RATING OF ACCEPTABLE LOADS IN MANUAL SORTING OF POSTAL PARCELS

The psychophysical test, the rating of acceptable load (RAL) were used to assess acceptable weights for dynamic lifting in postal workers en gaged in sorting parcels. The standard test (RAL(St)) and a work-simul ating test (RAL(w)) were administered to 103 volunteers: all experienc ed male sorters. Ln the RAL(St), subjects selected the weight which wo uld be acceptable for lifting in a box with handles from table to floo r and back to the table once every 5 min for the working day. For the RAL(W), the box was without handles and the weight was chosen to be ac ceptable for transfer 4-6 times/min from a table to the parcel contain er and back to the table. Both tests were made during normal working h ours at postal sorting centres. The overall means for RAL(St) and RAL( W) were 16.4 kg and 9.4 kg respectively (p <0.001): both being substan tially higher than the average parcel weight of 4 kg. The RAL(St) and RAL(W) tests proved to be repetitive and sensitive for differentiating the effects of load and task variables in actual manual materials han dling. Thus they appear to be applicable to the evaluation of manual m aterials handling problems.