JPS5757942A - Transmission gear - Google Patents

Abstract

PURPOSE: To achieve a secure and quick operation of speed change in the case of a gear speed changeover unit of a machine tool etc., by arranging the driving gear always to stop at its engagable position when the driven gear stops at a given position.

CONSTITUTION: When a low speed operation is switched over to a high speed operation, the rotating main shaft 16 is stopped at the position assigned by a constant position mechanism 23 and a high speed gear 13 and a low speed gear 14 are stopped while securing such a condition that either of the reference stopping lines 24 is aligned with the line connecting those rotational centers 27, 28. Resultantly, the high speed shift gear 9 is always kept engaged with the high speed gear 13 at this rotational position. Thereafter, a shifter arm 10 is raised through operation of a gear shift cylinder 12, a low speed shift gear 8 is raised on a spline 7 in relation to a intermediate shaft 6 and the high speed shift gear 9 fined to the low speed shift gear 8 is engaged with a high speed gear 13. Just by the time of this engagement, the low speed shift gear 8 has been engaged with the low speed gear 14.

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