EXTENDABLE ARM

BRAS DEPLIABLE

English Abstract

An extendable arm has a first arm portion and a second arm portion slideably
mounted
in the first arm portion for extension and retraction relative thereto to
extend and contract the
arm. A fluid pressure operated extandable and contractible piston and cylinder
device is
connected to the first arm portion and to the second arm portion whereby
extension of the piston
and cylinder device extends the second arm portion relative to the first arm
portion and vice
versa. A third arm portion is extendable and contractible relative to the
second arm portion, and
a flexible elongated pulling element has opposite ends connected to the first
arm portion and
passes around at least one guide on the second arm portion. The flexible
pulling element is also
secured to the third arm portion, whereby extension and contraction of piston
and cylinder device
causes extending and retracting movement of the second arm portion relative to
the first arm
portion and such movement also causes similar movement of the third arm
portion relative to
the second arm portion.

Claims

CLAIMS
1. An extendable arm having a first arm portion, a second arm portion
slideably mounted
in the first arm portion for extension and retraction relative thereto to
extend and contract the
arm,
a fluid pressure operated extandable and contractible piston and cylinder
device
connected to the first arm portion and to the second arm portion whereby
extension of the
piston and cylinder device extends the second arm portion relative to the
first arm portion
and vice versa,
a third arm portion extendable and contractible relative to the second arm
portion, and
a flexible elongated pulling element having opposite ends connected to the
first arm
portion and passing around at least one guide on the second arm portion, said
flexible
pulling element also being secured to the third arm portion, whereby extension
and
contraction of piston and cylinder device causes extending and retracting
movement of
the second arm portion relative to the first arm portion and such movement
also causes
similar movement of the third arm portion relative to the second arm portion.
2. An extendable arm according to claim 1 also having a fourth arm portion
secured to the
first arm portion, a fifth arm postion slideably mounted in the fourth arm
portion for extension
and retraction relative thereto, a sixth arm portion indentable and
retractable relative to the fifth
arm portion, and a second flexible elongated pulling element having opposite
ends connected to
the fourth arm portion and passing around at least one guide on the fifth arm
portion, said second
pulling element also being secured to the sixth arm portion.
whereby extension and retraction of the piston cylinder device also causes
extending and
retracting movement of the fifth arm portion relative to the fourth arm
portion and said
movement also causes similar movement of the sixth inn -portion relative to
the fifth inn
portion

Description

CA 02398738 2002-08-19
EXTENDAB1,E ARM
FIE:I_D OF INVENTION
(0001 ] This invention relates to extendable arms.
BACKGROUND OF INVENTION
[0002) Extendable anus are useful for various purposes. An extenable arm is
suitable for use
in a fruit catcher as described in U.S. patent 6,052,981 (Pavonc). 7"he
extendable arm
described in the Pavone patent is operated by rotation of a spool. Although
this
arrangement works well, it is not particularly fast in opevation.
(0003] It is therefore an object of the present im~ention to provide an
extendable armwhich is
more quickly extended and contracted.
SUMMARY OF INVENTION
[0004) According to the invention, an extendable arm has a first arm portion,
a second arm
portion slideably mounted in the first am portion for e:Ktcnsion and
retraction relative
thereto to extend and contract the amp,
a fluid pressure operated extendable and contract able piston and cylinder
device
connected to the first arm portion and to the second arm portion whereby
extension of the piston and cylinder device extends the second arm portion
relative to the first arn~ portion acrd vice versa,
a third arm portion extendable and contractable relative to the second ann
portion, and
a flexible elongated pulling element having opposite ends connected to the
first
arm portion and passing around at least one guide on the second arm portion,
said

CA 02398738 2002-08-19
flexible pulling element also being secured to the third arm portion, whereby
extension and contraction of piston and cylinder device causes extending and
retractins; movement of the second arn~ portion relative to the first arm
portion
and such movement also causes similar movement of the third arm portion
relative to the second arm portion.
[0005] The extendable ann may also have a fourth ann portion secured to the
first ann portion,
a fifth arm postion slidcably mounted in the fourth arm portion for extension
and
retraction relative thereto, a sixth arm portion indentablf; and retractable
relative to the
fifth ann portion, and a second flexible elongated pullinf; element having
opposite ends
connected to the fourth ann portion and passing around at least one guide on
the fifth arn~
portion, said second pulling element also being secured to the sixth ann
portion.
whereby extension and retraction of the pistol cylinder device also causes
extending and retracting movement of the fifth ar-m portion relative to the
fourth
ann portion and said movement also causes similar movement of the sixth arm
portion relative to the fifth ann portion.
DESC'RIP'TION OF TI-iE DRAWINGS
[0006] Embodiments of the lllvetlOtl wlll now be described, by way of example
only, with
reference to the accompanying drawings, of which:
[0007] Fig. l is a front view ofan extendable arn1 in the contracted condition
in accordance with
one embodiment of tire invention,
[0008] Fig.2 is a rear view of the arm of Fig.l,
)0009] Fig.3 is a diagramatic view showing the flexible holing element
arrangement, in the
contracted condition,

CA 02398738 2002-08-19
[0010] Fig.4 is a front view of the extendable arm in an extended condition,
[0011 ) Fig.S is a rear view of the arm of Fig.4,
[0012] Fig.6 is a diagramatic view showing the flexible holing; clement
arrangement, in the
extended condition,
[0013) Fig.7 is a front view of an extendable arm in the contracted condition
in accordance with
a second embodiment of the invention, and
[0014] Fig.8 is a rear view of the arn~ of Fig.7 in an extended condition.
I:)ESC'R1P'I~ION OF PREFERRED EME30DIMEN'I~S
(0015] Referring first to Figs.l to 6 of the accompanying drawings, an
extendable arm in
accordance with one embodiment of the invention has a laterally spaced pair of
hallow
rear arn~ portions 10, 12 of rectangular section. The rear arm portions 10,
1:? aresecured
in laterally spaced relationship by a rear cross member 14 and a front cross
member 16
bolted at opposite ends to the rear arm portions 10, 12. A hydraulically
operated
extendable and contractible piston and cylinder device has the rear end of its
cylinder I 8
bolted to the rear cross member I 6 and the front end of its cylinder 18
bolted to the front
cross memberl (>.
[0016] A pair of intermediate arm portions 20, 22 of similar construction to
the rear arn~ portions
10, 12 are slidcably mounted therein and are secured at their front ends by a
further cross
member 24 to which the front end of the 1)lSt0I1 26 of the piston and cylinder
device is
secured. A pair of further arm portions 28, 30 of channf;l section are
slideibly mounted
in the intermediate inn portions 20, 22 respectively.
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CA 02398738 2002-08-19
(0017[ A first wire 32 has opposite ends secured to an anchor block 34 secured
to tl°ie front end
of the rear ann portion 10. From the anchor block 34, they first wire 32
passes around a
rotatable pulley 3(i mounted in the rear end of the intec-mediate ann portion
10, and then
extends forwardly through ate anchor block 38 mounted in the rear end of the
front end
portion 28. The wire 32 is secured to the anchor blocb; 38 in a suitable
manner, for
example by a grub screw (not shown). The wire 32 then extends fonvardly from
the
anchor block 38 and passes around a rotatable pulley 40 mounted at the front
end of the
intermediate arn~ portion 20 to then extend rearwardly back to the anchor
block 34.
[0018] A second wire 33 is connected in a similar manner to the rear arm
portion 12,
intern~ediate ann portion 22 and front arm portion 30. For ease of
illustration, like
reference numerals are used for like items.
[0019] Figs.l to 3 show the extendable arm in its contracted condition. When
hydraulic fluid
under pressure is applied to the piston and cylinder device 18, 26 in an
extending sense,
the piston rod 26 moves to the cxteded position shown in Figs.4 to 6. And
thereby move
the intennediatv arn~ portion 20, 22 to their extended positions relative to
the rear ann
portions 10, 12. At the same time, the wires 32, 33 also cause the front arm
portions 28,
30 to be moved to their extended positions relative to th~~ intermediate arm
portions 20,
22.
[0020] Contraction of the extendable arn~ back to the contracted condition is
effected by
reversing the fluid pressure to the piston and cylinder device 18, 20 to cause
contraction
thereof so that the intermediate arm portions 20, 22 retract into the rear ann
portions 10,
12 and the front end portions 28, 30 refract into the intermediate arm
portions 20, 22.
[0021 ] A second embodiment of the invention is shown in Figs.7 and 8. This
embodiment it in
fact omits the rear arm portion 12 intermediate arn~ portion 22 and front end
portion 30,
wire 33 and related components of the embodiment shown in Figs.l to 6. The
cross
members 14, l6 and 24 are replaced by shorter cross members 15, 17 and 25. The
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CA 02398738 2002-08-19
operation of this embodiment will be readily apparent from the foregoing
description of
the previous embodiment.
(0022] Further embodiments of the invention will also now be readily apparent
to a person
skilled in the art, the scope of the invention being defined in the appended
claims.
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