FORM 2
The Patents Act 1970
(39 of 1970)
&
The Patent Rules 2003
COMPLETE SPECIFICATION
(See Section 10 and rule 13)
TITLE OF THE INVENTION:
PALLETS HANDLING SYSTEM WITH AUTOMATIC LEVEL ADJUSTEMNT MECHANISM FOR CONVEYORISED ASSEMBLY LINE
APPLICANT:
LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No. 278,
Mumbai, 400 001, Maharashtra. INDIA.
PREAMBLE OF THE DESCRIPTION:
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

A) TECHNICAL FIELD
[0001] The present invention generally relates to conveyor system in assembly line and particularly to pallet handling systems for conveyor system in assembly line. The present invention more particularly relates to an automatic level adjust system in the pallet handling systems to load and unload pallets automatically to the conveyor line.
B) BACKGROUND OF THE INVENTION
[0002] Conveyor lines are used in various industrial applications, factories, warehousing and freight-handling for the movement of raw materials. The conveyor belt forming a continuous loop is supported either on rollers (for heavy loads) or on a metal slider pan (if loads are light enough to prevent frictional drag on the belt). The conveyor line constitutes a power driven chain conveyor on which the products are processed on the stations. These products are then transferred on the pallets from one station to another. The pallet is a small platform made of wood, metal or any other material that is used to store and transport stacks of goods or materials. Usually the pallets are moved with forklifts or pallet jacks.
[0003] The pallets are used for product movement, indexing and product
manoeuvring for assembly purposes. When the pallets reach to the end of the line,
those need to be collected and fed back to the conveyor at the starting station. At the
end of the conveyor line, the products are removed for further processing and the
pallets are left behind there. These pallets are required to be collected manually and to
be sent back to the first station.
2

[0004] Earlier operators used to stack the pallets on a trolley one above the other. They had to lift the pallets and keep it at shoulder height. Typical pallet weight is more than 10 Kg. Multiple pallets are handled per shift resulting in fatigue. Then the pallets were to be loaded to the conveyor by lifting from the stack, which was at shoulder height. This was inconvenient and resulting in fatigue of the operator. In addition to this the process was not safe.
[0005] For this purpose, a pallet return mechanism is required to transfer the pallets automatically to the first station from the last station. Generally the conveyorised system is built with a pallet return mechanism installed at the bottom of the conveyor line. This system carries the pallets from the final station to the first station. This system is a complex system to transport the pallets using a return belt at bottom of the line. The pallet return mechanism could not be installed due to lack of space at the bottom of the conveyor line and also the cost of the system would be around 40-50% of the total cost of the conveyor line. Also, there is no system available at present to automatically load and unload the pallets onto the conveyor line.
[0006] Hence there is a need to provide a system and method for automatically loading and unloading of pallets onto the conveyor line. Also there is a need to provide a trolley system for stacking the pallets and then sending them from the last station to the first station of the conveyor line with minimum consumption of space, money and human effort. Further there is a need to maintain the feeding height at the height of the conveyor irrespective of number of pallets.

[0007] The abovementioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.
C) OBJECTS OF THE INVENTION
[0008] The primary object of the present invention is to develop system and method for handling return pallets and automatic level adjustment of pallet stacks in a conveyorised assembly flow line.
[0009] Another object of the present invention is to develop a system for loading and unloading of pallets automatically onto the conveyor line.
[0010] Yet another object of the present invention is to develop a system which is able to automatically adjust the level of pallet stack for placing the pallets onto the conveyor line with respect to the level of the conveyor line at the first station, whenever a pallet is loaded from the trolley.
[0011] Yet another object of the present invention is to develop a system which is able to automatically adjust the level of pallet stack for receiving the pallets at the last station of the conveyor line.
[0012] Yet another object of the present invention is to develop a system for collecting and sending the pallets from the last station to the first station of the conveyor line with minimum consumption of space, money and human effort.
4

[0013] Yet another object of the present invention is to develop a system for loading and unloading of pallets safely with very less human effort, thereby reducing fatigue and improving productivity.
[0014] These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.
D) SUMMARY OF THE INVENTION
[0015] The various embodiments of the present invention provide system and method for handling return pallets and automatic level adjustment of pallet stacks in a conveyor at an assembly flow line. According to one embodiment of the present invention, a pallet handling system with automatic level adjustment mechanism for assembly line is provided with a trolley at the loading end and a trolley at the unloading end. A pallet support storage rack is provided at the trolleys. A top pallet pusher system and a bottom pallet elevator system are provided on the trolleys. A control module provided at the trolleys is connected to the top pallet pusher system and to the bottom pallet elevator system. Pluralities of castor wheels are provided at the trolleys. The control module activates the bottom pallet elevator system to move vertically downwards by a preset level during the receipt of a pallet from a conveyor in an assembly line and to move vertically upwards by a preset level during the loading of a pallet into the conveyor sothat the height of the pallet to be loaded into the conveyor line is maintained always at a preset height.
[0016] The control module activates the bottom pallet elevator system to move vertically downwards by a preset level to receive and store a pallet into the pallet
5

support storage rack in the trolley during the receipt of a pallet from a conveyor in an assembly line and to move vertically upwards by a preset level to unload the pallet at the top most position to the conveyor line using the top pallet pusher system during the loading of a pallet into the conveyor sothat the height of the pallet to be loaded into the conveyor line is maintained at a preset height.
[0017] The trolley has a first limit switch to detect the presence of a pallet in the trolley and a photoelectric sensor to detect the movement of the pallet in the trolley. The pallet storage rack has a pallet support mechanism which is moved vertically upwards or downwards. The pallet support mechanism is provided with a second limit switch at the bottom to detect that the pallet support mechanism has reached the bottom most position of the trolley, to prevent further loading of the pallet into the pallet support storage rack.
[0018] The bottom pallet elevator mechanism has a first motor with a shaft provided at the bottom of the trolley. A gear train is attached to the shaft of the first motor. A main shaft is coupled to the shaft of the first motor through the gear train. A bevel gear train is provided at both the ends of the main shaft. Pluralities of lead screws are coupled to the ends of the main shaft through the bevel gear train. Pluralities of guide rods are provided at the two sides of the trolley.
[0019] The control module activates the first motor provided at the bottom of the trolley to rotate the main shaft to move the lead screws along with the guide rods to move the pallet support mechanism by a preset level vertically in upward direction or downward direction. The control module activates the first motor provided at the bottom of the trolley to rotate the main shaft to move the lead screws along with the guide rods to move the pallet support mechanism by a preset level vertically in

downward direction to receive an incoming pallet from the conveyor in the assembly line during the loading of the pallet into the trolley, when the pallet support mechanism is at the topmost position of the trolley. The control module activates the first motor provided at the bottom of the trolley to rotate the main shaft to move the lead screws along with the guide rods to move the pallet support mechanism by a preset level vertically in upward direction during the loading of the pallet from the trolley onto the conveyor so that the pallet at the top most position in the pallet support mechanism is at a preset height. The preset level is equal to the height of the pallet. The photoelectric sensor in the trolley detects the movement of the pallet in the trolley to output a signal to the control module to regulate movement of the bottom motor.
[0020] The top pallet pusher system has a second motor provided at the top of the trolley. A timing pulley is coupled to the second motor. The control module activates the second motor to push a single pallet out of the trolley, when a pallet loading signal is given to the control module.
[0021] The control module has programmable relays to control the operation of the top pallet pusher system and the bottom pallet elevator system. The trolley has a third limit switch to detect the presence of top pallet pusher system at a final position to output a signal to the control module to reverse the direction of rotation in the second motor to move the top pallet pusher system to an initial position, after the loading of a pallet into the conveyor. The trolley has a fourth limit switch to detect the presence of the top pallet pusher system back at an initial position after the loading of the pallet into the conveyor from the trolley, to output a signal to the control module to restart the pallet loading operation.
7

[0022] The top pallet pusher system is at the initial position during the starting of the loading of pallet onto the conveyor. The top pallet pusher system is at the final position after the completion of the loading of pallet onto the conveyor.
[0023] The pluralities of castor wheels are provided at the front side and at the rear side of the trolley. The pluralities of the castor wheels at the front side are fixed. The pluralities of the castor wheels at the rear side are moved and locked so that the alignment of the trolley with respect to an alignment bracket which is fixed on the floor, is perfect. The pluralities of the castor wheels enable to move the trolley at the last station to the first station after the complete loading of the pallets from the conveyor into the trolley.
[0024] The control module has a processor provided with a software to control the entire loading operation of the pallets into the conveyor from the trolley and the unloading operation of the pallets into the trolley from the conveyor.
[0025] According to one embodiment, the trolley system consists of a pallet support storage rack, a bottom pallet elevator system, a top pallet pusher system and a control unit. The pallet support storage rack stores one or more pallets and includes a bottom pallet support mechanism which is movable up and down along with the loaded pallets. The control unit consists of programmable relay to control the entire operation of the trolley system with the help of switched mode power supply (SMPS) and relays.
8

[0026] The bottom pallet elevator system is used to move the pallet support storage rack vertically up and down. The bottom pallet elevator system includes a bottom motor, a main shaft and a pair of vertical lead screw on each side. The bottom motor drives a motor shaft. The motor shaft drives the main shaft through a gear system. The each end of main shaft is coupled to the each vertical lead screw whose axis is perpendicular to the main shaft axis, through bevel gear arrangements. Each bevel gear arrangement transfers the motion of the main shaft to the vertical lead screws which adjusts the level of the pallet support storage rack up and down with the help of guide rods. The bottom pallet elevator system includes a set of limit switches which detect the presence of the pallet which enters into the pallet support storage rack and maximum limit of the pallets loaded in the pallet support storage rack.
[0027] The top pallet pusher system is used to load the topmost pallet of the pallet support storage rack onto the conveyor line by pushing out in the horizontal position. The top pallet pusher system includes a top motor, a timing pulley arrangement, a horizontal lead screw, and top guide rods. The top motor is coupled to the timing pulley arrangement. When the control signal is received from the control unit, the top motor operates the timing pulley arrangement. The timing pulley arrangement operates the horizontal lead screw along with the top guide rods to push out the topmost pallet of the pallet support storage rack. After pushing out the pallet, the timing pulley arrangement returns back the horizontal lead screw and the top guide rods to their initial position. The top pallet pusher system includes a set of limit switches which detect initial and final positions of the horizontal lead screw and top guide rods.

9

[0028] The trolley system is provided with a handle which enables an operator to move the trolley system easily with the help of front and rear castor wheels on which the entire system is mounted. The alignment of the trolley system is made to be perfect with alignment brackets fixed on the floor while loading or unloading of the pallets onto the conveyor line. The trolley system is connected to the conveyor line through a male-female connector switch for drawing electrical power during the operation of loading or unloading pallets. So that the trolley system becomes a portable trolley which does not need to carry any external battery or power cable connection for its operation.
[0029] According to one embodiment, during unloading of the pallets from the conveyor line, an operator at the last station pushes a single pallet into the trolley system. The bottom pallet elevator mechanism is at the topmost position since there are no pallets loaded in the pallet support storage rack of the trolley system. As the pallet moves fully inside the trolley system in the horizontal position, a limit switch detects the presence of the pallet and sends a signal to the control unit. Meanwhile, the photoelectric sensor also detects the presence of the pallet. The control unit operates the bottom motor to step down the level of the pallet support storage rack by a step down which is equivalent to the width of the pallet. When the top pallet goes down beyond the level of the photoelectric sensor, the photoelectric sensor does not sense the pallet and sends a signal to the control unit. As soon as this signal is received from the photoelectric sensor, the control unit stops the operation of the bottom motor. Thus the level of the pallet support storage rack is adjusted automatically for the intake of next pallet. Similarly more number of pallets are loaded into the trolley system till the maximum limit is reached. Once the maximum
10

limit is reached, it is detected by a second limit switch. The second limit switch sends a signal to the control unit so that another pallet cannot enter into the trolley system.
[0030] According to one embodiment, during loading of the pallets onto the conveyor line, the operator presses the unload button and that signal is sent to the control unit. As soon as the signal is received from the unload button, the control unit runs the top pallet pusher system. Thus the top pallet pusher system pushes out the topmost pallet from the pallet support storage rack with the help of the horizontal lead screw and the top guide rods, onto the conveyor line. A third limit switch detects the position of the horizontal lead screw and the top guide rods when they reach their final position. This signal is used to return back the horizontal lead screw and the top guide rods to their initial position. As soon as the top pallet pusher system returns back to its initial position, a fourth limit switch detects that movement and sends a signal to the control unit. The control unit runs the bottom pallet elevator system to step up the level of the pallet support storage rack by a step up which is equivalent of the height of the pallet. Thus the height of the pallet support storage rack is adjusted automatically in line with the conveyor line. Similarly the trolley system continuously loads the pallets one by one onto the conveyor line as per the need of the operator.
E) BRIEF DESCRIPTION OF THE DRAWINGS:
[0031] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:
11

[0032] FIG. 1 illustrates a functional block diagram of material handling system in conveyor line provided with a pallet handling system according to one embodiment of the present invention.
[0033] FIG. 2 illustrates a side perspective view of a pallet handling system according to one embodiment of the present invention.
[0034] FIG. 3 illustrates a top view of a pallet handling system without the top cover according to one embodiment of the present invention.
[0035] FIG. 4 illustrates a perspective view of a pallet handling system without the side cover plates and control panel according to one embodiment of the present invention.
[0036] Although the specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.
F) DETAILED DESCRIPTION OF THE INVENTION
[0037] In the following detailed description, a reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and

12

other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.
[0038] The various embodiments of the present invention provide system and method for handling return pallets and automatic level adjustment of pallet stacks in a conveyorised assembly flow line. According to one embodiment of the present invention, a pallet handling system with automatic level adjustment mechanism for assembly line is provided with a trolley at the loading end and a trolley at the unloading end. A pallet support storage rack is provided at the trolleys. A top pallet pusher system and a bottom pallet elevator system are provided on the trolleys. A control module provided at the trolleys is connected to the top pallet pusher system and to the bottom pallet elevator system. Pluralities of castor wheels are provided at the trolleys. The control module activates the bottom pallet elevator system to move vertically downwards by a preset level during the receipt of a pallet from a conveyor in an assembly line and to move vertically upwards by a preset level during the loading of a pallet into the conveyor sothat the height of the pallet to be loaded into the conveyor line is maintained always at a preset height.
[0039] The control module activates the bottom pallet elevator system to move vertically downwards by a preset level to receive and store a pallet into the pallet support storage rack in the trolley during the receipt of a pallet from a conveyor in an assembly line and to move vertically upwards by a preset level to unload the pallet at the top most position to the conveyor line using the top pallet pusher system during the loading of a pallet into the conveyor sothat the height of the pallet to be loaded into the conveyor line is maintained at a preset height.

[0040] The trolley has a first limit switch to detect the presence of a pallet in the trolley and a photoelectric sensor to detect the movement of the pallet in the trolley. The pallet storage rack has a pallet support mechanism which is moved vertically upwards or downwards. The pallet support mechanism is provided with a second limit switch at the bottom to detect that the pallet support mechanism has reached the bottom most position of the trolley, to prevent further loading of the pallet into the pallet support storage rack.
[0041 ] The bottom pallet elevator mechanism has a first motor with a shaft provided at the bottom of the trolley. A gear train is attached to the shaft of the first motor. A main shaft is coupled to the shaft of the first motor through the gear train. A bevel gear train is provided at both the ends of the main shaft. Pluralities of lead screws are coupled to the ends of the main shaft through the bevel gear train. Pluralities of guide rods are provided at the two sides of the trolley.
[0042] The control module activates the first motor provided at the bottom of the trolley to rotate the main shaft to move the lead screws along with the guide rods to move the pallet support mechanism by a preset level vertically in upward direction or downward direction. The control module activates the first motor provided at the bottom of the trolley to rotate the main shaft to move the lead screws along with the guide rods to move the pallet support mechanism by a preset level vertically in downward direction to receive an incoming pallet from the conveyor in the assembly line during the loading of the pallet into the trolley, when the pallet support mechanism is at the topmost position of the trolley. The control module activates the first motor provided at the bottom of the trolley to rotate the main shaft to move the lead screws along with the guide rods to move the pallet support mechanism by a

preset level vertically in upward direction during the loading of the pallet from the trolley onto the conveyor so that the pallet at the top most position in the pallet support mechanism is at a preset height. The preset level is equal to the height of the pallet. The photoelectric sensor in the trolley detects the movement of the pallet in the trolley to output a signal to the control module to regulate movement of the bottom motor.
[0043] The top pallet pusher system has a second motor provided at the top of the trolley. A timing pulley is coupled to the second motor. The control module activates the second motor to push a single pallet out of the trolley, when a pallet loading signal is given to the control module.
[0044] The control module has programmable relays to control the operation of the top pallet pusher system and the bottom pallet elevator system. The trolley has a third limit switch to detect the presence of top pallet pusher system at a final position to output a signal to the control module to reverse the direction of rotation in the second motor to move the top pallet pusher system to an initial position, after the loading of a pallet into the conveyor. The trolley has a fourth limit switch to detect the presence of the top pallet pusher system back at an initial position after the loading of the pallet into the conveyor from the trolley, to output a signal to the control module to restart the pallet loading operation.
[0045] The top pallet pusher system is at the initial position during the starting of the loading of pallet onto the conveyor. The top pallet pusher system is at the final position after the completion of the loading of pallet onto the conveyor.

15

[0046] The pluralities of castor wheels are provided at the front side and at the rear side of the trolley. The pluralities of the castor wheels at the front side are fixed. The pluralities of the castor wheels at the rear side are moved and locked so that the alignment of the trolley with respect to an alignment bracket which is fixed on the floor, is perfect. The pluralities of the castor wheels enable to move the trolley at the last station to the first station after the complete loading of the pallets from the conveyor into the trolley.
[0047] The control module has a processor provided with a software to control the entire loading operation of the pallets into the conveyor from the trolley and the unloading operation of the pallets into the trolley from the conveyor.
[0048] According to one embodiment, the trolley system consists of a pallet support storage rack, a bottom pallet elevator system, a top pallet pusher system and a control unit. The pallet support storage rack stores one or more pallets. The pallet support storage rack includes a bottom pallet support mechanism which is movable up and down along with the loaded pallets. The control unit consists of programmable relay to control the entire operation of the trolley system with the help of switched mode power supply (SMPS) and relays.
[0049] The bottom pallet elevator system is used to move the pallet support storage rack vertically up and down. The bottom pallet elevator system includes a bottom motor, a main shaft and a pair of vertical lead screw on each side. The bottom motor is placed at the bottom part of the trolley, which drives a motor shaft. The motor shaft is coupled to the main shaft which is perpendicular to the motor shaft, through a gear system. This gear system transfers the motion of motor shaft to the main shaft. The
16

each end of main shaft is coupled to each vertical lead screw whose axis is perpendicular to the main shaft axis, through bevel gear arrangements. Each bevel gear arrangement transfers the motion of the main shaft to the vertical lead screws. The bottom pallet elevator system further includes guide rods along with the vertical lead screws, which assist in movements of the pallet support storage rack. Thus the bottom pallet elevator system moves the entire pallet support storage rack vertically up and down.
[0050] The top pallet pusher system is used to load the topmost pallet of the pallet support storage rack onto the conveyor line by pushing out in the horizontal position. The top pallet pusher system includes a top motor, a timing pulley arrangement, a horizontal lead screw, and top guide rods. The top motor is coupled to the timing pulley arrangement which provides continuous output rotation to the horizontal lead screw without slipping. When the control signal is received from the control unit, the top motor operates the timing pulley arrangement and the timing pulley arrangement pushes out the topmost pallet of the pallet support storage rack with the help of the horizontal lead screw along with the top guide rods. After pushing out the pallet, the horizontal lead screw and the top guide rods return back to the initial position by using the timing pulley arrangement.
[0051] According to one embodiment, the trolley system further includes plurality of limit switches which send signals to the control unit at various conditions. A first limit switch is placed at the top part of the trolley system and used to detect the presence of a pallet when the pallet is pushed into the trolley system by an operator. A second limit switch is placed at the bottom of the pallet support mechanism and used to detect the maximum limit of the pallets loaded into the trolley system. A third

limit switch is placed at top of the front side of the trolley system to detect the position of the horizontal lead screw and top guide rods when they reach their final position. A fourth limit switch is placed at the top of the trolley system and used to detect the initial position of the horizontal lead screw and top guide rods when they return from their final position.
[0052] The trolley system is also provided with a photoelectric sensor at the top the trolley system to sense the presence of the topmost pallet of the pallet support storage rack. The photoelectric sensor assists to adjust the level of the pallet support storage rack accurately while loading of pallets into the trolley system.
[0053] The entire trolley system is mounted on a set of front and rear castor wheels to make the trolley system as a portable trolley. The trolley system is provided with a handle which enables an operator to move the trolley system easily with the help of castor wheels. The rear castor wheels can be locked. The alignment of the trolley is made to be perfect with alignment brackets fixed on the floor while loading or unloading of the pallets to the conveyor line.
[0054] At the time of unloading of the pallets from the conveyor line, an operator at the last station pushes a single pallet into the trolley system. The bottom pallet elevator mechanism is at the topmost position since there are no pallets loaded in the pallet support storage rack of the trolley system. As the pallet moves fully inside the trolley system in the horizontal position, the first limit switch detects the presence of the pallet and sends a signal to the control unit. Meanwhile, the photoelectric sensor also detects the presence of the pallet. The control unit operates the bottom motor to step down the level of the pallet support storage rack by a step down which is equivalent to the height of the pallet. When the top pallet goes down beyond the level
18

of the photoelectric sensor, the photoelectric sensor does not sense the pallet and sends a signal to the control unit. As soon as this signal is received from the photoelectric sensor, the control unit stops the operation of the bottom motor. Thus the level of the pallet support storage rack is adjusted automatically for the intake of next pallet. Similarly more number of pallets are loaded into the trolley system till the maximum limit is reached. Once the maximum limit is reached, it is detected by the second limit switch. The second limit switch sends a signal to the control unit so that another pallet cannot enter into the trolley system.
[0055] At the time of loading of the pallets onto the conveyor line, the operator presses the unload button and that signal is sent to the control unit. As soon as the signal is received from the unload button, the control unit runs the top pallet pusher system. Thus the top pallet pusher system pushes out the topmost pallet from the pallet support storage rack with the help of the horizontal lead screw and the top guide rods, onto the conveyor line. The third limit switch detects the position of the horizontal lead screw and the top guide rods when they reach their final position. This signal is used to return back the horizontal lead screw and the top guide rods to their initial position. As soon as the top pallet pusher system returns back to its initial position, the fourth limit switch detects that movement and sends a signal to the control unit. The control unit runs the bottom pallet elevator system to step up the level of the pallet support storage rack by a step up which is equivalent of the height of the pallet. Thus the height of the pallet support storage rack is adjusted automatically in line with the conveyor line. Similarly the trolley system continues to load the pallets onto the conveyor line as per the need of the operator. When all the pallets inside the pallet support storage rack get exhausted, the first limit switch does

19

not sense any pallet and a signal is provided to the control circuit. Thus the trolley system works on Last-In-First-Out (LIFO) principle.
[0056] According to one embodiment, during the operation of loading or unloading pallets, the trolley system is connected to the conveyor line through a male-female connector switch through which electrical power and control are given to the trolley system. So that the trolley system becomes a portable trolley which does not need to carry any external battery or power cable connection for its operation.
[0057] FIG. 1 illustrates a functional block diagram of material handling system in conveyor line provided with a pallet handling system according to one embodiment of the present invention. With respect to FIG. 1, the conveyor line 102 constitutes of a power driven chain conveyor on which the products are processed on the stations. The conveyor line 102 is supported either on rollers or on a metal slider pan. The conveyor line 102 forms a continuous running conveyor loop in between a first station 104 where pallets 108 are loaded one by one and a last station 106 from where the pallets 108 are unloaded.
[0058] While loading the pallets 108 onto the conveyor line 102, a trolley system 110 is brought to the first station 104 of the conveyor line 102 and the alignment of the trolley system 110 is made to be perfect with alignment brackets fixed on the floor. The trolley system 110 loads the pallets 108 one by one onto the conveyor line 102 according to the need of the operator. Products are placed on these pallets 108 for processing. After removing the products, the pallets 108 reach the last station 106 of the conveyor line 102. Another trolley system 112 is brought to the last station 106 and the alignment of the trolley system 112 is made to be perfect with the alignment
20

brackets fixed on the floor. An operator at the last station 106 pushes the pallets 108 one by one into the trolley system 112 until the maximum limit of pallets in the trolley system 112 is reached. The arrow line in FIG. 1 illustrates the flow of pallets on the conveyor line 102.
[0059] FIG. 2 illustrates a side perspective view of a pallet handling system according to one embodiment of the present invention. With respect to FIG. 2, the trolley system includes a pallet support storage rack 202, a bottom pallet elevator system 204, a top pallet pusher system 206 and a control unit 208. The pallet support storage rack 202 is used to store one or more pallets. The bottom pallet elevator system 204 is used to move the pallet support storage rack 202 vertically up and down and the top pallet pusher system 206 is used to push out a single pallet from the pallet support storage rack 202 in the horizontal position. The control unit 208 consists of programmable relay to control the entire operation of the trolley system with the help of switched mode power supply (SMPS) and relays.
[0060] The trolley system includes a photoelectric sensor 210 at the top the trolley system to sense the presence of a pallet on the topmost part of the pallet support storage rack 202. The photoelectric sensor 210 assists to adjust the level of the pallet support storage rack while loading of pallets into the trolley system. The trolley system also includes limit switches which send signals to the control unit 208 at various conditions. A limit switch 212 is placed at the bottom of the trolley system and used to detect the maximum limit of the pallets loaded into the trolley system. A limit switch 214 is placed at the top of the trolley system and used to detect the initial position of the top pallet pusher system 206 when the top pallet pusher system 206 returns from its final position.

[0061] The entire trolley system is mounted on a set of front castor wheels 216 and a set of rear castor wheels 218 to make the trolley system as a portable trolley. The trolley system is provided with a handle 220 which enables an operator to move the trolley system easily with the help of the front castor wheels 216 and the rear castor wheels 218. The rear castor wheels 218 can be locked. So that alignment of the trolley is made to be perfect with alignment brackets 222 fixed on the floor while loading or unloading of the pallets to the conveyor line.
[0062] FIG. 3 illustrates a top view of a pallet handling system without the top cover according to one embodiment of the present invention. With respect to FIG. 3, the top pallet pusher system includes a top motor 302, a timing pulley arrangement 304, a horizontal lead screw 306, top guide rods 308 and limit switches 214 and 310. The top motor 302 is coupled to the timing pulley arrangement 304 which provides continuous output rotation to the horizontal lead screw 306 without slipping. When the control signal is received from the control unit, the top motor 302 operates the timing pulley arrangement 304 and the timing pulley arrangement 304 pushes out a topmost pallet 312 of the pallet support storage rack 202 onto the conveyor line with the help of the horizontal lead screw 306 along with the top guide rods 308. The limit switch 310 placed at the top of front side of the trolley system detects the position of the horizontal lead screw 306 and top guide rods 308 when they reach their final position. So that, the horizontal lead screw 306 and the top guide rods 308 return back to the initial position by using the timing pulley arrangement 304 after pushing out the pallet. The limit switch 214 detects the initial position of the horizontal lead screw 306 and top guide rods 308 when they return from their final position. The limit switch 214 sends a signal to the control unit to step up the level of the pallet support
22

storage rack 202 by using the bottom pallet elevator system for the next unloading of pallet from the pallet support storage rack 202 of the trolley system. According to the requirement, the operator unloads the pallets one by one from the pallet support storage rack 202 with the help of the top pallet pusher system 206. A limit switch 314 is placed at the top part of the trolley system and used to detect the presence of a pallet when the pallet is pushed into the trolley system by an operator while loading of pallets into the trolley system.
[0063] FIG. 4 illustrates a perspective view of a pallet handling system without the side cover plates and control panel according to one embodiment of the present invention. With respect to FIG. 4, the bottom pallet elevator system includes a bottom motor 402, a main shaft 404 and a pair of vertical lead screw 406 on each side. The bottom motor 402 is placed at the bottom part of the trolley, which drives a motor shaft 408. The motor shaft 408 is coupled to the main shaft 404 which is perpendicular to the motor shaft 408, through a gear system 410. This gear system 410 transfers the motion of motor shaft 408 to the main shaft 404. The each end of main shaft 404 is coupled to each vertical lead screw 406 whose axis is perpendicular to the main shaft axis, through bevel gear arrangements 412. Each bevel gear arrangement 412 transfers the motion of the main shaft 404 to the vertical lead screws 406. The bottom pallet elevator system further includes guide rods 414 along with the vertical lead screws 406, which assist in movements of the pallet support storage rack. Thus the bottom pallet elevator system moves the entire pallet support storage rack vertically up and down.

23

G) ADVANTAGES OF THE INVENTION
[0064] Thus the various embodiments of the present invention provide system and method for handling return pallets and automatic level adjustment of pallet stacks in a conveyorised assembly flow line. The trolley system is automatically loading the pallets to the conveyor line and automatically unloading the pallets from the conveyor line without the need of any manual requirements. It is noted that the manual effort is needed only for moving the trolley between the first and last station of the conveyor line.
[0065] The trolley system is able to automatically adjust the level of pallet stack for placing the pallets on the conveyor line at the first station with respect to the level of the conveyor line. Also, the trolley system is able to automatically adjust the level of pallet stack for in taking of the pallets from the conveyor line at the last station. The trolley system always maintains the level of the pallet stack irrespective of the number of pallets inside the trolley system.
[0066] The trolley system makes it possible to avoid further loading of pallets into the trolley once the limit is reached. Further the trolley system loads the pallets on the conveyor line as per the need of the operator. The trolley system itself gets aligned with the conveyor line with the help of alignment bracket and the castor wheels. During the operation of loading and unloading pallets, the trolley system is connected to the conveyor line through a male-female connector switch through which electrical power and control are given to the trolley system. So that the trolley system becomes a portable trolley which does not need to carry any external battery or power cable connection for its operation.
24

[0067] Moreover, the trolley system performs the operation of collecting and sending the pallets to the first station with minimum consumption of space, money and human effort. The proposed trolley system costs around only 2.5% of the total cost of the conveyor line as compared to the pallet return mechanism which would have taken about 40-50% of the total cost of the conveyor line.
[0068] Although the invention is described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims.
[0069] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the present invention described herein and all the statements of the scope of the invention which as a matter of language might be said to fall there between.
Dated this the 31st day of July 2009
RAKESH PRABHU Patent Agent,
ALMT Legal,
#2, Lavelle Road, Bangalore-560 001
To,
The Controller of Patents, The Patent Office, Mumbai

CLAIMS
What is claimed is:
1. A pallet handling system with automatic level adjustment mechanism for
assembly line comprising:
a trolley at the loading end;
a trolley at the unloading end;
a pallet support storage rack provided at the trolleys;
a top pallet pusher system provided at the trolleys;
a bottom pallet elevator system provided at the trolleys;
a control module provided at the trolleys and connected to the top pallet
pusher system and to the bottom pallet elevator system; and
pluralities of castor wheels provided at the trolleys;
wherein the control module activates the bottom pallet elevator system to
move vertically downwards by a preset level during the receipt of a pallet
from a conveyor in an assembly line and to move vertically upwards by a
preset level during the loading of a pallet into the conveyor sothat the height of
the pallet to be loaded into the conveyor line is maintained always at a preset
height.
2. The system according to claim 1, wherein the control module activates the
bottom pallet elevator system to move vertically downwards by a preset level
to receive and store a pallet into the pallet support storage rack in the trolley
during the receipt of a pallet from a conveyor in an assembly line and to move
vertically upwards by a preset level to unload the pallet at the top most
position to the conveyor line using the top pallet pusher system during the
26

loading of a pallet into the conveyor sothat the height of the pallet to be loaded into the conveyor line is maintained at a preset height.
3. The system according to claim 1, wherein the trolley has a first limit switch to
detect the presence of a pallet in the trolley.
4. The system according to claim 1, wherein the trolley has a photoelectric sensor to detect the movement of the pallet in the trolley.
5. The system according to claim 1, wherein the pallet support storage rack has a pallet support mechanism which is moved vertically upwards or downwards.
6. The system according to claim 1, wherein the pallet support storage rack is provided with a second limit switch at the bottom to detect that the pallet support mechanism has reached the bottom most position of the trolley, to prevent further loading of the pallet into the pallet support storage rack.
7. The system according to claim 1, wherein the bottom pallet elevator mechanism comprises:
a first motor with a shaft provided at the bottom of the trolley;
a gear train attached to the shaft of the first motor;
a main shaft coupled to the shaft of the first motor through the gear train;
a bevel gear train provided at both the ends of the main shaft;
pluralities of lead screws coupled to the ends of the main shaft through the
bevel gear train; and
pluralities of guide rods provided at the two sides of the trolley.
27

8. The system according to claim 1, wherein the control module activates the
first motor provided at the bottom of the trolley to rotate the main shaft to
move the lead screws along with the guide rods to move the pallet support
mechanism by a preset level vertically in upward direction or downward
direction.
9. The system according to claim 1, wherein the control module activates the first motor provided at the bottom of the trolley to rotate the main shaft to move the lead screws along with the guide rods to move the pallet support mechanism by a preset level vertically in downward direction to receive an incoming pallet from the conveyor in the assembly line during the loading of the pallet into the trolley, when the pallet support mechanism is at the topmost position of the trolley.
10. The system according to claim 1, wherein the control module activates the first motor provided at the bottom of the trolley to rotate the main shaft to move the lead screws along with the guide rods to move the pallet support mechanism by a preset level vertically in upward direction during the loading of the pallet from the trolley onto the conveyor so that the pallet at the top most position in the pallet support mechanism is at a preset height.
11. The system according to claim 1, wherein the preset level is equal to the height of the pallet.
12. The system according to claim 1, wherein the photoelectric sensor in the trolley detects the movement of the pallet in the trolley to output a signal to the control module to regulate movement of the bottom motor.
28

13. The system according to claim 1, wherein the top pallet pusher system has a second motor provided at the top of the trolley.
14. The system according to claim 1, wherein the top pallet pusher system has a timing pulley coupled to the second motor.
15. The system according to claim 1, wherein the control module activates the second motor to push a single pallet out of the trolley, when a pallet loading signal is given to the control module.

16. The system according to claim 1, wherein the control module has programmable relays to control the operation of the top pallet pusher system and the bottom pallet elevator system.
17. The system according to claim 1, wherein the trolley has a third limit switch to detect the presence of top pallet pusher system at a final position to output a signal to the control module to reverse the direction of rotation in the second motor to move the top pallet pusher system to an initial position, after the loading of a pallet into the conveyor.
18. The system according to claim 1, wherein the trolley has a fourth limit switch to detect the presence of the top pallet pusher system back at an initial position after the loading of the pallet into the conveyor from the trolley, to output a signal to the control module to restart the pallet loading operation.
19. The system according to claim 1, wherein the top pallet pusher system is at
the initial position during the starting of the loading of pallet onto the
conveyor.

20. The system according to claim 1, wherein the top pallet pusher system is at the final position after the completion of the loading of pallet onto the conveyor.
21. The system according to claim 1, wherein pluralities of castor wheels are provided at the front side and at the rear side.
22. The system according to claiml, wherein the pluralities of the castor wheels at the front side are fixed.
23. The system according to claiml, wherein the pluralities of the castor wheels at the rear side are moved and locked so that the alignment of the trolley with respect to an alignment bracket which is fixed on the floor, is perfect.
24. The system according to claim 1, wherein the pluralities of the castor wheels enable to move the trolley at the last station to the first station after the complete loading of the pallets from the conveyor into the trolley.
25. The system according to claim 1, wherein the control module has a processor provided with a software to control the entire loading operation of the pallets into the conveyor from the trolley and the unloading operation of the pallets into the trolley from the conveyor.

Place; Bangalore RAKESH PRABHU
Patent Agent
30