CN119465843B - Target point cleaning mechanism of scribing vehicle - Google Patents

Abstract

The invention relates to the technical field of road marking cleaning, and in particular to a target point cleaning mechanism of a road marking vehicle, which is used to solve the problem that paint is not firmly attached due to oil stains on the road. The mechanism comprises a vehicle body, a transmission assembly is arranged on the vehicle body, and a dust suction assembly and a paint spraying assembly are arranged on the transmission assembly. The dust suction assembly comprises a middle cylinder, an inner cylinder which is slidably connected to the inner wall of the middle cylinder, a pull rope is connected to the top of the inner cylinder, two rollers are vertically symmetrically rotatably connected to the side wall of the middle cylinder, the pull rope is inserted between the two rollers, the top wall of the inner cylinder is connected to an adsorption tube, and the end of the adsorption tube is connected to a negative pressure cylinder. The middle cylinder is connected to a cover body, and an infrared light oil stain sensor is arranged in the cover body. When the device detects that oil stains are attached to the road surface, the pull rope pulls the inner cylinder up to make the inner cylinder away from the road surface, thereby preventing the oil stains on the road surface from adhering to the inner cylinder, so that the subsequent road surface is contaminated by the oil stains on the inner cylinder.

Description

Target point cleaning mechanism for a marking vehicle

Technical Field

The invention relates to the technical field of road marking cleaning, in particular to a target point cleaning mechanism of a road marking vehicle.

Background Art

During the road marking construction process, ensuring the cleanliness of the road surface plays a vital role in the adhesion of the marking paint and the quality of the marking. Traditional marking vehicles often only focus on the marking function and ignore the road surface pretreatment link, which may lead to a series of problems. For example, if the sand, dust and other debris on the road surface are not cleaned up, they will be mixed between the paint surface and the road surface during painting, greatly weakening the adhesion of the paint surface, causing the marking to peel off and wear easily, which not only shortens the service life of the marking, but also may affect the clarity and accuracy of traffic signs, posing a potential threat to traffic safety.

In addition, with the development of modern transportation, oil pollution on the road has become more and more complicated. Oil leakage from vehicles and industrial areas occurs from time to time. Once these oil stains adhere to the road surface, they will not only seriously affect the adhesion effect of the marking paint, but also may cause environmental pollution. However, most of the existing marking vehicles are not equipped with effective oil pollution detection and response mechanisms, and are unable to detect and deal with oil pollution problems in time before marking, so that the marking work is carried out blindly on the road with oil pollution, which leads to the expansion of the scope of oil pollution.

Summary of the invention

The invention provides a target point cleaning mechanism for a road marking vehicle, so as to solve the problem that when there is oil stain on the road, the cleaning of the existing device will expand the scope of the oil stain.

In order to alleviate the above technical problems, the technical solution provided by the present invention is:

A target point cleaning mechanism of a marking vehicle comprises a vehicle body, a transmission assembly is arranged on the vehicle body, and a dust collecting assembly and a paint spraying assembly are arranged on the transmission assembly;

The dust collection assembly includes a middle cylinder, an inner cylinder in contact with the inner wall of the middle cylinder is slidably connected therein, a pull rope is connected to the top of the inner cylinder, two rollers are vertically symmetrically rotatably connected to the side wall of the middle cylinder, the pull rope is inserted between the two rollers, the top wall of the inner cylinder is connected to an adsorption tube, and the end of the adsorption tube is connected to a negative pressure cylinder;

The outer wall of the middle cylinder is connected with a bracket, the bottom of the bracket is connected with a cover body, and an infrared light oil sensor is arranged in the cover body. When oil is attached to the road surface to be marked, the roller rotates so that the pull rope pulls the inner cylinder to rise.

Furthermore, the middle tube is slidably connected to an outer tube that fits the outer wall, annular brushes are provided at the ports of the inner tube and the outer tube, and one end of the pull rope away from the inner tube is connected to the outer tube.

Furthermore, the transmission assembly includes a worm rotatably connected to the vehicle body, the worm is symmetrically provided with two sets of threads, the two sets of threads are respectively meshed with two worm wheels, the two worm wheels are respectively connected to a first connecting rod and a second connecting rod, the paint spraying assembly includes a paint spraying nozzle, the paint spraying nozzle is connected to the second connecting rod, and the middle cylinder is connected to the first connecting rod.

Furthermore, the transmission assembly also includes a swivel connected to the first connecting rod, and the middle cylinder is rotatably connected to the swivel.

Furthermore, the transmission assembly also includes a fixed seat, a first pulley is fixedly connected to the fixed seat, a second pulley is fixedly connected to the middle of the middle tube, and a belt is transmission-connected between the first pulley and the second pulley.

Furthermore, the vehicle body includes a vehicle body and moving wheels connected to the bottom of the vehicle body.

Furthermore, it also includes a brushing assembly, which includes a lower rack, the end of the lower rack is connected to a mounting frame, a motor is vertically slidably connected to the mounting frame, the output end of the motor is connected to a brush disc, and a nozzle for spraying a degreasing agent is connected to the mounting frame, the nozzle is facing the brush disc, and when oil stains are attached to the road surface to be marked, the motor moves downward to make the brush disc contact the road surface, and the nozzle sprays the degreasing agent toward the brush disc.

Furthermore, the brushing assembly also includes a gear connected to the middle part of the worm, and the lower rack is meshed with the gear.

Furthermore, the brushing assembly also includes an upper rack meshing with the gear, and a counterweight is connected to the end of the upper rack.

Furthermore, the counterweight block is slidably connected to the upper rack, and when the motor moves downward, the counterweight block slides toward the lower rack.

The beneficial effects of the present invention are analyzed as follows:

A target point cleaning mechanism of a road marking vehicle comprises a vehicle body, a transmission assembly is arranged on the vehicle body, a dust suction assembly and a paint spraying assembly are arranged on the transmission assembly; the dust suction assembly comprises a middle cylinder, an inner cylinder which is slidably connected to the inside of the middle cylinder and is in contact with the inner wall, a pull rope is connected to the top of the inner cylinder, two rollers are vertically symmetrically rotatably connected to the side wall of the middle cylinder, the pull rope is inserted between the two rollers, the top wall of the inner cylinder is connected to an adsorption tube, and the end of the adsorption tube is connected to a negative pressure cylinder; the outer wall of the middle cylinder is connected to a bracket, the bottom of the bracket is connected to a cover body, an infrared light oil pollution sensor is arranged in the cover body, and when oil pollution is attached to the road surface to be marked, the roller rotates so that the pull rope pulls the inner cylinder up.

The dust suction component is located at the end of the vehicle body in the direction of travel, and the paint spraying component is located at the rear of the vehicle body in the direction of travel. When the vehicle body moves forward, the dust suction component performs negative pressure adsorption on sand, gravel and other debris on the road surface to be painted, so that the debris on the road surface is cleaned, ensuring that the paint surface can be firmly attached to the road surface during subsequent painting. The infrared light oil pollution sensor monitors the road surface in real time. When it is detected that there is oil pollution attached to the road surface, the control system receives a signal and controls the roller to rotate, so that the roller drives the pull rope, so that the pull rope pulls the inner cylinder up, so that the inner cylinder is away from the road surface, thereby preventing the oil pollution on the road surface from adhering to the inner cylinder, so that the subsequent road surface is contaminated by the oil pollution on the inner cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the related technologies, the drawings required for use in the specific embodiments or the related technical descriptions will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a schematic diagram of the overall structure of the present invention;

FIG2 is a second schematic diagram of the overall structure of the present invention;

FIG3 is a schematic structural diagram of a transmission assembly of the present invention;

FIG4 is a schematic structural diagram of a dust collecting assembly of the present invention;

FIG5 is a schematic diagram of the structure of the brushing assembly of the present invention;

FIG. 6 is a schematic diagram of the structure of the gear of the present invention.

icon:

100, vehicle body; 110, vehicle body; 120, moving wheel; 130, negative pressure cylinder; 140, adsorption tube; 200, transmission assembly; 210, worm; 220, worm wheel; 230, first connecting rod; 240, second connecting rod; 250, first pulley; 251, fixed seat; 260, belt; 270, second pulley; 300, dust collection assembly; 310, middle cylinder; 320, swivel; 330 , inner cylinder; 340, outer cylinder; 350, annular brush; 360, pull rope; 370, roller; 380, bracket; 381, cover; 390, infrared oil sensor; 400, paint spraying assembly; 410, paint spraying nozzle; 500, brushing assembly; 510, gear; 520, lower rack; 521, mounting bracket; 530, motor; 540, brush plate; 550, upper rack; 560, counterweight.

DETAILED DESCRIPTION

The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

In the embodiment, as shown in FIGS. 1 to 6 , a target point cleaning mechanism of a marking vehicle comprises a vehicle body 100, a transmission assembly 200 is arranged on the vehicle body 100, a dust collection assembly 300 and a paint spraying assembly 400 are arranged on the transmission assembly 200; the dust collection assembly 300 comprises a middle cylinder 310, an inner cylinder 330 which is slidably connected to the inner wall of the middle cylinder 310, a pull rope 360 is connected to the top of the inner cylinder 330, and a pull rope 360 is connected to the side wall of the middle cylinder 310 in a vertically symmetrical rotation manner. There are two rollers 370, and the pull rope 360 is inserted between the two rollers 370. The top wall of the inner cylinder 330 is connected to the adsorption tube 140, and the end of the adsorption tube 140 is connected to the negative pressure cylinder 130; the outer wall of the middle cylinder 310 is connected to the bracket 380, and the bottom of the bracket 380 is connected to the cover body 381. An infrared light oil sensor 390 is arranged in the cover body 381. When oil is attached to the road surface to be marked, the roller 370 rotates so that the pull rope 360 pulls the inner cylinder 330 to rise.

The working mechanism of the target point cleaning mechanism of the marking vehicle provided in this embodiment is as follows:

The dust suction component 300 is located at the end of the vehicle body 100 in the direction of travel, and the paint spraying component 400 is located at the rear of the vehicle body 100 in the direction of travel. When the vehicle body 100 moves forward, the dust suction component 300 performs negative pressure adsorption on the sand and other debris on the road surface to be painted, so that the debris on the road surface is cleaned, ensuring that the paint surface can be firmly attached to the road surface during subsequent painting. The infrared light oil pollution sensor 390 monitors the road surface in real time. When it is detected that there is oil pollution attached to the road surface, the control system receives a signal and controls the roller 370 to rotate, so that the roller 370 drives the pull rope 360, so that the pull rope 360 pulls the inner cylinder 330 to rise, so that the inner cylinder 330 is away from the road surface, thereby preventing the oil pollution on the road surface from adhering to the inner cylinder 330, so that the subsequent road surface is polluted by the oil pollution on the inner cylinder 330.

The infrared light oil pollution sensor 390 is arranged in the cover body 381, so as to shield the rest of the light, so that the infrared light oil pollution sensor 390 is not affected by the rest of the light, thereby ensuring the measurement accuracy.

Among the optional methods of this embodiment, the more preferred ones are:

The outer cylinder 340 that fits the outer wall is slidably connected to the outside of the middle cylinder 310 , annular brushes 350 are provided at the ends of the inner cylinder 330 and the outer cylinder 340 , and the end of the pull rope 360 away from the inner cylinder 330 is connected to the outer cylinder 340 .

The setting of the annular brush 350 allows dust particles or fine stones on the road surface to be swept away, thereby preventing large-volume debris from entering the inner cylinder 330 and blocking the adsorption tube 140. The two ends of the pull rope 360 are respectively connected to the inner cylinder 330 and the outer cylinder 340, and the weight of the inner cylinder 330 and the outer cylinder 340 are close, so that the roller 370 is easy to rotate;

The outer cylinder 340 is larger than the diameter of the inner cylinder 330. When the width of the marking line is wide, the outer cylinder 340 can be switched to move downward, and the inner cylinder 330 is in an upward state;

In addition, the different sizes of the inner cylinder 330 and the outer cylinder 340 can not only be set according to the width of the marking, but also can be automatically switched when the annular brush 350 is adhered with oil or is too dirty. The switching timing can be when the control system receives the infrared light oil sensor 390 to detect the presence of oil on the road surface.

Regarding the structure of the transmission assembly 200, specifically:

The transmission assembly 200 includes a worm 210 rotatably connected to the vehicle body 100, and two sets of threads are symmetrically arranged on the worm 210. The two sets of threads are respectively meshed with two worm wheels 220, and the two worm wheels 220 are respectively connected to the first connecting rod 230 and the second connecting rod 240. The paint spraying assembly 400 includes a paint spraying nozzle 410, and the paint spraying nozzle 410 is connected to the second connecting rod 240. The middle cylinder 310 is connected to the first connecting rod 230.

When adjusting the marking position, the worm 210 is controlled to rotate. Since the threads on the worm 210 rotate in opposite directions, the worm 210 can drive the two worm wheels 220 to swing synchronously and in opposite directions, so that the connection line between the dust suction component 300 and the paint spraying component 400 is parallel to the direction of travel of the vehicle body 100, ensuring that the dust suction component 300 can clean the road surface that the paint spraying component 400 is about to spray, and by controlling the rotation of the worm 210, the angle between the first connecting rod 230 and the second connecting rod 240 can be changed, so that when marking the roadside, the vehicle body 100 can keep a distance from the roadside, and the dust suction component 300 and the paint spraying component 400 can clean and mark the roadside;

The paint spray nozzle 410 is opened and closed by a control system. When the control system detects that the vehicle body 100 is in a moving state, the paint spray nozzle 410 is opened synchronously.

Among the optional methods of this embodiment, the more preferred ones are:

The transmission assembly 200 further includes a swivel 320 connected to the first connecting rod 230 , and the middle cylinder 310 is rotatably connected to the swivel 320 .

The middle cylinder 310 can rotate relative to the rotating ring 320, so that the middle cylinder 310 can be driven to move, and the position of the infrared oil pollution sensor 390 can be adjusted to move to the direction on the middle cylinder 310 toward the vehicle body 100.

Among the optional methods of this embodiment, the more preferred ones are:

The transmission assembly 200 further includes a fixed seat 251 , to which a first pulley 250 is fixedly connected. A second pulley 270 is fixedly connected to the middle of the middle cylinder 310 . A belt 260 is transmission-connected between the first pulley 250 and the second pulley 270 .

Since the first pulley 250 is not rotatable, the belt 260 can move on the first pulley 250 when the first connecting rod 230 swings. At this time, the belt 260 drives the second pulley 270 to rotate, and the second pulley 270 is fixedly connected to the middle cylinder 310. Therefore, when the first connecting rod 230 swings, the middle cylinder 310 can rotate at the same time, and the rotation angle of the middle cylinder 310 increases and decreases synchronously with the swing of the first connecting rod 230, ensuring that the bracket 380 is always facing the moving direction of the vehicle body 100, so that when the position of the dust collection assembly 300 changes, the infrared light oil sensor 390 can always detect the road surface that the middle cylinder 310 is about to pass.

Among the optional methods of this embodiment, the more preferred ones are:

The vehicle body 100 includes a vehicle body 110 and moving wheels 120 connected to the bottom of the vehicle body 110 .

The vehicle body 110 carries various components and moves by satellite positioning or remote control.

Regarding the structure of the scrubbing assembly 500, specifically:

The brushing assembly 500 includes a lower rack 520, the end of which is connected to a mounting frame 521, a motor 530 is vertically slidably connected to the mounting frame 521, an output end of the motor 530 is connected to a brush plate 540, and a nozzle for spraying a degreasing agent is connected to the mounting frame 521, with the nozzle facing the brush plate 540. When oil stains adhere to the road surface to be marked, the motor 530 moves downward to make the brush plate 540 contact the road surface, and the nozzle sprays the degreasing agent toward the brush plate 540.

The dust suction component 300, the brush disc 540 and the paint spraying component 400 can always be in the same straight line. When the infrared oil sensor 390 detects oil on the road surface, the roller 370 rotates to make the pull rope 360 pull the inner cylinder 330 upward, so that the annular brush 350 does not contact the road surface, avoiding the annular brush 350 from being contaminated with oil. At the same time, the motor 530 moves downward and drives the brush disc 540 to rotate. In addition, the nozzle sprays a degreasing agent toward the position of the brush disc 540, so that the brush disc 540 can clean the oil on the road surface and ensure that the paint is stably attached to the road surface.

Among the optional methods of this embodiment, the more preferred ones are:

The brush assembly 500 further includes a gear 510 connected to the middle of the worm 210 , and a lower rack 520 meshes with the gear 510 .

As the worm 210 rotates, the gear 510 connected thereto also rotates synchronously. At this time, the gear 510 drives the lower rack 520 to move away from or close to the vehicle body 110, so that the brush plate 540 can be located on the connecting line of the dust collection component 300 and the paint spraying component 400.

Among the optional methods of this embodiment, the more preferred ones are:

The scrubbing assembly 500 further includes an upper rack 550 meshing with the gear 510 , and a counterweight 560 is connected to an end of the upper rack 550 .

The upper rack 550 and the lower rack 520 are symmetrically arranged. When the worm gear 220 rotates to move the brush plate 540 away from the vehicle body 110, the upper rack 550 simultaneously drives the counterweight block 560 away from the vehicle body 110 and the brush plate 540, so that the center of gravity of the vehicle body 110 is balanced, thereby increasing the stability of the vehicle body 100.

Among the optional methods of this embodiment, the more preferred ones are:

The counterweight block 560 is slidably connected to the upper rack 550 , and when the motor 530 moves downward, the counterweight block 560 slides toward the lower rack 520 .

The counterweight 560 is symmetrically arranged with the brush plate 540. The brush plate 540, the dust suction assembly 300 and the paint spray nozzle 410 are all arranged in the same straight line. The counterweight 560 offsets the offset force of the brush plate 540, the dust suction assembly 300 and the paint spray nozzle 410 on the vehicle body 110. When the infrared light oil pollution sensor 390 scans the presence of oil pollution on the road surface, the control system controls the motor 530 to move downward so that the brush plate 540 contacts the road surface. At the same time, the counterweight 560 slides in the direction close to the brush plate 540, so that the center of gravity of the vehicle body 110 is offset toward the brush plate 540, ensuring that the brush plate 540 can be in close contact with the road surface.

The counterweight 560 and the motor 530 can be connected to the upper rack 550 and the mounting frame 521 respectively through an electric slider or an electric telescopic rod, and the control system makes the counterweight 560 and the motor 530 slide by controlling the electric slider or the electric telescopic rod.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims (7)

1. The target point cleaning mechanism of the scribing vehicle comprises a vehicle body (100) and is characterized in that a transmission assembly (200) is arranged on the vehicle body (100), and a dust collection assembly (300) and a paint spraying assembly (400) are arranged on the transmission assembly (200);

the dust collection assembly (300) comprises a middle cylinder (310), an inner cylinder (330) attached to the inner wall of the middle cylinder (310) is connected inside the middle cylinder in a sliding manner, a pull rope (360) is connected to the top of the inner cylinder (330), two rollers (370) are connected to the side wall of the middle cylinder (310) in a vertically symmetrical rotation manner, the pull rope (360) is inserted between the two rollers (370), an adsorption tube (140) is communicated with the top wall of the inner cylinder (330), and a negative pressure cylinder (130) is communicated with the end part of the adsorption tube (140);

The outer wall of the middle cylinder (310) is connected with a bracket (380), the bottom of the bracket (380) is connected with a cover body (381), an infrared light oil stain sensor (390) is arranged in the cover body (381), and when oil stains are attached to a road surface to be marked, the roller (370) rotates to enable the pull rope (360) to pull the inner cylinder (330) to ascend;

The transmission assembly (200) comprises a worm (210) rotationally connected to the vehicle body (100), two groups of threads are symmetrically arranged on the worm (210), two worm gears (220) are respectively meshed with the two groups of threads, a first connecting rod (230) and a second connecting rod (240) are respectively connected to the two worm gears (220), the paint spraying assembly (400) comprises a paint spraying nozzle (410), the paint spraying nozzle (410) is connected to the second connecting rod (240), and the middle cylinder (310) is connected to the first connecting rod (230);

the transmission assembly (200) further comprises a swivel (320) connected to the first link (230), and the middle cylinder (310) is rotatably connected to the swivel (320);

The transmission assembly (200) further comprises a fixed seat (251), a first belt wheel (250) is fixedly connected to the fixed seat (251), a second belt wheel (270) is fixedly connected to the middle part of the middle cylinder (310), and a belt (260) is in transmission connection between the first belt wheel (250) and the second belt wheel (270);

Because the first belt wheel (250) is not rotatable, the belt (260) can move on the first belt wheel (250) when the first connecting rod (230) swings, at the moment, the belt (260) drives the second belt wheel (270) to rotate, and the second belt wheel (270) is fixedly connected with the middle cylinder (310), so that when the first connecting rod (230) swings, the middle cylinder (310) can rotate simultaneously, the rotation angle of the middle cylinder (310) and the swinging of the first connecting rod (230) increase and decrease synchronously, the support (380) is ensured to always face the moving direction of the vehicle body (100), and the infrared light oil stain sensor (390) can always detect the road surface which the middle cylinder (310) is about to pass through when the position of the dust collection assembly (300) changes.

2. The target point cleaning mechanism of the scribing vehicle as set forth in claim 1, wherein an outer cylinder (340) attached to an outer wall is slidably connected to an outside of the middle cylinder (310), annular brushes (350) are provided at ports of the inner cylinder (330) and the outer cylinder (340), and one end of the pull rope (360) away from the inner cylinder (330) is connected to the outer cylinder (340).

3. The scribing car as set forth in claim 2, characterized in that the car body (100) comprises a car body (110) and a moving wheel (120) connected to the bottom of the car body (110).

4. The target point cleaning mechanism of a scribing vehicle as set forth in claim 3, further comprising a brushing assembly (500), wherein the brushing assembly (500) comprises a lower rack (520), a mounting frame (521) is connected to an end portion of the lower rack (520), a motor (530) is connected to the mounting frame (521) in a vertically sliding manner, a brush plate (540) is connected to an output end of the motor (530), a nozzle for spraying a degreasing agent is connected to the mounting frame (521), the nozzle faces the brush plate (540), when oil stains are attached to a road surface to be scribed, the motor (530) moves down to enable the brush plate (540) to contact the road surface, and the nozzle sprays the degreasing agent to the brush plate (540).

5. The target point cleaning mechanism of scribing car as in claim 4, wherein the brushing assembly (500) further comprises a gear (510) connected to a middle portion of the worm (210), and the lower rack (520) is engaged with the gear (510).

6. The target point cleaning mechanism of scribing car as set forth in claim 5, wherein the brushing assembly (500) further comprises an upper rack (550) engaged with the gear (510), and a balancing weight (560) is connected to an end of the upper rack (550).

7. The target point cleaning mechanism of scribing car as set forth in claim 6, wherein said weight (560) is slidably connected to said upper rack (550), and said weight (560) slides in the direction of said lower rack (520) when said motor (530) moves downward.