch constructed according to the present invention. 2...Hitsuchi, 4...Hook, 6...Horizontal member,
8... Vertical member, 18... Engaging disc (lower engaging part), 26... Pipe member (upper engaging part), 30... Hook piece, 42... Lift arm, 46... Tilt link, 48... Working device, 50... Lower hook part, 52... Upper hook part, 58... Lower receiving surface (lower receiving part), 60... Pin (locked part), 64
...Upper receiving surface (upper receiving part), 84...Fluid pressure cylinder mechanism (operating mechanism).

Claims (1)

[Scope of Claims] 1. A hitch attached to a Z-bar linkage type earthmoving vehicle having a pair of lift arms spaced apart in the lateral direction and a tilt link positioned between the pair of lift arms in the lateral direction. , a hook fixed to the back of the working equipment to be connected to the earthmoving vehicle; a generally trapezoidal main body having an extending vertical member; a pair of lower engaging parts disposed at both ends of the horizontal member; at least one upper engaging part disposed at the upper end of the vertical member; a pair of hook pieces attached to the main body so as to be pivotable between a locked position and an unlocked position at intervals in the direction, and an actuation mechanism attached to the main body, the upper engaging portion formed from a tubular member;
The actuating mechanism is composed of a double rod type hydraulic cylinder mechanism disposed within the pipe member, each of the pair of rods of the hydraulic cylinder mechanism being connected to the pair of hook pieces, respectively, and The hitch is attached to the earthmoving vehicle by pivotally connecting both end portions to the tip portions of the pair of lift arms and pivotally connecting the vertical member to the tip portions of the tilt link; The hook includes a pair of lower hook parts fixed to the lower back surface of the working device at a distance from each other in the lateral direction, and a hook fixed between the pair of lower hook parts in the lateral direction at the upper back surface of the working device. an upper hook portion, each of the pair of lower hook portions having a lower receiving portion that cooperates with the pair of lower engaging portions of the hitch and an engaged portion that cooperates with the pair of hook pieces of the hitch; and the upper hook portion is formed with an upper receiving portion that cooperates with the upper engaging portion of the hit; By relatively moving upward, the upper receiving part is engaged with the upper receiving part, and the upper receiving part is restrained from moving forward and backward and downward with respect to the upper engaging part. When the hitch and the hook are relatively rotated in a direction in which they approach each other about the transverse axis of the upper engaging portion while the engaging portion is engaged with the upper receiving portion, the hitting portion of the hitch is rotated. The pair of lower engaging portions are engaged with the pair of lower receiving portions of the hook, thereby restricting the rearward and vertical movement of the pair of lower receiving portions with respect to the pair of lower engaging portions. , when the pair of hook pieces of the hitch are brought to the lock position with the pair of lower engaging parts of the hitch engaged with the pair of lower receiving parts of the hook, the pair of hook pieces A quick coupler that engages with the pair of engaged parts of the hook, thus restricting forward movement of the lower receiving part with respect to the lower engaging part. 2. A hitch attached to a Z-bar linkage type earthmoving vehicle having a pair of lift arms spaced apart laterally and a tilt link positioned between the pair of lift arms in the lateral direction, and a hitch connected to the earthmoving vehicle. a hook fixed to the rear side of a working device to be used; a trapezoidal main body, a pair of lower engaging parts disposed at both ends of the horizontal member, at least one upper engaging part disposed at the upper end of the vertical member; , a pair of hook pieces attached to the main body so as to be pivotable between a locked position and an unlocked position, and an actuation mechanism attached to the main body, and the vertical members of the main body are arranged at a predetermined interval. an inner support plate and an outer support plate are arranged, the pair of hook pieces are rotatably mounted between the inner support plate and the outer support plate, and the actuation mechanism is mounted on the outer support plate. The rods of the pair of hydraulic cylinder mechanisms are each connected to the pair of hook pieces, and both ends of the horizontal member are connected to the pair of lift arms. The hitch is attached to the earthmoving vehicle by pivotally connecting the vertical member to the tip of the tilt link; and the hook is attached to the lower rear of the working device. a pair of lower hook portions fixed at a laterally spaced interval, and an upper hook portion fixed at an upper rear side of the working device and between the pair of lower hook portions in the lateral direction; Each of the lower hook parts is formed with a lower receiving part that cooperates with the pair of lower engaging parts of the hitch and an engaged part that cooperates with the pair of hook pieces of the hitch, and the upper hook part is formed with a lower receiving part that cooperates with the pair of lower engaging parts of the hitch. is formed with an upper receiving portion that cooperates with the upper engaging portion of the hit; the upper engaging portion of the hit is configured to move upwardly relative to the upper receiving portion of the hook; Therefore, the upper engaging portion is engaged with the upper receiving portion, and the upper engaging portion is restrained from moving forward and backward and downward relative to the upper engaging portion, and the upper engaging portion is engaged with the upper receiving portion. When the hitch and the hook are rotated relative to each other in a direction in which they approach each other about the lateral axis of the upper engaging portion in the mated state, the pair of lower engaging portions of the hitch engage with the hook. The pair of lower engaging portions are engaged with each other, and the rearward and vertical movement of the pair of lower engaging portions is thereby restrained with respect to the pair of lower engaging portions of the hit. When the pair of hook pieces of the hitch are brought into the locked position with the upper part engaged with the pair of lower receiving parts of the hook, the pair of hook pieces engage the pair of engaged parts of the hook. A quick coupler characterized in that the lower receiving part is restrained from moving forward with respect to the lower engaging part.