| 摘要 |
<p>The invention relates to a device for preventing length measuring errors resulting from accidentally remaining local offshoots from a portion of the butt end of a tree stem which is continuously advanced toward a cross-cutting member for cutting the stem in predetermined length sections. A stem-measuring device periodically emits a cutting impulse to the cross-cutting member so that the advancing stem will be cut into predetermined lengths. Two detectors are provided in a spaced relationship for sensing the entering of the butt end into a detecting station and then emitting an actuating signal to start the measuring device. The spacing of the two detectors, which are symmetrically positioned with respect to the centerline of the stem path, does not exceed a predetermined minimum butt diameter. The measuring device is not actuated until signals from both detectors are emitted. Thus, sensing of a local offshoot from the butt end by only one of the detectors does not start the measuring device with the result that the offshoot does not cause a shorter-than-desired length of stem.</p> |
