A manual screw shaft driving device, comprising:
- a screw shaft, which is a rod-shaped member extending on an axis, being formed with screw threads around an outer peripheral surface of the screw shaft;
- a driving member, which has a tubular shape, being formed with driving threads on an internal surface of the driving member, the driving threads being corresponding in shape to the screw threads, wherein the driving member is fitted around the screw shaft in a relatively slidable and rotatable manner by meshing the screw threads with the driving threads, and the driving member is further formed with a front engaging portion at a front end of the driving member, a rear engaging portion at a rear end of the driving member, and a protruding portion protruding from an external surface of the driving member;
- a gripping member, which has a tubular shape, being formed with a sliding and rotating space inside the gripping member, wherein the screw shaft is provided passing through the sliding and rotating space in a manner that the screw shaft is slidable and rotatable with respect to the gripping member, the driving member is disposed in the sliding and rotating space in a relatively slidable and rotatable manner, and the gripping member is further formed with a front stop-rotation portion at an inner front end of the gripping member, the shape of the front stop-rotation portion is formed corresponding to the front engaging portion, an inner rear end of the gripping member is formed with a rear stop-rotation portion whose shape is corresponding to the rear engaging portion, and a peripheral side wall of the gripping member is formed with an opening communicating with the sliding and rotating space;
- and
- a driving direction switching member disposed at the opening of the gripping member in a slidable manner along the axis to switch between a first switching position and a second switching position, the driving direction switching member being formed protruding into the sliding and rotating space with a front limiting portion and a rear limiting portion behind the front limiting portion to define a sliding limitation space between the front limiting portion and the rear limiting portion, wherein the protruding portion protrudes into the sliding limitation space such that forward and backward sliding of the driving member in the sliding and rotating space is limited,
- wherein while the driving direction switching member is switched to the first switching position, operating conditions include:
- (1) when the gripping member slides backwardly with respect to the screw shaft, the front stop-rotation portion of the gripping member backwardly engages the front engaging portion of the driving member, rendering the driving member unable to rotate to cause the driving member is unable to rotate with respect to the gripping member, and therefore the screw shaft is driven to rotate in a first rotation direction with respect to the gripping member by a screw mechanism between the screw threads and the driving threads of the driving member, and
- (2) when the gripping member slides forwardly with respect to the screw shaft, the front stop-rotation portion of the gripping member forwardly disengages from the front engaging portion of the driving member, and the rear engaging portion of the driving member is spaced apart from the rear stop-rotation portion of the gripping member by means of a rear limitation of the rear limiting portion of the driving direction switching member to the protruding portion, rendering the driving member rotatable, and therefore the driving member rotates with respect to the screw shaft but does not drive the screw shaft to rotate,
- the above two operating conditions enable the screw shaft to rotate only in the first rotation direction by a manual forward and backward sliding operation of the gripping member,
- wherein while the driving direction switching member is switched to the second switching position, operating conditions include:
- (1) when the gripping member slides forwardly with respect to the screw shaft, the rear stop-rotation portion of the gripping member forwardly engages the rear engaging portion of the driving member, rendering the driving member unable to rotate to cause the driving member is unable to rotate with respect to the gripping member, and therefore the screw shaft is driven to rotate in a second rotation direction, which is opposite to the first rotating direction, with respect to the gripping member by the screw mechanism between the screw threads and the driving threads of the driving member, and
- (2) when the gripping member slides backwardly with respect to the screw shaft, the rear stop-rotation portion of the gripping member backwardly disengages from the rear engaging portion of the driving member, and the front engaging portion of the driving member is spaced apart from the front stop-rotation portion of the gripping member by means of a front limitation of the front limiting portion of the driving direction switching member to the protruding portion, rendering the driving member rotatable, and therefore the driving member rotates with respect to the screw shaft but does not drive the screw shaft to rotate,
- the above two operating conditions enable the screw shaft to rotate only in the second rotation direction by the manual forward and backward sliding operation of the gripping member.