This study with order picking problem with limited/unlimited capacity of the storage/retrieval machine (S/R machine) in automated warehousing systems. It is assumed that orders are handled by a man-on-board system or the S/R machine which can carry more than one pallet at a time. Several heuristic algorithms are developed which minimize the total travel time of the S/R machine using the property of Chebyshev travel. Using computer simulation, the performance of the algorithms are studied and compared to those of the previous studies.