# US 2013/0153253 A1 · Rotary hammer

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- Number: US 2013/0153253 A1
- Document ID: US20130153253A1
- Status: Published application
- Kind: A1
- Application number: 13/326,525
- Filed: 2011-12-15
- Published: 2013-06-20
- Earliest claimed: 2011-12-15
- Assignees: Milwaukee Electric Tool Corporation
- Inventors: Benjamin Ludy; Andrew J. Weber
- Web page: https://patentgrep.com/patent/US20130153253A1

## CPC

- B25D 11/04: in which the tool bit or anvil is hit by an impulse member
- B25D 11/005: {Arrangements for adjusting the stroke of the impulse member or for stopping the impact action when the tool is lifted from the working surface}
- B25D 16/00: Portable percussive machines with superimposed rotation {, the rotational movement of the output shaft of a motor being modified to generate axial impacts on the tool bit (combined percussion and rotary drilling adapted for earth drilling E21B6/00)}
- B25D 2211/068: Crank-actuated impulse-driving mechanisms
- B25D 2216/0023: Tools having a percussion-and-rotation mode
- B25D 2216/0038: Tools having a rotation-only mode
- B25D 2217/0015: Anvils
- B25D 2250/131: Idling mode of tools
- B25D 2250/191: Ram catchers for stopping the ram when entering idling mode
- B25D 2250/345: Use of o-rings
- B25D: PERCUSSIVE TOOLS {(percussive machines for forging B21J; hand-held drilling machines, in general B23B45/00, for wood B27C3/08; drilling machines, used for mining or quarrying, with reciprocating tool which is turned intermittently when out of contact with the working face E21B1/00)}

## Abstract

A rotary hammer includes a motor, a spindle coupled to the motor for receiving torque from the motor, a piston at least partially received within the spindle for reciprocation therein, a striker received within the spindle for reciprocation in response to reciprocation of the piston, and an anvil received within the spindle and positioned between the striker and a tool bit. The rotary hammer also includes a retainer received within the spindle for selectively securing the striker in an idle position in which it is inhibited from reciprocating within the spindle, and an O-ring positioned between the retainer and the spindle. The O-ring is disposed around an outer peripheral surface of the anvil. The O-ring is compressible in response to the striker assuming the idle position. The compressed O-ring imparts a frictional force on the outer peripheral surface of the anvil to decelerate the anvil.

## Claims

### Claim 1

A rotary hammer adapted to impart axial impacts to a tool bit, the rotary hammer comprising:
a motor;
a spindle coupled to the motor for receiving torque from the motor;
a piston at least partially received within the spindle for reciprocation therein;
a striker received within the spindle for reciprocation in response to reciprocation of the piston;
an anvil received within the spindle and positioned between the striker and the tool bit, the anvil imparting axial impacts to the tool bit in response to reciprocation of the striker;
a retainer received within the spindle for selectively securing the striker in an idle position in which it is inhibited from reciprocating within the spindle; and
an O-ring positioned between the retainer and the spindle, and disposed around an outer peripheral surface of the anvil;
wherein the O-ring is compressible in response to the striker assuming the idle position, wherein an inner diameter of the O-ring is reduced in response to being compressed, and wherein the compressed O-ring imparts a frictional force on the outer peripheral surface of the anvil to decelerate the anvil.

### Claim 2 (depends on 1)

The rotary hammer of claim 1, wherein the spindle includes a step defining an interior annular surface, and wherein the O-ring is positioned between the retainer and the annular surface of the spindle.

### Claim 3 (depends on 1)

The rotary hammer of claim 1, wherein the retainer includes a circumferential groove in an inner peripheral surface of the retainer, and an O-ring positioned within the circumferential groove, wherein the striker is engageable with the O-ring in the retainer when assuming the idle position.

### Claim 4 (depends on 3)

The rotary hammer of claim 3, wherein the O-ring in the retainer defines an inner diameter, and wherein the striker includes a nose portion defining an outer diameter greater than the inner diameter of the O-ring in the retainer.

### Claim 5 (depends on 4)

The rotary hammer of claim 4, wherein the nose portion of the striker is engageable with the O-ring in the retainer when assuming the idle position.

### Claim 6 (depends on 1)

The rotary hammer of claim 1, wherein the retainer is movable within the spindle between a first position, in which a light preload is applied to the O-ring, and a second position, in which a compressive load is applied to the O-ring greater than the preload.

### Claim 7 (depends on 6)

The rotary hammer of claim 6, wherein the retainer is movable from the first position to the second position in response to the striker impacting the retainer.

### Claim 8 (depends on 1)

The rotary hammer of claim 1, wherein the piston includes an interior chamber, and wherein the striker is at least partially received within the interior chamber.

### Claim 9 (depends on 1)

The rotary hammer of claim 1, further comprising an air pocket positioned between the piston and the striker, wherein expansion and contraction of the air pocket induces reciprocation of the striker.

### Claim at position 10

10-20. (canceled)