PROPELLING FORCE APPLICATION APPARATUS

摘要

A propelling force application apparatus wherein a cylindrical push member the front edge of which is brought into contact with a propelled member and which is equipped at least around the inner periphery on the rear side thereof with a female screw is supported by a stationary casing in such a manner that revolution round the axis thereof is inhibited but movement in the axial direction is permitted, a bearing member for enabling a rotary shaft to rotate round the axis and thrusts and supports the rotary shaft is interposed between the proximal end of the rotary shaft having a male screw meshing with the female screw on the distal end side and the casing, and a spring for urging the rotary shaft in the advancing direction of the push member is interposed between the casing and the rotary shaft. An effective friction diameter d1 between the rotary shaft (7) and the bearing member (8) is greater than an effective diameter d2 of the meshing portion between the male screw portion (7a) and the female screw portion (18) so that a drastic retreat of the push member due to the drop of the frictional coefficient due to an extended use can be reduced to minimum. <IMAGE>