DRIVING MECHANISM OF A POWER WRENCH

MECANISME D'ENTRAINEMENT POUR BOULONNEUSE

English Abstract

Abstract:
A power wrench for removing a bolt or nut, comprising a
housing in the shape of a pistol having provided in a rear portion
thereof a driving motor; a driving mechanism, which is connected to
a driving shaft of the driving motor with a clutch member; an
actuating shaft which is sleeved inside the driving mechanism;
wherein said driving mechanism is made partially of a cast iron and
partially of a plastic material.

Claims

What Is Claimed Is:
1. A power wrench for removing a bolt or nut, comprising
a housing in the shape of a pistol having provided in a rear
portion thereof a driving motor; a driving mechanism, which is
connected to a driving shaft of the driving motor with a clutch
member; an actuating shaft which is sleeved inside the driving
mechanism; wherein said driving mechanism is made partially of a
cast iron and partially of a plastic material.

Description

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TITLE: AN IMPROVEMENT ON THE DRIVING MECHANISM OF A POWER WRENCH



Field of The Invention
This inventi~n relates to an improvement on a power
wrench, and more particularly to an improvement on the driving
mechanism of a power wrench for removing a bolt or a nut from the
axle of a vehicle.


,
BACKGRO~ND OF THE INVENTION
This invention is an improvement on a driving device of
a power wrench described on the ~S patent No. 4,727,780, issued to
the inventor on March 1, 1988, which disclosed a power wrench for
removing or unscrewing the bolts or nuts fastening the hub of a
tire to an automobile axle. Such a power wrench comprises a ~`
housing in the shape of a pistol, having provided in the rear
portion a drlving motor; a driving mechanism, which is connected to
lS the driving shaft of the driving motor via a clutch memberi an
actuating shaft which is sleeved inside the driving mechanism.
When the driving shaft reaches a pre-cletermined angular speed, the
clutch member actuates the driving mechanism to rotate with the
actuating shaft to transmit a torque to remove a bolt or a nut from
~0 the automobile axle.
In the above described power wrench, the driving
mechanism is made of cast iron and thus having quite a weight. The
weight is relatively high with respect to the torque provided by -~
the driving mechanism. ~ ;~

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Hence a primary object of the invention is to provide an
improved driving mechanism of a power wrench, which is has a high
torque-to-weight ratio as compared to the prior art struc'cures.
These and other objects of the present invention will no
doubt become apparent to those of ordinary skill in the art after
having read the following detailed description of the preferred
embodiment illustrated in the drawings.
IN THE DRAWING
Figure 1 is a sectional view of the preferred embodiment
of the invention; and
Fig~re 2 is the an exploded perspective view of the
preferred embodiment of the present invention.
With reference to Figure 1, which is a sectional view of
a preferred embodiment of the present invention, a power wrench 1
according to the invention comprises a housing 1 in the shape of a
pistol which i5 divided into a rear apartment 11 and a front
apartment 12. A driving motor 20 is provided in the rear apartment
11 of the housing 10. The driving shaft 21 of the driving motor 20
extends from the rear apartment 11 of the housing 1 into the front
apartment 12 of the housing 10. A driving mechanism 40 which is
onnected to the driving shaft 21 via a clutch member 30. Hence
the driving mechanism 40 is rotatable with the driving shaft 21 of
the driving motor 20. The driving ~echanism 40 further includes a
swivel block 41 which is positioned with a rod member 31 of the
clutch member 30. Figure 2 will be described in detail. An
actuating shaft 50 which is installed within the driving mechanism

2

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40 and extends from the front apartment 12, out of the housing 10.
The actuating shaft 50 has a cam portion 51 which is in mechanical
connection with the swivel block 41.
In operation, as a power switch 60 which is in electrical
connection with and controlling the actuation of the motor 20 is
triggered, the driving shaft 21 rotates with the motor 20. The
driving mechanism 40 rotates with the driving shaft 21 as well.
When the angular speed is lower thatn a pre-set level, the swivel
block 41 will remain unmoved. As the angular speed increases to
the pre-set level, the clutch member 30 will act to withdraw the
rod member 31 and thus allowing the swivel block 41 to be in
contact with -the cam portion 51 of the actuating shaft 50. The
driving mechanism 40 will then provide a torque to the actuating
shaft 50 to remove a bolt or a nut from a axle.
In the prior art structure, the driving mechanism 40 is
made of a piece cast iron, hence the torque-to-weight ratio of the
power wrench is relatively small. The term "torque-to-weight
ratio" used herein indicates the ratio of the torque generated by
the power wrench to the weight of the driving mechanism. In ordér
to reduce the total weight of the power wrench, the driving
mechanism 40 of the instand invention is made partially of a cast
iron and partially of a plastic material. This can largely reduce
the weight of the driving mechanism 40 and still provide the
required torque to remove a bolt or a nut from a axle.
These advantages of the present invention will be
apparent to those skilled in the art. Thus the embodiment

--" '2 ~ 2 1

described herein is only by way of example and sho~ld not be
construed as restrictive. The scope of the invention is indicated
by the appended claim, and all -the modifications thereby embraced
are included in the present invention.




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Representative Drawing