U.S. patent application number 10/628417 was filed with the patent office on 2005-02-03 for power-assisted multidirectional jackhammer positioner.
Invention is credited to Argento, Settimio.
Application Number | 20050023015 10/628417 |
Document ID | / |
Family ID | 34378568 |
Filed Date | 2005-02-03 |
United States Patent
Application |
20050023015 |
Kind Code |
A1 |
Argento, Settimio |
February 3, 2005 |
Power-assisted multidirectional jackhammer positioner
Abstract
A jackhammer positioner comprising a support structure
displaceably or fixedly resting on the ground, a base pivotally
mounted onto the support structure, and an articulated arm
pivotally connected to the base carrying a jackhammer. The
articulated arm comprises two pivotally interconnected arm
portions. A yoke is pivotally installed at the end of the arm
opposite its connection to the base. The yoke pivotally carries a
jackhammer support mechanism for carrying a jackhammer, the
mechanism providing the positioner with the ability to linearly
translate the jackhammer. The positioner thus comprises five pivot
joints and one translation joint, and can consequently be operated
to take a large number of different conformations. The operative
tip of a jackhammer suspended to the positioner can thereby be
easily and rapidly juxtaposed to a surface which needs to be
worked.
Inventors: |
Argento, Settimio;
(Montreal, CA) |
Correspondence
Address: |
LESPERANCE & MARTINEAU
1440 WEST
STE-CATHERINE ROOM 700
MONTREAL
QC
H3G1R8
CA
|
Family ID: |
34378568 |
Appl. No.: |
10/628417 |
Filed: |
July 29, 2003 |
Current U.S.
Class: |
173/36 |
Current CPC
Class: |
B25D 17/28 20130101;
B25H 1/0021 20130101; B25D 17/30 20130101; B25H 1/0028
20130101 |
Class at
Publication: |
173/036 |
International
Class: |
E21B 019/00 |
Claims
1. A jackhammer positioner for assisting a worker in the over
ground handling of a jackhammer, comprising: a ground support
member; a base mounted onto said support member and moveable
relative thereto; an articulated arm having first and second ends,
moveably mounted onto said base at said first end, said arm
comprising a number of displacement joints, said articulated arm
further comprising a jackhammer support member at said second end
for interconnecting said arm to the jackhammer; power means for
power biasing said articulated arm into a continuously erected
posture; wherein at least three of said displacement joints are
pivot joints, and wherein one of said displacement joints is a
translation joint.
2. A jackhammer positioner as in claim 1, wherein said base is
pivotally mounted onto said ground support member.
3. A jackhammer positioner as in claim 2, wherein the range of
reach of said jackhammer support member sweeps a volume represented
by a virtual half sphere with said base forming approximately the
center of said half sphere.
4. A jackhammer positioner as in claim 1, further comprising
control means operatively connected to and controlling said power
means.
5. An articulated support member for assisting a worker in the over
ground handling of a jackhammer having a main body and a hammering
head at one end of the main body thereof, said support member
comprising: an articulated arm, movable between a retracted limit
first position and an extended limit second position, said arm
defining an inner end and an outer end; base means, for supporting
said articulated arm spacedly over ground; first mounting means,
mounting said arm inner end to said base means for free relative
movement of said articulated arm relative to said base means; power
means, for power biasing said articulated arm into a continuously
erected posture; a command and control unit, for securing and
operating the jackhammer in a continuously airborne fashion, said
unit defining an elongated main frame having a first end portion
with a jackhammer attachment assembly and a second end portion
opposite said first end portion with a manual command and control
template; and second mounting means, interconnecting said
jackhammer attachment assembly and said arm outer end for relative
movement therebetween, for continuously maintaining the jackhammer
spacedly over ground so that the weight load of the jackhammer be
fully compensated; wherein the range of reach of said jackhammer
attachment assembly over ground sweeps a volume represented by a
virtual half sphere with said base means forming approximately the
center of said half sphere.
6. A support member as in claim 5, wherein said second mounting
means includes means for anchoring the jackhammer main body at the
center of gravity thereof.
7. A support member as in claim 5, wherein said manual command and
control template includes means for remote control of said power
means.
8. A support member as in claim 5, further including translational
motion means, integral to said main frame of said command and
control unit for relative movement of said jackhammer attachment
assembly relative to said manual command and control template.
9. A support member as in claim 5, further including second power
means, operatively connected to said manual command and control
template for selectively powering the jackhammer head in a
reciprocating motion.
10. A support member as in claim 5, wherein said first mounting
means includes a turntable rotatably supporting said arm inner end
about an axis transverse to said turntable.
11. A support member as in claim 5, wherein said base means
includes a lift platform movable vertically over ground.
12. A support member as in claim 11, wherein said first mounting
means includes a turntable fixedly secured to said lift platform
and rotatably supporting said arm inner end about an axis
transverse to said turntable.
13. A support member as in claim 11, wherein said first mounting
means includes: an elongated rail member, fixedly mounted to said
lift platform, a carriage rollingly mounted to said rail member for
rolling displacement of said carriage therealong, said carriage
having a transverse frame, and a turntable, fixedly secured to said
carriage transverse frame and rotatably supporting said arm inner
end about an axis transverse to said turntable; wherein said
articulated arm and associated command and control unit are movable
into a translational motion over said platform.
14. A support member as in claim 12, wherein said turntable
includes a central axle with low-friction PTFE coating.
15. A jackhammer device comprising: a jackhammer comprising a
jackhammer operative tip; an articulated arm supporting said
jackhammer, said arm movable between a retracted limit first
position and an extended limit second position, said arm defining
an inner end and an outer end; first mounting means,
interconnecting said jackhammer and said arm outer end for relative
movement therebetween; base means, for supporting said articulated
arm spacedly over ground; second mounting means, mounting said arm
inner end to said base means for free relative movement of said
articulated arm relative to said base means; power means, for power
biasing said articulated arm into a continuously erected posture
and for maintaining said jackhammer spacedly over ground; wherein
the range of reach of said jackhammer operative tip sweeps a volume
represented by a virtual half sphere with said base means forming
approximately the center of said half sphere.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to tool positioners, and more
particularly to a jackhammer positioner with enhanced versatility
and manoeuvrability features.
BACKGROUND OF THE INVENTION
[0002] A jackhammer is a very heavy tool used to break concrete
structures apart for performing maintenance or repair tasks
thereon. It is difficult, not to say impossible, to use jackhammers
other than on the ground without mechanical assistance; for
instance, it would be impossible for a construction worker to
manually uplift a jackhammer and to maintain it in an uplifted
position, in order to apply its operative tip on an overhanging
upright wall and use the jackhammer thereon. Despite this fact,
jackhammers must be sometimes used on surfaces other than ground
surfaces. For example, the bottom concrete surface of bridges,
outdoors concrete ceilings, upright concrete walls of a given
structure, are all surfaces which may require maintenance or repair
interventions with a jackhammer. In order to assist a construction
worker in supporting over ground and positioning the jackhammer in
a desired position, it known to use jackhammer positioners.
However, existing jackhammer positioners are cumbersome,
inefficient and their versatility tends to be limited.
SUMMARY OF THE INVENTION
[0003] The invention relates to a jackhammer positioner for
assisting a worker in the over ground handling of a jackhammer,
comprising:
[0004] a ground support member;
[0005] a base mounted onto said support member and moveable
relative thereto;
[0006] an articulated arm having first and second ends, moveably
mounted onto said base at said first end, said arm comprising a
number of displacement joints, said articulated arm further
comprising a jackhammer support member at said second end for
interconnecting said arm to the jackhammer;
[0007] power means for power biasing said articulated arm into a
continuously erected posture;
[0008] wherein at least three of said displacement joints are pivot
joints, and wherein one of said displacement joints is a
translation joint.
[0009] In one embodiment, said base is pivotally mounted onto said
ground is support member.
[0010] In one embodiment, the range of reach of said jackhammer
support member sweeps a volume represented by a virtual half sphere
with said base forming approximately the center of said half
sphere.
[0011] In one embodiment, said positioner further comprises control
means operatively connected to and controlling said power
means.
[0012] The invention also relates to an articulated support member
for assisting a worker in the over ground handling of a jackhammer
having a main body and a hammering head at one end of the main body
thereof, said support member comprising:
[0013] an articulated arm, movable between a retracted limit first
position and an extended limit second position, said arm defining
an inner end and an outer end;
[0014] base means, for supporting said articulated arm spacedly
over ground;
[0015] first mounting means, mounting said arm inner end to said
base means for free relative movement of said articulated arm
relative to said base means;
[0016] power means, for power biasing said articulated arm into a
continuously erected posture;
[0017] a command and control unit, for securing and operating the
jackhammer in a continuously airborne fashion, said unit defining
an elongated main frame having a first end portion with a
jackhammer attachment assembly and a second end portion opposite
said first end portion with a manual command and control template;
and
[0018] second mounting means, interconnecting said jackhammer
attachment assembly and said arm outer end for relative movement
therebetween, for continuously maintaining the jackhammer spacedly
over ground so that the weight load of the jackhammer be fully
compensated;
[0019] wherein the range of reach of said jackhammer attachment
assembly over ground sweeps a volume represented by a virtual half
sphere with said base means forming approximately the center of
said half sphere.
[0020] In one embodiment, said second mounting means includes means
for anchoring the jackhammer main body at the center of gravity
thereof.
[0021] In one embodiment, said manual command and control template
includes means for remote control of said power means.
[0022] In one embodiment, said articulated support member further
includes translational motion means, integral to said main frame of
said command and control unit for relative movement of said
jackhammer attachment assembly relative to said manual command and
control template.
[0023] In one embodiment, said articulated support member further
includes second power means, operatively connected to said manual
command and control template for selectively powering the
jackhammer head in a reciprocating motion.
[0024] In one embodiment, said first mounting means includes a
turntable rotatably supporting said arm inner end about an axis
transverse to said turntable.
[0025] In one embodiment, said base means includes a lift platform
movable vertically over ground.
[0026] In one embodiment, said first mounting means includes a
turntable fixedly secured to said lift platform and rotatably
supporting said arm inner end about an axis transverse to said
turntable.
[0027] In one embodiment, said first mounting means includes:
[0028] an elongated rail member, fixedly mounted to said lift
platform,
[0029] a carriage rollingly mounted to said rail member for rolling
displacement of said carriage therealong, said carriage having a
transverse frame, and
[0030] a turntable, fixedly secured to said carriage transverse
frame and rotatably supporting said arm inner end about an axis
transverse to said turntable;
[0031] wherein said articulated arm and associated command and
control unit are movable into a translational motion over said
platform.
[0032] In one embodiment, wherein said turntable includes a central
axle with low-friction PTFE coating.
[0033] The invention also relates to a jackhammer device
comprising:
[0034] a jackhammer comprising a jackhammer operative tip;
[0035] an articulated arm supporting said jackhammer, said arm
movable between a retracted limit first position and an extended
limit second position, said arm defining an inner end and an outer
end;
[0036] first mounting means, interconnecting said jackhammer and
said arm outer end for relative movement therebetween;
[0037] base means, for supporting said articulated arm spacedly
over ground;
[0038] second mounting means, mounting said arm inner end to said
base means for free relative movement of said articulated arm
relative to said base means;
[0039] power means, for power biasing said articulated arm into a
continuously erected posture and for maintaining said jackhammer
spacedly over ground;
[0040] wherein the range of reach of said jackhammer operative tip
sweeps a volume represented by a virtual half sphere with said base
means forming approximately the center of said half sphere.
DESCRIPTION OF THE DRAWINGS
[0041] In the annexed drawings:
[0042] FIG. 1 shows a perspective view of a workman maneuvering a
jackhammer installed on a jackhammer positioner according to the
present invention;
[0043] FIG. 2 shows an enlarged perspective view of the support
structure and one embodiment of the base of the positioner of FIG.
1;
[0044] FIG. 3 shows an enlarged cross sectional view of the support
structure and the base of the positioner taken along lines III-III
of FIG. 3;
[0045] FIG. 4 shows an enlarged partial perspective view of the
positioner of FIG. 1;
[0046] FIG. 5 shows an enlarged perspective view of the jackhammer
positioner of FIG. 1, including the jackhammer and support yoke,
showing the jackhammer control mechanism;
[0047] FIG. 6 is a view similar to that of FIG. 4, but further
showing in phantom lines a half-sphere suggesting jackhammer's
operative tip span of accessibility;
[0048] FIG. 7 shows a perspective view of the support structure and
the base of the positioner according to an alternate embodiment of
the present invention, with arrow A symbolizing a force applied on
the base; and
[0049] FIG. 8 shows a cross sectional view at an enlarged scale of
the support structure and the base of the positioner taken along
lines VIII-VIII of FIG. 7.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0050] In FIG. 1, there is shown a workman W maneuvering a
jackhammer 5 installed on a jackhammer positioner 10 according to
the present invention.
[0051] Positioner 10 can be installed on a platform 1. Platform 1
is for example attached to a lifting mechanism of a utility vehicle
(not shown), and can thereby be vertically raised under the action
of the lifting mechanism. In one embodiment, a rail 6 is fixedly
attached to platform 1, rail 6 comprising a horizontal sheet-like
elongated track 6a, and three brackets 6b lengthwisely spaced apart
along and integrally attached to track 6a. Brackets 6b are affixed
to platform 1, and rail 6 is thus attached to platform 1, with
plate 6b being in a spaced apart and overhanging parallel
relationship with platform 1.
[0052] Jackhammer positioner 10 is slidably mounted onto rail 6 of
platform 1, as described hereinafter. As shown in FIG. 1-3,
positioner 10 comprises a support structure 12 comprising for
example two parallelely spaced-apart horizontal beams 13, and two
parallelely spaced-apart tubular beams 14 extending between beams
13 and integrally attached thereto. A transverse cylindrical
bushing 18 extends vertically through each beam 14 at the vicinity
of their middle and is integrally attached thereto. The top edge of
bushing 18 is slightly upwardly offset from the top surface of beam
14, and the internal wall of bushing 18 is covered with a bronze
sleeve 21. Moreover, an upright beam 15, 15' extends transversely,
for example at right angle, from one end of each one 20 of beams
13, and is fixedly attached thereto. Two engagement wheels 16, 17
and 16', 17' are provided on each beam 15, 15' respectively, and
are rotatably attached thereto in a spaced-apart fashion. Upper
wheels 16, 16' of the two beams 15, 15' form a virtual axis
parallel to that extending between lower wheels 17, 17'.
[0053] Support structure 12 is slidably mounted onto rail 6.
Indeed, wheels 16, 16' slidably engage the top edge of track 6a of
rail 6, and wheels 17, 17' slidably engage the lower edge of track
6a of rail 6. Support structure 12 can thereby be linearly slid
along track 6a of rail 6.
[0054] Jackhammer positioner 10 further comprises a base 20, base
20 comprising a transverse axle 22 fixedly attached at the center
thereof. Base 20 has a circular shape, and can be made of steel for
example. Axle 22 engages bushing 18 of one beam 14 of support
structure 12, and base 20 is thereby pivotally mounted thereon. In
the appended figures, base 20 engages the beam 14 which is the
furthest from beams 15, 15'. However, base 20 can be
interchangeably mounted on either one of beams 14.
[0055] An annular washer 23, which can be coated with a friction
reducing compound such as polytetrafluoroethylene (PTFE or
Teflon(g), is fitted over the top edge of bushing 18 and beneath
base 20. When base 20 is pivoted about its pivotal engagement with
beam 14, the bottom surface of base 20 will slide with low friction
onto PTFE washer 23, and axle 22 will slide against bronze sleeve
21. The pivotal movement of base 20 relative to bushing 18 is hence
carried out without being excessively impeded by friction-borne
forces.
[0056] As shown in FIGS. 1 and 4, a foot 20-1 is fixedly mounted
onto the top surface of base 20. Positioner 10 further comprises an
articulated arm 30 connected to foot 20-1, arm 30 comprising a
first arm portion 32 and a second arm portion 34. Arm portions 32,
34 are tubular and are made of a material which can withstand high
amounts of mechanical stress, like steel for example. Arm portion
32 is pivotally attached at one end 32A to foot 20-1, and is
pivotally attached at the other end 32B to one end of arm portion
34.
[0057] A pivot actuator 24 is pivotally connected at one end 24A to
foot 20-1, and is pivotally connected at the other end 24B to an
intermediate section of arm portion 32. Actuator 24 can be a
hydraulic or pneumatic cylinder, and is operatively connected to
and controlled manually by control handles, as described
hereinafter. Upon activation of actuator 24, arm 30 is pivoted
about its pivotal joint with foot 20-1 between two limit positions:
a first limit position, where arm portion 32 is substantially
vertical and where actuator 24 is retracted, and a second limit
position where arm portion 32 is pivoted downwardly into a
substantially horizontal position, and where actuator 24 is
extracted.
[0058] Similarly, a pivot actuator 26 is pivotally connected at one
end 26A to an intermediate portion of arm portion 32, and is
pivotally connected at another end 26B to an intermediate section
of arm portion 34. Pivotal mount 26A is distally located compared
to pivot mount 24B relative to base 20. Actuator 26 can be a
hydraulic or pneumatic cylinder, and is operatively connected to
and controlled by control handles, as described hereinafter. Upon
activation of actuator 26, arm portion 34 is pivoted at pivotal
mount 32B relative to arm portion 32 between two limit positions: a
first limit position, where arm portion 34 is coaxially aligned
with arm portion 32, and where actuator 26 is extracted, and a
second limit position where arm portion 34 forms a large acute
angle with arm portion 32, for example a 60.degree. angle, and
where actuator 26 is retracted.
[0059] Arm portion 34 integrally comprises an inner portion 38, and
an attachment outer end portion 36 integrally extending from fore
portion 38 in an elbowed fashion. Outer end portion 36 defines a
pivot axis 37, and further comprises a cross-sectionally circular
pivot pin 39 integrally axially extending from elbowed portion 36.
Moreover, positioner 10 comprises a yoke 40 pivotally connected to
end portion 36. As illustrated in FIG. 5, yoke 40 comprises two
parallel legs 42, 42', a crossbar 43 integrally extending between
one end of ribs 42, 42', and a pivot hole 41 recessed at the middle
of crossbar 43. Pivot hole 41 is pivotally engaged by pivot pin 39
of arm portion 34, and yoke 40 is thereby pivotally attached to arm
portion 36, and can therefore be pivoted about pivot axis 37.
Bearings (not shown) are preferably installed at the pivot joint
formed by the interconnection between pivot pin 36 and hole 41; the
pivotal displacement of yoke 40 about pivot axis 37 can therefore
be smoothly and frictionlessly carried out.
[0060] Yoke 40 pivotally carries a jackhammer control mechanism 50
defining a longitudinal axis 51. Mechanism 50 comprises a planar
grip plate 52 defining two opposite fingers 55, 55' laterally
extending from one end thereof transversely and away from axis 51.
Grip plate 52 defines a grip opening 53 recessed therethrough,
whereby a workman using positioner 10 can insert his hand and hang
on to displace grip plate 52. Control bars 54, 54' integrally and
co-extensively extend from both faces of plate 52, perpendicularly
to planar plate 52 and parallel to longitudinal axis 51. A control
handle 56, 56' is provided at the free end of each control bar 54,
54' respectively. Handles 56, 56' are operatively connected to and
control the activation actuators 24 and 26. Mechanism 50 further
comprises a rod attachment plate 58 integrally attached to grip
plate 52 perpendicularly thereto and to longitudinal axis 51.
Control mechanism 50 also comprises two elongated rods 60, 60'
fixedly attached at one end thereof to attachment plate 58. Rods
60, 60' are parallel, transversely spaced apart and symmetrically
arranged relative to axis 51.
[0061] Rods 60, 60' are slidably connected to a jackhammer
attachment member 62. Attachment member 62 comprises two
cylindrical hollow guides 64, 64', each guide 64, 64' being engaged
by a corresponding registering rod 60, 60' respectively. Guides 64,
64' are closed at one end. The engagement between rods 60, 60' and
guides 64, 64' is a translation joint, and rods 60, 60' can thereby
be axially slid along guides 64, 64'. Anti-egress means (not shown)
should be provided within guides 64, 64', on rod 60, 60', or both,
to prevent rods 60, 60' from accidentally egressing from guides 64,
64' respectively. A pivot node 70, 70' is provided on each guide
64, 64' respectively, and a pivot axis 71 extending between pivot
nodes 70, 70' is defined. Each leg 42, 42' of yoke 40 is pivotally
attached to a corresponding pivot node 70, 70', and mechanism 50
can thereby be pivoted about axis 71.
[0062] Pivot nodes 70, 70' are suitably positioned on mechanism 50
in order for the weight of jackhammer control mechanism 50 to be
evenly distributed half and half on opposite sides of pivot axis
71. As a result, a workman can easily pivot mechanism 50 about axis
71, and can easily maintain it in a desired position without
excessive effort.
[0063] Attachment member 62 also comprises a hollow cylindrical
neck 66 coaxially carrying jackhammer 5. The main body of
jackhammer 5 is partially engaged by and secured to neck 66, and
the elongated operative free end tip 7 of jackhammer 5 is arranged
coaxially with longitudinal axis 51, opposite handles 56, 56'.
[0064] Mechanism 50 is further provided with two actuators 68, 68',
which are operatively connected to and controlled by handles 56.
Actuators 68, 68' are preferably hydraulic cylinders, and therefore
possess a chamber end and a piston rod end. The chamber end of each
actuator 68, 68' is firmly connected to a finger 55, 55'
respectively of grip plate 52, and the piston rod end is connected
to a corresponding pivot node 70, 70'. Upon activation of actuators
68, 68', guides 64, 64' of jackhammer attachment member 62 are slid
along rods 60, 60'. Jackhammer 5 being affixed to jackhammer
attachment member 62, as actuators 68, 68' are activated,
jackhammer 5 is translated away or towards rod attachment plate 58
between two limit positions: a first limit position where rods 60,
60' are brought to their outward most extended limit position
guides 64, 64', and a second limit position where rods 60, 60' are
brought to their inward most retracted condition on the closed end
portion of guides 64, 64'.
[0065] Since pivot nodes 70, 70' of attachment member 62 link
mechanism 50 to the rest of positioner 10, the displacement of
attachment member 62 affects the conformation of positioner 10.
Indeed, as actuators 68, 68' are activated for translational motion
of attachment member 62, base 20 and arm portions 32, 34 can be
concurrently pivoted to follow the displacement of attachment
member 62.
[0066] To use jackhammer positioner 10, platform 1 must be
positioned at the vicinity of a structure which needs to be worked.
Thereafter, the positioner 10 must be manually operated by workman
W to position jackhammer 5, in order to juxtapose the operative tip
7 of jackhammer 5 in close proximity to the structure which needs
to be worked.
[0067] Base 20, as well as arm 30 installed on base 20, can be
manually pivoted for a full turn (360.degree.) about vertical axle
22, to sweep a circular horizontal area overhanging horizontal
platform 1.
[0068] Moreover, handles 56, 56' can be manipulated by worker W to
effortlessly control hydraulic actuators 24, 26; upon activation of
actuators 24, 26, arm portions 32, 34 can be pivotally articulated
about their shoulder joint 24A and elbow joint 32B, to retract or
extend arm 30 within a vertical plane.
[0069] Furthermore, workman W can pivot yoke 40 about pivot axis
37, to rotate for up to a full turn the jackhammer 5 about the
lengthwise axis of the latter. Workman W can also grip plate 52 by
grip opening 53 and manually pivot mechanism 50 about pivot axis
71.
[0070] Also, by appropriately maneuvering handles 56, 56' and
activating actuators 68, jackhammer 5 can be moved in translation
axially along longitudinal axis 51 between its first extended
position and second retracted limit positions, as guides 64, 64' of
attachment member 62 are slidably driven back and forth along rods
60, 60'.
[0071] Finally, support structure 12 can be slid along rail 6 of
platform 1, and the whole positioner 10 can thereby be linearly
displaced over platform 1.
[0072] Jackhammer 5 is then conventionally activated, and the work
can take place. An electric line 80 interconnects handles 56, 56'
to jackhammer 5, and a pneumatic line 82 interconnects jackhammer 5
to a pressurized air source. When the workman manipulates handles
56, 56' to selectively activate jackhammer 5, handles 56, 56' will
send an electric activation signal to jackhammer 5. As a result
thereof, pressurized air is injected into jackhammer 5 through the
instrumentality of pneumatic line 82 to enable repeated back and
forth hammering action of jackhammer tip 7 against the surface to
be treated.
[0073] By providing a positioner with such relative displacement
features, positioning the jackhammer in a desired position is
effortless and easily accomplished. The positioner is versatile and
can be operated to take numerous different conformations. Indeed,
as illustrated in FIG. 6, the positioner can be manipulated to
position operative tip 7 of jackhammer 5 at any point located
within at least the volume of a half-sphere 100. The center of
half-sphere 100 corresponds to pivotal base 20, and its radius
corresponds approximately to the maximum distance which can
separate the free extremity of operative tip 7 of jackhammer 5 and
base 20 (when arm is fully extended pivotally about hinge 32B).
[0074] Jackhammer positioner 10, as described herein, possesses
additional advantageous features. In the prior art, when a workman
W handles a jackhammer directly, the operative tip 7 thereof
forcefully and repeatedly pounds onto a concrete structure in
reciprocating fashion, and the hands of the workman W are
consequently jarred. On the contrary, in positioner 10 of the
present invention, jackhammer 5 is not directly in contact with the
workman; jackhammer 5 is attached to support member 62, which can
recoil and slide along rods 60 every time operative tip 7 pounds on
concrete. 20 The reciprocating motion of the jackhammer 5 is thus
not transmitted to the workman using jackhammer 5 when it is
installed on positioner 10, and the workman's hands are hence less,
or even not at all jarred.
[0075] Alternative embodiments of the invention will now be
described. As illustrated in FIGS. 7-8, there is shown a beam 114
of an alternate support structure 112, provided with a transverse
cylindrical channel 118 extending therethrough. A discoid pivot
plate 119 having a pivot hole 11 9a at its center is fixedly
attached to the internal walls of channel 118. A base 120,
comprising a transverse axle 122 fixedly extending from its center,
is pivotally mounted on beam 114. Indeed, axle 122 pivotally
engages pivot hole 119a, and base 120 abuts on a PTFE washer 123
fitted between the top edge of channel 118 and the bottom surface
of base 120.
[0076] Channel 118 has a diameter which is equal or slightly
inferior to that of base 120.
[0077] If base 120 is subjected to an off-centred force A, base 120
will tend to tilt laterally. Since channel 118 is slightly smaller
in diameter than base 120, the top peripheral edge of channel 118
will peripherally support base 120. Such a tilting motion, which
would be likely to provoke bending and permanent damage of axle
122, is hence accounted for by inherent tilt compensation.
[0078] In another alternate embodiment (not illustrated in the
appended drawings), support structure 12 is not slidable about a
rail. Rather, support structure 12 is fixedly anchored on platform
1, and therefore can not be linearly displaced.
[0079] Certain modifications and improvements will occur to those
skilled in the art upon a reading of the foregoing description. It
should be understood that all such modifications and improvements
have been omitted herein for the sake of conciseness and
readability but are properly within the scope of the following
claims.
* * * * *