rail dock push-pull forks are too heavy FOOTNOTES for some trailers; (4) few grocery trail- ers are loaded with slipsheet unit loads; lBouma, J. C. Truck unloading of (5) a high percentage of the truck manufacturer shipments at grocery receipts are less than trailer loads distribution warehouses, U.S. Dept. which are typically not unitized, (6) a Agr. ARS-NE-68, 23 pp. Feb. 1976. lack of incentive for wholesale distri- bution warehouses to use warehouse 2Bouma, J. C. and Shaffer, P. F., personnel to unload trucks when this Feasibility of using a second unit function is usually performed by the car- load size for distributing groceries; rier, and (7) labor and insurance con- from supplier to distribution ware- tracts may prohibit warehouse employees house. U.S. Dept. Agr., MT-NE-2, from entering trailers. 20 pp. Jan. 1979.

How then, can unitized shipment of grocery products on slipsheets be imple- mented? Probably, the first step needed would be to transfer the unloading allow- ance, now included in the tariff, from the carrier to the warehouse receiver who will unload the trailer. This will probably provide the incentive needed to get warehouse distributors to request product shipment on slip sheets. As indicated by Glen Johnson, the equipment needed for slipsheet unloading is now available. *********

THE PROS ANDCONSOFSLIP SHEETS

by

Glen R. Johnson Marketing Relations Manager Clark Equipment Company Battle Creek, Michigan

Introduction I happen to be one of the three originators of the 40 x 48 inches Thank you for the opportunity to concept and I am one of the three co- present another to the Food Distri- developers of the Pul-Pac slip sheet sys- bution Research Society. It’s difficult tem of handling. At the time to believe 20 years have passed since I of the Pul-Pac development, Clark Equip- became a charter member and presented a ment Company was in the pallet business paper at the first meeting. It’s also a and offering for sale three types of pleasure to participate in a panel dis- ; a permanent pallet which was cussing a subject of great interest to plywood sandwiched between layers of all food distribution people. metal and the construction was riveted

February 80/page 64 Journal of Food Distribution Research together; durable pallets were full four- shipment. A small crowd gathered to way double-faced plywood types and expend- witness this “folly” but they were sur- able pallets were corrugated sheets with prised when we were able to pull a load nine or twelve posts of rolled corruga- onto the plate and push it off several tion as support. So you see I have no times without mishap and then they be- axe to grind. came quite enthused when we were able to stack the first load on top of the QZQ.& second and retrieve it without incident.

What is a slip sheet? The concept Slip Sheets started in 1946 when we were trying to find a solution to a customer’s problem. What is a slip sheet? Well, basic- We were attempting to load a rail car ally it’s a flat sheet of material with with unit loads of bagged goods and re- tabs on one or more sides , used as a trieving the pallets. We did develop a base upon which to assemble, store, successful roller pallet to displace the handle and transport goods and materials wood pallet under the unit load of - as a unit load. ged goods. But when we deposited the load in the rail car, the drop of some How did it get its name? We origina- four inches from the roller pallet to lly called it a load sheet. It seems the floor resulted in damage to the . like later in the 1950’s some company developed a competitive technique for Also, at the same time, we had dev- paper to substitute as a load base for eloped a pusher device as an attachment a pallet except that this was a folded to a conventional counterbalanced lift over sheet of paper board into which truck to be used to push or shove unitized highly polished tapered chisel forks material off of a pallet. One day one of could slip between the sheets like the engineers who was a co-developer ap- putting a card into an . This proached me after visiting a paper mill technique and folded over sheet was with the observation that paper had named “slip sheet” and this coined name tensile strength. With this discovery, became a generic term to describe all then came the bright idea that since we sheets of material, principally paper, had the pusher and since paper had tensile as the substitute for the load base re- strength maybe we could put some mechan- placing the pallet. Another descriptive ism on our pusher and pull a load on a term, “push-pull” came along about the sheet of paper onto a broad load plate to same time when one of the major users support the load during in-plant transport. of this technique did not want to use the trademark name-of “Pul-Pat” of Clark This is how the Pul-Pac became a Equipment Company and so they coined the reality. The initial prototype had a name “push-pull” to be an all inclusive gripper jaw hydraulically operated which descriptive term in writing specifica- clamped down on the sheet of paper pro- tions for the necessary handling equip- truding from underneath the load and ment. So “push-pull” has become a generic thus was able to pull the load onto the term for the attachments on lift trucks plate. The first demonstration took place to handle the slip sheets. in a courtyard of our Battle Creek plant and we used cases of bathroom tissue Unit Load Handling Without Pallets which happened to be the only cased item around in sufficient quantity and the Slip sheets are made basically from paper we used for the load sheet was the three materials. , either cor- type used to wrap machine parts for rugated or solid fiber type, and plastic

Journal of Food Distribution Research February 80/page 65 are the basic slip sheet materials. I 3. Moisture. Corrugated and fiber- can tell you from our early days of board paper slip sheets cannot tolerate experimentation in the late 4.0’sthat moisture. Fiberboard can be treated we successfully used sheets of canvas with water repellent chemicals to give and also sheets of corrugated iron on it some resistance to moisture but if which we successfully handled unit loads they are exposed to soaking in a water of concrete blocks. However, I’m sure environment, the tensile integrity is you can visualize the inherent potential lost completely. for injury to a person if you have a storage area with protruding corrugated 4. The skill of lift truck operator. iron sheets. Basically, a higher degree of skill is required of the lift truck operator to We have experimented with many retrieve slip sheet unit loads, partic- types of paper and material but essen- ularly from the stack. Almost any tially most slip sheets are made of competent driver can be taught to re- heavy duty corrugated board or the solid trieve or discharge a load at floor level kraft fiberboard of .060 inches in thick- but it requires skill and coordination ness. Plastic slip sheets are something to tier and retrieve unit loads from a of recent years and brought about by the stack. need of material to be totally moisture resistant. 5. Product damage, Careless or un- trained lift truck operators driving one Disadvantages of Slip Sheets with a “push-pull” attachment can cause Versus Pallets considerable product damage, either deliberately or by carelessness if not There are several disadvantages properly trained. I have actually seen which you should be aware of so that you the load plates on a “push-pull” truck thoroughly understand the limitations driven half-way through a tier of cases with slip sheets compared to pallets. I spilling tomato -juiceon the floor. will enumerate several of the slip sheet disadvantages not necessarily in any order 6. Slower than conventional fork trucks. of importance but only as they come to my Basically, because of the degree of mind. skill plus the manipulation of hydraulic controls, the “push-pull” truck will 1. Limited load weight. Normally a slip handle fewer loads in the same time cycle sheet is capable of handling loads up to as a fork truck. Essentially, its about about 5,000 pounds in gross weight. Any- 15 percent slower than a lift truck is thing greater than 5,000 pounds becomes capable of handling palletized unit loads. an exceptional problem requiring special attention and handling equipment. 7. Restricted air circulation. A slip sheet being a solid sheet prevents any 2. Limited stacking height. Slip sheet air circulation through or between unit unit loads stacked three high is probably loads. Some users have resorted to cut- the most efficient. Four unit loads high ting holes in a slip sheet without com- is the absolute maximum, assuming a 54 promising its tensile integrity and thus inch high load because the visibility and have been able to obtain limited air depth perception required of the lift circulation from top to bottom through truck operator to grip the tab on the slip the loads. sheet and retrieve the load precludes stacking any higher. 8. Lift truck equipment. Until 1977 only counterbalanced lift trucks with

February 80/page 66 Journal of Food Distribution Research “push-pull” attachments were available to as great as 96 percent less than the handle slip sheets. In 1977 Clark intro- cost of a pallet. duced the HWP-30P Powrworker hand truck equipped with a “push-pull” attachment 2. Less storage cube required. Because to the trade. This was the first walkie the slip sheet is .060 inches in thick- hand truck with slip sheet handling ness compared to approximately 6 inch capability. Since our pioneering effort thickness of a pallet, it sometimes can there’s been a few other companies who mean one more tier of cases or bags in have followed with their own versions, a unit load. This multiplied in a and I would anticipate that before the stack of merchandise three loads high end of 1979 almost all lift truck manu- can mean greater cube utilization in a facturers producing pallet hand trucks particular given storage area. Basic- will be in a position to offer some type ally, slip sheets will provide 10 to of an attachment permitting slip sheet 12 percent more cube utilization than handling. will pallets in storage.

9. Restricted use in warehousing. Slip 3. Lower center of gravity in a trans- sheets cannot be used in storage racks port vehicle. While you may think that unless the slip sheet unit load is sup- this is not significant, however, I can ported by a rigid platform such as a wood tell you the situation which occurred pallet or plywood decking in the pallet in the mid-1950’s in Canada which was rack. Likewise, it is impossible to blessed with many high crowned roads in store slip sheet loads in drive-in or that period time. This particular user drive through racks without putting the at the time was shipping unit loads of slip sheet load on a pallet. grocery items to retail stores on pal- lets. The combination of the high 10. Wider storage aisles. Because a crown road plus the higher center of Pul-Pac “push-pull” equipped lift truck gravity on pallets reduced the road must approach its load at a 90° angle speed of the transport vehicles. They versus a 60-70° angle possible when using changed to using slip sheets and by re- pall,etsunder a unit load, the aisle ducing the center of gravity of the must be six to seven inches wider for trailer load, they increased their aver- the same weight loads to be handled on age road speed by better than five miles slip sheets. A larger truck capacity per hour. Today, that is probably not chassis also is required for slip sheet as significant as it was then but it is handling. something that should be recorded for your information. Advantages of Slip Sheets Versus Pallets 4. Recyclable materials. Slip sheets being made from paper and/or plastic Now, let’s look at the other side offer materials which are readily dis- and I’m sure this is what you’re most posable and capable of being recycled. interested in hearing is where the slip In fact, manufacturers of plastic slip sheets hold a distinct advantage over sheets will actually reimburse the user pallets in the unit load system of hand- at a pre-agreed price for the slip sheet ling. when the user wants to return it and the manufacturer will recycle the materials. 1. Lower cost. Undoubtedly, the greatest advantage is the lower initial cost of a 5. One way unit load base. Definitely slip sheet versus a pallet as a unit load slip sheets have the distinct advantage base. The cost for a slip sheet can be over pallets, even disposable pallets,

Journal of Food Distribution Research February 80/page 67 strictly on an initial cost basis. But compared to pallets that are substandard in addition, which we just previously because of protruding nails, splinters mentioned, slip sheets are more easily and the load shifting on the pallets. disposed of than one way wood pallets. Whereas on a slip sheet, if there is Another thing to consider is that some any load shifting in the transport slip sheet users reuse the sheets several vehicles, the sheet and load move times. For example, one major grocery together. manufacturer uses his slip sheet for six round trips. This computes to approxi- 12. No theft. Again, slip sheets are mately 20 cents per trip. To achieve not subject to the degree of theft or this cost level would mean that comparable diverting to other uses as are pallets wood pallets would have to make 20 to 40 and the monetary loss if theft occurs trips to achieve the same cycle cost. is considerably less.

6. No repairs. Obviously, slip sheets, These are the principle “pros and cons” be they made of paper or plastic, cannot of slip sheets. be repaired, when once damaged they are discarded. Therefore, there is no main- Slip Sheet Users tenance required as there is with pallets. Here are some companies who have 7. Slip sheets tailored to requirements. used slip sheets somewhere in their It is very possible for the user to tailor operations for at least fifteen years, the material and the cost of slip sheets some as long as twenty-five years. to the load weight to be handled and the Northrup-King Company, a seed producer handling cycles required. Whereas with and distributor, has used slip sheets the pallet, this is not economically since 1948 to handle bagged pr~ducts. feasible, although it is possible. Here are some others who are long-time users: 8. Storage for empties. A stack of slip sheets six inches high will be 60 to 70 Carnation Company sheets versus 30 to 36 feet of pallets for Del Monte Corporation the same quantity. Normally, a typical General Mills Company rail car shipment on pallets requires 56 Kellogg Company unit loads. The same 56 unit load bases Ralston-Purina Company of slip sheets represents a stack of five Libby-McNeil and Libby and one-half inches high. H. J. Heinz Company Hunt-Wesson Division of Norton 9. No return shipping charges. With slip Simon sheets being a one way or limited cycle Packaging Corporation of America load base, there are no costs involved in Corporation - Division returning slip sheets to point of origin. of Mobil Oil Mead Corporation 10. Serves as a paper liner. In many Kraft Company rail car shipments the cars must be Pillsbury Company lined with paper both on walls and floors Green Giant Company - Division of before products for human consumption can Pillsbury be loaded into the rail cars. Slip sheets Standard Brands Incorporated will perform the dual function of being a Larsen Company paper liner as well as a unit load base. Grief Brothers Company Tropicana Products Co. - Div. of 11. Product damage. In some instance, Beatrice Foods there will be less product damage when

February 80/page 68 Journal of Food Distribution Research --and many chain stores and wholesale What’s in the Future grocery companies who receive their products from many of the grocery manu- Slip sheets as a 100 percent medium facturers in rail car shipments. as a load base for unit loads in the total distribution cycle will never hap- Here’s a list of companies using pen or at most it would be less than slip sheets who started within the last one percent of the total. ten years: Slip sheets will not replace 3 M Company pallets completely. Pallets will tend Seagrams to remain captive within a facility. Nabisco Company Products will be stored on pallets with Citrus World a slip sheet between the top deck of the Holly Sugar Company pallet and the bottom surface of the unit Witco Chemical Company load. Slip sheet loads will be with- Quaker State Motor Oil drawn from pallets and loaded into Crown Zellerbach Company transport vehicles. At the destination Hercules Incorporated the slip sheet loads will be retrieved Morgan Packing Company and placed on pallets captive to that Reynolds Metals Company facility, The loading and unloading Southwest Forest Industries cycle may be repeated two or three Kerr Company times from the grower/manufacturer to General Foods Corporation the ultimate consumer. American Home Products Company American Consumer Industries A national standard on slip sheets Armour & Company - Division of is presently being developed. It en- Greyhound Corp. compasses terminology, materials, sizes, McDonald’s Systems performance values related to materials Coors Brewery in the slip sheet and testing. It is anticipated this standard could be Coors Brewery was the first to introduce accepted and published by mid 1980. plastic slip sheets on a larger scale.

The United Fresh Fruit and Vegetable Growers Association have adopted slip sheets as a unit load base and they are expressing the base dimensions in metric measurements of 1000 by 1200 mm as being a standard. *******

Journal of Food Distribution Research February 80/page 69