Masonry Magazine April 1964 Page. 6
Dunnage bags prevent damage by filling void spaces compacting and seating the load.
Inflating the dunnage bag to seat the load. Deflate the bags to shipping pressure and close the deer. Lend is ready to ship.
Air Absorbs Shock
(Continued from page 5)
Dunnage bags were used. For example, one shipment involving a carload of brick arrived at its destination, South Chicago, in excellent shape even though the bag was inflated with a bicycle pump.
Two men inflated the rubber container in 20 minutes. The dunnage bag, inflated with about 10 pounds of air per square inch, increased the gap between the load of bricks in the car from 3 inches to 12 inches. What this means is that two men were able to make a rugged rubber bag move 110,000 pounds of brick in order to eliminate the void in the load and with a minimum of effort. Of course, in the majority of instances the available air line to which the adaptor and safety valve is attached for seconds-quick inflation of dunnage bags is in apple pie operating order.
Users of Goodyear inflatable dunnage include such firms as: Alton Brick; Acme Brick Company; Alberen Stone Company; Appalachian Shale Products; Central Commercial Company; Chattahoochee Brick Company: Coral Ridge Brick & Tile: Cun-
ningham Brick Company; Dalton Brick & Tile Company; General Shale Products Company; Gladding McBean Company; Georgia-Carolina Brick & Tile Company; Key James Brick Company; Mason City Brick & Tile; Senford Brick & Tile Company; Sioux City Brick & Tile; Lockheed Aircraft; Monolith Portland Cement; Northwest Magnesite; Royal Jet, and Straitsville Brick Company.
The principle involved in the use of dunnage bags is simple. Any shifting occurring in transit due to impact creates unbalanced forces. These forces, directed against the car, cannot be completely dissipated. On the other hand, pneumatic dunnage will absorb the shock because they are filled with air so compression occurs without damaging the shipment.
The gradual increase in pressure dissipates the resultant energy by increasing or compacting the pressure of the
More and more brick, tile and associated ceramic products are being shipped safely by means of inflated dunnage. Goodyear pioneered in development of the bags.
air in the dunnage. After the momentum of the impact has been balanced, the lading stops shifting, and the increased pressure creates a force that is exerted against the lading, returning it to its original position of equilibrium.
Consider this in terms of figures. A small standard size dunnage bag (4' x 4) with a bearing surface of about 40 in. x 40 in. (or 1600 square inches) is placed in a freight car shipment. If five pounds per square inch is carried in the dunnage bag, a fore of 8,000 pounds will be exerted against the load in each direction. An impact that would cause a relatively small shift of cargo could increase the pressure to 10 pounds per square inch and the force to 16,000 pounds in each direction (a total of 32,000 pounds). This entire force will be trying to push the shipment back into place against the force of friction between the car floor and the commodity being shipped.
From this, it can be deduced that the unusual success of pneumatic dunnage lies in its large effective area. Even a small pressure of four to six pounds distributed over such a large area usually about 10,000 square
inches in a freight car gives a total of some 40,000 to 60,000 pounds of force available to hold the load tightly against the freight car ends.
While Goodyear is not alone pioneering inflatable dunnage, it does claim outstanding advantages, besides those just described. For instance, the single unit construction eliminates the need for a separate bladder. When a dunnage bag with a bladder is used, there is the possibility of the bladder bursting due to improper positioning of the bag.
Single unit construction reduces weight and bulk, cuts down in return costs. All 8 and 9 Goodyear bags feature two valves located diagonally from each other. This provision makes inflation and deflation easier. In practice, if a car is loaded at a right-hand dock and unloaded at a left-hand dock, the valve arrangement is such that it is not necessary to climb over the entire load or go all around the car to gain access to a valve.
Further, Super-Cushion dunnage bags are made from special compounds which are much more abrasion-resistent that high quality neoprene stocks.
A standard repair kit has been developed so that in the event of a puncture (Continued on page 16)
At Straitsville Brick Company, Straitsville Ohio, a Goodyear dunnage bag is inflated to secure this load of clay-tile heating d flues. Dunnage bags are being used by more industries to deflate damages in rail tron
MASONRY April, 19