| 摘要 |
A head rest is made up of an outer casting having a head-receiving trough and opposed bosses formed at each end of the trough. A rod having a turning knob at one end has bearing in both said bosses. A sleeve surrounds the rod and is keyed thereto. The sleeve has threads of opposite pitch at each of its ends. A nut is threaded on each end of said sleeve. Each nut is pivoted at each of its ends to a link of a lazy-tongs linkage. A second, inner casting provides support for the foregoing structure and has horizontal guides for the free ends of the links at the opposite end of said lazy-tongs unit.
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