Oil Seals for Tractors and Excavators

The causes of oil seal failures in the field have been itemized by the authors of these papers. In the case of Beer, who deals with the case of a Model C Tournapull, which is a 20 ton machine on the 200 + class with a tourmatic drive consisting of a six speed transmission with a single stage torque converter, and on which there are fifteen shaft type oil seals, he states as follows :—Providing transmission shafts are correct hardness and finish and bore concentricities and shaft run‐outs meet the minimum requirements, the seals failed because (1) Incorrect spring tension held the sealing lip too tightly against the shaft causing increased frictional heat which hardened the material and with existing shaft run‐out did not permit the seal to follow the shaft resulting in leakage. The grooves in the shafts could also be associated with tight springs. (2) High operating temperatures exceeded the temperature limits of the seal material thus causing it to harden and lose its sealing effectiveness.