# US 5,346,023 A · Slipping torque changing apparatus for impact tool

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- Number: US 5,346,023 A
- Document ID: US5346023A
- Status: Granted
- Kind: A
- Application number: 08/016,310
- Filed: 1993-02-11
- Granted: 1994-09-13
- Earliest claimed: 1993-02-11
- Assignees: Hitachi Koki Co., Ltd.
- Inventors: Toshiaki Takagi; Yoshihiko Watanabe
- Web page: https://patentgrep.com/patent/US5346023A

## CPC

- B25D 16/003: {Clutches specially adapted therefor}
- 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 slipping torque changing mechanism for an impact tool includes a driving source for generating a rotational motion. A motion converting mechanism is connected with this driving source for converting the rotational motion of the driving source into a reciprocating motion. An impact mechanism is connected with this motion converting mechanism for transmitting the reciprocating motion to a tool end. A rotational motion transmitting mechanism is disposed separately from the motion converting mechanism for transmitting the rotational motion of the driving source to the tool end. A plurality of clutches, having different slipping torques, are disposed at different portions on the rotational motion transmitting mechanism.

## Claims

### Claim 1

A slipping torque changing apparatus for an impact tool comprising:
a driving source for generating a rotational motion:
a motion converting mechanism portion, connected with said driving source, for converting the rotational motion of said driving source into a reciprocating motion;
an impact mechanism portion, being connected with said motion converting mechanism portion, for transmitting said reciprocating motion to a tool end;
a rotational motion transmitting mechanism portion, being disposed separately from said motion converting mechanism portion, for transmitting the rotational motion of said driving source to the tool end; and
first and second slipping clutches being disposed at different portions on said rotational motion transmitting mechanism portion;
said first slipping clutch having a slipping torque larger than a slipping torque of said second slipping clutch;
said second slipping clutch including a lock-and-unlock member for selectively locking and unlocking said second slipping clutch, so that the second slipping clutch works prior to said first slipping clutch when said lock-and-unlock member is positioned to unlock the second slipping clutch, and conversely, does not work prior to said first slipping clutch when said lock-and-unlock member is positioned to lock the second slipping clutch.

### Claim 2 (depends on 1)

A slipping torque changing apparatus in accordance with claim 1 in which said lock-and-unlock member is connected to a handle member, so that an operator can manipulate said lock-and-unlock member by hand.

### Claim 3 (depends on 2)

A slipping torque changing apparatus in accordance with claim 2 in which said lock-and-unlock member is formed with a guide portion, and said handle member is formed with and engaging portion which can engage with said guide portion of said lock-and-unlock member.

### Claim 4 (depends on 3)

A slipping torque changing apparatus in accordance with claim 3 in which said lock-and-unlock member is a cylindrical member and said guide portion is formed on an outer surface thereof in a circumferential direction as a guide groove.

### Claim 5 (depends on 4)

A slipping torque changing apparatus in accordance with claim 4 in which said engaging portion of the handle member is a projection, which protrudes from the handle member so as to slidably engage into said guide groove of said lock-and-unlock member.

### Claim 6 (depends on 3)

A slipping torque changing apparatus in accordance with claim 3 in which said engaging portion of the handle member is disposed offset from a rotational center of the handle member, so that the engaging portion rotates about a rotational center of the handle member when the handle member is turned.

### Claim 7 (depends on 6)

A slipping torque changing apparatus in accordance with claim 6 in which said engaging portion of the handle member cooperates with a guide groove of the lock-and-unlock member so as to shift the lock-and-unlock member in such a manner that, when the handle member is turned, the lock-and-unlock member engaging with the engaging portion of the handle member is switched between a lock position and an unlock position in accordance with rotational movement of the handle member.

### Claim 8 (depends on 1)

A slipping torque changing apparatus in accordance with claim 1 in which said lock-and-unlock member is a slidable member which is changed over between a lock position and an unlock member.

### Claim 9 (depends on 8)

A slipping torque changing apparatus in accordance with claim 8 in which said second slipping clutch includes a cylindrical elastic member and said lock-and-unlock member has a cylindrical shape, wherein said lock-and-unlock member suppresses said cylindrical elastic member of the second slipping clutch from expanding.

### Claim 10 (depends on 9)

A slipping torque changing apparatus in accordance with claim 9 in which said cylindrical elastic member of said second slipping clutch is a C-shaped sleeve.