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A multi-speed hammer-drill has a rotary-reciprocatory output spindle journaled in its housing. A fixed hammer member is mounted about the spindle in a forward portion of the housing and a cooperating hammer member is carried on the spindle. A cam member cooperates with the rearward end of the spindl

A multi-speed hammer-drill has a rotary-reciprocatory output spindle journaled in its housing. A fixed hammer member is mounted about the spindle in a forward portion of the housing and a cooperating hammer member is carried on the spindle. A cam member cooperates with the rearward end of the spindle for selectively changing between drilling and hammer-drilling modes. A three-speed transmission includes an axially-shiftable gear member carried by the spindle and disposed axially between the cam member and the cooperating hammer members with two non-axially movable gears freely rotatably mounted on said spindle one on each side of the axially-shiftable gear. A key is received in a longitudinal keyway in the spindle and keys the axially-shiftable gear member to the spindle. The key has a length substantially equal to the axial distance between the non-axially movable gears for maintaining a spaced relationship therebetween. The keyway is longer than the key to allow the key to slide axially relative to the keyway to accommodate reiprocatory movement of the spindle in the hammer-drilling mode. The axially-shiftable gear serves to provide a direct torque couple between an idler shaft and the spindle, or as a clutch for axially engaging either non-axially movable gear.

대표청구항 ▼

In a compact multi-speed hammer-drill having a housing with a motor therein, the hammer-drill having a “drilling”mode of operation and a “hammer drilling”mode, the combination of a rotary-reciprocatory output spindle journaled in the housing and having a limited axial floating movement therein, a fi

In a compact multi-speed hammer-drill having a housing with a motor therein, the hammer-drill having a “drilling”mode of operation and a “hammer drilling”mode, the combination of a rotary-reciprocatory output spindle journaled in the housing and having a limited axial floating movement therein, a fixed hammer member mounted concentrically about the spindle and retained in a forward portion of the housing, a movable hammer member carried on the spindle, concentrically therewith, and cooperating with the fixed hammer member to deliver vibratory impacts to the spindle in the hammer-drilling mode of operation, shiftable means mounted in the housing and engaging an inner portion of the spindle remote from the hammer members for switching from the drilling mode to the hammer-drilling mode, and vice versa, and a three-speed transmission comprising an intermediate shaft journaled in the housing, respective first, second and third idler gears of different sizes on the shaft for conjoint rotation therewith, respective first, second and third output gears of different sizes on the spindle, the first and third output gears being freely rotatably mounted on the spindle, the first output gear being disposed adjacent to the cooperating hammer members and being constantly in mesh with the first idler gear, the third output gear being disposed adjacent to the shiftable means and being constantly in mesh with the third idler gear, the second output gear being in mesh with the second idler gear in one of the three speeds of operation, keying means between the second output gear and the spindle for conjoint rotation therewith in all three speeds of operation, means for moving the second output gear axially in either direction along the spindle in juxtaposition to the first and third output gears, respectively, and means responsive to the juxtaposition of the second output gear to either the first and third output gears, respectively, for coupling either the first or third output gears to the spindle, respectively, thereby providing for two additional speeds of operation.