Claims
- 1. An impact mechanism comprising:a motor; a shaft rotatable about an axis and coupled to the motor and having a first shaft groove with first and second axial ends spaced apart by an axial extent; a hammer disposed about the shaft and having a first hammer groove; a ball disposed in the first hammer groove and in the first shaft groove and coupling the hammer to the shaft for relative axial and rotatable movement with the ball moveable along the grooves; a rotatable anvil for coupling to a load; a bias member resiliently biasing the hammer axially into an impact position in engagement with the anvil; and stop structure coupled to the shaft and spaced from the hammer in its impact position an axial distance less than the axial extent of the shaft groove for engagement with the hammer to limit axial movement of the hammer away from the anvil so as to prevent the ball from contacting the second axial end of the first shaft groove, the stop structure being spaced from the bias member and out of engagement therewith.
- 2. The impact mechanism of claim 1, wherein the stop structure is a generally cylindrical spacer disposed about the shaft.
- 3. The impact mechanism of claim 2, wherein the spacer is formed of a plastic material.
- 4. The impact mechanism of claim 2, wherein the spacer is formed of a hard nylon.
- 5. The impact mechanism of claim 2, wherein the spacer is discrete from the shaft.
- 6. The impact mechanism of claim 2, wherein the spacer is press fitted onto the shaft.
- 7. The impact mechanism of claim 5, wherein the bias member is a coil spring and the spacer is totally disposed within the coils of the spring.
- 8. The impact mechanism of claim 1, wherein the first shaft groove and first hammer groove are helical.
- 9. The impact mechanism of claim 1, wherein the shaft includes a second shaft groove with first and second axial ends, and the hammer includes a second hammer groove, and further including a second ball disposed in and moveable along the second hammer groove and the second shaft groove, wherein when the hammer engages the stop structure the second ball is prevented from contacting the second axial end of the second shaft groove.
- 10. The impact mechanism of claim 1, wherein the motor is an electric motor.
Parent Case Info
This is a continuation of application Ser. No. 09/265,054, filed Mar. 9, 1999, now U.S. Pat. No. 6,158,526.
US Referenced Citations (22)
Continuations (1)
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Number |
Date |
Country |
Parent |
09/265054 |
Mar 1999 |
US |
Child |
09/633079 |
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US |