bags, he should be able to open and dump a bag into the hopper in about 

 the same time it would take him to lift a bag and place it on a conventional 

 conveyor. For purposes of uniformity of analysis, let us assume further that 

 the truck will be loaded by hand truck, and that one man would do the 

 loading (as for regular bagged and bulk comparisons). In Table 13 

 it was observed that one man using a hand truck could unload a railroad 

 car onto a truck at a rate of 0.20 man minutes per 100 pounds. But since 

 the loading of a delivery truck might be more complex, 0.30 man minutes 

 per 100 pounds has been used herein. Note that this rate is actually only 

 slightly lower than was achieved in certain instances of efficient loading 

 by hand. 



In order to attempt to offset in part the time savings of gravity loading 

 of regular bulk feed, it would probably pay to mechanize loading, perhaps 

 to the extent of using a chute, conveyor, and additional men. This would 

 not tie up the truck for as long as having one man do the loading, but the 

 final decision would be based upon comparison of man minutes and truck 

 time involved. 



Table 23. Estimated Costs of Depreciation on Hopper-Elevating Delivery Truck 



^ 280 working days per year. 



Having outlined the assumptions of the analysis, they can be tested in 

 two ways: 



(1) Using the hopper-elevating system as a pure method, paralleling 

 the calculations presented in Table 20 for regular bagged and bulk feed 

 as pure methods. This will test the costs of the hopper-elevating method 

 against the regular systems, (Hypothesis 3.) 



(2) Since the hopper-elevating system offers greatest promise where 

 there may be a mixture of bagged and bulk customers, but perhaps not 

 enough of either to keep separate delivery units occupied at capacity, a 

 second test can be made of average costs (see Figure 10). Here, for sim- 



46 



