the plunger 86 is withdrawn beyond the keyway member 93 and the plunger handle 91 is turned such that the key 92 engages against an outer surface 94 of the keyway member 93 so that the tip 87 is in disengaged relation relative to the toothed wheel 88 the manual actuation will generally be done when the auger has advanced into compacted silage and it is desired to continue the rotation of the auger on its own axis for clearing the compacted silage while the auger remains in a fixed position relative to the silo floor and consequently it is desired to disengage temporarily the sweeping motion of the auger 12 across the floor 11 this will leave the drive rod 82 moving in a back and forth motion without transmitting a drive to the toothed wheel 88 it will be noted that the operation described above for driving the rod 82 and consequently the plunger tip 87 by means of the eccentric 80 effects a conversion of a continuous rotary motion into a discontinuous or intermittent linear back and forth motion of the plunger tip 87 that acts to drive the toothed wheel 88 in an intermittent rotational motion also the toothed wheel 88 is driven through only a short arc with each rotation of the eccentric 80 and consequently a greater rotational motion of the shaft 20 and of the eccentric 80 is translated into a lesser or shorter arcuate or intermittent rotational motion of the sprocket 88 and thereby the mechanism for doing so functions as a force or torque multiplier for allowing a larger motion.