Building construction concrete conveying anti-blocking feeding mechanism

Abstract

The invention discloses a building construction concrete conveying anti-blocking feeding mechanism which comprises a grating grid plate arranged in a conveying hopper and first strip-shaped holes formed in the two sides of the outer wall of the conveying hopper, first sliding rods are fixedly connected to the inner walls of the two first strip-shaped holes correspondingly, and the outer walls of the two first sliding rods are sleeved with first springs correspondingly; supporting plates are slidably connected to the outer walls of the two first sliding rods correspondingly, and one sides of the two supporting plates are fixedly connected with the two sides of the grating plate, large agglomerates located at the top of the grating plate can be shaken to be scattered in the shaking process, and it is prevented that when the large agglomerates fall to the bottom of the conveying hopper, the large agglomerates cannot fall into the conveying hopper, and the conveying hopper cannot fall into the conveying hopper. The problem that blocking of the hopper and even a conveying channel is directly caused due to the fact that blocking occurs at the connection key positions of a discharging port of the hopper, the hopper and the conveying belt, continuous pushing of feeding operation occurs, and clotted objects can be continuously accumulated and extruded is solved, the blocking condition in the concrete conveying process is prevented, and the feeding efficiency in the concrete conveying process is improved.

Description

Technical Field

[0001] This invention belongs to the field of concrete feeding technology, and specifically relates to a concrete conveying and anti-blocking feeding mechanism for building construction. Background Technology

[0002] In the construction industry, concrete, as a core load-bearing material, directly determines project progress, construction quality, and cost control through the efficiency and stability of its conveying and feeding processes. With modern buildings becoming increasingly tall and large-scale, concrete conveying distances and heights are constantly increasing, placing higher demands on the reliability of conveying and feeding mechanisms. Among these challenges, pipeline blockage has long been a core pain point for the industry. Blockages not only lead to construction interruptions but can also cause material waste, equipment damage, and even safety hazards. Therefore, the research and optimization of anti-blockage concrete conveying and feeding mechanisms are of significant practical importance. Currently, the mainstream concrete conveying and feeding mechanisms used in construction mainly include belt conveyors, bucket elevators, screw conveyors, and pumping systems, with different mechanisms applied differently according to the needs of different construction scenarios. Belt conveyors, with their large conveying capacity and strong adaptability, are widely used for horizontal or inclined conveying of aggregates. They achieve material transfer through the cooperation of conveyor belts and idlers, and some are equipped with covers to reduce dust and slippage in rainy weather. Bucket elevators, due to their small footprint, are suitable for lifting aggregates in narrow spaces. They use winches to pull buckets to complete lifting and unloading. Screw conveyors are mostly used for sealed conveying of powdery materials such as cement and admixtures. They use rotating screw blades to propel the material forward and can achieve horizontal, vertical, and inclined conveying. Pumped feeding systems use pressure to continuously transport mixed concrete along pipelines to the work site and are core equipment for high-rise and long-distance construction.

[0003] In concrete conveying operations during construction, the hopper is the core component for conveying and transferring concrete. After mixing, the concrete needs to be guided by the hopper to the conveyor belt so that subsequent continuous conveying operations can be completed. This connection is the foundation for ensuring a smooth concrete conveying process. As a cementitious mixture, concrete, due to its inherent characteristics such as cohesiveness and aggregate ratio, is prone to forming large, unevenly sized clumps even after standardized mixing processes. These clumps are a major cause of material obstruction during conveying. Currently, the concrete conveying systems commonly used in the construction industry have significant functional shortcomings in their structural design. They lack suitable crushing and screening components for the large clumps commonly found in mixed concrete, and there is no corresponding real-time processing structure design. This means that the equipment cannot effectively decompose and clean these clumps during actual conveying. Untreated large clumps, after entering the hopper with the concrete, easily become stuck at the hopper discharge port and the critical connection between the hopper and the conveyor belt. As the feeding operation continues, the clumps accumulate and compress, directly causing blockages in the hopper and even the conveying channel. This not only disrupts the continuity of concrete feeding but also becomes a significant factor restricting the efficiency of concrete conveying operations. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a concrete conveying and anti-blocking feeding mechanism for building construction, thereby resolving the issues raised in the background section.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a concrete conveying anti-blocking feeding mechanism for building construction, comprising a conveying hopper, wherein an anti-blocking mechanism is provided inside the conveying hopper, and a conveying mechanism is provided at the bottom of the conveying hopper; The anti-blocking mechanism includes a grid plate inside the conveying hopper, first strip holes on both sides of the outer wall of the conveying hopper, first sliding rods fixedly connected to the inner walls of the two first strip holes, first springs sleeved on the outer walls of the two first sliding rods, support plates slidably connected to the outer walls of the two first sliding rods, and one side of the two support plates fixedly connected to the two sides of the grid plate. Cams are rotatably connected to both sides of the conveying hopper, and the cams are located at the top of the support plates.

[0006] In one example, a timing wheel is fixedly connected to one side of each of the two cams, two baffles are fixedly connected to one side of the conveying hopper, and timing wheels are rotatably connected to one side of each of the two baffles. A timing belt is fitted on the outer wall of each pair of timing wheels. A first connecting rod is rotatably connected to one side of each of the two baffles, and one end of the first connecting rod is fixedly connected to one side of the timing wheel. A first bevel gear is fixedly connected to the other end of the two first connecting rods, and a second bevel gear is meshed with one side of each of the two first bevel gears.

[0007] In one example, a support frame is fixedly connected to the middle of one side of the conveying hopper, a first servo motor is fixedly connected to one side of the support frame, and the drive shaft of the second bevel gear is fixedly connected to the output end of the first servo motor.

[0008] In one example, the bottom of both sides of the conveying hopper is provided with a second strip-shaped hole, the inner wall of each of the two second strip-shaped holes is fixedly connected with a second sliding rod, the outer wall of each of the two second sliding rods is fitted with a second spring, the outer wall of each of the two second sliding rods is slidably connected with a base plate, one end of each of the two base plates is fixedly connected with a first scraper, and the top of each of the two base plates is fixedly connected with a support rod, and the top of the support rod is fixedly connected to the bottom of the support plate.

[0009] In one example, the conveying mechanism includes a first support fixedly connected to the bottom of the conveying hopper. A conveyor belt is provided on one side of the first support. Side plates are fixedly connected to both ends of one side of the first support. A circular roller is rotatably connected between the two side plates. A lever is fixedly connected at equal intervals to the outer wall of the circular roller. A second servo motor is fixedly connected to one side of one of the side plates, and the drive shaft of the circular roller is fixedly connected to the output end of the second servo motor.

[0010] In one example, the other end of the conveyor belt is provided with a second support seat, and both ends of the second support seat are provided with second grooves. The inner wall of each second groove is fixedly connected with a third slide rod, and the outer wall of each third slide rod is fitted with a third spring.

[0011] In one example, a top plate is slidably connected to the outer wall of each pair of opposite third slide bars, and a second scraper is fixedly connected to the top of each of the two top plates. A hopper is provided at the bottom of the second support.

[0012] In one example, an intelligent control panel is provided on one side of the conveying hopper. The surface of the intelligent control panel is provided with a first servo motor switch and a second servo motor switch. The first servo motor is electrically connected to an external power supply through the first servo motor switch and the second servo motor is electrically connected to an external power supply through the second servo motor switch.

[0013] The technical effects and advantages of this invention are as follows: 1. This invention utilizes a grid plate disposed at the temporal portion of a conveying hopper. First strip-shaped holes are provided on both sides of the conveying hopper. First sliding rods are fixedly connected to the inner walls of the two first strip-shaped holes. First springs and support plates are respectively provided on the outer walls of the first sliding rods. One side of the support plate is connected to both sides of the grid plate. Furthermore, a cam is provided on the outer wall of the conveying hopper, located at the top of the support plate. This allows concrete to fall onto the grid plate inside the conveying hopper during use, where large clumps of concrete are retained on the grid plate. The grid plate is capable of vertical displacement. During the rotation of the cam, the cam drives the support plate to move up and down, which in turn causes the internal grid plate to vibrate. During the vibration, large clumps located at the top of the grid plate are dispersed, preventing them from getting stuck at the bottom of the conveyor hopper or at the critical connection between the hopper and the conveyor belt when they fall to the bottom. As the feeding operation continues, the clumps will accumulate and be compressed, which will directly cause blockages in the hopper and even the conveying channel. This prevents blockages during concrete conveying and improves the feeding efficiency during concrete conveying.

[0014] 2. In this invention, a second sliding rod is provided inside a second slotted hole at the bottom of both sides of the conveying hopper. A second spring and a base plate are respectively provided on the outer wall of the second sliding rod. A first scraper is fixedly connected to one end of the base plate. The first scraper is positioned against the inner wall of the discharge end of the conveying hopper. A support rod is fixedly connected to the top of the base plate and is connected to the bottom of a support plate. During use, the rotation of the top cam causes the support plate to move up and down. Simultaneously, the support plate, connected to the base plate via the support rod, moves accordingly. This causes the first scraper to scrape the bottom of the inner wall of the discharge end of the conveying hopper, preventing concrete from accumulating at the bottom of the inner wall and adhering to the inner wall of the conveying hopper. This further prevents blockages inside the conveying hopper.

[0015] 3. In this invention, a first support base is set at the bottom of the conveying hopper, a conveyor belt is provided on one side of the first support base, and a side plate is fixedly connected to one side of the first support base. A circular roller is provided between the side plates, and a lever is provided on the outside of the circular roller. During use, the rotation of the circular roller can drive the lever to move on the surface of the concrete. During the movement, the concrete in the conveying process can be flattened, preventing excessive concrete in some areas and avoiding irregular accumulation of material on the belt surface, thus preparing for uniform unloading.

[0016] 4. In this invention, a second support seat is provided at the other end of the conveyor belt. A second groove is provided on one side of the second support seat. A third slide rod is provided inside the second groove. A third spring and a top plate are respectively provided outside the third slide rod. A second scraper is provided on the top of the top plate. During use, the second scraper located at the bottom of the conveyor belt can adhere to the surface of the conveyor belt under the action of the third spring, thereby cleaning the concrete residue on the surface of the conveyor belt. The residue will then fall into the bottom collection hopper, thus preventing concrete from sticking to the surface of the conveyor belt during the concrete conveying process.

[0017] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims, and drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the internal structure of the conveying hopper of the present invention; Figure 3 This is the present invention. Figure 2 Enlarged structural diagram at point A; Figure 4 This is a schematic diagram of the bottom structure of the inner wall of the conveying hopper of the present invention; Figure 5 This is a schematic diagram of the conveying mechanism structure of the present invention; Figure 6 This is a schematic diagram of the second support structure of the present invention.

[0020] In the diagram: 1. Conveying hopper; 2. Anti-blocking mechanism; 201. Grating plate; 202. First slotted hole; 203. First sliding rod; 204. First spring; 205. Support plate; 206. Cam; 207. Synchronous pulley; 208. Synchronous belt; 209. Baffle; 210. First connecting rod; 211. First bevel gear; 212. Second bevel gear; 213. Support frame; 214. First servo motor; 215. Second slotted hole; 216. 217. Second slide bar; 218. Second spring; 219. Base plate; 220. First scraper; 221. Support rod; 3. Conveying mechanism; 301. First support seat; 302. Conveyor belt; 303. Side plate; 304. Circular roller; 305. Toggle lever; 306. Second servo motor; 307. Second support seat; 308. Second groove; 309. Third slide bar; 310. Third spring; 311. Top plate; 312. Second scraper; 313. Collection hopper. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1-6 The present invention provides a technical solution: a concrete conveying anti-blocking feeding mechanism for building construction, including a conveying hopper 1, an anti-blocking mechanism 2 inside the conveying hopper 1, and a conveying mechanism 3 at the bottom of the conveying hopper 1; The anti-blocking mechanism 2 includes a grid plate 201 disposed inside the conveying hopper 1, two first strip holes 202 on both sides of the outer wall of the conveying hopper 1, a first slide rod 203 fixedly connected to the inner wall of each of the two first slide rods 202, a first spring 204 sleeved on the outer wall of each of the two first slide rods 203, a support plate 205 slidably connected to the outer wall of each of the two first slide rods 203, and one side of each support plate 205 fixedly connected to both sides of the grid plate 201. A cam 206 is rotatably connected to both sides of the conveying hopper 1, and the cam 206 is located on the top of the support plate 205.

[0023] In use, a grid plate 201 is installed at the temporal part of the conveying hopper 1. First strip holes 202 are also provided on both sides of the conveying hopper 1. First sliding rods 203 are fixedly connected to the inner walls of the two first strip holes 202. First springs 204 and support plates 205 are respectively provided on the outer walls of the first sliding rods 203. One side of the support plate 205 is connected to both sides of the grid plate 201. A cam 206 is also provided on the outer wall of the conveying hopper 1, located at the top of the support plate 205. This allows concrete to fall onto the grid plate 201 inside the conveying hopper 1 during use. Large clumps of concrete inside the concrete will be retained on the grid plate 201, and the grid... Plate 201 can move up and down. During the rotation of cam 206, cam 206 will drive support plate 205 to move up and down, which will cause the internal grid plate 201 to shake. During the shaking process, large clumps located on the top of the grid plate 201 will be shaken off, preventing large clumps from getting stuck at the bottom of the conveying hopper 1, at the hopper discharge port, or at the connection between the hopper and the conveyor belt 302. As the feeding operation continues, the clumps will accumulate and be squeezed, which will directly cause blockage in the hopper and even the conveying channel. This will prevent blockage during the concrete conveying process and improve the feeding efficiency during the concrete conveying process.

[0024] Furthermore, a synchronous wheel 207 is fixedly connected to one side of each of the two cams 206, and two baffles 209 are fixedly connected to one side of the conveying hopper 1. The synchronous wheel 207 is rotatably connected to one side of each of the two baffles 209. A synchronous belt 208 is sleeved on the outer wall of each pair of synchronous wheels 207. A first connecting rod 210 is rotatably connected to one side of each of the two baffles 209. One end of the first connecting rod 210 is fixedly connected to one side of the synchronous wheel 207. The other end of the two first connecting rods 210 is fixedly connected to a first bevel gear 211. A second bevel gear 212 is meshed with one side of each of the two first bevel gears 211. A baffle 209 is provided on one side of the conveying hopper 1. Synchronous pulleys 207 are provided on one side of the baffle 209 and the cam 206 respectively. The synchronous pulleys 207 are connected by a synchronous belt 208. A first connecting rod 210 is provided on one side of the two synchronous pulleys 207. A first bevel gear 211 is provided at one end of the first connecting rod 210. A second bevel gear 212 is meshed with one side of the first bevel gear 211. The rotation of the second bevel gear 212 can drive the first bevel gear 211 to rotate, thereby driving the synchronous pulleys 207 on both sides to rotate synchronously, so that the cams 206 on both sides can rotate synchronously, thereby achieving the purpose of shaking and breaking up the clumps.

[0025] Furthermore, a support frame 213 is fixedly connected to the middle of one side of the conveying hopper 1, a first servo motor 214 is fixedly connected to one side of the support frame 213, and the transmission shaft of the second bevel gear 212 is fixedly connected to the output end of the first servo motor 214. A support frame 213 is provided on one side of the conveying hopper 1, and a first servo motor 214 is provided on one side of the support frame 213. The first servo motor 214 is mainly used to drive the second bevel gear 212 to rotate, and is the main driving source for the vibration of the grid plate 201.

[0026] Furthermore, the bottom of both sides of the conveying hopper 1 is provided with a second strip hole 215. The inner walls of the two second strip holes 215 are fixedly connected with a second slide rod 216. The outer walls of the two second slide rods 216 are fitted with a second spring 217. The outer walls of the two second slide rods 216 are slidably connected with a base plate 218. One end of the two base plates 218 is fixedly connected with a first scraper 219. The top of the two base plates 218 is fixedly connected with a support rod 220, and the top of the support rod 220 is fixedly connected to the bottom of the support plate 205. In use, a second slide bar 216 is provided inside the second strip-shaped hole 215 at the bottom of both sides of the conveying hopper 1. A second spring 217 and a base plate 218 are respectively provided on the outer wall of the second slide bar 216. A first scraper 219 is fixedly connected to one end of the base plate 218. The first scraper 219 is positioned to fit against the inner wall of the discharge end of the conveying hopper 1. A support rod 220 is fixedly connected to the top of the base plate 218. The support rod 220 is connected to the bottom of the support plate 205, so that when using… During use, the rotation of the top cam 206 drives the support plate 205 to move up and down. At the same time, the support plate 205 is connected to the bottom plate 218 through the support rod 220, so that the bottom plate 218 will also move accordingly. This causes the first scraper 219 to scrape the bottom of the inner wall of the discharge end of the conveying hopper 1, preventing concrete from accumulating at the bottom of the inner wall of the conveying hopper 1 and preventing concrete from sticking to the inner wall of the conveying hopper 1. This can further prevent blockage inside the conveying hopper 1.

[0027] Furthermore, the conveying mechanism 3 includes a first support base 301 fixedly connected to the bottom of the conveying hopper 1. A conveyor belt 302 is provided on one side of the first support base 301. Side plates 303 are fixedly connected to both ends of one side of the first support base 301. A circular roller 304 is rotatably connected between the two side plates 303. A lever 305 is fixedly connected at equal intervals to the outer wall of the circular roller 304. A second servo motor 306 is fixedly connected to one side of one of the side plates 303, and the drive shaft of the circular roller 304 is fixedly connected to the output end of the second servo motor 306.

[0028] In use, a first support 301 is set at the bottom of the conveying hopper 1, a conveyor belt 302 is provided on one side of the first support 301, and a side plate 303 is fixedly connected to one side of the first support 301. A circular roller 304 is provided between the side plates 303, and a lever 305 is provided on the outside of the circular roller 304. During use, the rotation of the circular roller 304 can drive the lever 305 to move on the surface of the concrete. During the movement, the concrete in the conveying process can be flattened, and there will be no excessive concrete in some areas. This avoids the irregular accumulation of material on the belt surface and prepares for uniform unloading.

[0029] Furthermore, the other end of the conveyor belt 302 is provided with a second support seat 307. Both ends of the second support seat 307 are provided with second grooves 308. The inner wall of each second groove 308 is fixedly connected with a third slide rod 309. The outer wall of each third slide rod 309 is fitted with a third spring 310.

[0030] Each pair of relative third slide bars 309 is slidably connected to a top plate 311 on its outer wall. The top of each of the two top plates 311 is fixedly connected to a second scraper 312. The bottom of the second support base 307 is provided with a collection hopper 313.

[0031] In use, a second support seat 307 is provided at the other end of the conveyor belt 302. A second groove 308 is provided on one side of the second support seat 307. A third slide rod 309 is provided inside the second groove 308. A third spring 310 and a top plate 311 are respectively provided on the outside of the third slide rod 309. A second scraper 312 is provided on the top of the top plate 311. During use, the second scraper 312 located at the bottom of the conveyor belt 302 can adhere to the surface of the conveyor belt 302 under the action of the third spring 310, thereby cleaning the concrete residue on the surface of the conveyor belt 302. Afterwards, it will fall into the bottom collection hopper 313, thus preventing concrete from sticking to the surface of the conveyor belt 302 during the concrete conveying process.

[0032] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A concrete conveying anti-blocking feeding mechanism for building construction, including a conveying hopper (1), an anti-blocking mechanism (2) is provided inside the conveying hopper (1), and a conveying mechanism (3) is provided at the bottom of the conveying hopper (1). Its features are: The anti-blocking mechanism (2) includes a grid plate (201) disposed inside the conveying hopper (1), two first strip holes (202) on the outer wall of the conveying hopper (1), a first slide rod (203) fixedly connected to the inner wall of each of the two first strip holes (202), a first spring (204) sleeved on the outer wall of each of the two first slide rods (203), a support plate (205) slidably connected to the outer wall of each of the two first slide rods (203), and one side of each support plate (205) fixedly connected to the two sides of the grid plate (201). A cam (206) is rotatably connected to both sides of the conveying hopper (1), and the cam (206) is located at the top of the support plate (205).

2. The anti-blocking feeding mechanism for concrete conveying in building construction according to claim 1, characterized in that: One side of each of the two cams (206) is fixedly connected to a synchronous wheel (207). One side of the conveying hopper (1) is fixedly connected to two baffles (209), and one side of each baffle (209) is rotatably connected to a synchronous wheel (207). The outer wall of each pair of synchronous wheels (207) is fitted with a synchronous belt (208). One side of each of the two baffles (209) is rotatably connected to a first connecting rod (210), and one end of the first connecting rod (210) is fixedly connected to one side of the synchronous wheel (207). The other end of the two first connecting rods (210) is fixedly connected to a first bevel gear (211), and one side of the two first bevel gears (211) is meshed with a second bevel gear (212).

3. The anti-blocking feeding mechanism for concrete conveying in building construction according to claim 2, characterized in that: A support frame (213) is fixedly connected to the middle of one side of the conveying hopper (1), and a first servo motor (214) is fixedly connected to one side of the support frame (213). The transmission shaft of the second bevel gear (212) is fixedly connected to the output end of the first servo motor (214).

4. The anti-blocking feeding mechanism for concrete conveying in building construction according to claim 1, characterized in that: The bottom of both sides of the conveying hopper (1) is provided with a second strip hole (215). The inner walls of the two second strip holes (215) are fixedly connected with a second slide rod (216). The outer walls of the two second slide rods (216) are fitted with a second spring (217). The outer walls of the two second slide rods (216) are slidably connected with a base plate (218). One end of the two base plates (218) is fixedly connected with a first scraper (219). The top of the two base plates (218) is fixedly connected with a support rod (220), and the top of the support rod (220) is fixedly connected to the bottom of the support plate (205).

5. The anti-blocking feeding mechanism for concrete conveying in building construction according to claim 1, characterized in that: The conveying mechanism (3) includes a first support base (301) fixedly connected to the bottom of the conveying hopper (1). A conveyor belt (302) is provided on one side of the first support base (301). Side plates (303) are fixedly connected to both ends of one side of the first support base (301). A circular roller (304) is rotatably connected between the two side plates (303). A lever (305) is fixedly connected at equal intervals to the outer wall of the circular roller (304). A second servo motor (306) is fixedly connected to one side of one of the side plates (303), and the drive shaft of the circular roller (304) is fixedly connected to the output end of the second servo motor (306).

6. The anti-blocking feeding mechanism for concrete conveying in building construction according to claim 5, characterized in that: The other end of the conveyor belt (302) is provided with a second support seat (307). Both ends of the second support seat (307) are provided with second grooves (308). The inner wall of each second groove (308) is fixedly connected with a third slide rod (309). The outer wall of each third slide rod (309) is fitted with a third spring (310).

7. The anti-blocking feeding mechanism for concrete conveying in building construction according to claim 6, characterized in that: Each pair of relative third slide bars (309) is slidably connected to a top plate (311), and the top of each of the two top plates (311) is fixedly connected to a second scraper (312). The bottom of the second support (307) is provided with a collection hopper (313).

8. The anti-blocking feeding mechanism for concrete conveying in building construction according to claim 3, characterized in that: The conveying hopper (1) is provided with an intelligent control panel on one side. The surface of the intelligent control panel is provided with a first servo motor switch and a second servo motor switch. The first servo motor (214) is electrically connected to an external power supply through the first servo motor switch and the second servo motor (306) is electrically connected to an external power supply through the second servo motor switch.

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