Tool driving or impacting – Means to drive tool about an axis – Electric motor
Reexamination Certificate
1999-07-06
2001-03-13
Vo, Peter (Department: 3721)
Tool driving or impacting
Means to drive tool about an axis
Electric motor
C173S216000, C173S029000, C200S00100B, C310S050000
Reexamination Certificate
active
06199642
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to electrically driven power tools, such as rotary drivers and, in particular, to ratcheting-type drivers.
It is known to provide an electrically driven screwdriver which is of the ratcheting type. Such a power tool is disclosed, for example, in U.S. Pat. No. 4,448,098, and includes a battery-powered, reversible, DC electric motor. The ratchet mechanism is controlled by a selector cap which also simultaneously actuates a single reversible direction control switch for reversing the motor direction simultaneously with reversing of the ratchet direction. This arrangement permits a fastener to be run down by the use of the electric motor and, when the torque increases, final tightening can be performed manually, the manual operation being facilitated by the ratchet mechanism. However, if the single direction-control switch fails, the motor cannot be operated.
U.S. Pat. No. 2,979,089 discloses a battery-powered portable electric screwdriver, with a reversible motor controlled by a control circuit which includes two direction-control switches. However, the switches are ganged, and both switches must be operated to change the motor direction. Thus, if either switch fails, the motor cannot be operated in either direction.
SUMMARY OF THE INVENTION
It is a general object of the invention to provide an improved reversible ratcheting electric power tool which avoids the disadvantages of previous power tools while affording additional structural and operating advantages.
An important feature of the invention is the provision of a power tool of the type set forth which reliably changes motor direction simultaneously with change of ratchet direction.
In connection with the foregoing feature, another feature of the invention is the provision of a power tool of the type set forth, which includes independently operable direction control switches.
Another feature of the invention is the provision of a power tool of the type set forth, which is of relatively simple and economical construction.
Certain ones of these and other features of the invention may be attained by providing a reversible ratcheting electric power tool comprising: a reversible electric motor having an output, a reversible ratchet assembly coupled to the output of the motor and adapted to be coupled to an associated driving device, a manually operated reversing mechanism coupled to the ratchet assembly for selectively controlling the ratcheting direction thereof, an electric control circuit coupled to the motor and including two direction control switches each having a normal deactuated condition and being operable to an actuated condition, said switches respectively controlling forward and reverse directions of operation of the motor, and two switch actuators carried by said reversing mechanism for respectively actuating said direction control switches one at a time substantially simultaneously with selection of the ratcheting direction so that the motor direction is compatible with the ratcheting direction.
Other features of the invention may be attained by providing a power tool of the type described, wherein the motor is normally connected to only one terminal of the DC power source.
Still other features of the invention may be attained by providing a power tool of the type set forth, wherein the direction control switches are single-pole, double-throw switches and wherein the motor is connected to the movable contacts of the switches.
The invention consists of certain novel features and a combination of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the details may be made without departing from the spirit, or sacrificing any of the advantages of the present invention.
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Becker Thomas P.
Beer Joshua M.
Nowak Dennis A.
Calve Jim
Seyfarth Shaw
Snap-on Tools Company
Vo Peter
LandOfFree
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