Note: Descriptions are shown in the official language in which they were submitted.
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This invention is for improvements in or relating
to backhoe assemblies and in particular to assemblies
including backhoes arranged to be supported on a frame `
to be mounted on a vehicle.
Backhoes are known in whicll a digging boom constituting
the main operating member is mounted on a mast for movement !
relative to a supporting frame secured to a vehicle. In
such an arrangement it is provided that the boom can be
traversed horizontally relative to the frame for positioning 1
prior to operation, SUCll traversing being known as
"offsetting". However effective clamping means must
necessarily be provided for clamping the boom relative to
the frame prior to operating the backhoe and it is in the
provision of suitable clamping means that this invention
primarily lies.
There have bèen previous ~roposals for providing ;
suitable clamping means for the purpose described but these
have suffered from various disadvantages. For example
in one arrangement clamping means have been arranged to act
vertically on a supportlng frame but this has tended
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to distort the frame when the mast is in a central position.
In a further arrangement the clamping means has acted
horizontally but in this case the mast has not been
adequately located in the vertical direction and there has
been a tendency for the mast to oscillate relative to the
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frame as the backhoe is operated.
An object of the invention is to obviate at least ;,
; some of the disadvant'ages of such prior bac~hoe support
systems.
According to the invention a backhoe assembly comprises
a support frame arranged to be attached to a support 9 for '~
example a vehicle, and including generally horizontal frame
members, and an intermediate frame mounted so as to be
movable along the frame members, and arranged to support
a digging boom, the backhoe assembly further comprising '
clamping means for clamping the intermediate frame to the -
support frame said clamping means inc,luding a vertically- ,
acting clamp for clamping the intèrn)ediate frame to one of
-the horizontal frame members and a horizontally-acting
clamp for clamping the intermediate frame to another of
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the horizontal frame members.
'' ' Preferable the horizontal frame members comprise a ,
''pair of upper frame members and a lower frame member and'
the horizontally-acting clamp acts upon the upper frame
members and the vertically-acting clamp acts upon the
lower'frame member. `,
Conveniently two vertically-acting cla`mps are
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provided in spaced rclationship along the lower frame
, member.
' - Preferably- the vertically-acting c'lamp is arranged
to impart clamping forces to the associated frame member
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which is reacted in such a way as to gcnerate vertical ~
and horizontal components of the clamping forces to :.
thereby counteract horizontal forces imparted on the
intermediate frame durin~ operation. ' :
Preferably also the~intermediate frame includes
a hook-shaped member having'an abutment surface inclined ~
to the vertical and horizontal directions, the .abutment '~''
surface being arranged to abut a similarly-inclined
surface formed'on the associa~ed frame member. This
arrangement is intended to ensure that minimal bending'
forces are imparted to the vertical clamp, thereby ` ;
ncreasing the useful life of the clamp. : :
Accor~ding to a further as~ect of the in.uention a backhoe
assembly comprises a support frame, an intermediate frame :
slidably mounted upon said support frame and arranged to
support a backhoe boom, clamping means operable to.lock :' '
Said intermediate frame.to-said support frame, said^ ~ . ... ~
clamping means comprising first and second clamps, one of ~
which is operable to cause relative movement ~etween said .
support frame and said intermedia~e frame, and control ':'
means operable so as to operate saicl one clamp to cause ..
said movement prior to operation of the other clamp. . :.'
According ~lso to the invention there is provided an :
assembly comprising a frame, a bracket slidably mounted on
said frame, clampin~ means for locking said b'racket to said
frame, said clamping nleans including a hydraulic motor having
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two parts telescopically arranged, one of said parts
bearing on said bracket and the other of said parts
bearing on said ~rame, sai~ motor being detachably
secured in said assembly by interaction bet~een a lug
formed on a first of said parts and a groove formed
in a second of said parts, said groove being L-shaped
so that said lug may slide along one ar~ of said L during
telescoping and may move along the other arm to remove
said motor from said assembly.
Further features of the invention appear from the -
following description of an embodiment of the invention
given by way of example only and with reference ~o the
accompanying drawings, in which:-
Figure l is a schematic perspective view-of a
backhoe assembly mounted on a ve]licle,
Figure 2 is a vertical section through a support frame and
an intermediate frame or mast of the assembly of Figure l,
Figure 3 is a view in the direction of arrow III ln
Figure 2, partly broken away for clarity,
Figure 4 is a view on the line IV - IV o Figure 2,
Figure 5 is a circuit diagram showing eed of hydraulic~
fluid to the assembly. ~ ~
Referring to the drawings, a backhoe assembly includes
a pair of upper, parallel, horizontal support frame members
10 and 11 whicll are spaced apart vertically and which are
interconnected at their ends, by stablliser legs 15. The
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frame members 10~ 11 are enclosed along their forward
sides by a bracket 12 and connected rigidly to a ;
support vehicle, in this case a tractor 13 (only part :~
of which is shown in Figure 1). A lower horizontal ~
support frame member 14 is connected to the s~abiliser
legs 15 vertically below and parallel to the members 10
and 11 and together the frame members 10, 11 and 14 and ::
the stabiliser legs lS constitute a support frame ~
whereby the backhoe is attached to the vehicle 13. The .
frame member 14 is attached to the vehicle by a bracket 16. .
Each of the frame members 10, 11 and 14 is generally .
of box-section and the members extend horizontally the ~
full width of the tractor 13 to an extent sufficient for `.
the backhoe to be traversed horizontally, or-"of~set",
relative to the vehicle. - . ................................. ' :
A~ intermediate frame or mast 17 is movably mounted
on the support frame members 10, 11 and 14, and the mast 17 :.
~ supports a digging boom 18 (Figure 1) which may be oE known
fo.rm and does not in itsel.f form part of th~e present .
~ inventlon.
The mast 17 is movable horizontally along the members
10, 11 and 14 and can be clamped i.n any selected position
along the member by clamping means to be descrihed. The ;
.mast 17 includes upper and lower brackets 19 and 20 :
:respectively, each having bores Z~ and-23 whose vertical :
.axes are aligned and which are arranged to recieve the boom 18. ..
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Referring ~o Figure,2 the lower bracket 20 is :
formed integrally with a l~ook-sllaped member 24 whose `
free end forms an abut.ment surface 25 engaging an , ' :
inclined surface 26 formed b)~ the lower rearward edge Or the .
lower frame member 14. The surfaces 25 and 26 are equally
inclined at about 4.5 degrees to the horizontal and the surface ~:
25 is formed by a bearing member 27 secured to the
hook member 24 by bolts 28. . ,, .
Intermediate the frame members 10 and 11 the mast 17 is
formed with a, pair of forwardly directed arms 30 ('only one '
of which.is seen in Figure 2) each of which carries a' -'
horizontally-spaced clamp 31 forming part of the clamping means
for clamping the mast 17 to the support ~rame.- . .
The clamps 31 are s~aced apart,in-,'the dir.ection of .
the frame member 14 and each includes a piston 32 ~nd' .
cylinder 33 whose common axis is vertic~l. Figure 3 shows
in more detail one of the clamps 31 and from this can be . .. .
seen that the cylinder.33 is of annular form l~ith~~a corresponding :
annular piston 32. Both the piston and the cylinder are
supported from the arm 30 which has a generally U-shaped
portion having limbs 34 extending along.. opposite sides of the .
cylinder 33. The ends of the limbs 34'are each formed with
grooves 36 and 37, the grooves 36 lying parallel with ~he
longitudinal axis of the cylinder and th,~e grooves 37 lying .
transverse to the grooves 36. The cy~in~der 33 is formed
with laterally-projectin~ lu~s 38 which'are arranged-to
engage in the grooves 36 and 37 to locate the cylinder 33
relative to the arm 30. The lugs 38 and grooves 36 and 37
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are arranged in the manner of a bayonet fitting so that
to asemble tlle clamp the piston is inserted fully into the .
cylindeT, and the lugs 38 are entered into the grooves.37,
the cylinder is then moved along the groove 37 until .
the lugs 38 are aligned Wit]l the grooves 36 whereupon ..
the cylinder can be extended relative to ~he piston under
the action of hydraulic pressure between the cyliuder and .~ .
piston. .It will be apparent with this arrangement that .-
the piston and cylinder can be extended and retracted with the ~.
cylinder being positively located during operation against .:
for and aft movement relative to the arm 30 because when ..
the cylinder is not being extended the limbs 34 abut the
frame member 14 to prevent the cylinder being fully retracted and .
allow the lugs 38 ~o be aligned Wit]l groove 37.
It will also be seen that the end of the plston 32 remote `
from the cylinder 33 engages a backing plate 39 carried by the
arm 30 and a resilient cover 40 is locate.d between the plate 3?
and the cylinder 33 and is held in place on the cylinder by a
ring 42. Operating fluid is introduced into and
discharged from the cylinders 33 through a bore 43 formed
in each cylinder.
In operation the cylinders 33 engage the upper wall of the
frame member 14 and, when pressurised exert a vertical force :
on the mcmber 14 which is reacted by cooperation between the
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hook member 24 and the inclined surface 25. The inclin~tion :
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of the surfaces 25 and 26 resolves the clamping Force at
these surfaces into a vertical and a horizontal component,
the horizontal component acting to counteract the
horizontal forces generated when the boom is in use. The
forces acting on the cylinder and piston assembly are
substantially in the vertical dlrection thereby preventing
undesirable side loading of the seal between the piston and
cylinder.
The clamping means also includes a harizontally-acting
clamp 44 which is located at the upper end of the mast and
clamps the mast to the upper frame member 10 and 11. The
clamp 44 is of similar form to the clamp 31 in having an
annular piston and cylinder assembly 49 and is located on
the mast by a bolt 45 which extends through the piston and
mast and between the members lO and 11. The head 46 of the
bolt 45 is located within the bracket 12 and bears on the
forward sides of the members 10 and 11 through a plate 47.
The bolt 45 carries a nut 48 at the end remote from
the head 46 for locating the piston and cylinder in
position. The clamp cylinder 49 engages with an upward
extension 50 of the mast whlch is located between the
cylinder 49 and the members 10 and 11 so that on extension
of the clamp 44 when fluld power is lntroduced into the
cylinder, the members 10 and 11 are firmly clamped in the
horizontal direction between the plate 47 and the extension
50.
It will be apparent that since the operation of the
clamp 31 involves some vertical adjustment of the mast
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relative to the members 10, 11 and 14, the piston 32 and
cylinder 33 must be energised before the clamp 44. In order ¦; " '
to achieve this the feed of hydraulic fluid to the clamps is ~ ''
controlled by the hydraulic circuit illustrate~l in Figure 4~ ¦
Referring to Figure 4, hydraulic fluid is pumped from
a tank T by a pump P to provide operating fluid for operating ' '~
the backhoe through spool valves V and for operatin~ the clamps,
31 and'44 through a one-way check valve 52 and a spool valve 53. -,
As shown the spool valve 53 is positioned to direct fluid to
the clamps 31 and 44 and a restrictor 54 is located in the ' , ,
line carrying fluid to the clamp 44 so that the clamp 44 does ',` ' ,
not receive fluid until the clamps 31 are extended and are
clamping the support frame. As an alternative to the, ,
restrictor 54 the fluid line to the clamp 44 may include t~Yo
lines in parallel one of which includes a one-l~ay check valve ,'
for allowing fluid to be dischargcd from t~le clamp cylinder
49 and the other of which includes a spring-controlled
check valve which can only open to admit fluid to the clamp `'~ '
cylinder 49 when the pressure in the clamps 31 has reached ,
a level at which any vertical movement of the mast has takcn
place. The spool valves used may be of the form described
,in our prior patent specification No. 1136241. The circuit
ensures that when the valve 53 is in the clamping position
the pressure in the clamp cylinders is''constan~ly topped up
by the fluid delivered to the backhoe valve V yet when the valve
53 is moved to disengage the clamps fluid is still available
to the backhoes se,rvices.
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It will be appreciated that althoug]l there is shown and
described an arrangement in which the upper frame member .
is clamped by a horizontal clamping force and the lo~er :`
frame member is clamped by a vertical clamping force, the
position of the frame members and tlleir associated clamps
may be reversed.
Furthermore although the use of a bayonet type connection
for the clamp has been described in relation to a backhoe
assembly, the connection could find application in connecting
hydraulic clamps or other fluid actuators for other :
purposes in which the use of bolted connection or the li~e
are impractical or disadvantages. '
Similarly the arrangemen~ for the delaycd operation of
the horizontal cylinder af~er that of the vertical cylinder .
can be a.pplied to clamping means other than those described
in which it is desirable for one clamp to be operated before
another.
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