CN115534127B

CN115534127B - Concrete mixer truck

Info

Publication number: CN115534127B
Application number: CN202211514922.5A
Authority: CN
Inventors: 徐元虎; 许莲; 荆一波; 王亚成; 高雯洁
Original assignee: Jiangsu Guangya Construction Group Co ltd
Current assignee: Jiangsu Guangya Construction Group Co ltd
Priority date: 2022-11-30
Filing date: 2022-11-30
Publication date: 2023-04-11
Anticipated expiration: 2042-11-30
Also published as: CN115534127A

Abstract

The invention relates to the technical field of mixer trucks, in particular to a concrete mixer truck which comprises a cab and a chassis, and further comprises a base, a mixing drum, a supporting mechanism, a feeding mechanism and a discharging mechanism, wherein a rotating assembly is installed in the chassis, an output shaft of the rotating assembly extends out of the chassis and is fixedly connected with the bottom of the base, the supporting mechanism comprises a fixed frame and a supporting frame, the feeding mechanism comprises a connecting seat, a feeding swing arm and a feeding cylinder, the discharging mechanism comprises a connecting support, a discharging hopper and a discharging frame, and a material blocking assembly is arranged in the discharging frame. The automatic feeding device can not move the mixer truck, can also align the material opening of the mixing drum to different positions, avoids frequent moving of the mixer truck, realizes automatic feeding through the feeding mechanism, greatly reduces the labor intensity of workers, realizes the control of the feeding speed through the material blocking assembly, and can effectively prevent concrete from falling and splashing.

Description

Concrete mixer truck

Technical Field

The invention relates to the technical field of mixer trucks, in particular to a concrete mixer truck.

Background

Mixer trucks are specialized trucks used to transport concrete for construction, and are also commonly referred to as field snails and olive carts due to their unique profile. The trucks are all provided with a round and simple mixing drum to carry mixed concrete, and the mixing drum can be kept to rotate all the time in the transportation process so as to ensure that the carried concrete cannot be solidified.

In actual use, the existing concrete mixer truck still has some defects: (1) In the process of feeding and discharging of the mixer truck, if the material port of the mixing drum is aligned to different positions, the mixer truck needs to be driven to back and move back and forth in a construction site, and the volume of the mixing drum is generally large, so that the mixer truck is inconvenient to move in the construction site; (2) In the feeding process of the existing concrete mixer truck, workers generally climb to a feeding hole through a crawling ladder to perform manual feeding, so that the labor intensity is high, and the feeding efficiency is low; (3) The blanking speed can not be controlled in the blanking process of the existing concrete mixer truck, so that the condition that the concrete splashes is caused, the splashed concrete wastes raw materials, and the concrete is difficult to clean after hardening.

Disclosure of Invention

The invention aims to provide a concrete mixer truck, and aims to solve the technical problems that the mixer truck in the prior art is inconvenient to move in a construction site, the labor intensity of manual feeding is high, and material splashing is easy to occur in the blanking process:

the purpose of the invention can be realized by the following technical scheme:

a concrete mixer truck comprises a cab and a chassis, and further comprises a base, a mixing drum, a supporting mechanism, a feeding mechanism and a discharging mechanism, wherein a rotating assembly is installed in the chassis, and an output shaft of the rotating assembly extends out of the chassis and is fixedly connected with the bottom of the base;

the supporting mechanism comprises a fixed frame and supporting frames, the fixed frame is fixedly arranged on the base, the mixing drum is rotatably arranged between the supporting frames, one end of the fixed frame is rotatably connected with the supporting frames through supporting shafts, the other end of the fixed frame is connected with a supporting cylinder through a hinge shaft, and the supporting cylinder drives the supporting frames to deflect around the supporting shafts;

the feeding mechanism comprises a connecting seat, a feeding swing arm and a feeding air cylinder, the connecting seat is fixedly arranged on two sides of the end part of the supporting frame, one end of the feeding swing arm is rotatably arranged at the bottom of the connecting seat through a rotating shaft, the other end of the feeding swing arm is fixedly connected with a feeding shovel, the feeding air cylinder is rotatably arranged at the top of the connecting seat through a rotating shaft, and the output end of the feeding air cylinder is connected with an ear seat hinge shaft on the feeding swing arm;

the discharging mechanism comprises a connecting support, a discharging hopper and a blanking frame, the discharging hopper is fixedly installed on the connecting support, the opening of the discharging hopper is opposite to the opening at the tail end of the mixing drum, the blanking frame is arranged between the connecting support and is communicated with the bottom of the discharging hopper, and a material blocking assembly is arranged in the blanking frame.

As a further scheme of the invention: the striker assembly includes the striker plate, the top of striker plate is rotated and is cup jointed on the bracing piece, the both ends of bracing piece are connected with the supporting seat, the both sides of striker plate are connected with the oscillating axle, the oscillating axle cup joints mutually with the one end of drive connecting rod, the other end and the actuating lever of drive connecting rod cup joint mutually, the both sides of blanking frame are provided with adjust cylinder, adjust cylinder's piston rod and actuating lever fixed connection, adjust cylinder drives the striker plate through the drive connecting rod and rotates round the bracing piece.

As a further scheme of the invention: limiting plates are installed on two sides of the blanking frame, limiting grooves are formed in the limiting plates along the swinging direction of the swinging shaft, the swinging shaft penetrates through the limiting grooves in a matched mode and extends out of the limiting plates, and the swinging shaft is connected with the limiting grooves through extrusion springs.

As a further scheme of the invention: the width of striker plate is unanimous with the inside blanking passageway width of blanking frame, the bottom of striker plate is passed through the inclined plane and is laminated mutually with the surface of blanking passageway.

As a further scheme of the invention: the both ends of support frame are connected with front beam and rear frame member respectively, fixed mounting has the drive assembly on the front beam, the output of drive assembly is connected with the churn front end and rotates in order to drive the churn, install a pair of stabilizer pulley on the rear frame member, be connected with stable circle on the outer wall of churn, stable circle erect between the stabilizer pulley and with stabilizer pulley roll cooperation.

As a further scheme of the invention: the feed mechanism still includes the feeder hopper, the feeder hopper be located the top of discharge hopper and with linking bridge fixed connection, the feed inlet of feeder hopper is relative with the opening of churn tail end.

As a further scheme of the invention: the utility model discloses a feed hopper, including connecting bracket, feed hopper, rear frame member, linking bridge and back beam fixed connection, the linking bridge is located between two feeding swing arms, and when the extreme position of feeding swing arm swing to top, the feeder hopper is located the feeding shovel under.

As a further scheme of the invention: the feeding shovel bottom is equipped with the feeding opening, rotate through the pivot in the feeding opening and install a pair of electric valve plate.

The invention has the beneficial effects that:

(1) According to the invention, through the chassis, the base and the rotating assembly, the stirring cylinder above the base can realize 360-degree rotation, so that a material port of the stirring cylinder can be aligned to different positions without moving the stirring vehicle, the frequent moving of the stirring vehicle in a construction site is avoided, and the feeding and discharging processes of the concrete stirring vehicle are facilitated;

(2) When the automatic feeding device is used for feeding, the feeding air cylinder drives the feeding swing arm to deflect, so that the feeding shovel is aligned to a concrete material, the feeding process is realized by matching with the back-and-forth movement of the chassis, then the feeding swing arm is driven to deflect reversely along the original path, so that the feeding shovel swings to the position above the feeding hopper, the concrete material enters the mixing drum from the feeding hopper, the automatic feeding is realized, the manual labor intensity is greatly reduced, and the feeding efficiency is improved;

(3) The striker plate is attached to the surface of the blanking frame under the action of the extrusion spring, so that the residual concrete in the blanking frame can be blocked, the condition that the concrete drops in the moving process of the mixer truck is prevented, in the unloading process, the transmission connecting rod is driven by the adjusting cylinder, so that the striker plate is driven to deflect, a discharge opening is formed between the striker plate and the surface of the blanking frame, the striker plate can block poured materials to avoid concrete splashing, the opening size of the discharge opening can be controlled by controlling the deflection amplitude of the striker plate, the unloading speed control is realized, and the condition that the concrete splashing is further prevented.

Drawings

The invention will be further described with reference to the accompanying drawings.

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic structural view of a supporting mechanism, a feeding mechanism and a discharging mechanism in the present invention;

FIG. 3 is an exploded view of the structure of the present invention;

fig. 4 is a schematic structural view of a material blocking assembly in the invention;

fig. 5 is a schematic movement diagram of the striker assembly of the present invention;

FIG. 6 is a schematic view of the movement of the feeding mechanism in the present invention;

fig. 7 is a schematic view of the structure of the feeding shovel of the present invention.

In the figure: 1. a cab; 2. a chassis; 3. a base; 4. a mixing drum; 41. a stabilizing ring; 5. a support mechanism; 51. a fixed mount; 511. a support shaft; 512. a support cylinder; 52. a support frame; 521. a front cross member; 522. a rear cross member; 523. a drive assembly; 524. stabilizing the pulley; 6. a feeding mechanism; 61. a connecting seat; 62. a feeding swing arm; 621. an ear mount; 63. a feed cylinder; 64. feeding shovels; 641. a feed port; 642. an electrically powered valve plate; 65. a feed hopper; 7. a discharge mechanism; 71. connecting a bracket; 72. a discharge hopper; 73. a blanking frame; 74. the material blocking component; 741. a striker plate; 742. a support bar; 743. a supporting seat; 744. a swing shaft; 745. a transmission connecting rod; 746. a drive rod; 747. an adjusting cylinder; 748. a limiting plate; 7481. a limiting groove; 749. a compression spring; 8. and a rotating assembly.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, the present invention is a concrete mixer truck, including a cab 1 and a chassis 2, further including a base 3, a mixing drum 4, a supporting mechanism 5, a feeding mechanism 6 and a discharging mechanism 7, wherein a rotating assembly 8 is installed in the chassis 2, and an output shaft of the rotating assembly 8 extends from the chassis 2 and is fixedly connected with the bottom of the base 3.

Wherein, the rotating assembly 8 adopts built-in hidden design, installs inside chassis 2, has effectively saved the installation space of chassis 2 top, and the power supply in the rotating assembly 8 can adopt rotating electrical machines or revolving cylinder.

As shown in fig. 2, the supporting mechanism 5 includes a fixed frame 51 and a supporting frame 52, the fixed frame 51 is fixedly mounted on the base 3, the mixing drum 4 is rotatably mounted between the supporting frames 52, one end of the fixed frame 51 is rotatably connected with the supporting frame 52 through a supporting shaft 511, the other end of the fixed frame 51 is connected with a supporting cylinder 512 through a hinge shaft, the supporting cylinder 512 drives the supporting frame 52 to deflect around the supporting shaft 511, when the supporting frame 52 deflects by a certain angle, the mixing drum 4 erected on the supporting frame 52 can also swing by the same angle until reaching a proper discharging angle, that is, the discharging process of the mixer truck is realized by the supporting cylinder 512 driving the supporting frame 52 to deflect.

Specifically, two ends of the supporting frame 52 are respectively connected with a front beam 521 and a rear beam 522, a driving assembly 523 is fixedly mounted on the front beam 521, an output end of the driving assembly 523 is connected with a front end of the mixing drum 4 to drive the mixing drum 4 to rotate, a pair of stabilizing pulleys 524 is mounted on the rear beam 522, a stabilizing ring 41 is connected to an outer wall of the mixing drum 4, and the stabilizing ring 41 is erected between the stabilizing pulleys 524 and is matched with the stabilizing pulleys 524 in a rolling manner.

The power source of the driving assembly 523 can adopt a rotating motor or a rotating cylinder, which is used for keeping the mixing drum 4 rotating in the transportation process, and the stabilizing ring 41 and the stabilizing pulley 524 are adapted to slide, so that the stability of the mixing drum 4 in the rotating process can be effectively improved.

As shown in fig. 3, the feeding mechanism 6 includes a connecting seat 61, a feeding swing arm 62 and a feeding cylinder 63, the connecting seat 61 is fixedly installed on both sides of the end of the supporting frame 52, one end of the feeding swing arm 62 is installed on the bottom of the connecting seat 61 through the rotation of a rotating shaft, the other end of the feeding swing arm 62 is fixedly connected with a feeding shovel 64, the feeding cylinder 63 is installed on the top of the connecting seat 61 through the rotation of a rotating shaft, and the output end of the feeding cylinder 63 is connected with an ear seat 621 hinged on the feeding swing arm 62.

Specifically, feed mechanism 6 still includes feeder hopper 65, and feeder hopper 65 is located discharge hopper 72 top and with linking bridge 71 fixed connection, and the feed inlet of feeder hopper 65 is relative with the opening of churn 4 tail end.

More specifically, the connecting bracket 71 is fixedly connected to the rear cross member 522, the connecting bracket 71 is located between the two feeding swing arms 62, and when the feeding swing arms 62 swing to the upper limit position, the feeding hopper 65 is located right below the feeding shovel 64.

As shown in fig. 6, when the feeding cylinder 63 extends outward, the feeding swing arm 62 is driven to swing around the shaft until the feeding shovel 64 at the front end of the feeding swing arm 62 rotates to a proper feeding angle; when the feeding cylinder 63 is retracted inwards, the feeding swing arm 62 is driven to deflect reversely around the shaft, when the feeding swing arm 62 swings to the upper limit position, the feeding hopper 65 is located under the feeding shovel 64, and at the moment, materials in the feeding shovel 64 can be fed into the stirring cylinder 4 through the feeding hopper 65, so that the feeding process is realized. In this process, the feed swing arm 62 is deflected over an angle in the range of 0 to 150 °.

As shown in fig. 7, a feeding port 641 is disposed at the bottom of the feeding shovel 64, a pair of electric valve plates 642 is rotatably mounted in the feeding port 641 through a rotating shaft, the electric valve plates 642 are electrically connected to a PLC controller in the cab 1, and the electric valve plates 642 are controlled to open and close by controlling corresponding switches, so as to be closed during charging to avoid material leakage and opened during feeding to dump the material.

As shown in fig. 3, the discharging mechanism 7 includes a connecting bracket 71, a discharging hopper 72 and a blanking frame 73, the discharging hopper 72 is fixedly mounted on the connecting bracket 71, an opening of the discharging hopper 72 is opposite to the through opening at the tail end of the mixing drum 4, the blanking frame 73 is disposed between the connecting brackets 71 and is communicated with the bottom of the discharging hopper 72, and a material blocking assembly 74 is disposed in the blanking frame 73. In-process of unloading, churn 4 deflects to certain angle along with support frame 52, and in the material in the churn 4 pours into discharge hopper 72 from the tail end opening into, gets into blanking frame 73 by discharge hopper 72 again, discharge hopper 72 can realize the buffering effect to a large amount of materials of empting, avoids a large amount of materials direct impact blanking frame 73.

As shown in fig. 4, the material blocking assembly 74 includes a material blocking plate 741, the top of the material blocking plate 741 is rotatably sleeved on the support rod 742, two ends of the support rod 742 are connected to the support base 743, swing shafts 744 are connected to two sides of the material blocking plate 741, the swing shafts 744 are sleeved to one end of a transmission link 745, the other end of the transmission link 745 is sleeved to a driving rod 746, adjustment cylinders 747 are disposed on two sides of the material blocking frame 73, a piston rod of the adjustment cylinder 747 is fixedly connected to the driving rod 746, and the adjustment cylinders 747 drive the material blocking plate 741 to rotate around the support rod 742 through the transmission link 745.

In the normal transportation process of the mixer truck, the material baffle 741 is blocked in the blanking frame 73, so that the concrete remained in the blanking frame 73 can be blocked and cannot fall off, and the concrete is prevented from polluting the ground in the transportation process; and in the process of unloading, as shown in fig. 5, the adjusting cylinder 747 extends, drives the driving rod 746 to move, transmits the acting force to the swinging shaft 744 through the transmission connecting rod 745, thereby making the striker plate 741 rotate around the supporting rod 742, and form the discharge opening with the surface of the blanking frame 73, at this moment, the striker plate 741 can still block part of the material, avoid the material to pour down too fast and splash everywhere, can control the opening size of the discharge opening through controlling the deflection amplitude of the striker plate 741 simultaneously, and then realize the control of the blanking speed: the larger the deflection angle is, the larger the opening of the discharge opening is, and the faster the blanking speed is; the smaller the deflection angle is, the smaller the opening of the discharge opening is, and the slower the blanking speed is.

In the practical application process, the opening size of discharge opening is not only being controlled to the amplitude of deflection of striker plate 741, can also influence the direction of dumping of material and the scope of unloading, when unloading volume is bigger, the material can paste all the time when the discharge opening and lean on striker plate 741, when striker plate 741 takes place to deflect, can make the material that pastes on striker plate 741 pour along the direction after striker plate 741 deflects, can adjust the region of unloading and the direction of unloading according to the range of deflection of actual place position through striker plate 741 promptly.

Specifically, limiting plates 748 are mounted on two sides of the blanking frame 73, a limiting groove 7481 is formed in each limiting plate 748 along the swinging direction of the swinging shaft 744, the swinging shaft 744 is matched with and penetrates through the limiting groove 7481 and extends out of the limiting plate 748, and the swinging shaft 744 is connected with the limiting groove 7481 through an extrusion spring 749.

The limiting groove 7481 is used for limiting and guiding the swinging process of the swinging shaft 744, so as to ensure the stability of the striker plate 741 during deflection; the function of the pressing spring 749 is to apply an acting force to the swinging shaft 744, so that the striker plate 741 can tightly cling to the surface of the blanking frame 73 during normal transportation, and the striker plate 741 is prevented from rotating unnecessarily.

More specifically, the width of the striker 741 is consistent with the width of a blanking channel inside the blanking frame 73, so that a shielding area of the striker 741 can cover the blanking channel inside the blanking frame 73, the bottom of the striker 741 is attached to the surface of the blanking channel through an inclined plane, and the attaching tightness between the striker 741 and the surface of the blanking frame 73 is increased.

The working principle of the invention is as follows:

when feeding, the feeding cylinder 63 drives the feeding swing arm 62 to rotate around the shaft, so that the feeding shovel 64 at the front end of the feeding swing arm 62 rotates to a proper feeding angle, the feeding shovel is matched with the back and forth movement of the chassis 2 to shovel concrete materials into the feeding shovel 64, the electric valve plate 642 is closed at the moment to avoid material leakage, then the feeding cylinder 63 drives the feeding swing arm 62 to rotate around the shaft in the reverse direction until the feeding swing arm 62 swings to an upper limit position, the feeding hopper 65 is positioned right below the feeding shovel 64 at the moment, the electric valve plate 642 is opened through the control switch, and the materials in the feeding shovel 64 enter the stirring cylinder 4 through the feeding hopper 65 to complete the automatic feeding process;

in the normal transportation process, the rotating assembly 8 drives the stirring cylinder 4 to keep rotating, the striker plate 741 is attached to the surface of the blanking frame 73 under the action of the extrusion spring 749, and the residual concrete in the blanking frame 73 is placed to fall onto the road surface;

during the unloading, rotatory assembly 8 drives the churn 4 realization rotation of base 3 and top, until rotating to suitable unloading position, support cylinder 512 drive support frame 52 and churn 4 take place to deflect, until deflecting to suitable unloading angle, the concrete material in churn 4 drops to blanking frame 73 in through discharge hopper 72, adjust cylinder 747 starts this moment, drive actuating lever 746 removes, transmit effort to oscillating axle 744 through drive link 745, thereby make striker plate 741 rotatory around bracing piece 742, and form the discharge opening with the surface of blanking frame 73, striker plate 741 not only can block the material that pours out in order to avoid the concrete splash, can control the opening size of discharge opening through the range of deflecting of control striker plate 741 simultaneously, the concrete material pours out from the discharge opening, accomplish the unloading process.

While one embodiment of the present invention has been described in detail, the description is only a preferred embodiment of the present invention and should not be taken as limiting the scope of the invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.

Claims

1. A concrete mixer truck comprises a cab (1) and a chassis (2), and is characterized by further comprising a base (3), a mixing drum (4), a supporting mechanism (5), a feeding mechanism (6) and a discharging mechanism (7), wherein a rotating assembly (8) is installed in the chassis (2), and an output shaft of the rotating assembly (8) extends out of the chassis (2) and is fixedly connected with the bottom of the base (3);

the supporting mechanism (5) comprises a fixed frame (51) and a supporting frame (52), the fixed frame (51) is fixedly installed on the base (3), the mixing drum (4) is rotatably installed between the supporting frames (52), one end of the fixed frame (51) is rotatably connected with the supporting frame (52) through a supporting shaft (511), the other end of the fixed frame (51) is connected with a supporting cylinder (512) through a hinge shaft, and the supporting cylinder (512) drives the supporting frame (52) to deflect around the supporting shaft (511);

the feeding mechanism (6) comprises a connecting seat (61), a feeding swing arm (62) and a feeding cylinder (63), the connecting seat (61) is fixedly arranged on two sides of the end part of the supporting frame (52), one end of the feeding swing arm (62) is rotatably arranged at the bottom of the connecting seat (61) through a rotating shaft, the other end of the feeding swing arm (62) is fixedly connected with a feeding shovel (64), the feeding cylinder (63) is rotatably arranged at the top of the connecting seat (61) through a rotating shaft, and the output end of the feeding cylinder (63) is in hinge connection with an ear seat (621) on the feeding swing arm (62);

the discharging mechanism (7) comprises a connecting support (71), a discharging hopper (72) and a blanking frame (73), the discharging hopper (72) is fixedly installed on the connecting support (71), an opening of the discharging hopper (72) is opposite to a through hole at the tail end of the mixing drum (4), the blanking frame (73) is arranged between the connecting support (71) and is communicated with the bottom of the discharging hopper (72), and a material blocking assembly (74) is arranged in the blanking frame (73);

the material blocking assembly (74) comprises a material blocking plate (741), the top of the material blocking plate (741) is rotatably sleeved on a supporting rod (742), two ends of the supporting rod (742) are connected with a supporting seat (743), two sides of the material blocking plate (741) are connected with swinging shafts (744), the swinging shafts (744) are sleeved with one end of a transmission connecting rod (745), the other end of the transmission connecting rod (745) is sleeved with a driving rod (746), two sides of the material dropping frame (73) are provided with adjusting cylinders (747), a piston rod of each adjusting cylinder (747) is fixedly connected with the driving rod (746), and the adjusting cylinders (747) drive the material blocking plate (741) to rotate around the supporting rod (742) through the transmission connecting rod (745);

limiting plates (748) are mounted on two sides of the blanking frame (73), limiting grooves (7481) are formed in the limiting plates (748) along the swinging direction of the swinging shafts (744), the swinging shafts (744) penetrate through the limiting grooves (7481) in a matched mode and extend out of the limiting plates (748), and the swinging shafts (744) are connected with the limiting grooves (7481) through extrusion springs (749);

the width of the material baffle (741) is consistent with the width of a blanking channel in the blanking frame (73), and the bottom of the material baffle (741) is attached to the surface of the blanking channel through an inclined plane.

2. The concrete mixer truck according to claim 1, wherein a front cross beam (521) and a rear cross beam (522) are respectively connected to two ends of the support frame (52), a driving assembly (523) is fixedly mounted on the front cross beam (521), an output end of the driving assembly (523) is connected with a front end of the mixing drum (4) to drive the mixing drum (4) to rotate, a pair of stabilizing pulleys (524) is mounted on the rear cross beam (522), a stabilizing ring (41) is connected to an outer wall of the mixing drum (4), and the stabilizing ring (41) is erected between the stabilizing pulleys (524) and is in rolling fit with the stabilizing pulleys (524).

3. A concrete mixer truck according to claim 2, characterized in that said feed mechanism (6) further comprises a feed hopper (65), said feed hopper (65) being located above said discharge hopper (72) and being fixedly connected to said connecting bracket (71), said feed hopper (65) having its inlet opening opposite the opening at the end of the mixing drum (4).

4. A concrete mixer truck according to claim 3, characterized in that the connecting bracket (71) is fixedly connected to the rear cross member (522), the connecting bracket (71) being located between the two feeding arms (62), the feeding hopper (65) being located directly below the feeding shovel (64) when the feeding arms (62) are swung to the upper extreme position.

5. The concrete mixer truck according to claim 1, wherein the bottom of the feeding shovel (64) is provided with a feeding port (641), and a pair of electric valve plates (642) are rotatably mounted in the feeding port (641) through a rotating shaft.