JP2946283B2 - Automatic feeding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic feeder for transporting a feed loaded on a carry to a predetermined tub and automatically supplying the feed to the tub.

[0002]

2. Description of the Related Art Conventionally, as an automatic feeder capable of automatically supplying feed weighed for each cow body to each tub provided with a plurality of stalls, there is an automatic feeder disclosed in Japanese Patent Application Laid-Open No. 60-55359. Feeding devices are known.

[0003] This automatic feeder comprises a circulation type hopper running conveyor suspended from a ceiling or the like, a driving device for driving the conveyor, a feed hopper mounted movably on the conveyor, and A feed supply device for supplying feed at a predetermined position to a hopper for feed transportation,
A push rod is provided corresponding to each tub, and when feeding the feed, the push rod corresponding to the tub to which the feed is to be supplied is projected, and the hopper carrying the feed is circulated in the forward direction (forward direction). By doing so, when the hopper passes through the push rod, the push rod opens the bottom lid of the hopper, and the feed falls from the hopper and is supplied to the breeding tank.

[0004]

However, such a conventional automatic feeding apparatus has the following problems.

[0005] First, since the push rods individually controlled by the control device are provided for each breeding tub, a large number of push rods and wiring for connecting each push rod to the control device are required, which makes the equipment complicated and costly. In addition to the above, troubles are more likely to occur and reliability is lacking.

Second, since the amount of movement of the hopper cannot be accurately controlled, the hopper is circulated in the forward direction so that food is fed when the hopper passes a target tub (push rod). Therefore, since the hopper always needs to make the endless conveyer make a round, the feeding time becomes long, and efficient feeding cannot be performed, and wasteful energy consumption is caused.

[0007] Third, when a worker or a cow hits the moving hopper, the detection and abnormal processing such as automatic stop control cannot be performed quickly and accurately.

The present invention has solved the above-mentioned problems in the prior art, and can greatly simplify equipment and reduce costs, and further improve reliability, feed efficiency and energy saving. In addition, an object of the present invention is to provide an automatic feeding device that can quickly and accurately perform abnormality detection and automatic stop control.

[0009]

According to the present invention, there are provided a plurality of tanks.
a, 2b..., a wire moving mechanism 4 for moving the wire member 6 along the transfer rail 3 by the driving unit 5, and a feed tank 2a.
And one or more carry 7x, 7y fixed to the wire member 6 while being movably loaded on the transport rail 3.
... and the carry 7x located at the home position Ps ...
And a control unit 9 for controlling the wire moving mechanism unit 4 and the feed mounting unit 8.
When the automatic feeder 1 is configured to transport the feed loaded on the carry 7x to a predetermined tub 2a and automatically supply the feed to the tub 2a, in particular, a dog 10a provided corresponding to the tub 2a. , 10b, a lock mechanism 12 for locking the bottom cover 11 of the carry 2x, which opens in a natural state, in a closed position, and the dog only when the carry 7x passes in the opposite direction to the dog 10a. 10a
, And a control unit 9 for controlling the movement of the wire member 6 in the forward direction Df and the reverse direction Dr.

In this case, the lock mechanism 12 has a lock lever 15 for locking the bottom cover 11 of the carry 7x. Are pushed by the dog 10a only when the carry 7x passes in the reverse direction with respect to the dog 10a, thereby displacing the lock lever 15 to release the lock of the lock mechanism portion 12. ...

Further, according to the most preferred embodiment, the wire moving mechanism 4 includes a wire running mechanism 18 having a wire member 6 spanned over guide pulleys 17o, 17p, 17q,. Pulley 17m
Is provided. Furthermore, a predetermined tension is applied to the wire member 6 by urging a tension pulley 17n that is displaceably provided to the wire moving mechanism unit 4.
For example, a tension applying mechanism 19 using a suspended weight 20 is provided.

On the other hand, the control unit 9 includes a movement amount detection unit 21 for detecting the movement amount of the wire member 6 by rotation of the detection pulley (tension pulley) 17n, and includes a drive pulley 17m and a detection pulley 17n. An abnormality detection function for detecting an abnormality by a change in the relative rotation difference is provided.

[0013]

According to the automatic feeder 1 of the present invention, the drive pulley 17m rotates when the drive unit 5 of the wire moving mechanism 4 is operated.
The wire member 6 spanning 7 m is also moved in the forward direction Df or the backward direction Dr. Also, since the carry 7x fixed to the wire member 6 follows the wire member 6,
While moving along the transport rail 3, the transport rail 3
Are arranged along a plurality of tanks 2a, 2b ...
The carry 7x moves along the plurality of tubs 2a.

At the time of feeding, the control unit 9 controls the wire moving mechanism unit 4, and the carry 7x moves in the forward direction Df and is set to the home position Ps. And
The feed unit 8 is controlled by the control unit 9, and the feed for an arbitrary cow body is measured, and the measured feed is mounted on the carry 7x by the feed mounting unit 8. In addition,
The bottom lids 11 of the carry 7x set at the home position Ps are closed and locked by the lock mechanism 12. That is, the lower ends of the lock levers 15 are locked to the bottom lids 11, and the bottom lids 11 are locked in the closed position.

[0015] Carry 7x by feed loading unit 8 ...
When the loading of the feed is completed, the wire moving mechanism unit 4 is controlled by the control unit 9 and the carry 7x loaded with the feed moves in the forward direction Df and reaches the target tank 2a to be supplied. , The dogs 10a... At this time, the clutch mechanism 13
The clutch levers 16 are displaced in contact with the dogs 10a, but the clutch levers 16 are displaced away from the lock levers 15 of the lock mechanism parts 12, so that the bottom lids 11 by the lock mechanism parts 12 are formed.
Is not unlocked. Further, the moving position of the carry 7x, that is, the moving amount of the wire member 6 is determined by the moving amount detecting unit 21.
Thus, the rotation is accurately detected from the rotation of the detection pulley 17n.

If the carry 7x is moved in the reverse direction Dr by controlling the wire moving mechanism 4, the clutch levers 16 in the clutch mechanisms 13 are again displaced by hitting the dogs 10a. At this time, since the clutch levers 16 hit the dogs 10a in the reverse direction Dr, the clutch levers 16 push the lock levers 15 to be rotationally displaced. As a result, the lock levers 15 ...
Are also displaced, and the lock on the bottom lids 11 is released. Therefore, the bottom lids 11 are opened by their own weight, and the feed contained in the carry 7x falls and is supplied to the inside of the tub 2a. In this case, since the dogs 10a can use a fixed simple rod, the facility can be simplified and the cost can be reduced. On the other hand, in order to return the carry 7x to the home position Ps, the carry 7x may be moved in the reverse direction Dr as it is.
Efficient feeding and energy saving are achieved.

Meanwhile, the tension pulley (detection pulley) 17n provided movably is urged by a suspended weight 20 in a tension applying mechanism 19, and a constant tension is applied to the wire member 6. Therefore, a predetermined slippage can be generated between the driving pulley 17m and the wire member 6, so that, for example, even when an operator or a cow hits the moving carry 7x. The sliding between the members 6 reduces the impact. At this time, the driving pulley 1
Since the relative rotation difference between the detection pulley 7m and the detection pulley 17n changes, if the change in the relative rotation difference is detected by the abnormality detection function of the control unit 9, abnormality processing such as automatic stop control can be quickly performed. Note that even if slippage occurs, the amount of movement of the wire member 6 is detected by the rotation of the detection pulley 17n, so that the amount of movement is accurately detected without being affected by the slippage.

[0018]

Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, the configuration of the automatic feeding apparatus 1 according to the present embodiment will be described with reference to FIGS.

In FIG. 1, Aa, Ab... Are a plurality of stalls arranged in two rows in a pair of tails.
are arranged in front of the tanks 2a, 2b,. Further, one dairy cow C (FIG. 2) is moored to each stall Aa.

On the other hand, 3 is a transport rail,
a, 2b... are disposed along the breeding tanks 2a, 2b. In this case, the transport rails 3 are installed using some frames F constituting the stalls Aa, Ab. As shown in FIG. 3, the transport rail 3 is formed in a C-shaped channel shape by providing a slit 31 along the longitudinal direction on the bottom surface of the internal hollow member having a rectangular cross section, and is installed in a U shape in plan view. .

Reference numeral 4 denotes a wire moving mechanism, which has a function of moving the wire member 6 along the transport rail 3 by the driving unit 5. The wire moving mechanism 4 includes a plurality of guide pulleys 17o, 17p, 17q, 17r, 17s, 1 at a predetermined position such as a corner position below the transport rail 3.
7t, and an endless wire member 6 is bridged over the guide pulleys 17o. In this case, some guide pulleys 17p, 17q
Are installed above the other guide pulleys 17o and secure a passage below.

Further, a drive box 32 is provided on the traveling path of the wire member 6, and a drive unit 5 having a motor and a speed reduction mechanism is provided inside the drive box 32 as shown in FIG. . The rotation output shaft 5s of the drive unit 5 is exposed from the upper surface of the drive box 32, and a driving pulley 17m is attached to the tip thereof. On the other hand, inside the drive box 32, a movement amount detection unit 21 using a rotary encoder or the like is arranged, and its rotation input shaft 21s is exposed from the upper surface of the drive box 32 and slidably moves on the upper surface of the drive box 32. The detection pulley 17n is attached to the rotation input shaft 21s which is rotatably supported by the movable bearing 33 provided and is exposed to the outside. And the driving pulley 17m
And the wire member 6 is bridged over the detection pulley 17n. Note that the positional relationship between the driving pulley 17m and the detection pulley 17n is such that the wire member 6 spans a half circumference of the driving pulley and a half circumference of the detection pulley so as to form an S-shaped traveling path.

On the other hand, a small pulley 35 supported by a bracket 34 is provided on a side surface of the drive box 32, and a suspension wire 36 having one end connected to the movable bearing portion 33 is connected to the small pulley 3.
The tension applying mechanism 19 is formed by hanging the suspension wire 5 and attaching the weight 20 to the other end of the suspension wire 36. As a result, the detection pulley 17n is urged by the weight 20, and a predetermined amount of tension determined by the weight of the weight 20 is applied to the wire member 6. For this reason, the detection pulley 17n also serves as a tension pulley. Therefore, by changing the weight of the weight 20, the magnitude of the tension can be arbitrarily set, and in particular, the magnitude of the slip between the driving pulley 17m and the wire member 6 can be set.

On the other hand, 7x, 7y... Are arranged at the same intervals as the breeding tanks 2a, 2b... And are movably loaded on the transport rails 3 and fixed to the wire member 6. I do. The carry 7x (the other carry 7y... Are the same) is configured as shown in FIGS.
That is, the carry 7x is formed in a rectangular parallelepiped box shape, and a feed opening 41 which is fully open is provided at a lower end, and a feed loading opening 42 which is semi-open at an upper end. In addition, a bottom lid 11 for opening and closing the feed drop opening 41 is provided. The bottom lid 11 is rotatably mounted at one end to one end of the carry 7x via support shafts 43. As a result, the bottom cover 11 is opened by its own weight in a natural state. On the other hand, the lower ends of the pair of support stays 45, 45 are fixed to the upper surface portion 44, and the disk-shaped sliders 46, 46 formed of a low friction material such as Teflon (trade name) are accommodated in the transport rail 3. The upper ends of the support stays 45, 45 are connected to the sliders 46, 46, respectively. By using such sliders 46, it is possible to provide a self-cleaning function for discharging dust, dust and the like in the transport rail 3 to the outside. Note that rotating rollers may be used instead of the sliders 46.

Further, a wire member 6 is fixed to an intermediate portion between the support stays 45,45. In this case, as shown in FIGS. 8 and 9, the support stays 45 are constituted by an upper stay 45u and a lower stay 45d, and a flange portion 47u is provided at a lower end of the upper stay 45u, and a flange portion is provided at an upper end of the lower stay 45d. 47d is provided, and the two are joined with the wire member 6 interposed therebetween. Reference numerals 48... Denote wire regulating pins. Thereby, the outer surfaces of the flange portions 47u and 47d engage with the inner surfaces of the groove portions of the guide pulleys 17s and are guided.

On the other hand, on the inner side of the carry 7x with respect to the support shafts 43, the support side surfaces 4 parallel to the support shafts 43 are provided.
8, and the lock mechanism 12 and the clutch mechanism 13 shown in FIG. The lock mechanism unit 12 includes a lock lever 15 bent into an L shape,
The upper intermediate portion is rotatably attached to the support side surface portion 48 via the support shaft portion 49. At this time, by interposing a collar member 50 between the support side surface portion 48 and the lock lever 15, the lock lever 15 is separated from the support side surface portion 48, and the locking position between the lower end of the lock lever 15 and the bottom cover 11 is established. Are located outside the axis of the support shafts 43. Therefore, the lock lever 15 is located vertically in the natural state. The clutch mechanism 13 has a clutch lever 16. This clutch lever 16 is the same as the lock lever 15. The clutch lever 16 is turned upside down by 180 ° with respect to the lock lever 15, and is rotatably attached to a support side surface portion 48 located directly above the lock lever 15 via a support shaft portion 51. In this case, the collar member 52 is interposed in the same manner as the lock lever 15 to separate the clutch lever 16 from the support side portion 48, and the clutch lever 16
Of the lower end of the lock lever 15 overlaps a part of the upper end of the lock lever 15, and the clutch lever 16 is
5 is positioned on the positive direction Df side in the moving direction of the wire member 6.

On the other hand, reference numeral 8 denotes a feed loading section for weighing (including blending) the feed on the carry 7x... Located at the home position Ps. The feed is a TMR (total mixture ration) feed (food residue such as okara). 61, a first screw auger 62 for supplying concentrated feed, and a second screw auger 63 for supplying additives such as salt and calcium. The mixer 61, the first screw auger 62 The feed supplied from the second screw auger 63 is supplied to the bottom tank 64 and then sent to and carried by the carry 7x located at the home position Ps while being stirred by the screw conveyor 65. If necessary, water or the like may be added on the way.

In FIG. 7, reference numeral 9 denotes a control section for controlling the wire moving mechanism section 4 and the feed mounting section 8, and comprises a control unit section 71, a computer section 72 and the movement amount detecting section 21. The control unit 71 is connected to the drive unit 5 in the wire moving mechanism unit 4 and the feed loading system drive unit 73 in the feed loading unit 8. Further, the control unit 9 has an abnormality detection function of detecting an abnormality based on a change in a relative rotation difference between the driving pulley 17m and the detection pulley 17n.

Next, the operation of the automatic feeding apparatus 1 according to the present embodiment will be described with reference to the flowcharts shown in FIGS.

First, in the computer section 72, various feeding conditions such as feeding time (about six times a day), the amount of feed to individual cows, and preparation conditions are set in advance. The feed amount and preparation conditions for each cow can be set based on milk yield, milk period, body weight, and the like.

On the other hand, the feeding operation proceeds as follows.
Now, assume that the first carry 7x is waiting at the standby position (step S1). At the set time, first, feed loading processing is performed (steps S2 and S3). The feed loading process is executed as shown in FIG. First, the control unit 71 operates the drive unit 5 to move the wire member 6 in the forward direction Df (step S31).

Thus, the carry 7x is set at the home position Ps immediately below the exit of the screw conveyor 65 (steps S32 and S33). At this time, the bottom lid 11 of the carry 7x is automatically closed by the automatic lid closing mechanism (not shown) and locked by the lock mechanism 12.

In the feed loading section 8, the feed corresponding to the bovine in the feeding tanks 2a to be fed is measured.
In this case, the TMR feed is measured by the mixer 61,
In addition, the concentrated feed is measured by the first screw auger 62, the additive is measured by the second screw auger 63, and the measured feed is mounted on the carry 7x while being stirred by the screw conveyor 65 from the bottom tank 64. (Steps S34, S35, S36). Such mounting processing is similarly executed for all the remaining carry 7y (Step S37).

When the loading of the feed on all the carry 7x by the feed loading unit 8 is completed, the carry 7x on which the feed is loaded is moved in the forward direction Df (steps S4 and S5). In this case, the carry 7x is moved to the target breeding tank 2a, and stopped at a position slightly passing the corresponding dog 10a (steps S6, S7).
At this time, the upper ends of the clutch levers 16 in the clutch mechanism sections 13 are rotationally displaced by hitting the dogs 10a, but the lower ends of the clutch levers 16 are
Are displaced away from the lock levers 15 so that the lock of the bottom lids 11 by the lock mechanisms 12 is not released. Further, the moving position of the carry 7x, that is, the moving amount of the wire member 6 is accurately detected from the rotation of the detection pulley 17n by the moving amount detecting unit 21, and the moving position of the carry 7x is set in advance. Are stopped when the movement amount detected by the movement amount detection unit 21 matches the set movement amount.

On the other hand, if the wire moving mechanism section 4 is controlled to move the carry 7x in the reverse direction Dr, the clutch levers 16 in the clutch mechanism sections 13 rotate again when their upper ends again hit the dogs 10a. (Steps S8 and S9). At this time, since the clutch levers 16 hit the dogs 10a in the reverse direction Dr, the lower ends of the clutch levers 16 press the upper ends of the lock levers 15 to be rotationally displaced. As a result, the lower ends of the lock levers 15 are also displaced, and the lock on the bottom lids 11 is released.
Therefore, the bottom lids 11 open by their own weight, and the carry 7x ...
Are dropped and supplied into the breeding tanks 2a (steps S10, S11). In this case, dog 1
.. Are simple fixed rods, so that the equipment can be simplified and the cost can be reduced. On the other hand, if the carry 7x is moved in the reverse direction Dr, the home position P
It is returned to the s side (step S12). Therefore, efficiency of feeding and energy saving can be achieved. And the whole tank 2a ...
May be performed in the same manner as in step S1.
3).

Incidentally, the tension pulley (detection pulley) 17n which is provided so as to be freely displaced is urged by a suspended weight 20 in a tension applying mechanism 19, and a constant tension is applied to the wire member 6. Therefore, a predetermined slippage can be generated between the driving pulley 17m and the wire member 6, so that, for example, even when an operator or a cow hits the moving carry 7x. The sliding between the members 6 reduces the impact. At this time, the driving pulley 17
m and the relative rotation difference between the detection pulley 17n change.
If the change in the relative rotation difference is detected by the abnormality detection function of the control unit 9, abnormality processing such as automatic stop control can be quickly performed. Note that even if slippage occurs, the amount of movement of the wire member 6 is detected by the rotation of the detection pulley 17n, so that the amount of movement is accurately detected without being affected by the slippage.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment.
For example, the transport rail may be shaped other than a C-shaped channel, and does not prevent the use of a circulating rail. Further, the tension applying mechanism does not prevent the use of other urging means such as a spring. Further, the tension pulley and the detection pulley may be used separately and independently. In addition, the configuration, shape, method, and the like of the details can be arbitrarily changed without departing from the gist of the present invention.

[0039]

As described above, the automatic feeding device according to the present invention is particularly designed so that the dog provided corresponding to the breeding tub and the bottom cover of the carry which opens in a natural state are locked to the bottom cover at the closed position. A lock mechanism portion having a lock lever that locks the lock mechanism, and a clutch lever that displaces the lock lever by being pushed by the dog only when the carry passes through the dog in the opposite direction to release the lock of the lock mechanism. The provision of the control unit for controlling the movement of the wire member in the forward direction and the reverse direction provides the following remarkable effects.

[0040] Since the dog need only be a fixed simple rod, the facility can be simplified and the cost can be reduced, and there is no risk of trouble such as a failure, so that reliability can be improved.

By providing the movement amount detection unit for detecting the movement amount of the wire member by the rotation of the detection pulley in the control unit, the carry can be accurately controlled in the forward and reverse directions, so that useless movement is eliminated. It can improve the efficiency of feeding and save energy.

Even if a worker or a cow hits the moving carry, the detection and abnormal processing such as automatic stop control can be performed quickly and accurately.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of an automatic feeding device according to the present invention,

FIG. 2 is a side view of one stall and surroundings of the automatic feeding device;

FIG. 3 is a side view of a carry in the automatic feeding device,

FIG. 4 is a perspective view of a lock mechanism and a clutch mechanism provided for a carry in the automatic feeding device;

FIG. 5 is a front view of a carry in the automatic feeding device;

FIG. 6 is a front view showing a state in which a dog has hit a clutch mechanism of the carry in the automatic feeding apparatus;

FIG. 7 is a block diagram showing a configuration of a drive unit and a control unit in the automatic feeding device;

FIG. 8 is a partial cross-sectional plan view showing a connection structure of a carry and a wire member in the automatic feeding device;

FIG. 9 is a front view showing a coupling structure of the carry and the wire member in the automatic feeding device;

FIG. 10 is a flowchart showing the entire operation of the automatic feeding device;

FIG. 11 is a flowchart showing feed loading processing in the operation of the automatic feeding apparatus;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Automatic feeding device 2a ... Feeding tank 3 Transport rail 4 Wire moving mechanism part 5 Drive part 6 Wire member 7x ... Carry 8 Feed loading part 9 Control part 10a ... Dog 11 Bottom cover 12 Lock mechanism part 13 Clutch mechanism part 15 Lock lever 16 Clutch Lever 17o ... Guide pulley 17m Driving pulley 17n Detection pulley (tension pulley) 18 Wire traveling mechanism 19 Tension applying mechanism 20 Weight 21 Movement amount detection unit Ps Home position Df Forward direction Dr Reverse direction

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mitsuhiro Seibu 246 Sachika, Oaza, Suzaka City, Nagano Prefecture Inside (72) Inventor Isao Harada 246 Sachika, Sazaka, Suzaka City, Nagano Prefecture Orion Machine Co., Ltd. (72) Inventor Shigetada Tsuchiya 246 Sachika, Oaza, Suzaka City, Nagano Prefecture Inside (72) Inventor Takashi Kuwana 246 Sachika, Sazaka, Suzaka City, Nagano Prefecture Inside Orion Machinery Corporation (72) Nobuaki Ishizuka 1-40-2 Nisshin-cho, Omiya City, Saitama Prefecture Inside the Biotechnology-Specific Industrial Technology Research Promotion Organization (72) Inventor Manjo Ichito 1-40-2 Nisshin-cho, Omiya City, Saitama Prefecture Biotechnology-Specific Industrial Technology Research Within the Propulsion Agency (72) Inventor Mitsuru Hachiya 1-40-2 Nisshin-cho, Omiya City, Saitama Prefecture Within the Biotechnology-Specific Industrial Technology Research Promotion Agency (56) References Akira 49-54167 (JP, A) (58 ) investigated the field (Int.Cl. ^6, DB name) A01K 5/00 - 5/02 A01K 39/00 - 39/04

Claims (8)

(57) [Claims] 1. A transport rail arranged along a plurality of tubs, a wire moving mechanism unit for moving a wire member along the transport rail by a driving unit, and arranged at the same interval as the tub, and Controlling one or more carry fixedly mounted on the wire member, a feed loading unit for weighing and loading the feed on the carry located at the home position, a wire moving mechanism unit and a feed loading unit. In an automatic feeding device that transports the feed loaded on the carry to a predetermined tank and automatically feeds the feed to the tank, a dog provided corresponding to the tank and a bottom of the carry that opens in a natural state are provided. A lock mechanism having a lock lever that locks by locking to the bottom cover when the cover is closed, and pressing the dog only when the carry passes in the opposite direction to the dog. An automatic feeding device having a clutch mechanism having a clutch lever for displacing the lock lever to release the lock of the lock mechanism, and a controller for controlling the movement of the wire member in the forward and reverse directions. apparatus. 2. The automatic feeder according to claim 1, wherein the wire moving mechanism includes a wire running mechanism in which a wire member is stretched over a guide pulley. 3. The automatic feeding device according to claim 1, wherein the wire moving mechanism includes a driving pulley that is rotated by a driving unit. 4. A wire moving mechanism section comprising a tension applying mechanism for applying a predetermined tension to a wire member by urging a displaceable tension pulley. Automatic feeding device as described. 5. The automatic feeding device according to claim 4, wherein the tension applying mechanism uses a suspended weight. 6. The automatic feeding device according to claim 1, wherein the control unit includes a movement amount detection unit that detects a movement amount of the wire member by rotation of the detection pulley. 7. The automatic feeder according to claim 4, wherein the tension pulley also serves as a detection pulley. 8. The automatic feeding apparatus according to claim 1, wherein the control unit has an abnormality detecting function for detecting an abnormality based on a change in a relative rotation difference between the driving pulley and the detection pulley.