A production line comprising: - at least one assembly station, - a chain-conveyor device comprising a chain for conveying a plurality of pallets along said production line, wherein each pallet is provided for conveying parts to be assembled; - motor means for moving said chain; and - an electronic control system, - said motor means and said electronic control system being configured for feeding the aforesaid pallets conveyed by said chain with continuous movement through said at least one assembly station; - associated to said at least one assembly station there is a tool guided on a supporting structure in such a way as to be freely mobile in the direction of conveyance of the pallets, so that said tool can be used by an operator assigned to the assembly station for carrying out manual assembly operations on the parts conveyed by each pallet, said tool thus being adapted to be pulled by the operator while the latter follows the pallet in its continuous movement through the assembly station, for carrying out the aforesaid manual operations; - in association with each pallet, said chain is provided with a front hook assembly and a rear hook assembly set longitudinally apart from one another and designed to engage the pallet for referencing the pallet with respect to said chain and for feeding the pallet together with the chain; - said rear hook assembly being designed to disengage from the pallet when an obstacle prevents the pallet from advancing together with the chain, and to move, in said condition, into a position of optical-beam interception, in which a first interception element forming part of the rear hook assembly intercepts a first optical beam emitted by a first optical sensor; and - said electronic control system being programmed for generating a control signal when said first optical beam is intercepted by said first interception element, wherein said production line further comprises at least one module for carrying containers provided with a plurality of part-holder containers for supplying parts to said at least one assembly station, wherein said module comprises a plurality of drawers associated to a paternoster conveyor system. - at least one assembly station, - a chain-conveyor device comprising a chain for conveying a plurality of pallets along said production line, wherein each pallet is provided for conveying parts to be assembled; - motor means for moving said chain; and - an electronic control system, - said motor means and said electronic control system being configured for feeding the aforesaid pallets conveyed by said chain with continuous movement through said at least one assembly station; - associated to said at least one assembly station there is a tool guided on a supporting structure in such a way as to be freely mobile in the direction of conveyance of the pallets, so that said tool can be used by an operator assigned to the assembly station for carrying out manual assembly operations on the parts conveyed by each pallet, said tool thus being adapted to be pulled by the operator while the latter follows the pallet in its continuous movement through the assembly station, for carrying out the aforesaid manual operations; - in association with each pallet, said chain is provided with a front hook assembly and a rear hook assembly set longitudinally apart from one another and designed to engage the pallet for referencing the pallet with respect to said chain and for feeding the pallet together with the chain; - said rear hook assembly being designed to disengage from the pallet when an obstacle prevents the pallet from advancing together with the chain, and to move, in said condition, into a position of optical-beam interception, in which a first interception element forming part of the rear hook assembly intercepts a first optical beam emitted by a first optical sensor; and - said electronic control system being programmed for generating a control signal when said first optical beam is intercepted by said first interception element,