Motor driven hand-held machine with two part tool assembly

Claim 1

In a motor-driven portable machine tool, the combination comprising: (a) a housing; (b) a drive motor in said housing including a rotatable output shaft; (c) a tool driving member mounted for reciprocation in said housing at a point spaced from said output shaft and having means for mounting a tool for reciprocation thereby; (d) a tool drive assembly operatively connected to said tool driving member to effect its reciprocation; (d) a first gear mechanism including a gear driven by said output shaft; (f) a second gear mechanism drivingly engaged with said tool drive assembly; (g) coupling means between said first and second gear mechanisms to effect transfer of rotation from said output shaft to rotate of said second gear mechanism and thereby said tool drive assembly, said coupling means including: (i) axially adjacent first and second coupling halves supported for rotation in said housing about a common axis, said coupling halves being relatively rotatable; (ii) a coil spring disposed about axially adjacent circumferential surfaces on said coupling halves, said first gear mechanism including a second gear operatively connected to the adjacent first coupling half to effect its rotation, said second gear mechanism including a driven gear operatively connected to the adjacent second coupling half to be rotated thereby and transmit the rotation to said tool drive assembly, said spring being engaged at one end with said second coupling half; (iii) a clutch member having the other end of said spring engaged therewith and rotatable about said axial surface of first coupling half; and (iv) a releasable latch member engageable with said clutch member to prevent its rotation, release thereof from such engagement causing said spring to coil tightly about said adjacent surfaces of both coupling halves and thereby effecting driving engagement therebetween, said latch member upon reengagement with said clutch member producing an enlargement of the diameter of said coil spring about said surfaces to disengage said coupling halves; and (h) a stop mechanism operatively connected to said latch member for moving said latch member into engagement with said clutch member to stop said tool driving member in one extreme position of reciprocation.