Compact multi-speed hammer-drill

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 pair of hammer members, one fixed in the housing and the other carried by the spindle 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 for switching from the drilling mode to the hammer-drilling mode, and vice versa, a multi-speed transmission including an intermediate shaft journaled in the housing and having at least a pair of idler gears of different size mounted thereon for conjoint rotation therewith, a corresponding pair of output gears of different size freely rotatably mounted on the spindle and constantly meshing with the pair of idler gears, respectively, each of the output gears having respective inner and outer faces, a member carried by the spindle between the pair of output gears, keying means between the member and the spindle for conjoint rotation therewith, said keying means comprising a longitudinal key disposed radially between the member and the spindle, the spindle having a longitudinal keyway formed extenally thereon to receive the key, the key engaging the respective inner faces of the output gears, thereby maintaining an axial spacing between the output gears, means for shifting the member axially along the spindle to engage one or the other of the output gears, respectively, thereby coupling one or the other of the output gears to the spindle, respectively, for establishing at least two different speeds of operation, first abutment means in the housing and engaging the outer face of one of the output gears, and second abutment means in the housing and engaging the outer face of the other output gear, whereby the output gears are restrained against axial movement in the housing, and whereby the constant meshing engagement of the output gears with the respective idler gears is assured, and the longitudinal keyway extending axially beyond the key and within the hub of one of the output gears, thereby accommodating the floating axial movement of the rotary-reciprocatory output spindle in the hammer-drilling mode of operation for both speeds of operation.

A hammer-drill having "drilling" and "hammer-drilling" modes of operation, comprising:

• a housing with a motor therein;
• a rotary-reciprocatory output spindle journaled in the housing;
• a fixed hammer member mounted about the spindle and retained in a forward portion of the housing;
• a movable hammer member carried on the spindle and cooperating with the fixed hammer member to deliver vibratory impacts to the spindle in the hammer-drilling mode of operation;
• means, mounted in the housing and cooperating with said spindle, for selectively changing the hammer-drill from the drilling mode to the hammer-drilling mode, and vice versa;
• a three-speed transmission comprising an intermediate shaft journaled in the housing, respective first, second and third idler gears on said shaft for conjoint rotation therewith, respective first, second and third output gears on said spindle and disposed axially between said mode changing means and the cooperating hammer members, said first and third output gears being freely rotatably mounted on said spindle, said first output gear being disposed adjacent to the cooperating hammer members and being constantly in mesh with said first idler gear, said third output gear being disposed adjacent to said mode changing means and being constantly in mesh with said third idler gear, and said second output gear being in mesh with said second idler gear in one of the three speeds of operation;
• a longitudinal key disposed between said second output gear and said spindle for conjoint rotation therewith in all three speeds of operation, said key being received in a longitudinal keyway formed in said spindle;
• said keyway being axially longer than said key to allow said key to slide axially relative to said keyway to accommodate reciprocatory movement of said spindle in the hammer-drilling mode;
• means for moving said second output gear axially along said spindle in either direction into juxtaposition to said first and third output gears, respectively;
• and
• means responsive to the juxtaposition of said second output gear to said first and third output gears, respectively, for coupling either said first or third output gears, respectively, to said spindle.