Towline conveyor increases productivity
Case New Holland's conveyor system for 60,000-pound tractors pays for itself in less than a year.
By Sara Pearson Specter, Editor at Large -- Modern Materials Handling, 1/1/2006
At its tractor manufacturing plant in Fargo, N.D., Case New Holland relies on a unique towline conveyor system to help workers assemble massive, articulated agricultural tractors. The system features four different connected, towline conveyors (SI Systems, 610-252-7321) that complete assembly of the 60,000 pound machines.
Since implementing the system, Case New Holland has documented an assembly time savings in thousands of manufacturing hours. This savings alone allowed the company to recoup its initial investment less than a year after implementing the new towline system.
The assembly process begins on a mainline indexing conveyor. This initial section uses two towline carts positioned back-to-back to support the tractor. The first cart carries the front axle half of the tractor unit, while the second cart supports the rear axle half. The tractor indexes through this phase of the system at 20 feet per minute as the front and rear axle assemblies receive power transmissions and other components.
The system is configured in a "U" shape. At the indexing mainline conveyor's midpoint—where the conveyor turns 180 degrees—the rear half carts divert to a separate indexing conveyor. This allows the front half carts to continue along the initial conveyor where they receive cab subassemblies and other parts.
The separate indexing conveyor section features three workstations for additional build-up of the rear axles. Once the appropriate parts are added, the completed rear half carts merge back into the mainline indexing conveyor. There, the driveshaft and other parts—including the main pivot assembly—physically connect the tractor's two halves.
The now-joined halves of the tractor are then positioned at the starting point of the third conveyor section, a continuously moving, slow-speed mainline conveyor on which the final assembly takes place. To accomplish this transfer, a fourth towline conveyor—the short auxiliary conveyor section—advances the connected tractor from the initial assembly mainline conveyor to the final assembly mainline conveyor.
For final assembly operations, the mainline slow-speed conveyor of the third section transfers the tractors through a range of work areas. Running at a variable speed of 0.25 to 0.75 feet per minute, this mainline slow-speed conveyor handles 448,000 pounds of gross moving load. And, only one cart tows the tractor at this point, since the two halves are now connected.
When each tractor's assembly is complete and the finished product is removed, the empty carts are returned to the staging area to be re-engaged with the first mainline indexing conveyor, and the process begins again.
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