JP3269254B2 - Belt clamping device for steep conveyors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt clamping device for a steeply inclined conveyor.

[0002]

2. Description of the Related Art When a bulk material such as crushed stone, limestone, sand, steel stone, ready-mixed concrete or the like is transported from the ground to a high place by a belt conveyor, the inclination angle of the belt conveyor is limited by the angle of repose of the bulk material. For this reason, the inclination angle of the conventional belt conveyor is at most about 15 degrees. As a result, there is a problem that the installation space of the belt conveyor is widened and the site cannot be effectively used.

[0003] In recent years, in order to save space, two sets of independent belt conveyors have been installed at the top and bottom, respectively, and loose materials have been placed between the upper belt of the lower belt conveyor and the lower belt of the upper belt conveyor. Steep conveyors, including vertical ones that sandwich, wrap and convey, have been put to practical use.

[0004] As this kind of steeply inclined conveyor, conventionally,
For example, there is an apparatus disclosed in Japanese Patent Publication No. 3-13123, and a belt clamping device for a steeply inclined conveyor described in this publication includes a lower belt conveyor as shown in FIGS. The idlers 33 and 34 are disposed on one side of one conveyor belt 7, and a plurality of rollers 35 and 36 are disposed on the other side of the conveyor belt 17 of the upper belt conveyor 2.
The unit 37 is formed so as to be pressed by a spring 38.

[0005]

However, in the above-described belt holding device for steeply inclined conveyors, the unit 3
Since the rollers 35 and 36 formed as 7 are pressed against the conveyor belt 17 of the upper belt conveyor 2 by one spring 38, the center in the width direction of the conveyor belt 17 among the plurality of rollers 35 and 36 in the unit 37. It is difficult to individually adjust the pressing force of the roller 35 disposed at the portion and the roller 36 disposed at both sides in the width direction, and in some cases, the loose material 20 can be stably conveyed. May disappear,
A long arm 39 for supporting the unit 37 and the like are also required, so that the apparatus becomes large and the structure is complicated.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to adjust the pressing force of the rollers individually to maintain an appropriate state, to always stably transport loose materials, and to reduce the size and structure. It is an object of the present invention to provide a belt holding device for a steeply inclined conveyor which can simplify the above.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to an upper belt conveyor in which a loose material contact surface of a conveyor belt in a lower belt conveyor faces a loose material contact surface of a conveyor belt in an upper belt conveyor. A belt clamping device for a steeply inclined conveyor in which a belt conveyor is arranged, and bulk materials are sandwiched between the two conveyor belts at the rising portions of the conveyor belts, and the conveyor belts are wrapped and conveyed, and a width of a conveyor belt of a lower belt conveyor. A main fixed roller supporting the central portion in the direction, and an upper belt conveyor side from the center side of the conveyor belt to the width end side in order to support both sides in the width direction of the conveyor belt of the lower belt conveyor and form a trough angle on the conveyor belt. Position of the main fixed roller extending in the longitudinal direction of the conveyor belt and the required amount of deviation A secondary fixed roller which is disposed at a position,
A main presser roller for pressing the central portion in the width direction of the conveyor belt of the upper belt conveyor, rotatably supported to the main pressing roller
Conveyor bell of upper belt conveyor for the arm to be held
A torsion bar for applying rotational power to the
Adjust the twist applied to the control bar and press the main holding roller.
A torque adjusting bolt for adjusting an applied force and the arm
When the bulk material is not conveyed, the rotation of the
To prevent the main press roller from contacting the conveyor belt.
A main holding roller pressing adjustment mechanism for pressing the main pressing roller against the conveyor belt of the upper belt conveyor, and a widthwise lower side of the conveyor belt of the upper belt conveyor in a state substantially parallel to the auxiliary fixing roller. A steeply inclined conveyor comprising: a belt end roller for pressing a conveyor belt of a belt conveyor; and a belt end roller pressing adjustment mechanism for pressing the belt end roller to both sides in the width direction of the conveyor belt of the upper belt conveyor. Of the present invention.

In the belt holding device for the steeply inclined conveyor, a torsion bar for applying a rotating force to the conveyor belt side of the upper belt conveyor with respect to a shaft rotatably supporting a belt end roller, and to the torsion bar. A torque adjusting bolt for adjusting the twist and adjusting the pressing force of the belt end roller can constitute a belt end roller pressing adjustment mechanism.

Further, in the belt holding device for the steeply inclined conveyor, the tilting angle and the pushing amount of the shaft for rotatably supporting the belt end roller with respect to the conveyor belt of the upper belt conveyor are adjusted to press the belt end roller. The belt end roller pressing adjustment mechanism may be configured by a position adjustment bolt for adjusting the distance.

[0010]

Accordingly, when the bulk material is conveyed, when the pressing force of the main pressing roller is adjusted by the main pressing roller pressing adjusting mechanism, the desired pressing force is loosened by the main pressing roller via the conveyor belt of the upper belt conveyor. The pressing force applied to the bulk material and applied to the bulk material is shifted by a required amount from the main fixed roller and the arrangement position of the main fixed roller in the longitudinal direction of the conveyor belt via the conveyor belt of the lower belt conveyor. Is distributed to the auxiliary fixing rollers disposed at the same position, and a desired frictional force is generated between both conveyor belts and the bulk material. As a result, the pressing force of the main pressing roller is applied to the bulk material to be conveyed. It works reliably, and the pressing force of the belt end roller is held in an appropriate state by the belt end roller pressing adjustment mechanism, and slipping may occur inside the bulk material. No longer, without being transferred to the loose product pressure according to the weight of the loose material on the upper side is positioned more on the lower side it loose material is to be transported stably.

The main press roller pressing adjustment mechanism includes a torsion bar for applying a turning force to the conveyor belt side of the upper belt conveyor to an arm for rotatably supporting the main press roller, and a torsion applied to the torsion bar. A torque adjusting bolt for adjusting and adjusting the pressing force of the main holding roller, and a rest bar for restricting the rotation of the arm to the conveyor belt side so as to prevent the main holding roller from contacting the conveyor belt during non-transportation of loose objects. Consists of
Therefore , in the initial state in which the bulk material is not conveyed, the arm abuts on the rest bar, the rotation of the arm toward the conveyor belt is limited, and the main pressing roller does not contact the conveyor belt. By using the adjustment bolt, the torsion applied to the torsion bar can be adjusted, and the initial value of the pressing force of the main pressing roller can be arbitrarily set.

A torsion bar for applying a rotating power to the conveyor belt side of the upper belt conveyor with respect to a shaft rotatably supporting the belt end roller, and a torsion applied to the torsion bar being adjusted to press the belt end roller. When the belt end roller pressing adjustment mechanism is configured from the torque adjustment bolt for adjusting the force, the torque adjustment bolt
The twist applied to the torsion bar can be adjusted, and the pressing force of the belt end roller is adjusted to a desired value.

[0013] Further, a position adjusting bolt for adjusting a tilting angle and a pushing amount of an upper belt conveyor with respect to a conveyor belt of a shaft rotatably supporting a belt end roller to adjust a pressing force of the belt end roller is used. When the end roller pressing adjustment mechanism is configured, the tilt angle and the amount of pushing of the upper belt conveyor with respect to the conveyor belt can be adjusted by the position adjusting bolt, and the pressing force of the belt end roller is adjusted to a desired value.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 10 show one embodiment of the present invention.
In the drawing, reference numeral 1 denotes a lower belt conveyor, and 2 denotes an upper belt conveyor installed above the lower belt conveyor 1.

The lower belt conveyor 1 has a head pulley 3 disposed above and a tail pulley 4 disposed behind the head pulley 3 and below the head pulley 3. A drive belt wheel 5 disposed below the head pulley wheel 3, an aperture belt wheel 6a disposed near the drive belt wheel 5, the throttle belt wheel 6a and the head belt wheel 3 And an aperture belt wheel 6b disposed between the
An endless conveyor belt 7 is wound around each of the belt wheels 3, 4, 5, 6a, and 6b. A drive device 8 such as a reduction motor or a hydraulic motor is connected to the drive belt wheel 5,
By driving the driving device 8, the conveyor belt 7 can run in the direction of arrow A.

Between the tail belt pulley 4 and the head pulley 3, there is provided a horizontal portion 9 capable of supplying and transporting the bulk material 20 onto the conveyor belt 7, and a bulk material which has been transported along the horizontal portion 9. The maximum angle at which 20 can be transported upwards is 45
A rising portion 10 having a steeply inclined portion (vertical in the example of FIG. 1) is formed, and a horizontal portion 9 and a rising portion 10 are formed.
Is provided with a plurality of carrier roller devices 11 at required intervals in the bulk material transport direction D, and the carrier roller device 11 and a pressing roller device 19 described later constitute a belt clamping device. is there.

The upper belt conveyor 2 has a head belt wheel 12 disposed on the upper front side of the head belt wheel 3 of the lower belt conveyor 1 and a tail part disposed on the lower rear side of the head belt wheel 12. An endless conveyor belt 17 is provided on each of the belt wheels 12, 13, 15a, 14, 15b, and 15c with a belt belt 13, a drive belt wheel 14, and aperture belt wheels 15a, 15b, and 15c. It is wound so as to be located immediately above the conveyor belt 7 of the conveyor 1. The drive belt wheel 14 is connected to a drive device 16 such as a reduction motor or a hydraulic motor. By driving the drive device 16, the conveyor belt 17 can be sent in the direction of arrow B.

Between the tail belt wheel 13 and the head belt wheel 12, there is a maximum angle of 45 which can hold the bulk material 20 conveyed on the horizontal portion 9 of the lower belt conveyor 1 and convey it upward. A rising portion 18 having a steeply inclined portion (vertical in the example of FIG. 1) is formed at the rising portion 18.
A plurality of pressing roller devices 19 are provided at required intervals in the bulk transport direction D.

As shown in FIGS. 2 to 4, the carrier roller device 11 constituting the belt holding device includes a main fixed roller 21 for supporting a central portion of the conveyor belt 7 in the width direction, and two opposite sides of the conveyor belt 7 in the width direction. Conveyor belt 7
In order to form a trough angle, the position extends from the center side of the conveyor belt 7 toward the width end side toward the upper belt conveyor 2 and is shifted from the arrangement position of the main fixed roller 21 in the longitudinal direction of the conveyor belt 7 by a required amount. , And each of the rollers 21 and 22 is provided with a bracket 2.
3 and 24 are rotatably supported. The length of the main fixed roller 21 is longer than the conventional one by a required amount, and both ends of the main fixed roller 21 are overlapped with the respective ends of the sub fixed roller 22 as shown in FIG. I try to wrap.

As shown in FIGS. 2 and 3, the pressing roller device 19 constituting the belt holding device includes a main pressing roller 25 for pressing the central portion of the conveyor belt 17 in the width direction.
A main pressing roller pressing adjusting mechanism 42 for pressing the main pressing roller 25 against the conveyor belt 17 of the upper belt conveyor 2
And the conveyor belt 1 in a state parallel to the auxiliary fixing roller 22.
A belt end roller 26 for pressing both sides in the width direction of 7, 7;
A belt end roller pressing adjustment mechanism 43 for pressing the belt end roller 26 to both sides in the width direction of the conveyor belt 17 of the upper belt conveyor 2 is provided.

As shown in FIGS. 3 and 6, the main holding roller 25 is provided with a bracket 41 fixed to a support pipe 40.
The main holding roller pressing adjustment mechanism 42 is rotatably supported by the tip of the arm 28 that is swingably attached to the tip.
As shown in FIG. 2, FIG. 5, and FIG. 7, the torsion bar 27 for applying a turning power to the arm 28 toward the conveyor belt 17 of the upper belt conveyor 2 and the torsion applied to the torsion bar 27 are adjusted. A torque adjusting bolt 44 for adjusting the pressing force of the main pressing roller 25; and restricting the rotation of the arm 28 toward the conveyor belt 17 so that the main pressing roller 25 contacts the conveyor belt 17 when the bulk material 20 is not conveyed. And a rest bar 45 for preventing the movement.

As shown in FIGS. 2 and 7, the torque adjusting bolt 44 has a base end pivotally connected to a fixed bracket 47 via a yoke 46 and a nut 48 at the tip end.
Slide block 49 whose position can be adjusted by tightening
The slide block 49 is pivotally mounted on a bracket 51 integral with a rotation block 50 to which the base end of the torsion bar 27 is connected, and the slide block 49 is rotated by adjusting the position of the slide block 49 by tightening the nut 48. The block 50 is rotated by a required amount so that the torsion applied to the torsion bar 27 can be adjusted and the pressing force of the main pressing roller 25 can be adjusted.

The belt end roller 26 is shown in FIGS.
As shown in FIG. 0, the belt end roller pressing adjustment mechanism 43 is rotatably supported by a shaft 29 that is swingably attached to a bracket 52, and moves toward the conveyor belt 17 of the upper belt conveyor 2 with respect to the shaft 29. And a torque adjustment bolt 54 for adjusting the torsion applied to the torsion bar 53 and adjusting the pressing force of the belt end roller 26. .

The torsion bar 53 has a base end fixed to the end of the adjusting pipe 55 and a distal end integrated with the shaft 29.
The torque adjusting bolt 54 is screwed and fixed to the bracket 52 having a plurality of adjusting screw holes 57 formed at a required pitch in the circumferential direction at the required pitch in the circumferential direction. By appropriately selecting the fixing angle with respect to the bracket 52, the torsion applied to the torsion bar 53 can be adjusted, and the pressing force of the belt end roller 26 can be adjusted.

The bracket 52 is provided with a support pipe 4
0, and is fixed to a base plate 58 provided with a long hole extending in the width direction of the conveyor belt 17 by tightening bolts 59 and nuts 60. The width of the conveyor belt 17 can be adjusted in the width direction. In FIG. 1, reference numeral 30 denotes a chute for supplying the bulk material 20 to the upstream end of the horizontal portion 9 of the lower belt conveyor 1, and reference numeral 31 denotes a width of the bulk material 20 supplied from the chute 30 onto the conveyor belt 7. A pair of skirts 32 are chutes for transferring the loose materials 20 to equipment of the next process on the downstream side (not shown).

Next, the operation of the above embodiment will be described.

When the bulk material 20 is conveyed by the steeply inclined conveyor, the driving devices 8 and 16 drive the driving belt wheels 5 and 5.
Conveyor belts 7 and 17 are fed through arrows 14 in the directions of arrows A and B. For this reason, the bulk material 20 supplied from the chute 30 onto the conveyor belt 7 of the lower belt conveyor 1 is
After being discharged from the downstream end outlet of the skirt 31 under the widthwise regulation by the pair of skirts 31, the horizontal portion 9
Is transported to the rising portion 10, where the rising portion 10 is sandwiched between the conveyor belt 7 and the conveyor belt 17 sent to the rising portion 18 of the upper belt conveyor 2, and is transported upward in a wrapped state, and It is thrown into the chute 32 from the part belt wheel 3 and sent to the equipment of the next process.

Here, as shown in FIGS. 3 and 6, in an initial state in which the loose objects 20 are not conveyed, the arm 28 abuts on the rest bar 45, and the arm 28 rotates toward the conveyor belt 17 side. Since the main holding roller 25 is limited and does not contact the conveyor belt 17, in this state, the position of the slide block 49 is adjusted by tightening the nut 48 to the torque adjusting bolt 44, and the rotating block 50 is rotated by a required amount. Thereby, the torsion applied to the torsion bar 27 is adjusted, and the initial value of the pressing force of the main pressing roller 25 can be set arbitrarily. When the bulk material 20 is conveyed, the desired pressing force is conveyed by the main pressing roller 25 to the conveyor. While being applied to the bulk material 20 via the belt 17, the pressing force applied to the bulk material 20 is reduced by the lower belt conveyor. The main fixed roller 21 and the auxiliary fixed roller 22 disposed at a position shifted by a required amount from the position of the main fixed roller 21 in the longitudinal direction of the conveyor belt 7 via the conveyor belt 7 of the conveyor 1, A desired frictional force is generated between the conveyor belts 7, 17 and the bulk material 20.

Further, as shown in FIG.
After adjusting the position of the bracket 52 with respect to the width of the conveyor belt 17 of the belt end roller 26 in the width direction of the conveyor belt 17, the torque adjusting bolt 54 is screwed into the desired adjusting screw hole
By fixing the flange portion 56 of the adjustment pipe 55 to the bracket 52 by screwing into the bracket 52, if the fixing angle of the adjustment pipe 55 to the bracket 52 is appropriately selected, the torsion applied to the torsion bar 53 is adjusted, and the belt end roller 26 Is adjusted to a desired value.

As a result, the pressing force of the main pressing roller 25 reliably acts on the bulk material 20 conveyed at the rising portions 10 and 18, and the pressing force of the belt end roller 26 is maintained in an appropriate state. Slip does not occur inside the bulk material 20, and the pressure due to the weight of the bulk material 20 located above is not transmitted to the bulk material 20 located below the bulk material 20, and the bulk material 20 is stably conveyed. It will be.

In this way, the pressing force of the main pressing roller 25 and the belt end roller 26 can be individually adjusted to maintain an appropriate state, and the loose material 20 can always be stably conveyed. It is also possible to reduce the size of the device and simplify the structure.

FIGS. 11 to 13 show another example of the belt end roller pressing adjustment mechanism 43, in which FIG.
10 denote the same components, and are substantially perpendicular to the surface of the upper belt conveyor 2 at the width end of the conveyor belt 17 on the bracket 52 attached to the base plate 58 so as to be position adjustable. The position adjusting bolts 61 and 62 extending in the direction are attached by nuts 63 and 64, and the position adjusting bolts 61 and 62 hold two required portions in the longitudinal direction of the shaft 29 that rotatably supports the belt end roller 26. The clamp pieces 65, 66 that can be supported as described above are mounted so that the nuts 67, 68 can be fixed at required positions in the axial direction of the position adjustment bolts 61, 62, and the clamp pieces 65, 66 for the position adjustment bolts 61, 62 can be fixed. By appropriately changing the position of the shaft 66, the inclination of the shaft 29 with respect to the conveyor belt 17 of the upper belt conveyor 2 is adjusted. Adjust the angle and pushing amount is obtained by adapted to adjust the pressing force of the belt end portions roller 26.

In the figure, reference numeral 69 denotes the clamp pieces 65, 6;
This is a stopper for restricting the movement of the shaft 29 supported by 6 in the axial direction.

In the case of the belt end roller pressing adjustment mechanism 43 shown in FIGS. 11 to 13, the position of the bracket 52 with respect to the base plate 58 is adjusted and the belt end roller 26 is adjusted.
In the state where the width direction of the conveyor belt 17 is adjusted, the clamp pieces 65 and 66 are fixed to required axial positions of the position adjustment bolts 61 and 62 by tightening the nuts 67 and 68, whereby the position adjustment bolts 61 and 62 are fixed. If the positions of the clamp pieces 65 and 66 with respect to
The tilt angle of the upper belt conveyor 2 with respect to the conveyor belt 17 and the pushing amount are adjusted, and the pressing force of the belt end roller 26 is adjusted to a desired value.

Thus, even if the belt end roller pressing adjustment mechanism 43 is constructed as shown in FIGS. 11 to 13, the pressing force between the main pressing roller 25 and the belt end roller 26 is the same as in the above-described embodiment. Can be individually adjusted and held in an appropriate state, and the loose objects 20 can always be stably transported, and the apparatus can be downsized and the structure can be simplified as compared with the related art.

The belt clamping device for a steeply inclined conveyor according to the present invention is not limited to the above-described embodiment.
It goes without saying that various changes can be made without departing from the spirit of the present invention.

[0038]

As described above, according to the belt clamping device for a steeply inclined conveyor of the present invention, the pressing force of the main pressing roller and the belt end roller can be individually adjusted to maintain the proper state. Thus, an excellent effect can be achieved in that the bulk material can always be stably transported, and the size and the structure can be simplified.

[Brief description of the drawings]

FIG. 1 is an overall side view showing an embodiment of a steeply inclined conveyor in which a belt holding device of the present invention is used.

FIG. 2 is an enlarged view of a portion II in FIG.

FIG. 3 is a view taken in the direction of arrows III-III in FIG. 2;

FIG. 4 is a view taken in the direction of arrows IV-IV in FIG. 2;

FIG. 5 is a view taken in the direction of arrows VV in FIG. 2;

FIG. 6 is a view taken in the direction of arrows VI-VI in FIG. 5;

FIG. 7 is an enlarged view of a portion VII in FIG. 5;

8 is a view taken in the direction of arrows VIII-VIII in FIG. 5, and is a view illustrating an example of a belt end roller pressing adjustment mechanism.

FIG. 9 is a view as viewed in the direction of arrows IX-IX in FIG. 8;

FIG. 10 is a view as viewed in the direction of arrows XX in FIG. 8;

FIG. 11 is a diagram illustrating another example of a belt end roller pressing adjustment mechanism.

FIG. 12 is a view taken in the direction of arrows XII-XII in FIG. 11;

FIG. 13 is a view taken in the direction of arrows XIII-XIII in FIG. 11;

FIG. 14 is a plan view of a conventional example.

FIG. 15 is a view taken in the direction of arrows XV-XV in FIG. 14;

FIG. 16 is a view taken in the direction of arrows XVI-XVI in FIG. 15;

[Explanation of symbols]

 1 Lower Belt Conveyor 2 Upper Belt Conveyor 7 Conveyor Belt 10 Rise 17 Conveyor Belt 18 Rise 20 Bulk 21 Main Fixed Roller 22 Sub-Fixed Roller 25 Main Holding Roller 26 Belt End Roller 27 Torsion Bar 28 Arm 29 Shaft 42 Main Pressing roller pressing adjustment mechanism 43 Belt end roller pressing adjustment mechanism 44 Torque adjustment bolt 45 Rest bar 53 Torsion bar 54 Torque adjustment bolt 61 Position adjustment bolt 62 Position adjustment bolt

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichi Komori 1-19-10 Mori, Koto-ku, Tokyo Ishikawa Shima Harima Heavy Industries, Ltd. Koto Office (56) References JP-A-4-354707 (JP, A (58) Field surveyed (Int.Cl. ⁷ , DB name) B65G 15/14-15/18 B65G 39/16

Claims (3)

(57) [Claims] 1. An upper belt conveyor is disposed above a lower belt conveyor so that a bulk contact surface of the conveyor belt of the lower belt conveyor and a bulk contact surface of the conveyor belt of the upper belt conveyor face each other. This is a belt holding device for steeply inclined conveyors that sandwiches and wraps and transports loose materials between both conveyor belts at the rising part of the conveyor belt, and the main fixing supporting the widthwise center of the conveyor belt of the lower belt conveyor. A roller extending from the center of the conveyor belt toward the width end side toward the upper belt conveyor to support a widthwise side of the conveyor belt of the lower belt conveyor and to form a trough angle on the conveyor belt; Sub-fixed at a position shifted by the required amount from the position of the conveyor belt in the longitudinal direction of the conveyor belt Over la and a main pressing roller for pressing the central portion in the width direction of the conveyor belt of the upper conveyor belt, the upper with respect to the arm for rotatably supporting the main pressing roller
Gives a turning power to the conveyor belt side of the belt conveyor.
Torsion bar and a screw provided to the torsion bar
To adjust the pressing force of the main holding roller.
Luk adjustment bolt and the arm to the conveyor belt side
Rotate the main presser roller when the bulk material is not being conveyed.
With a rest bar to prevent contact with
A main press roller pressing adjustment mechanism for pressing the main press roller against the conveyor belt of the upper belt conveyor; and a lower belt conveyor on both sides in the width direction of the upper belt conveyor in a state substantially parallel to the sub-fixing rollers. And a belt end roller pressing adjustment mechanism for pressing the belt end rollers against both sides in the width direction of the conveyor belt of the upper belt conveyor. 2. A torsion bar for applying a turning power to an upper belt conveyor to a conveyor belt side with respect to a shaft rotatably supporting a belt end roller, and a torsion bar applied to the torsion bar for adjusting a torsion applied to the torsion bar. the pressing force steep conveyor belt clamping device according to claim 1, wherein configuring the belt ends roller pressing adjustment mechanism and a torque adjustment bolt to adjust the. 3. A belt using a position adjusting bolt for adjusting a tilt angle and a pushing amount of an upper belt conveyor with respect to a conveyor belt of a shaft rotatably supporting a belt end roller and adjusting a pressing force of the belt end roller. belt clamping device steep conveyor according to claim 1, wherein configuring the end roller pressing adjustment mechanism.