Order picking system

1. An order picking system comprising:

first and second pairs of uprights each pair attached to two separate shelvings delineating a centre aisle;

an automatic guided vehicle having a chassis, at least two running wheels for picking up objects for an order in at least one of said shelvings, and a motorised climbing module, which cooperates with said uprights so as to allow said vehicle to rise along said uprights,

said climbing module comprising first, second, third and fourth gear wheels of substantially parallel axes, each gear wheel cooperating with one of the uprights, the axes of the gear wheels being substantially orthogonal to axes of the running wheels,

each of the gear wheels being mounted on a support that can be moved relative to the chassis of said vehicle between:

a spaced-apart position in which at least a portion of said gear wheel mounted on said support protrudes laterally out of alignment with said chassis;

a retracted position, in which the gear wheel mounted on said support is facing said chassis;

a substantially stretched roller chain fixed on each of said uprights, said chain extending substantially parallel to a longitudinal axis of the upright to which it is fixed and receiving at least one tooth of the gear wheel cooperating with the upright to which it is fixed, first and second adjacent rollers of said chain being substantially spaced apart by a pitch value of said gear wheel,

and wherein each movable support is secured with one of said uprights so as to maintain a predetermined distance between the axis of the gear wheel mounted on said movable support and the chain receiving the teeth of said gear wheel.

2. The order picking system according claim 1 , wherein said movable supports are mounted substantially at first, second, third and fourth ends of the chassis of said vehicle.

3. The order picking system according to claim 1 , wherein at least one of said uprights comprises a longitudinal groove adapted to receive said chain.

4. The order picking system according to claim 1 , wherein at least one of said uprights is an omega profiled rail.

5. The order picking system according to claim 1 , wherein said vehicle comprises a gripper configured to grip an object storage bin.

6. The order picking system according to claim 1 , further comprising a brake for braking said climbing module.

7. The order picking system according to further comprising first and second independent motors each driving one of pair of the gear wheels.

8. The order picking system according to claim 1 , further comprising a securing mechanism for securing each movable support to one of said four uprights, which comprises at least one support wheel and a counter-wheel of axes parallel to the axis of the gear wheel mounted on the movable support, suitable for rolling on one of said uprights.

9. The order picking system according to claim 8 , wherein at least one of said uprights comprises at least one aisle extending substantially perpendicular to the longitudinal axis of said upright, said support wheel bearing upon one side of said aisle and said counter-wheel bearing upon an opposite side of said aisle.

10. The order picking system according to claim 1 , wherein each of said chains is attached substantially to both ends of one of said uprights.

11. The order picking system according to claim 10 , further comprising an adjustment mechanism, which adjusts a position at which at least one of said chains is fixed substantially at one end of one of said uprights, along the longitudinal axis of said upright, allowing said chain to be stretched.

12. The order picking system according to claim 11 , wherein said adjusting mechanism comprises a spring.