Jump indexing pallet and method for heat exchanger assembly

A pallet system for the assembly of heat exchanger elements comprising;

• a plurality of pallets movable in an advancing manner through a loading station,
• lead screw means selectively engagable with the pallets for controlling pallet position,
• motor means drivingly connected to the lead screw means for advancing each pallet with respect to the loading station,
• the lead screw means having a first screw means for indexing one pallet in an advancing manner through the loading station and for discharging the one pallet in an advancing manner from the station and having a second screw means synchronized with said first screw means for advancing another pallet to the loading station for operative engagement with the first screw means simultaneously with but only during the discharge of the said one pallet whereby the rate of movement of the said another pallet relative to said one pallet is under positive control of the motor means for rapid indexing,
• the first and second screw means being separate lead screws having the same pitch and spaced in the direction of pallet advancing and mounted on a common drive means for synchronous rotation by the motor means so that the said pallets move together when advanced by the lead screw means.