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1. (US20050194165) Impact drill
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Claims

1. An impact drill comprising:
a spindle rotated by a motor and movable in an axial direction;
a drill chuck fixed to the spindle and mountable with a drill bit;
a first ratchet fixed to the spindle and having a face including an irregular portion;
a second ratchet having a face including an irregular portion opposed to the face of the irregular portion of the first ratchet and movable in the axial direction, and
a spring for urging the second ratchet in a direction of the first ratchet, in which the spindle is given an axial vibration by a contact and separation action between the irregular faces of the first and second ratchets due to a relative rotation of the first ratchet to the second ratchet, wherein
the second ratchet is supported to be rotatable within a predetermined range in a rotational direction thereof.
2. The impact drill according to claim 1, wherein
the second ratchet is supported to be rotatable by an angle or more from a first position at which the irregular face of the second ratchet overrides the irregular face of the first ratchet to a second position at which the irregular face of the second ratchet engages the irregular face of the first ratchet most deeply, when the first ratchet is in a stopped state.
3. The impact drill according to claim 1, wherein
the second ratchet is supported to be rotatable by 0.6 times an angle or more from a first position at which the irregular face of the second ratchet overrides the irregular face of the first ratchet to a second position at which the irregular face of the second ratchet engages the irregular face of the first ratchet most deeply, when the first ratchet is in a stopped state.
4. The impact drill according to claim 1, wherein
the second ratchet is supported to be rotatable by 0.3 times an angle or more from a first position at which the irregular face of the second ratchet overrides the irregular face of the first ratchet to a second position at which the irregular face of the second ratchet engages the irregular face of the first ratchet most deeply, when the first ratchet is in a stopped state.
5. The impact drill according to claim 1, wherein
a notch portion is provided on an outer circumference of the second ratchet,
a projection portion provided in a main frame portion of the impact drill is inserted into the notch portion, and
a predetermined clearance is provided between the notch portion and the projection portion.
6. The impact drill according to claim 1, wherein
a width across flat of two parallel faces is provided in a part on a cylindrical portion of the second ratchet,
a notch portion opposed to the width across flat is provided on a main frame portion of the impact drill, and
a predetermined clearance is provided between the width across flat and the notch portion.
7. The impact drill according to claim 1, wherein
a projection portion is provided on an outer circumference of the second ratchet,
the projection portion is inserted into a notch portion provided in a main frame portion of the impact drill, and
a predetermined clearance is provided between the projection portion and the notch portion.
8. The impact drill according to claim 5, wherein an elastic body is disposed in the predetermined clearance.
9. The impact drill according to claim 5, wherein
a thrust bearing is provided between the second ratchet and the spring.
10. The impact drill according to claim 5, wherein
a thrust bearing is provided between the spring and a side wall portion extending from the main frame portion.
11. The impact drill according to claim 9, wherein
the thrust bearing is provided between the spring and a side wall portion extending from the main frame portion.