| 摘要 |
A hardened brake shoe insert 28 for use in bi-directional backstopping clutches is formed from a base material of high speed alloy tool steel, which is relatively inexpensive and easy to machine. The base material is formed into the desired shape for the insert 28, then hardened and tempered to achieve a desired hardness. Then, a coating of titanium nitride is applied to the insert by a physical vapor deposition process or a chemical vapor deposition process. The titanium nitride coating provides a very hard surface to the insert, which permits the insert to be used in the backstopping clutch. In an alternative embodiment, the brake shoe 15, 16 itself is formed in the manner described above, and no inserts are used in the clutch. The base material may have a hardness within the range of 62-65 on the Rockwell C scale and the titanium nitride coating may have a hardness of approximately 85 on the Rockwell C scale. <IMAGE> |
