When driving spline shaft 8 rotates continuously about fixed axis C, worm 1, which can slide along the splines of shaft 8 and meshes with worm wheel 2, rotates the wheel counterclockwise. Worm wheel 2 is keyed to shaft 9 with which it rotates about fixed axis B. When pin a of wheel 2 runs up against one end of bell-crank lever 3, wheel 2 and shaft 9 stop rotating and worm 1, continuing to mesh with wheel 2 and to rotate with shaft 8, travels to the left (like a screw in a nut) along axis C of shaft 8, together with slide 4 and screw 5, overcoming the resistance of spring 6. This motion continues until nut b on screw 5 reaches the other leg of lever 3, turning the lever and releasing pin a and worm wheel 2. After this, rapid rotation is transmitted to wheel 2 until lever 7 reaches pin d. Then wheel 2 and shaft 9 begin to rotate at uniform velocity until pin a engages lever 3 again.
$2822$WG,ML$