JP5930842B2 - Elevator installation method and installation jig - Google Patents

Description

  The present invention relates to an elevator installation method in which a car return car and a counterweight return car are installed at the upper part in a hoistway, and an installation jig used when the elevator is installed.

  In the conventional elevator installation method, the car return beam and the counterweight return beam are lifted separately, and then the carage return beam and the counterweight return beam are connected at the upper part of the hoistway to return the car. A rope is hung on the car and the counterweight car (see, for example, Patent Document 1).

JP 2008-308248 A

  In the conventional elevator installation method as described above, the car returning and counterweight returning beams are lifted separately, so that the number of times of lifting is large and workability is lowered. Moreover, since it is necessary to perform a rope hanging operation | work at the upper part of a hoistway, workability | operativity also falls by this.

  The present invention has been made in order to solve the above-described problems, and an object thereof is to obtain an elevator installation method and an installation jig capable of improving workability.

  In the elevator installation method according to the present invention, a return car beam having a car return car mounting part to which a car return car is attached and a counterweight car return attaching part to which a counterweight car is attached is installed in the hoistway. The step of placing the suspension means for hanging the car and the counterweight on the lower part of the car, the process of hanging the car and the counterweight on the counterweight and the counterweight return car, and lifting and fixing the return car beam to a predetermined position in the upper part of the hoistway The process of carrying out is included.

  According to the elevator installation method of the present invention, a return wheel beam having a car return wheel mounting portion and a counterweight return wheel mounting portion is disposed in the lower part of the hoistway, and the suspension means is mounted on the car return wheel and the counterweight return wheel. After that, the returning beam is lifted and fixed at a predetermined position in the upper part of the hoistway, so that the number of lifting operations can be suppressed and the work at high places can be reduced to improve workability.

1 is a perspective view showing an elevator according to Embodiment 1 of the present invention. It is process drawing which shows a part of installation method of the elevator of FIG. It is a perspective view which shows the state in the middle of installation of the elevator of FIG. It is a perspective view which shows the state which installed the raising stand in the buffer stand of FIG. It is a perspective view which shows the state which installed the rope guide on the counterweight buffer stand of FIG. It is a perspective view which shows the state which temporarily fixed the counterweight return vehicle beam to the 2nd raising stand of FIG. It is a perspective view which shows the state which temporarily fixed the cage return vehicle beam to the 1st raising stand of FIG. 6, and connected the cage return vehicle beam and the balance weight return vehicle beam. FIG. 8 is a perspective view illustrating a state in which a main rope is hung on the car return wheel, the counterweight return wheel, and the rope guide of FIG. 7. It is a perspective view which shows the state in the state of lifting of the cage return vehicle beam of FIG. It is a perspective view which shows the state which fixed the cage return vehicle beam of FIG. 9 to the hoistway top part. It is a top view which shows the return wheel beam of FIG. It is a top view which shows the principal part of the elevator by Embodiment 2 of this invention. FIG. 13 is a right side view showing the return wheel beam of FIG. 12. It is process drawing which shows a part of elevator installation method by Embodiment 3 of this invention. It is a perspective view which shows the state in the middle of installation by the installation method of FIG. It is a top view which shows the pulling-up rope guide of FIG. It is a side view which shows the pulling-up rope guide of FIG. It is a top view which shows the state which installed the pulling-up top rope guide of FIG. 16 in the back fall type elevator. It is a top view which shows the state which installed the pull-up rope guide of FIG. 16 in the side-falling type elevator. It is a side view which shows the state which installed the pulling-up rope guide of FIG. 16 in the elevator with a shallow pit depth. It is a side view which shows the state which installed the pulling-up rope guide of FIG. 16 in the elevator with a deep pit depth.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a perspective view showing an elevator according to Embodiment 1 of the present invention, which is seen through a hoistway. In the figure, a car shock absorber base 2 and a counterweight shock absorber base 3 are fixed to the bottom of the hoistway 1. A car shock absorber (not shown) is installed on the car shock absorber base 2. On the counterweight buffer stand 3, a counterweight buffer (not shown) is installed.

  A pair of car guide rails 4a and 4b is erected on the car shock absorber base 2. In addition, a pair of counterweight guide rails 5a and 5b are erected on the counterweight buffer base 3.

  The car 6 is raised and lowered in the hoistway 1 while being guided by the car guide rails 4a and 4b. The counterweight 7 is raised and lowered in the hoistway 1 while being guided by the counterweight guide rails 5a and 5b. The counterweight 7 is disposed behind the car 6 so as to face the back of the car 6 when positioned at the same height as the car 6 (rear fall-off type).

  A hoisting machine 8 that raises and lowers the car 6 and the counterweight 7 is installed in the lower part of the hoistway 1. The hoisting machine 8 includes a drive sheave, a hoisting machine motor that rotates the driving sheave, and a hoisting machine brake that brakes the rotation of the driving sheave.

  At the top of the hoistway 1, an L-shaped return beam 9 is installed. The return wheel 9 includes a car return car beam (car return car mounting part) 10 and a counterweight car return car beam (a counterweight car return mounting part) connected to one end of the car return car beam 10 at a right angle. 11.

  A pair of car return wheels 12 a and 12 b is attached to the car return beam 10. A counterweight return wheel 13 is attached to the counterweight return beam 11.

  A pair of car suspension wheels 14 a and 14 b are provided at the lower part of the car 6. On the upper part of the counterweight 7, a counterweight suspension wheel 15 is provided.

  The car 6 and the counterweight 7 are suspended in the hoistway 1 by a plurality of main ropes 16 (only one is shown in the figure) as suspension means.

  Between the vicinity of the upper end portion of the car guide rail 4b and the vicinity of the upper end portion of the counterweight guide rail 5b, a leashing beam 17 is fixed horizontally. The tie-down beam 17 is provided with a cage-side tie-down portion (not shown). The counterweight return beam 11 is provided with a counterweight-side leash stopper 18.

  The main rope 16 has a first end connected to the car-side rope stopper and a second end connected to the counterweight-side rope stopper 18. The main rope 16 is, in order from the first end, the car suspension wheels 14a and 14b, the car return wheels 12a and 12b, the driving sheave of the hoisting machine 8, the counterweight return wheel 13, and the counterweight suspension wheel 15. (2: 1 roping).

  A control panel 19 is installed on the hoistway wall near the lowermost floor. The control panel 19 is provided with an elevator control device that controls the operation of the car 6. A control cable 20 is suspended between the hoistway wall and the car 6.

  A pair of lifting beams 21 a and 21 b are fixed to the top of the hoistway 1. The lifting beams 21 a and 21 b are arranged in parallel to the width direction of the car 6 and horizontally, spaced from each other in the depth direction of the car 6.

  Next, FIG. 2 is a process diagram showing a part of the elevator installation method of FIG. 1, and particularly shows the procedure up to the installation of the return wheel 9. In the elevator installation method of the first embodiment, first, as shown in FIG. 3, the lifting beams 21a and 21b are installed at the top of the hoistway 1 (step S1), and the car shock absorber is installed at the bottom of the hoistway 1. The stand 2 and the counterweight buffer stand 3 are installed (step S2).

  Thereafter, as shown in FIG. 4, a first raising base 22 is erected at one end of the car shock absorber base 2, and a pair of second raising bases 23 a and 23 b are provided on the counterweight shock absorber base 3. Is set up (step S3). The height dimensions of the second raising bases 23 a and 23 b are the same as each other, and are smaller than the height dimension of the first raising stage 22. Each raising base 22, 23a, 23b has a column portion fixed (bolted) to the shock absorber tables 2, 3, and a horizontal receiving portion provided at the upper end of the column portion.

  Subsequently, as shown in FIG. 5, a hoisting machine-corresponding rope guide 24 as a hoisting machine-corresponding guide body is installed (bolted) on the counterweight buffer base 3 (step S4). For example, a pulley can be used as the rope guide 24 for the hoisting machine. The rope guide 24 for the hoisting machine is disposed at a position lower than the position where the lower hoisting machine 8 in the hoistway 1 is installed. That is, the hoisting machine-corresponding rope guide 24 is disposed directly below the planned installation position of the hoisting machine 8.

  After the installation of the hoisting machine-corresponding rope guide 24, as shown in FIG. 6, the counterweight carriage 11 is temporarily fixed on the second raising bases 23a, 23b (step S5). On the counterweight return beam 11, a counterweight return wheel 13 and a counterweight side rope stopper 18 are attached in advance.

  After this, as shown in FIG. 7, the car return wheel 10 is temporarily fixed on the first raising base 22 (step S6). Car return wheels 12 a and 12 b are attached in advance to the car return beam 10. Then, the car return beam 10 and the counterweight return beam 11 are connected and integrated (step S7).

  At this time, the difference between the height dimension of the first raising platform 22 and the height dimension of the second raising platform 23a, 23b is made the same as the thickness dimension (vertical dimension) of the counterweight carriage 11. As a result, the height of the upper surface of the counterweight return beam 11 becomes the same as the height of the upper surface of the first height raising table 22, and the space between the first height raising table 22 and the counterweight return beam 11. The basket cage 10 is installed horizontally.

  Thereafter, as shown in FIG. 8, the main rope 16 is hung in the order of the counterweight return wheel 13, the hoisting machine-corresponding rope guide 24, the basket return wheel 12b, and the basket return wheel 12a (step S8). At this time, by using the hoisting machine-corresponding rope guide 24 instead of the hoisting machine 8, the rope hanging work can be performed at a position closer to the pit surface, and a stepladder becomes unnecessary. Further, the tip end portion (first end portion) of the main rope 16 is connected to the car shock absorber stand 2.

  Next, while lifting the integrated return beam 9 toward the top of the hoistway 1 as shown in FIG. 9 by a lifting machine (not shown) set on the lifting beams 21a and 21b. The main rope 16 is sent out (step S9). Then, as shown in FIG. 10, the return wheel 9 is fixed at a predetermined position in the upper part of the hoistway 1 (step S10).

  Thereafter, the raising bases 22, 23a, 23b and the hoisting machine rope guide 24 are removed, and the guide rails 4a, 4b, 5a, 5b, the car 6, the counterweight 7 and the hoisting machine 8 are installed. The main rope 16 is hung on the suspension vehicles 14a, 14b and the counterweight suspension vehicle 15, and the installation of the elevator is completed. Here, after removing the hoisting machine-corresponding rope guide 24, the hoisting machine 8 is installed and the main rope 16 is hung on the drive sheave. However, the work is difficult because the main rope 16 is not under tension. It is not a thing.

  FIG. 11 is a plan view showing the return beam 9 of FIG. The return wheel 9 is fixed to the car guide rail 4a and the counterweight guide rails 5a and 5b. The cage return vehicle beam 10 is connected to the counterweight return vehicle beam 11 by, for example, a plurality of bolts 30.

  In such an elevator installation method, the cage return car beam 10 to which the car return vehicles 12a and 12b are attached and the counterweight return vehicle beam 11 to which the counterweight return vehicle 13 is attached are integrated. The main rope 16 is hung on the car return wheels 12a and 12b and the counterweight return wheel 13 in a state where the car beam 9 is arranged at the lower part in the hoistway 1, and then the carousel 9 is attached to the upper part in the hoistway 1. Since it is lifted and fixed at a predetermined position, the number of times of lifting can be suppressed. Also, by performing the rope hanging work in the hoistway pit, the rope hanging time can be shortened, the height work can be reduced, and the workability can be improved.

  In addition, since the car return beam 10 and the counterweight return beam 11 are connected and integrated at the lower part in the hoistway 1, the car return wheel 10 and the counterweight return beam 11 are separate bodies. Even in this case, the number of lifting operations can be reduced. In addition, it is not necessary to perform the connection work between the car return beam 10 and the counterweight return beam 11 at the upper part of the hoistway 1, and work at high places can be reduced and workability can be improved.

  Furthermore, since the mounting height of the car return wheel beam 10 and the counterweight return beam beam 11 is different, it is difficult to assemble on a plane such as a pit surface. Since 23a and 23b are used, the connection operation | work with the cage return vehicle beam 10 and the balance weight return vehicle beam 11 can be performed easily.

  Furthermore, since the raising bases 22, 23a and 23b are installed on the shock absorber bases 2 and 3, the shock absorber bases 2 and 3 which are elevator equipments are used, so that they can be placed at appropriate positions without depending on the hoistway layout. Raising tables 22, 23a, 23b can be installed.

  Further, when the hoisting machine-corresponding rope guide 24 is arranged at a position lower than the position where the hoisting machine 8 is installed, and the main rope 16 is hung on the car return wheel 12a, 12b and the counterweight return wheel 13, The main rope 16 is also hung on the rope guide 24 for the upper machine, the rope guide 24 for the hoisting machine is removed, the hoisting machine 8 is installed in the hoistway 1, and the main rope 16 is attached to the rope guide 24 for the hoisting machine. Since the hoisting machine 8 is switched to the hoisting machine 8, the rope can be easily hung near the pit surface, and a stepladder becomes unnecessary. Further, when the main rope 16 is hung on the drive sheave of the hoisting machine 8, it is possible to prevent a mistake in hooking the rope into the rope groove of the drive sheave.

  Further, since the hoisting machine rope guide 24 is installed on the counterweight buffer stand 3, the hoisting machine rope guide 24 can be installed at an appropriate position without depending on the hoistway layout.

Embodiment 2. FIG.
Next, FIG. 12 is a plan view showing a main part of an elevator according to Embodiment 2 of the present invention, and FIG. 13 is a right side view showing the return wheel 31 of FIG. In this example, the counterweight 7 is disposed on the side of the car 6 so as to face the side surface of the car 6 when positioned at the same height as the car 6 (side-falling type).

  On the top of the hoistway 1, a return beam 31 is installed. The return wheel 31 is provided with a car return wheel attachment portion 31a and a counterweight return wheel attachment portion 31b. That is, the return beam 31 is an integral beam that serves as both a car return beam and a counterweight return beam. In addition, the car return wheel mounting portion 31a is located immediately below the counterweight return wheel mounting portion 31b.

  The car return wheel 12 is attached to the car return wheel attachment portion 31a. The car return wheel 12 is arranged below the return wheel 31. A counterweight suspension vehicle 13 is attached to the counterweight return vehicle attachment portion 31b. The counterweight return wheel 13 protrudes above the return wheel 31. Other configurations are the same as those in the first embodiment.

  Even when such an integrated return beam 31 is used, the return vehicle 31 to which the return wheel 12 and the counterweight return wheel 13 are attached is arranged in the lower part of the hoistway 1 and the return wheel 31 is returned. 12 and the counterweight return wheel 13 are hung by the main rope 16, and then the return beam 31 is lifted and fixed at a predetermined position in the upper part of the hoistway 1. It is possible to reduce and improve workability.

Embodiment 3 FIG.
Next, FIG. 14 is a process diagram showing a part of an elevator installation method according to Embodiment 3 of the present invention, and FIG. 15 is a perspective view showing a state during installation by the installation method of FIG. In the installation method of the third embodiment, after the hoisting machine compatible rope guide 24 is installed on the counterweight buffer base 3 (step S4), the support rod 26 is horizontally placed between the second raising bases 23a and 23b. Fix it. Then, a pull-up rope guide 25 as a pull-up guide body is installed at the intermediate portion of the support rod 26 (step S11).

  The pull-up rope guide 25 guides the main rope 16 drawn out from the bundle of the main ropes 16 right above when the return wheel 9 is lifted. The pull-up rope guide 25 is disposed directly below the counterweight wheel 13 at the lower part in the hoistway 1.

  Thereafter, the counterweight return beam 11 is temporarily fixed on the second raising bases 23a and 23b (step S5), and the car return wheel 10 is temporarily fixed on the first raising base 22 (step S6). The car return beam 10 and the counterweight return beam 11 are connected and integrated (step S7).

  The main rope 16 is hung in the order of the pull-up rope guide 25, the counterweight return wheel 13, the hoisting machine compatible rope guide 24, the reverse wheel 12b, and the reverse wheel 12a. The first end) is connected to the car shock absorber stand 2 (step S8).

  Thereafter, the return wheel 9 is lifted to the top of the hoistway 1 (step S9) and fixed at a predetermined position (step S10).

  Finally, the raising bases 22, 23a, 23b, the pull-up rope guide 25 and the hoisting machine compatible rope guide 24 are removed, and the guide rails 4a, 4b, 5a, 5b, the car 6, the counterweight 7 and the hoisting machine 8 are removed. Etc., and the main rope 16 is hung on the car suspension vehicles 14a and 14b and the counterweight suspension vehicle 15, and the installation of the elevator is completed. That is, it is the same as the installation method of Embodiment 1 except that the pull-up rope guide 25 is used.

  16 is a plan view showing the pull-up rope guide 25 of FIG. 15, and FIG. 17 is a side view showing the pull-up rope guide 25 of FIG. The pull-up rope guide 25 includes a pair of single clamps 27 as fixed portions fixed to the support rod 26, a guide roller 28 as a guide portion on which the main rope 16 is hung, and a space between the single clamp 27 and the guide rollers 28. And a support arm 29 as an arm portion connected to the.

  The support arm 29 has a fixed plate 29a fixed to the single clamp 27, a swivel plate 29c capable of swiveling left and right with respect to the fixed plate 29a around a vertical swivel shaft 29b, and a horizontal swing shaft 29d. And an arm body 29e that can swing in the vertical direction with respect to the swivel plate 29c. Accordingly, the guide roller 28 is supported by the support arm 29 so as to be displaceable in the horizontal direction and the vertical direction within a predetermined range with respect to the single clamp 27. The guide roller 28 is supported at the tip of the arm body 29e so as to be rotatable about a horizontal rotation axis.

  Here, when the pull-up rope guide 25 is not used, it is necessary to turn the rope untwisting jig 32 by hand in order to send out the main rope 16 when the return beam 9 is lifted. There is a need to. In addition, if the speed at which the main rope 16 is sent out with respect to the lifting speed is delayed, the angle of the main rope 16 with respect to the counterweight return wheel 13 is deteriorated, and the return wheel 9 rotates or is balanced in the worst case. There is a possibility that the main rope 16 may come off the rope groove of the return wheel 13.

  On the other hand, in the elevator installation method of the third embodiment, since the pull-up rope guide 25 is disposed directly below the counterweight return wheel 13, the main rope 16 is attached to the counterweight return wheel 13. The main rope 16 can be prevented from coming off from the counterweight return wheel 13 and the return beam 9 can be prevented from rotating during lifting.

Moreover, it is not necessary to turn the rope twisting jig 32 by hand, and one worker can be reduced.
Furthermore, since the pull-up rope guide 25 is installed on the second raising bases 23a, 23b that are installed at the time of installation, the pull-up rope guide 25 can be easily installed without depending on the building frame or hoistway layout. it can.

  Furthermore, since the arm main body 29e and the swivel plate 29c can swivel about the swivel shaft 29b, the rear drop-type elevator as shown in FIG. 18 can also be used with the rope untwisting jig 32 placed on the landing. Further, a falling-down type elevator as shown in FIG. For this reason, the pull-up rope guide 25 can be used in common, the types of installation jigs can be reduced, and jig management can be facilitated. Note that the guide rails 4a, 4b, 5a, 5b are not yet installed at the stage where the pull-up rope guide 25 is installed, but in FIGS. 18 and 19, the guide rail 4a is shown in order to clarify the type of the elevator. , 4b, 5a, 5b.

  Further, since the arm main body 29e can swing up and down around the swing shaft 29d, the pit depth as shown in FIG. 20 (the floor surface of the lowest floor landing where the rope untwisting jig 32 is placed) To the elevator having a shallow pit depth as shown in FIG. 21. In other words, the pit depth changing for each property can be handled by the common pull-up rope guide 25, which can also reduce the types of installation jigs and facilitate jig management. it can.

  Further, by fixing the single clamp 27 to the support rod 26, the pull-up rope guide 25 is fixed to the raising bases 23a, 23b. Therefore, the pull-up rope guide 25 can be easily attached and detached, and the workability is improved. improves.

In the above example, the first end portion (the end portion on the car 6 side) of the main rope 16 is connected to the car shock absorber table 2 as the leading end portion at the time of installation, but the second end portion (the counterweight) 7 side end) may be connected to the counterweight buffer stand 3 as a tip at the time of installation. In this case, the pulling-up guide body may be disposed directly under the car return wheel.
In the above example, the main rope 16 is shown as the suspension means, but the suspension means may be a plurality of belts.
Furthermore, in the above example, the pull-up rope guide 25 is installed on the second raising bases 23a, 23b, but is not limited to this. For example, the car shock absorber base 2 or the counterweight shock absorber base 3 May be installed directly or via a support base.

  1 hoistway, 2 car shock absorber base, 3 counterweight shock absorber base, 6 car, 7 counterweight, 8 hoisting machine, 9,31 return car beam, 10 car return car beam (car return car mounting part) , 11 Balance weight return beam (balance weight return vehicle mounting portion), 12, 12a, 12b Cage return wheel, 13 Balance weight return vehicle, 16 Main rope (suspension means), 22 First raising base, 23a 23b 2nd raising stand, 24 hoisting machine compatible rope guide (hoisting machine compatible guide body), 25 pulling upper rope guide (pulling upper guide body), 27 single clamp (fixing part), 28 guide roller (guide part) ), 29 Support arm (arm part), 31a Car-return wheel mounting part, 31b Counterweight return-car mounting part.

Claims (8)

A step of disposing a return car beam having a car return car mounting part to which a car return car is attached and a counterweight car return part to which a counterweight return car is attached to the lower part in the hoistway;
A step of hanging suspension means for suspending a car and a counterweight on the car return wheel and the counterweight return car, and a step of lifting and fixing the return car beam to a predetermined position in the upper part of the hoistway. seen including,
In the step of disposing the return wheel beam in the lower part of the hoistway, the car return wheel beam that is the car return wheel mounting portion and the balance weight return wheel beam that is the counterweight return wheel mounting portion are described above. Connect and integrate at the bottom of the hoistway,
After the first raising table and the second raising table having a height different from that of the first raising table are installed in the lower part of the hoistway, the car raising vehicle beam is placed on the first raising table. And mounting the counterweight return beam on the second raising platform, and connecting the cage return beam and the counterweight return beam . It said first and second elevating block, method of installation according to claim 1, wherein the elevator, characterized in that to fix the shock absorber mount fixed to the bottom of the hoistway. A step of disposing a return car beam having a car return car mounting part to which a car return car is attached and a counterweight car return part to which a counterweight return car is attached to the lower part in the hoistway;
Hanging the suspension means for suspending the car and the counterweight on the car return wheel and the counterweight return car, and
The step of lifting and fixing the return carriage beam at a predetermined position in the upper part of the hoistway
Including
A hoist corresponding to the hoisting machine for guiding the suspension means is disposed at a position lower than the position where the lower hoisting machine is installed in the hoistway,
When hanging the suspension means on the car return wheel and the counterweight return wheel, the suspension means is also hung on the hoist corresponding to the hoisting machine,
After lifting the return beam, the hoisting machine corresponding guide body is removed, the hoisting machine is installed in the hoistway, and the suspension means is lifted from the hoisting machine corresponding guide body. features and be Rue elevators method of installation that to change over to the machine. 4. The elevator installation method according to claim 3 , wherein the hoisting machine-compatible guide body is fixed to a shock absorber base fixed to a bottom portion of the hoistway. A pull-up guide body that guides the suspension means pulled out from the bundle of suspension means when the return carriage beam is lifted up is provided as the car return wheel or the counterweight return car below the hoistway. disposed beneath the, said suspension means after subjected to the lifting portion guide body according to any one of claims 1, characterized in that Agekasane the return pulley beam to claim 4 How to install the elevator. After placing a return beam having a basket return car mounting part to which a car return car is attached and a counterweight car return part to which a counterweight return car is attached at the bottom of the hoistway, the car is suspended. For installing the elevator used in the installation work of the elevator that hangs the suspension means to be lowered on the car return wheel and the counterweight return wheel, and lifts and fixes the return car beam to a predetermined position in the upper part of the hoistway. A jig,
A fixed portion fixed to a lower portion in the hoistway; and a lower portion in the hoistway, which is disposed directly below the car return wheel or the counterweight return wheel, the suspension means is hung, and A guide part that guides the suspension means that is pulled out from the bundle of suspension means at the time of lifting, and is connected between the fixing part and the guide part, and the guide part is connected to the fixing part. An elevator installation jig comprising: a pull-up guide body having an arm portion that is supported so as to be displaceable in a horizontal direction and a vertical direction within a predetermined range. Further comprising a raising stand that is erected at the lower part in the hoistway and on which the return beam before lifting is temporarily fixed at the upper part;
The elevator installation jig according to claim 6 , wherein the pull-up guide body is fixed to the raising base. The elevator installation jig according to claim 6 or 7 , wherein the guide portion is a guide roller that is rotatable about a horizontal rotation axis.

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