Abstract: A transmission housing for a hammer drill 320 is formed from three housing portions. A generally L-shaped first housing portion 380a accommodates a spindle 348, a hollow piston 358, the respective spindle and hollow piston drive mechanisms and a mode change mechanism. The first housing portion 380a is mounted to a second housing portion 380b such that a first O-ring 382a is trapped between the two portions to prevent the ingress of dust. The second housing portion 380b holds the lower part of the transmission mechanism inside the first housing portion 380a. The second housing portion 380b forms a motor output aperture 390 for enabling the motor output shaft 336 to engage the transmission mechanism. A third transmission housing portion 380c is mounted to the front of the first housing portion 380a such that spindle 348 projects out of the third transmission housing portion 380c. A second O-ring 382b seals the join between the first and third transmission housing portions 380a, 380c.

Abstract: A power tool cooling system comprises a cooling fan disposed on a motor in a position between the upper field coil and the lower commutator. A transmission housing encapsulates the transmission mechanism. During operation, the fan is driven by the motor and draws air axially through the motor and expels the air radially outwardly through holes in the outer housing of the motor. This causes air to be drawn in through the air vents formed on the top of a tool housing, in the side of the housing and between the housing and a battery pack. The cool air flows outside of the transmission housing, but inside the tool housing such that air does not pass through the transmission mechanism. A plurality of motor openings are also formed in the outer housing of the motor to enable cool air to pass into the motor to cool the motor.

Abstract: A transmission housing for a hammer drill comprises two clamshell halves and that mate to define a first transmission housing chamber and a second transmission housing chamber disposed on either side of a ball bearing race. The first and second transmission housing chambers are interconnected by channels. The rear end of a hollow piston, a cylindrical bearing, a crank pin and a crank plate are disposed in the first transmission housing chamber, and a spindle is disposed in the second transmission housing chamber. Overflow channels and allow movement of air between the first and second transmission housing chambers to reduce compression of air iduring reciprocation of the hollow piston.

Abstract: A hammer drill has a transmission housing 280 is formed from two clamshell halves of durable plastics or cast metal material. The transmission housing 280 is mounted on first and second damping springs 284 and 286 at its rearward end. The transmission housing 280 is also mounted on parallel rails (not shown) disposed within the tool housing 222 such that the transmission housing 280 can slide a small distance relative to the tool housing 222. The forward end of the transmission housing 280 has a generally part conical portion 290, which abuts a corresponding part conical portion 292 formed on the tool housing 222. The interface defined by conical portions 290 and 292 defines a stop against which the transmission housing 280 rests against the tool housing 222 in the inoperative condition of the hammer drill 220.

Abstract: A gear wheel is rotatably mounted on a drive shaft. The drive shaft has a plurality of longitudinal splines formed thereon. A drive sleeve surrounds the drive shaft and has a plurality of the inner splines formed on its interior surface. The inner splines slidably intermesh with outer splines of the drive shaft such that the drive sleeve can slide up and down on but cannot rotate relative to the drive shaft. A coil spring biases the drive sleeve downwardly. Drive sleeve teeth are formed around the bottom edge of the drive sleeve. Corresponding gear plate teeth are formed on the upper surface of the gear wheel and are adapted to engage the drive sleeve teeth when the drive sleeve is in its downward most position under the influence of the coil spring. In this position, the gear wheel is operatively coupled to the drive shaft.

Abstract: A battery powered, hand guided power tool, such as a hammer, includes a tool housing 3 that contains an electric motor M, a grip portion 2 and a rail-and-channel structure 36,37,54,55 for releasable mounting of a rechargeable battery pack 50. A locking device is provided on the tool housing 3 and includes a latch element 18,19 which is movable into a latch recess 52,53 formed in a housing of the battery pack 50, whereby the battery pack is locked in an operative position on the tool housing, movable by a user, against the force of a spring 20,21. The latch element 18,19 can be pivoted by a user to extract the latch element from the latch recess 52,53 for the release of the battery pack 50 from assembly with the tool housing 3. On the tool housing 3 adjacent to the rail-and-channel structure 36,37,54,55, there is provided a frame part 15 that includes at least one frame-part recess 16,17.

Abstract: A mode change switch for a power tool, which switch is moveable between at least two positions corresponding to different operating modes of the tool in which different components of the tool are brought into a meshing engagement. The switch comprises a manually operable driving member moveable between at least two positions in each of which it is adapted to be realizably restrained and a driven member which is adapted to be driven by the driving member between associated positions to directly or indirectly facilitate a change in operating mode. A spring engages between the driving member and driven member, to urge the driven member to follow the movement of the driving member. The switch is arranged so that a first end of the spring abuts a first pair of stop members and a second end of the spring abuts a second pair of stop members. One of each pair of stop members is located on the driving member. And the other of each pair is located on the driven member.