Automatic-locking mechanical drive construction

An automatic-locking mechanical drive construction for raising and lowering a window blind, comprising in combination:

• a) a fixed cylindrical member,
• b) a rotary drive member mounted to rotate about an axis with respect to said cylindrical member,
• c) a rotary driven member turnable with respect to said cylindrical member and about the axis of said drive member,
• d) said drive and driven members having pairs of facing, abuttable walls effecting a two-directional, lost-motion rotary driving connection between the drive and driven members,
• e) helical coil spring means engaging and frictionally seizing and locking to said cylindrical member, said spring means being thereby normally temporarily fixed with respect to the cylindrical member,
• f) said spring means having a radially-extending shoulder intermediate its ends,
• g) spaced-apart shoulders on the driven member, individually engageable with said radially-extending shoulder on the spring means whereby said spring means normally prevents turning of the driven member in either of opposite directions, and
• h) lugs on said drive member, respectively engageable with end portions of the spring means to unlock the grip of the latter on the cylindrical member, thereby enabling the abuttable walls of the driven and drive members to turnably drive the driven member in either of two directions as the drive member is turned in said directions.

An automatic-locking mechanical drive construction for raising and lowering a window blind, comprising in combination:

• a) a fixed cylindrical shaft,
• b) a rotary drive member mounted to rotate about an axis with respect to said shaft,
• c) a rotary driven member turnable with respect to said shaft and about the axis of said drive member,
• d) said drive and driven members having pairs of facing, abuttable walls effecting a two-directional, lost-motion rotary driving connection between the members,
• e) helical coil spring means on and frictionally seizing and locking to said shaft with its convolutions, said spring means being thereby normally temporarily fixed on the shaft,
• f) said spring means having a radially-projecting shoulder intermediate its ends, dividing the convolutions into two groups,
• g) spaced-apart shoulders on the driven member, individually engageable with said projecting shoulder on the spring means whereby one group or the other of the convolutions of said spring means normally prevents turning of the driven member in one direction or the other of opposite rotary directions, said group which does not prevent turning constituting a frictional drag on the driven member to thereby prevent stair-stepping of the latter as it is being driven, and
• h) lugs on said drive member, respectively engageable with end portions of the spring means to unlock the grip of the latter on the shaft, thereby enabling the abuttable walls of the driven and drive members to turnably drive the driven member in either of two directions as the drive member is turned in said directions.