CN112619285A

CN112619285A - River sewage inclined tube precipitator for environmental improvement and treatment

Info

Publication number: CN112619285A
Application number: CN202110242969.XA
Authority: CN
Inventors: 东庆德
Original assignee: Shandong Lanchi Environment Technology Co ltd
Current assignee: Shandong Lanchi Environment Technology Co ltd
Priority date: 2021-03-05
Filing date: 2021-03-05
Publication date: 2021-04-09
Anticipated expiration: 2041-03-05
Also published as: CN112619285B

Abstract

The invention discloses a river sewage inclined tube precipitator for environment improvement and treatment, and belongs to the technical field of sewage treatment equipment. The river sewage inclined tube precipitator for environment improvement and treatment comprises a fixed box body, supporting legs and a water collecting box, wherein the supporting legs are fixedly connected to four corners of the bottom surface of the fixed box body; the water collecting tank is fixedly connected to the upper end of the fixed tank body, the top surface of the water collecting tank is rotatably connected with a sealing cover plate through a connecting hinge, and the side wall of the water collecting tank is fixedly connected with a river sewage injection pipe; the invention effectively solves the problems that the honeycomb inclined pipe is easy to block, time and labor are wasted in manual cleaning and maintenance, bottom sludge is easy to silt, and sludge discharge cannot be normally carried out in the existing design and use process.

Description

River sewage inclined tube precipitator for environmental improvement and treatment

Technical Field

The invention relates to the technical field of sewage treatment equipment, in particular to a river sewage inclined tube precipitator for environment improvement and treatment.

Background

The inclined tube precipitator is a precipitation tank provided with inclined tubes in a precipitation zone, the assembly form of the inclined tubes and a branch tube is two, the inclined tubes or parallel pipelines (sometimes honeycomb fillers can be used) are utilized to be divided into a series of shallow precipitation layers in the precipitation zone of a horizontal flow type or vertical flow type precipitation tank, the treated and settled sludge moves and is separated in each precipitation shallow layer, and the inclined tube precipitator is often applied to purification treatment work of river sewage.

In the existing common riverway sewage inclined tube precipitator on the market, in the use process, the honeycomb filling inclined tube in the inner part is easy to be blocked by sludge, and the normal work of the device body is influenced due to the fact that the honeycomb filling inclined tube needs to be cleaned and maintained manually and is troublesome and laborious; in addition, current design is in the use, and the mud production siltation of device bottom leads to the device can't carry out normal row mud work, in order to solve above-mentioned problem, we have proposed an environment improves treatment and uses river course sewage pipe chute settler.

Disclosure of Invention

The invention aims to solve the problems that in the use process of the existing design, a honeycomb inclined pipe is easy to block, manual cleaning and maintenance are time-consuming and labor-consuming, bottom sludge is easy to silt, and the sludge discharge work cannot be normally carried out.

In order to achieve the purpose, the invention adopts the following technical scheme:

the river sewage inclined tube precipitator for environment improvement and treatment comprises a fixed box body, supporting legs and a water collecting box, wherein the supporting legs are fixedly connected to four corners of the bottom surface of the fixed box body; the utility model discloses a water collecting tank, including water collecting tank, connecting hinge, water collecting tank.

Preferably, the water discharge control mechanism comprises a mounting base plate, the mounting base plate is arranged as the bottom surface of the water collecting tank, a mounting opening is formed in the mounting base plate, a first servo motor is fixedly connected to the side wall of the water collecting tank, and a linkage shaft is fixedly connected to an output shaft of the first servo motor.

Preferably, a worm is fixedly connected to the linkage shaft, the worm is meshed with a worm wheel, the worm wheel is rotatably connected to the mounting base plate, connecting shafts are fixedly connected to the two sides of the worm wheel in front of the worm wheel, a water plugging plate is fixedly connected to the connecting shafts and matched with the mounting opening, and the water plugging plate is rotatably mounted on the mounting base plate through the connecting shafts and the worm wheel.

Preferably, booster mechanism is including the booster pump, booster pump fixed mounting is subaerial, fixedly connected with booster pipe on the booster pump, booster pipe keeps away from booster pump one end fixed connection on the intercommunication return bend, the terminal of intercommunication return bend and the top surface fixed connection of header tank, still fixed mounting has the pressure monitoring table on the intercommunication return bend.

Preferably, the mud discharging device comprises a mud discharging hopper, the mud discharging hopper is fixedly connected to the bottom end of the fixed box body, a mud discharging pipe is fixedly connected to the bottom end of the mud discharging hopper, an active mud discharging mechanism is installed at the bottom end of the mud discharging pipe, and a mud discharging opening is formed in the bottom end of the side wall of the mud discharging pipe.

Preferably, the initiative mud discharging mechanism comprises a mounting frame and a second servo motor, the mounting frame is fixedly connected to the supporting legs, the second servo motor is fixedly mounted on the mounting frame, a first mud discharging auger is fixedly connected to an output shaft of the second servo motor, a second mud discharging auger and a third mud discharging auger are respectively arranged on two sides of the first mud discharging auger, the second mud discharging auger and the third mud discharging auger are all rotatably mounted inside the mud discharging tube, the bottom ends of the second mud discharging auger and the third mud discharging auger are rotatably connected to the mounting frame, a first belt pulley is fixedly connected to the lower end of the first mud discharging auger, a first belt pulley, a second belt pulley and a third belt pulley are respectively fixedly connected to the lower ends of the first mud discharging auger, the second mud discharging auger and the third mud discharging auger, a first linkage belt is connected between the first belt pulley and the second belt pulley, and a second linkage belt is connected between the first belt pulley and the third belt pulley in a surrounding manner.

Preferably, the mud discharging device is still including fixed crossbearer and connecting block, fixed crossbearer fixed connection is on the lateral wall of mud pipe, connecting block fixed connection is on the lateral wall of the mud pipe at second servo motor both ends, it is connected with the dwang to rotate on the connecting block, the top fixedly connected with eccentric cam of dwang, the bottom fixedly connected with fourth pulley and the fifth pulley of dwang, it is connected with the third driving belt to encircle between fourth pulley and the first pulley, it is connected with the fourth linkage belt to encircle between fifth pulley and the third pulley.

Compared with the prior art, the invention provides the river sewage inclined tube precipitator for the environmental improvement and treatment, which has the following beneficial effects:

(1) according to the invention, the water collecting tank is arranged at the top end of the device body, when the device is used, river sewage is injected into the water collecting tank from the sewage injection pipe on the side wall of the water collecting tank, the filtering frame is fixedly connected in the water collecting tank close to the sewage injection pipe, garbage, sundries and the like with large volume in the river sewage can be filtered by using the filtering frame, and meanwhile, the sealing cover plate is movably connected on the top surface of the water collecting tank through the connecting hinge, so that a user can conveniently clean the garbage, the sundries and the like filtered out in the filtering frame; meanwhile, a water discharge control mechanism is also installed in the water collecting tank, when the water collecting tank is used, when sewage in the water collecting tank is accumulated to a certain water level, the water discharge control mechanism is started, the first servo motor works to drive the linkage shaft to rotate, the worm is fixedly connected to the linkage shaft and meshed with the worm wheel, so that the worm wheel can be driven to rotate, the worm wheel is fixedly connected to the connecting shaft, and the connecting shaft is fixedly connected to the connecting shaft; in addition, the water discharge control mechanism can be matched with a supercharging mechanism, if the speed of sewage entering the lower fixed box body from the water collecting tank is increased, the pressure in the water collecting tank can be increased through the supercharging mechanism, the sewage injection speed is increased, meanwhile, if the lower honeycomb inclined pipe is blocked, the water blocking plate can be properly opened, then the pressure in the water collecting tank is increased through the supercharging mechanism, so that the water flow quickly washes the lower honeycomb inclined pipe, and the problem of blockage of the honeycomb inclined pipe can be solved.

(2) In addition, the side walls of the sludge discharge pipes at two sides are rotatably connected with rotating rods through connecting blocks, and the bottom ends of the rotating rods are rotatably connected with a fourth belt disc through the fourth belt disc, The fifth belt pulley, the linkage with first belt pulley and third belt pulley is accomplished to third linkage belt and fourth linkage belt, and the shaft diameter of fourth belt pulley and fifth belt pulley will be less than first belt pulley and third belt pulley, thereby first belt pulley and third belt pulley can drive fourth belt pulley and fifth belt pulley rotatory with very fast when rotating, top fixedly connected with eccentric cam at the dwang, thereby can make the dwang produce the vibration of very fast frequency when the fast turn, effect through fixed crossbearer, can make three mud pipe all synchronous production vibration, the work of cooperation initiative mud discharging mechanism, help the discharge of silt more, the siltation easily takes place for current design bottom mud has effectively been solved, the problem of the mud work is arranged to unable normal clear.

Drawings

FIG. 1 is a schematic structural view of an inclined tube settler for river sewage for environmental improvement and treatment according to the present invention;

FIG. 2 is a schematic diagram of an explosion structure of the river sewage inclined-tube precipitator for environmental improvement treatment according to the present invention;

FIG. 3 is a schematic structural view of a water discharge control mechanism of the river sewage inclined-tube settler for environmental improvement and treatment according to the present invention;

FIG. 4 is an enlarged schematic structural view of part A in FIG. 3 of the river sewage inclined-tube settler for environmental improvement treatment according to the present invention;

FIG. 5 is a schematic diagram of an explosion structure of a pressurizing mechanism of the river sewage inclined-tube precipitator for environmental improvement treatment according to the present invention;

FIG. 6 is a schematic structural view of a sludge discharge device of the river sewage inclined-tube settler for environmental improvement and treatment according to the present invention;

fig. 7 is a schematic structural diagram of an auxiliary sludge discharge mechanism of the river sewage inclined tube precipitator for environmental improvement and treatment provided by the invention.

Description of the figure numbers:

1. fixing the box body; 2. supporting legs; 3. a drain pipe; 4. a water collection tank; 5. sealing the cover plate; 6. a sewage injection pipe; 7. a water discharge control mechanism; 701. mounting a bottom plate; 702. an installation opening; 703. a first servo motor; 704. a linkage shaft; 705. a worm; 706. a worm gear; 707. a connecting shaft; 708. a water plugging plate; 8. a pressurization mechanism; 801. a booster pump; 802. a pressure increasing pipe; 803. a communication elbow; 804. a pressure monitoring meter; 9. a sludge discharge device; 901. a mud discharging hopper; 902. a sludge discharge pipe; 903. a sludge discharge port; 904. a mounting frame; 905. a second servo motor; 906. a first sludge discharge auger; 907. a first linkage belt; 908. a second linkage belt; 909. a second sludge discharge auger; 910. a third mud discharging auger; 911. fixing the transverse frame; 912. connecting blocks; 913. rotating the rod; 914. an eccentric cam; 915. a fourth belt pulley; 916. a fifth belt pulley; 917. a third drive belt; 918. a fourth linkage belt; 10. a honeycomb inclined pipe; 11. and (5) filtering the frame.

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.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

Example 1:

referring to fig. 1-5, the river sewage inclined tube precipitator for environmental improvement and treatment comprises a fixed box body 1, supporting legs 2 and a water collecting tank 4, wherein the supporting legs 2 are fixedly connected to four corners of the bottom surface of the fixed box body 1, the upper end inside the fixed box body 1 is a precipitation treatment cavity, the lower end inside the fixed box body 1 is a sludge accumulation cavity, a honeycomb inclined tube 10 is fixedly installed inside the precipitation treatment cavity, and a drain pipe 3 is fixedly connected to the side wall of the fixed box body 1; water collection tank 4 fixed connection is in the upper end of fixed box 1, it is connected with sealed apron 5 to rotate through connecting the hinge on water collection tank 4's the top surface, fixedly connected with river course sewage injection pipe 6 on water collection tank 4's the lateral wall, be close to sewage injection pipe 6 fixedly connected with filter frame 11 on water collection tank 4's the inner wall, water control mechanism 7 that drains is still installed to water collection tank 4's inside, be connected with booster mechanism 8 on water collection tank 4's the top surface, fixed box 1's lower extreme still is connected with row mud device 9.

The water discharge control mechanism 7 comprises an installation bottom plate 701, the installation bottom plate 701 is arranged as the bottom surface of the water collecting tank 4, an installation opening 702 is arranged on the installation bottom plate 701, a first servo motor 703 is fixedly connected to the side wall of the water collecting tank 4, and a linkage shaft 704 is fixedly connected to an output shaft of the first servo motor 703.

The linkage shaft 704 is also fixedly connected with a worm 705, the worm 705 is meshed with a worm wheel 706, the worm wheel 706 is rotatably connected to the mounting base plate 701, the worm wheels 706 on the two sides are fixedly connected with a connecting shaft 707 in front, the connecting shaft 707 is also fixedly connected with a water blocking plate 708, the water blocking plate 708 is matched with the mounting opening 702, and the water blocking plate 708 is rotatably mounted on the mounting base plate 701 through the connecting shaft 707 and the worm wheel 706.

The supercharging mechanism 8 comprises a supercharging pump 801, the supercharging pump 801 is fixedly installed on the ground, a supercharging pipe 802 is fixedly connected to the supercharging pump 801, one end, far away from the supercharging pump 801, of the supercharging pipe 802 is fixedly connected to a communication elbow 803, the tail end of the communication elbow 803 is fixedly connected with the top surface of the water collecting tank 4, and a pressure monitoring meter 804 is further fixedly installed on the communication elbow 803.

According to the invention, the water collecting tank 4 is arranged at the top end of the device body, when the device is used, river sewage is injected into the water collecting tank 4 from the sewage injection pipe 6 on the side wall of the water collecting tank 4, the filtering frame 11 is fixedly connected in the water collecting tank 4 close to the sewage injection pipe 6, large-volume garbage, sundries and the like in the river sewage can be filtered by using the filtering frame 11, meanwhile, the sealing cover plate 5 is movably connected on the top surface of the water collecting tank 4 through the connecting hinge, and by using the design, a user can conveniently clean the garbage, sundries and the like filtered out from the inside of the filtering frame 11; meanwhile, a water discharge control mechanism 7 is also arranged in the water collecting tank 4, when the water collecting tank is used and sewage in the water collecting tank 4 is accumulated to a certain water level, the water discharge control mechanism 7 is started, the first servo motor 703 works to drive the linkage shaft 704 to rotate, a worm 705 is fixedly connected to the linkage shaft 704, the worm 705 is meshed with a worm wheel 706, thereby driving the worm wheel 706 to rotate, the worm wheel 706 is fixedly connected with a connecting shaft 707, the connecting shaft 707 is fixedly connected with a water plugging plate 708, so that the worm wheel 706 can drive the water blocking plate 708 to turn over and open when rotating, after the water blocking plate 708 is opened, the water in the water collection tank 4 can fall more evenly through the plurality of mounting openings 702 onto the honeycomb chute 10 below, which, compared to prior designs, the water injection method can ensure that the honeycomb inclined tube 10 below can better play a role in precipitation and separation, the water purifying effect is better, and the probability of blockage of the honeycomb inclined tube 10 is reduced; besides, the water discharge control mechanism 7 of the invention can be matched with the booster mechanism 8, if the speed of the sewage entering the lower fixed box body 1 from the water collecting tank 4 is to be increased, the pressure in the water collecting tank 4 can be increased through the booster mechanism 8, the sewage injection speed is increased, meanwhile, if the lower honeycomb inclined pipe 10 is blocked, the water blocking plate 708 can be properly opened, then the pressure in the water collecting tank 4 is increased through the booster mechanism 8, so that the water flow rapidly washes the lower honeycomb inclined pipe 10, and the problem of blockage of the honeycomb inclined pipe 10 can be solved.

Example 2:

referring to fig. 6, the embodiment 1 is different from the above embodiments;

the sludge discharging device 9 comprises a sludge discharging hopper 901, the sludge discharging hopper 901 is fixedly connected to the bottom end of the fixed box body 1, a sludge discharging pipe 902 is fixedly connected to the bottom end of the sludge discharging hopper 901, an active sludge discharging mechanism is installed at the bottom end of the sludge discharging pipe 902, and a sludge discharging port 903 is formed in the bottom end of the side wall of the sludge discharging pipe 902.

The driving mud discharging mechanism comprises a mounting frame 904 and a second servo motor 905, the mounting frame 904 is fixedly connected to the supporting foot 2, the second servo motor 905 is fixedly installed on the mounting frame 904, an output shaft of the second servo motor 905 is fixedly connected with a first mud discharging auger 906, two sides of the first mud discharging auger 906 are respectively provided with a second mud discharging auger 909 and a third mud discharging auger 910, the first mud discharging auger 906, the second mud discharging auger 909 and the third mud discharging auger 910 are rotatably installed in the mud discharging pipe 902, the bottom ends of the second mud discharging auger 909 and the third mud discharging auger 910 are rotatably connected to the mounting frame 904, the lower end of the first mud discharging auger 906 is fixedly connected with a first belt pulley, the lower ends of the first mud discharging auger 906, the second mud discharging auger 909 and the third mud discharging auger 910 are respectively fixedly connected with a first belt pulley, a second belt pulley and a third belt pulley, a first linkage belt 907 is encircled between the first belt pulley and the second belt pulley, a second coupling pulley 908 is connected between the first pulley and the third pulley.

The sludge discharging device 9 is arranged below the fixed box body 1, when the device is used, the sludge discharging hopper 901 is fixedly connected at the bottom end of the fixed box body 1 to collect sludge at the bottom of the fixed box body 1 downwards, after the sewage in the device body is purified by standing, precipitating and separating, the layered clean water is discharged through the water discharging pipe 3 on the side wall of the fixed box body 1, then the second servo motor 905 at the bottom end is started, the second servo motor 905 drives the first sludge discharging auger 906 to rotate, meanwhile, the first sludge discharging auger 906 drives the second sludge discharging auger 909 and the third sludge discharging auger 910 at two sides to rotate through the first linkage belt 907 and the second linkage belt 908, so that the device can play a role of active sludge discharging, can effectively avoid sludge deposition at the bottom of the device body and can not be discharged, in addition, the device is also rotatably connected with the rotating rod 913 through the connecting blocks 912 on the side walls of the sludge discharging pipes 902 at two sides, the bottom end of the rotating rod 913 is linked with the first belt pulley and the third belt pulley through a fourth belt pulley 915, a fifth belt pulley 916, a third linkage belt 917 and a fourth linkage belt 918, and the fourth pulley 915 and the fifth pulley 916 have a smaller axial diameter than the first pulley and the third pulley, so that the first belt pulley and the third belt pulley can rotate to drive the fourth belt pulley 915 and the fifth belt pulley 916 to rotate at a faster speed, an eccentric cam 914 is fixedly attached to the tip end of the rotating rod 913, so that the rotating rod 913 can generate vibration of a relatively fast frequency at the time of fast rotation, through the effect of fixed crossbearer 911, can make three mud pipe 902 all produce the vibration in step, the work of cooperation initiative mud discharging mechanism helps the discharge of silt more, has effectively solved the easy siltation that takes place of current design bottom mud, the unable problem of normally carrying out mud discharging work.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be able to cover the technical scope of the present invention and the equivalent alternatives or modifications according to the technical solution and the inventive concept of the present invention within the technical scope of the present invention.

Claims

1. River course sewage pipe chute precipitator for improvement and treatment of environment, including fixed box (1), supporting legs (2) and header tank (4), its characterized in that: the supporting legs (2) are fixedly connected to four corners of the bottom surface of the fixed box body (1), the upper end inside the fixed box body (1) is a precipitation treatment cavity, the lower end inside the fixed box body (1) is a sludge accumulation cavity, a honeycomb inclined tube (10) is fixedly installed inside the precipitation treatment cavity, and a drain pipe (3) is fixedly connected to the side wall of the fixed box body (1); header tank (4) fixed connection is in the upper end of fixed box (1), be connected with sealed apron (5) through connecting the hinge rotation on the top surface of header tank (4), fixedly connected with river course sewage injection pipe (6) on the lateral wall of header tank (4), be close to sewage injection pipe (6) fixedly connected with of department on the inner wall of header tank (4) and cross filter frame (11), the inside of header tank (4) still installs control mechanism (7) that drains, be connected with booster mechanism (8) on the top surface of header tank (4), the lower extreme of fixed box (1) still is connected with row mud device (9).

2. The riverway sewage inclined-tube precipitator for environmental improvement treatment according to claim 1, wherein: the water discharging control mechanism (7) comprises an installation bottom plate (701), the installation bottom plate (701) is arranged as the bottom surface of the water collecting tank (4), an installation opening (702) is formed in the installation bottom plate (701), a first servo motor (703) is fixedly connected to the side wall of the water collecting tank (4), and a linkage shaft (704) is fixedly connected to an output shaft of the first servo motor (703).

3. The riverway sewage inclined-tube precipitator for environmental improvement treatment according to claim 2, wherein: still fixedly connected with worm (705) on universal driving shaft (704), worm (705) and worm wheel (706) meshing are connected, worm wheel (706) rotate to be connected on mounting plate (701), both sides worm wheel (706) preceding fixedly connected with connecting axle (707), still fixedly connected with water shutoff board (708) on connecting axle (707), water shutoff board (708) and installation opening (702) phase-match, water shutoff board (708) rotate through connecting axle (707) and worm wheel (706) and install on mounting plate (701).

4. The riverway sewage inclined-tube precipitator for environmental improvement treatment according to claim 1, wherein: booster mechanism (8) are including booster pump (801), booster pump (801) fixed mounting is subaerial, fixedly connected with booster pipe (802) on booster pump (801), booster pipe (802) are kept away from booster pump (801) one end fixed connection on intercommunication return bend (803), the terminal of intercommunication return bend (803) and the top surface fixed connection of header tank (4), it has pressure monitoring table (804) still to fixed mounting on intercommunication return bend (803).

5. The riverway sewage inclined-tube precipitator for environmental improvement treatment according to claim 1, wherein: the sludge discharging device (9) comprises a sludge discharging hopper (901), the sludge discharging hopper (901) is fixedly connected to the bottom end of the fixed box body (1), a sludge discharging pipe (902) is fixedly connected to the bottom end of the sludge discharging hopper (901), an active sludge discharging mechanism is installed at the bottom end of the sludge discharging pipe (902), and a sludge discharging opening (903) is formed in the bottom end of the side wall of the sludge discharging pipe (902).

6. The riverway sewage inclined-tube precipitator for environmental improvement treatment according to claim 5, wherein: initiative mud discharging mechanism is including mounting bracket (904) and second servo motor (905), mounting bracket (904) fixed connection is on supporting legs (2), second servo motor (905) fixed mounting is on mounting bracket (904), first row of mud auger (906) of fixedly connected with on the output shaft of second servo motor (905), the both sides of first row of mud auger (906) still are provided with second row of mud auger (909) and third row of mud auger (910) respectively, first row of mud auger (906), second row of mud auger (909) and third row of mud auger (910) are all rotated and are installed inside mud pipe (902), the bottom of second row of mud auger (909) and third row of mud auger (910) is rotated and is connected on mounting bracket (904), the first belt pulley of lower extreme fixedly connected with of first row of mud auger (906), first row of mud auger (906), The lower extreme of mud auger (909) is arranged to the second and third row mud auger (910) is fixedly connected with first belt pulley, second belt pulley and third belt pulley respectively, it is connected with first linkage belt (907) to encircle between first belt pulley and the second belt pulley, it is connected with second linkage belt (908) to encircle between first belt pulley and the third belt pulley.

7. The riverway sewage inclined-tube precipitator for environmental improvement treatment according to claim 6, wherein: arrange mud device (9) still including fixed crossbearer (911) and connecting block (912), fixed crossbearer (911) fixed connection is on the lateral wall of mud pipe (902), connecting block (912) fixed connection is on the lateral wall of mud pipe (902) at second servo motor (905) both ends, it is connected with dwang (913) to rotate on connecting block (912), the top fixedly connected with eccentric cam (914) of dwang (913), the bottom fixedly connected with fourth belt pulley (915) and fifth belt pulley (916) of dwang (913), it is connected with third linkage belt (917) to encircle between fourth belt pulley (915) and the first belt pulley, it is connected with fourth linkage belt (918) to encircle between fifth belt pulley (916) and the third belt pulley.