TWI424910B - Shock attenuating device for a rotary impact tool - Google Patents

Description

Damping device for a rotary impact tool

The present invention relates to a rotary impact tool. More specifically, the present invention relates to a rotary impact tool having a transient torque absorbing drive coupling provided between a hammer mechanism and a drive anvil.

Numerous designs are known for the manufacture of rotary impact tools. Several variations of rotary impact tools having conventional rotary impact mechanisms are disclosed in U.S. Patent Nos. 2,285,638, 3,661,217, and 6,491,111. The mechanisms are configured to transmit rotational force via a series of transient shocks, which allows the operator to operate the impact wrench while transmitting relatively high torque with a short duration shock. By applying a relatively high duration of torque shock for a relatively short duration, the ability to hold an impact wrench on an ordinary human entity is imparted while giving relatively high torque. If such forces are delivered in a continuous manner, the operator will be required to give a relatively continuous reaction force to the impact wrench, which will prove to be too large for the operator.

One problem with the rotary impact tool mentioned above is that it is not possible to transmit a relatively high torque with a short duration shock while reducing the peak transient force generated by the impact in the rotary impact mechanism.

Therefore, it may be advantageous to control or limit the resulting peak transient force transmitted to the anvil via the rotary impact mechanism of the rotary impact tool.

The present invention provides a shock absorbing coupling device for use on a rotary impact tool between an impact mechanism and an anvil. An elastic member is configured to interact between a drive shaft and a driven shaft to provide an elastic rotational coupling device for insertion between a hammer mechanism and a drive anvil. In some cases, a compression band is provided between a drum and a shoe assembly on one of the first coupling member of the drive shaft and the second coupling member of the driven shaft. In such a condition, the impact mechanism can be of any known form, including a single (or dual) pendulum weight mechanism, and a double pin (or double pin) hammer mechanism. In such conditions, the resilient rotational coupling is configured to attenuate the impact from the hammer mechanism to the drive anvil. In a certain situation, the impact mechanism is a rotary impact mechanism.

According to one aspect, a damper coupling device for a rotary impact tool to drively connect a hammer mechanism to a drive anvil is provided. The shock absorbing coupling device comprises a first coupling member, a second coupling member, a drum, a shoe and an elastic material body. The first coupling member has a first drive portion. The second coupling member has a second drive portion. The drum is provided proximate to the first drive portion and the second drive portion and has a radially intermeshing surface. The shoe is provided in the drum and between the first drive portion and the second portion. The shoe has a radially outer surface that is expandable in a radially outward direction. The body of elastic material is inserted between the drum and the shoe. The first drive portion and the second drive portion are configured to deploy the shoe in response to a torsional displacement between the first coupling member and the second coupling member to compress an intermeshing surface with the drum Engaged elastic material body.

According to another aspect, a rotary impact tool having a housing, a hammer mechanism, a drive anvil, and an elastic rotational coupling device is provided, the elastic rotary coupling device having at least one shoe, a drum, and an elastomeric body. The at least one shoe has a radially outer surface configured to expand in a radially outward direction. The drum has a radially inner meshing surface. The body of elastic material is inserted between the drum and the shoe. One of the drums is configured to be driven by the hammer mechanism. Another drum in the shoe is configured to be driven by the drive anvil. The resilient rotary coupling device is inserted between the hammer mechanism and the drive anvil and configured to attenuate the impact from the hammer mechanism to the drive anvil.

According to yet another aspect, a damper device for a rotary impact tool is provided. The damper device has a hammer handle, a drive shaft, a casing, a compression member and a deployable shoe. The hammer handle has a first coupling member. The drive shaft has a second coupling member. The outer casing includes the first coupling member and the second coupling member. The compression member is provided within the outer casing. The deployable shoe is provided within the compression member and configured to be engaged by the first coupling member and the second coupling member to cause the shoe to respond to a torsional displacement between the hammer handle and the drive shaft Expand radially outward.

This disclosure of the present invention has been made to promote the constitutive purpose of the "Promoting the Process of Science and Useful Technologies" (Section 1, Section 8) of the U.S. Patent Law.

Reference will now be made to the applicant's invention for several preferred embodiments of a rotary impact tool having a shock absorbing coupling between an impact mechanism and an anvil. Although the present invention has been described with respect to a preferred embodiment, it is understood that the description is not intended to limit the invention to the embodiment, but is intended to cover alternatives that are broader than the embodiments but are included in the scope of the appended claims. Things, equals and modifications.

In order to prevent the present invention from being difficult to understand, only the details that are closely related to the practice of the present invention will be described in detail, and the details of the presently known are now incorporated by reference.

1-11 illustrate a rotary impact tool in the form of a pneumatic impact wrench 10 in accordance with one aspect of the present invention. More specifically, the impact wrench 10 is provided with an elastic rotational coupling 12 (see Figures 3-10) provided between an impact mechanism or hammer 14 and an anvil 16. According to one configuration, the resilient coupling device provides elastic or shock absorbing rotational coupling in the forward direction, but does not provide resilience in the opposite, reverse directions. Therefore, when used in a torque wrench, the elastic coupling device limits the peak transient impact load from the wrench when a fastener is fastened to a drive slot (not shown) provided on the anvil. Transfer to the anvil. However, when operating in the reverse or release direction, the torque wrench produces a larger peak transient impact load that ensures a greater force to loosen a fastening fastener.

As shown in FIG. 1, the wrench 10 has a tool housing 18 that includes a motor housing member 20 and a hammer housing member or probe housing 26. Motor housing member 20 includes a hollow motor sleeve 22 and an integrally formed handle 24. The handle 24 can be formed from a separate piece that is fastened to the sleeve 22, as appropriate. A resilient front gasket 30 is provided between the members 20 and 26 via four screws 36. The anvil 16 terminates at an end with an anvil ring 32 provided around an elastic o-ring 34 located within a recess around the anvil 16. When the impact slot or tool from the anvil 16 is retained and released, the anvil collar 32 is urged to compress in a radially inward direction.

As shown in FIG. 1, the handle 24 of the impact wrench 10 includes a trigger 38 that is guided to be compressed and released via a press-fit spring pin 42. Additionally, a grease nipple 72 is provided on the outer casing member 26 to enable application of grease to the internal components of the impact wrench 10. Another spring pin 44 is provided in the handle 24 to anchor the air inlet fitting or member 60.

2 illustrates an assembly of a supply air source, a trigger mechanism, and a muffler in the handle 24 of the impact wrench 10 of FIG. More specifically, a trigger mechanism is provided by trigger 38, which acts via pin 42 to move and tilt a valve stem 48 relative to a bushing 46 while resisting the action of a coil spring 50. When pressed, the trigger 38 moves the valve stem 48 relative to the bushing 46 to an open, unsealed position to transfer air from the source into the impact wrench. The trigger mechanism includes o-rings 54, 56 and 70 that are secured against a washer 58 on top of an air inlet member 60 that is configured to receive from a line such as a compressed air line. Air supply (not shown). A muffler is provided in the handle 24 by two sets of felt rings 62, 64 each configured to be annularly mounted about an exhaust pipe 66. Exhaust gas from the impact wrench is received via felt rings 62, 64, tube 66 and via a muffler 68 in which exhaust gas exits handle 24 via a plurality of holes in an exhaust deflector 52. Figure 3 further illustrates these features and additional construction details as discussed below.

Figure 3 further illustrates the assembly of the parts of the pneumatic impact wrench 10 of Figures 1-2. More specifically, the outer casing member 20 is engaged with the outer casing member 26 using a screw 36 (shown in a partial separation view), the screw 36 being screwed into an insert 74 having complementary threads, and the insert 74 being screwed into the member 20. The anvil 16 that houses the elastic rotational coupling device 12 is rotated via an anvil bushing 28 within the member 26. The device 12 is directly engaged with the impact mechanism 14. The impact mechanism 14 includes a single hammer configuration having a hammer 76, a pair of hammer pins 78, and a hammer cover 80. The hammer cover 80 is mounted for rotation onto a pneumatic motor 93 that drives the cover 80 to rotate to create an impact between the hammer pin 78 and a hammer handle 122. An air valve 95 is capable of adjusting the supply air source to the motor 93 to change the operating parameters of the impact wrench 10.

Motor 93 includes a front end disk 84, a rotor 86, a plurality of rotor blades 88, and a cylinder 92. Each vane 88 is received in a respective slot 90 provided along the rotor 86 at circumferentially spaced locations. (The end disc 84 houses a ball bearing assembly 82 that supports one of the front ends of the rotor 86). The cylinder 92 also houses a valve sleeve gasket 94 and a valve sleeve 96. The valve sleeve 96 houses a ball bearing assembly 98 that supports one of the rear ends of the rotor 86. A reverse valve 102, an o-ring 108, a rear gasket 110 and a gasket 112 are fitted between the valve sleeve 96 and the motor sleeve 22. The reverse valve 102 supports a spring pin 100, a spring 104, and a steel ball 106. An air passage seal 114 is also mounted within the motor sleeve 22.

In accordance with an embodiment of the present invention, the resilient rotational coupling device 12 includes a jaw portion 116, a compression ring spring assembly 118, and another jaw portion 120. The jaw portion 120 is coupled directly to a hammer handle 122, and since the cover 80 is rotated via the motor 93, the hammer handle 122 is driven together with the hammer 76 via intermittent impact. In operation, the anvil 16 houses an impact slot that is coupled to a fastener. At each impact, the jaw portion 120 is driven to rotate. When the anvil 16 is subjected to greater resistance due to a fastening fastener, the jaw portion 116 resists rotation and the jaw portion 120 continues to be subjected to a torsional transient shock load. Under such conditions, the spring assembly 118 is twisted flexed to reduce peak impact transmission between the hammer impact mechanism 14 and the anvil 16. The spring assembly 118 provides the features of a rotary impact tool or a shock absorbing coupling within the impact wrench 10.

The jaw portion 116 is provided as part of a second coupling member and the jaw portion 120 is provided as part of a first coupling member. The first coupling member has a longitudinal drive portion having an input configured to couple for rotation with a hammer mechanism 14 and an output having a first jaw portion 120. The second coupling member has an input configured to couple with rotation of a drive anvil 16 and an input having a second jaw portion 116 configured to cooperate in a longitudinally overlapping and circumferentially spaced relationship. The spring assembly 118 provides a body of resilient material or compression strip 123 that is inserted between a drum 125 and a shoe assembly 119, 121. The first jaw portion 120 and the second jaw portion 116 cooperate with the shoe assemblies 119, 121 to drive the individual shoes 119 and 121 apart to resist radial intermeshing of one of the drums 125 in a radially outward direction. The compression belt 123 is compressed on the surface. Thus, when a wrench is driven in the forward drive direction, the compression band 123 cooperates with the shoes 119, 121 and the drum 125 to provide a torsion spring.

Figure 4 illustrates the components of the impact wrench 10 in assembly, including the resilient rotational coupling device 12. More specifically, the display coupling device 12 is mounted between the impact mechanism 14 and the anvil 16. In addition, a motor 93 and an air valve 95 are also shown. In addition to the novel features of the elastic rotary coupling device 12, the remaining features of the wrench 10 are currently known in the art. Impact wrenches with these remaining features are currently available as "Composite impact wrenches are commercially available but have a pair of hammers, such as the model #1000 ^{T M} from the Exhaust Technologies, Inc., North 230 Division, Spokane, Washington 99202, Aircat impact wrench. Alternative construction of a double hammer mechanism The details are disclosed in U.S. Patent No. 6,491,111, the disclosure of which is incorporated herein by reference in its entirety in its entirety in its entirety in the the the the the the the A typical construction of the assembly is incorporated herein by reference.

5 illustrates the elastic rotational coupling device 12 in an exploded perspective view to better illustrate the cooperation between the jaw portion 116, the compression ring spring assembly 118, and the jaw portion 120. This cooperation provides rotational compliance or spring deformation between the hammer shank 122 and the anvil 16. The jaw portion 120 is provided on a first coupling member 126 that is directly attached to a hammer handle 122. The hammer handle 122 drives the first coupling member 126 in response to a hammer impact from the hammer 14 (see Figures 3-5).

The first coupling member 126 includes a drive pawl 134, a guide pawl 135, and a cylindrical base portion 142 that cooperate to provide a first torsional coupling member 130. The drive pawl 134 includes a drive finger or a dogleg bend 138. The pawls 134, 135 and the base portion 142 are integrally expanded from a drive plate 127 to form a first coupling member 126. According to one configuration, the pawls 134, 135, the base portion 142, the disk 127 and the hammer shank 122 are mechanically fabricated from a single piece of 8260 case hardened steel.

The second coupling member 128 includes a driven pawl 136, a guide pawl 137, and a cylindrical recess 144 that overlaps the cylindrical outer portion of the base portion 142, which cooperate to provide a second torsional coupling during assembly. Member 132. The driven pawl 136 includes a driven finger or a dogleg bend 140. The pawls 136, 137 extend integrally from a driven disk 129 to form a second coupling member 128. According to one configuration, the pawls 136, 137, the driven disc 129, the enlarged shaft 124, and the anvil 16 are mechanically fabricated from a single piece of 8260 case hardened steel.

According to one configuration, the spring assembly 118 includes a drum or outer casing band 125 having a radially inner engagement surface that internally receives a compression band 123 of elastomeric or elastomeric material. According to one configuration, the compression belt 123 consists of a single cylindrical piece such as Duralast Nylon Elastic material construction of rubber, or some other elastic and/or elastomeric material. The spring assembly 118 also includes a shoe assembly that includes a pair of shoes 119 and 121 having a radially outer surface that is expandable in a radially outward direction. The free ends of each of the shoes 119 and 121 provided along a gap are driven open by fingers 138 and 140 that cause the shoes to move in a radially outward direction and a compression band 123 within the drum 125. The opposite ends of the shoes 119 and 121 are brought together to form a pivot point.

According to one configuration, the shoe pieces 119 and 121 are constructed from a single piece of 5160 spring steel having an arrangement around the pawls 134, 135, 136 and 137, between the fingers 138 and 140, and within the belt 123. Suitable for the size of the fit. In assembly, the shoes 119 and 121 have an open slot or opening portion that forces the fingers 138 and 140 together during assembly. The bevel on the open end of the shoes 119 and 121 facilitates assembly. Details of the unloaded assembly configuration are shown and described below with reference to FIG. The transient rotational impact force causes rotation between the coupling members 126 and 128, which causes the fingers 138 and 140 to be further rotated apart, thereby forcibly shifting the open gap or gap between the shoes 119 and 121 further. This applies pressure to the shoe in a radially outward direction against the radially intermeshing surface of the drum (or compression band) 125 to compress the compression band 123. In this manner, the spring assembly 118 provides compliance between the coupling members 126 and 128 that attenuates the transfer of peak transient impact forces from the hammer shank 122 to the anvil 16. According to an alternative configuration, the shoes 119 and 121 may be comprised of a plurality of parts such as a radially inner c-shaped spring and a radially outer c-shaped spring or a plurality of c-shaped spring layers laminated to each other along a common axis. Pressure. Further depending on the situation, the shoes 119 and 121 may be constructed of any form of spring material, including spring metals and composites, such as fiberglass or carbon fiber composites. Still further, the shoes 119 and 121 may be formed of hardened steel to have little or no spring characteristics.

Figure 6 illustrates the resilient rotational coupling device 12 and hammer impact mechanism 14 in a configuration that is assembled together, shown in an exploded perspective view. The elastic rotational coupling device 12 is shown attached to the anvil 16. The hammer 76 is supported for pivotal movement about one of the pins 78, which imparts an impact between one of the inner surfaces of the hammer 76 and a corresponding surface on the hammer shank 122. The remaining pins 78 limit the pivoting movement of the hammer 76 to an impact cycle. The hammer cover 80 is driven to rotate via an internal cogging coupled to one of the outer slots on the rotary air motor. The first jaw portion 120 is coupled to the second jaw portion 116 in an elastic rotational relationship via a c-shaped spring 118.

The elastic rotary coupling device 12 is shown assembled with the hammer 14 in FIG. The display hammer 76 is in a position just prior to impact with a hammer surface on the hammer shank 122 (see Figure 6). The hammer 76, which is later in time, just after impact with the hammer surface on the hammer shank, is shown in Fig. 8, which causes the hammer 76 to pivot.

Figure 9 depicts the resilient rotational coupling device 12 assembled together without any impact load on the spring assembly 118. The spring assembly 118 has a size that fits snugly around the pawls 134-137 and engages the drive fingers 138 and the driven fingers 140. In this configuration, a ten degree gap is provided between the pawls 134, 137 and the pawls 135, 136.

Figure 10 depicts the resilient rotational coupling device 12 under an impact load from an impact hammer, when the drive fingers 138 and the driven fingers 140 forcibly urge the gaps or gaps between the shoes 119 and 121 apart, This impact load causes the spring assembly 118 to flex to a more open position. Thus, the spring assembly 118 provides sufficient compliance for the pawls 134, 135 of the first coupling member 126 to rotate five degrees relative to the jaws 136, 137 of the second coupling member 128. After the transient impact, the spring assembly 118 is recompressed to force the first coupling member 126 and the second coupling member 128 back to the position illustrated in FIG.

In accordance with the Act, the present invention has been described in a language that is more or less specific to the features of the structure and method. However, it is to be understood that the invention is not limited to the particular features shown and described. Therefore, the invention is to be construed as being in any form or modification within the proper scope of the appended claims.

10. . . Impact wrench / pneumatic impact wrench / wrench

12. . . Elastic rotary coupling device/device

14. . . Hammer impact mechanism / impact mechanism / hammer / hammer mechanism

16. . . anvil

18. . . Tool housing

20. . . Motor housing member / housing member / member

twenty two. . . Hollow motor bushing / motor bushing / bushing

twenty four. . . handle

26. . . Hammer shell member / probe shell / shell member / member

28. . . Anvil bush

30. . . Elastic front gasket

32. . . Anvil ring

34. . . Elastic o-ring

36. . . Screw

38. . . trigger

42. . . Press-in cooperative spring pin/pin

44. . . Spring pin

46. . . bushing

48. . . Valve stem

50. . . Coil seat spring

52. . . Exhaust deflector

54. . . O-ring

56. . . O-ring

58. . . washer

60. . . Air inlet fitting / air inlet member

62. . . Felt ring/felt ring

64. . . Felt ring/felt ring

66. . . Exhaust pipe/tube

68. . . silencer

70. . . O-ring

72. . . Grease nozzle

74. . . Insert

76. . . hammer

78. . . Hammer pin/pin

80. . . Hammer cover/hood

82. . . Ball bearing assembly

84. . . Front end disk / end disk

86. . . Rotor

88. . . Rotor blade / blade

90. . . groove

92. . . Cylinder

93. . . Air motor/motor

94. . . Valve sleeve gasket

95. . . Air valve

96. . . Valve sleeve

98. . . Ball bearing assembly

100. . . Spring pin

102. . . Reverse valve

104. . . spring

106. . . Steel ball

108. . . O-ring

110. . . Rear gasket

112. . . washer

114. . . Air passage gasket

116. . . Clamp section / second jaw section

118. . . Compression ring spring assembly / spring assembly / c-spring

119. . . Shoe assembly / shoe

120. . . Clamp section / first jaw section

121. . . Shoe assembly / shoe

122. . . Hammer handle

123. . . Elastic material body / compression belt / belt

124. . . Expanding the axis

125. . . Drum/shell tape/compression tape

126. . . First coupling member / coupling member

127. . . Drive disk/disk

128. . . Second coupling member / coupling member

129. . . Driven disc

130. . . First torsional coupling member

132. . . Second torsional coupling member

134. . . Drive jaw/claw

135. . . Guided paw/claw

136. . . Passive claw / claw

137. . . Guided paw/claw

138. . . Drive finger / canine shoe bend / finger

140. . . Driven finger or dog's shoe bend/finger

142. . . Cylindrical base portion / base portion

144. . . Cylindrical recess

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side elevational view of a rotary impact tool having a shock absorbing coupling between a rotary impact mechanism and an anvil, in accordance with an embodiment of the present invention.

2 is an enlarged partial view showing a supply source, a trigger mechanism, and a muffler provided in one of the handles of the rotary impact tool of FIG. 1 in a vertical center line section.

Figure 3 is a simplified exploded perspective view of the rotary impact tool of Figures 1-2.

4 is an enlarged partial view showing a pneumatic valve, a pneumatic motor, a rotary impact mechanism, a shock absorbing coupling device and an anvil of the rotary impact tool of FIGS. 1-3 in a partial vertical center line section.

Figure 5 is an enlarged exploded and perspective view of the shock absorbing coupling of Figure 4;

Figure 6 is an enlarged partial exploded and perspective view of the shock absorbing coupling, anvil and hammer of the rotary impact tool of Figures 1-4.

Figure 7 is an enlarged perspective view of the damper coupling device, the anvil and the hammer of Figure 6 in an assembled state and illustrating the single pendulum weight assembly in the first position.

Figure 8 is an enlarged perspective view of the damper coupling device, the anvil and the hammer of Figure 7 in an assembled state and illustrating the single pendulum weight assembly in the second position.

Figure 9 is a cross-sectional view of the shock absorbing coupling device taken along line 9-9 of Figure 5 illustrating the device prior to the impact of the torsional load from an impact hammer.

Figure 10 is a view of the damper coupling device of Figure 9 taken along line 10-10 of Figure 5 and illustrating the device when the torsional load is from an impact hammer impact to a compliant displacement position.

12. . . Elastic rotary coupling device/device

16. . . anvil

32. . . Anvil ring

116. . . Clamp section / second jaw section

118. . . Compression ring spring assembly / spring assembly / c-spring

119. . . Shoe assembly / shoe

120. . . Clamp section / first jaw section

121. . . Shoe assembly / shoe

122. . . Hammer handle

123. . . Elastic material body / compression belt / belt

124. . . Expanding the axis

125. . . Drum/shell tape/compression tape

126. . . First coupling member / coupling member

127. . . Drive disk/disk

128. . . Second coupling member / coupling member

129. . . Driven disc

130. . . First torsional coupling member

132. . . Second torsional coupling member

134. . . Drive jaw/claw

135. . . Guided paw/claw

136. . . Passive claw / claw

137. . . Guided paw/claw

138. . . Drive finger / canine shoe bend / finger

140. . . Driven finger or dog's shoe bend/finger

142. . . Cylindrical base portion / base portion

144. . . Cylindrical recess

Claims (21)

A damper coupling device for driving a rotary impact tool to drive a hammer mechanism to a drive anvil, comprising: a first coupling member having a first driving portion; a second coupling member Having a second driving portion; a drum provided adjacent to the first driving portion and the second driving portion and having a radially inner meshing surface; a shoe piece provided in the drum and interposed therebetween Between the first driving portion and the second driving portion and having a radially outer surface that can be unfolded in a radially outward direction; and a body of elastic material inserted between the drum and the shoe; The first drive portion and the second drive portion are configured to deploy the shoe in response to a torsional displacement between the first coupling member and the second coupling member to compress the body of resilient material and the drum The internal meshing surface engages. The shock absorbing coupling of claim 1, wherein the shoe is formed by one of a first shoe member and a second shoe member that are pivotally engaged together in a generally circular form and has a general diameter Outward surface. The shock absorbing coupling of claim 1, wherein the body of elastic material comprises a spring. The shock absorbing coupling of claim 3, wherein the spring comprises a cylindrical compression band formed of an elastomeric elastomeric material. The damper coupling device of claim 2, wherein the first drive portion includes a first drive pawl and the second drive portion includes a second drive pawl. The shock absorbing coupling of claim 5, wherein the first drive pawl engages a free end of the first shoe member and the second drive pawl engages a free end of the second shoe member. The shock absorbing coupling of claim 1, wherein the drum comprises a rigid material cylindrical outer casing member having a cylindrical inner surface configured to receive the body of resilient material. The shock absorbing coupling of claim 7, wherein the body of resilient material comprises a cylindrical strip of resilient material configured to be received within the cylindrical outer casing. The shock absorbing coupling of claim 1, wherein the shoe comprises at least one spring steel arcuate segment configured to be received within the body of resilient material and the radially inner meshing surface of the drum. A rotary impact tool comprising: a housing; a hammer mechanism; a drive anvil; and an elastic rotary coupling device having at least one radially outer surface configured to expand in a radially outward direction a shoe, a drum having a radially inner engagement surface, and a body of resilient material interposed between the drum and the shoe, the drum and one of the shoe being configured to be hammered by the hammer The mechanism is driven and the other of the drum and the shoe is configured to be driven by the drive anvil, and the resilient rotary coupling is inserted between the hammer mechanism and the drive anvil and configured to attenuate the hammer The impact of the mechanism to the drive anvil. The rotary impact tool of claim 10, further comprising a first coupling member having a first drive portion coupled to the hammer mechanism and a second coupling member having a second drive portion coupled to the drive anvil. A rotary impact tool of claim 11, wherein the first drive portion cooperates with the second drive portion to deploy the shoe in a radially outward direction. A rotary impact tool according to claim 10, wherein the at least one shoe comprises a pair of shoes assembled together in a generally circular form and having a generally radially outer surface. A rotary impact tool of claim 13 wherein a gap is provided between the shoes at a first end and a pivot point is provided between the shoes at a second end. A rotary impact tool according to claim 10, wherein the body of elastomer comprises a cylindrical band of elastomeric material. A damper device for a rotary impact tool, comprising: a hammer handle having a first coupling member; a drive shaft having a second coupling member; a housing including the first coupling member and a second coupling member; a compression member provided in the housing; and a deployable shoe provided in the compression member and configured to be engaged by the first coupling member and the second coupling member The shoe is flared radially outward in response to a torsional displacement between the hammer handle and the drive shaft. The shock absorbing device of claim 16, wherein the outer casing comprises a rigid cylindrical band. The shock absorbing device of claim 16, wherein the compression member comprises a cylindrical band of elastomeric material. The shock absorbing device of claim 16, wherein the deployable shoe comprises a pair of contact shoes. The shock absorbing device of claim 16, wherein the compression member comprises an elastic material. The shock absorbing device of claim 20, wherein the elastic material comprises an elastomeric material.