Assembly in Action: Cart Gives Tractors a Productive Ride
CNH Global builds tractors at its Racine, WI, location for its Case IH and New Holland brands. This equipment will go on to work the fields on farms in over 160 countries.
As this farm equipment becomes more sophisticated, coming up with ways to move them through the assembly process increases in complexity as well.
The manufacturing management at CNH concluded the plant could reduce capital costs on a new assembly line by switching to a combination overhead conveyor with a floor imbedded chain drive system. This approach would save 50 percent over the slat conveyor systems previously used.
Development of the replacement system turned out to be a work in progress. Engineers from CNH and Topper Industrial Inc. (Sturtevant, WI) collaborated to design a special chassis cart for this project.
Most of the design issues revolved around engineering the height of the supports that propped the chassis at the point of the axle housing. Furthermore, the cart had to accommodate chassis designs for eight different tractor models.
If a support positions the chassis too low, the unit would nearly drag along the floor. If it was too high, the chassis would not clear various points along the production line.
Casters presented the same difficulty. Topper engineers experimented with a range of caster sizes before finding one that met the operator’s clearance requirements. The casters have sealed bearings that provide long life with low maintenance and smooth cart movement.
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The other issue was getting the cart back to the start of the line once the tractor is completely assembled.
Topper added forking pockets at the end of the cart. These enable a large forklift to transport the carts lengthwise back to the start of the line. The forklift then uses side forking pockets to maneuver the cart back into place. This forklift also sets the tractor tires into place onto the mounting fixture.
Ergonomic access to the various areas of the chassis was another concern. The cart has steps with gripper pads to allow shorter employees to attach components with ease.
The cart has a front toe pin for pick up by the chain drive, propelling the cart at a constant speed with a time gap between tractors on the line. However, tire mounting takes longer than the gap of time between tractors on the line. To solve the problem, engineers set up the system so the chain system indexes the cart just before it reaches the tire-mounting station. At that point, the front pin is forced out of the chain, and the pin at the rear of the cart clicks onto the indexing chain.
At the tire-mounting station, the cart rests over a platform that elevates the cart and the chassis into position for tire mounting. Once the fixture mounts the tires, the elevated platform brings the cart back to floor level, separating it from the tractor. The vehicle drives off to its final production operations. Then the cart pulls off the line for pick up by the tire-mounting forklift to return to the start of the line.
For more information about conveyors, call 800-529-0909 or visit www.topperindustrial.com.
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