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Certain roll over protective structures, ROPS, require resistance to the propagation of brittle fractures at low temperatures. It is demonstrated that the Charpy test is not suitable for characterizing crack propagation resistance. A drop weight test of thin wall tubular specimens was developed which uses a brittle crack starter weld. This test provides an indication of the temperature transition from low to high crack propagation resistance. Because of toughened heat affected zones which can occur in cold formed steel this test is reliable only for hot formed tubes. The temperature transition to high propagation resistance can be determined with precracked Charpy and Dynamic Tear Energy, DT, specimens applicable to cold or hot formed steel. A weld joint simulation specimen was developed to determine energy absorption capacity and low temperature fracture behavior of ROPS joint designs and material.

As the American farmer continues to substitute capital and technology for labor, his need for more powerful tractors will increase. Utilization of this increased power can be achieved by the use of tools with greater working widths, performance of several combined operations in one pass, and increasing the field speed at which the various operations are performed. This paper explores some of the advantages (and disadvantages) of high tractor field speeds, first from the farmer's viewpoint and second from the engineer's or manufacturer's viewpoint.