초록 ▼

A hammer drill comprises a motor including an output shaft, a shaft assembly rotationally engaged therewith, a hollow spindle, and a hammer mechanism comprising a piston arranged for reciprocating motion within the spindle. The shaft assembly comprises a first part carrying a first gear engaged with

A hammer drill comprises a motor including an output shaft, a shaft assembly rotationally engaged therewith, a hollow spindle, and a hammer mechanism comprising a piston arranged for reciprocating motion within the spindle. The shaft assembly comprises a first part carrying a first gear engaged with a gear on the spindle to cause spindle rotation, a second part carrying a crank member to cause piston reciprocation, and a connecting part configured to rotationally interconnect, or disconnect, the first and second parts. In a first position of the connecting part only one of the first and second parts is rotationally engaged with the output shaft to enable rotation of only one of the first gear and the crank member respectively, while in a second position both the first and second parts are rotationally engaged with the output shaft to enable rotation of both the first gear and the crank member.

대표청구항 ▼

1. A hammer drill, comprising: a motor including a motor output shaft;a hollow spindle;a hammer mechanism comprising a piston arranged for reciprocating motion within the hollow spindle; andan intermediate shaft assembly rotationally engaged with the motor output shaft and comprising a first part, a

1. A hammer drill, comprising: a motor including a motor output shaft;a hollow spindle;a hammer mechanism comprising a piston arranged for reciprocating motion within the hollow spindle; andan intermediate shaft assembly rotationally engaged with the motor output shaft and comprising a first part, a second part and a connecting part, the first part carrying a first gear which is in engagement with a second gear on the hollow spindle to cause rotation of the spindle, the second part carrying a crank member arranged to cause the reciprocating motion of the piston, and the connecting part arranged for movement with respect to the first and second parts to rotationally interconnect, or disconnect, the first and second parts such that in a first position of the connecting part only one of the first and second parts is rotationally engaged with the motor output shaft to enable rotation of only one of the first gear and the crank member respectively, and such that in a second position of the connecting part both of the first and second parts are rotationally engaged with the motor output shaft to enable rotation of both the first gear and the crank member,wherein the second part comprises a shaft which extends through the first part and an end region that extends beyond an end of the first part, and wherein the connecting part is located or locatable on the end region of the second part. 2. A hammer drill according to claim 1, wherein the first part comprises a hollow part, and the second part extends through the first part. 3. A hammer drill according to claim 1, wherein the first part carries a driven gear which is in engagement with the motor output shaft and is arranged to rotate the first part when the motor output shaft rotates in use. 4. A hammer drill according to claim 1, wherein the first gear is formed in a single piece with the first part. 5. A hammer drill according to claim 1, wherein one or more of the first gear and the second gear comprises a bevel gear. 6. A hammer drill according to claim 5, wherein the bevel gear comprises a crown gear. 7. A hammer drill according to claim 1, wherein the shaft of the second part extends beyond two opposite ends of the first part. 8. A hammer drill according to claim 7, wherein the crank member is located at another end region of the second part which extends beyond an end of the first part opposite the connecting part. 9. A hammer drill according to claim 1, wherein when the connecting part is in its first position the connecting part is located on only one of the first and second parts, and when the connecting part is in its second position the connecting part is located on both of the first and second parts. 10. A hammer drill according to claim 9, wherein when the connecting part is in its first position the connecting part is located on only the second part to enable rotation of only the first gear and not the crank member. 11. A hammer drill according to claim 1, wherein the connecting part comprises a hollow part located on the first part and/or the second part. 12. A hammer drill according to claim 1, further comprising a movable linkage arrangement configured to move the connecting part between its first and second positions. 13. A hammer drill according to claim 12, further comprising a mode change collar rotatably mounted on a housing of the hammer drill and configured such that rotation of the mode change collar causes the movable linkage arrangement to move the connecting part between its first and second positions. 14. The hammer drill according to claim 13, wherein the movable linkage arrangement comprises an elongate member configured to pivot the pivoting arm, and wherein the mode change collar includes a cam surface configured such that rotation of the mode change collar causes the elongate member to move. 15. A hammer drill according to claim 14, wherein the pivoting arm is spring-biased towards the elongate member and the mode change collar. 16. A hammer drill according to claim 1, further comprising: a housing;a movable linkage arrangement configured to move the connecting part between its first and second positions; anda mode change collar rotatably mounted on the housing and configured such that rotation of the mode change collar causes the movable linkage arrangement to move the connecting part between its first and second positions. 17. A hammer drill according to claim 16, wherein the movable linkage arrangement comprises a pivoting arm. 18. A hammer drill according to claim 16, wherein the movable linkage arrangement comprises an elongate member configured to pivot the pivoting arm.