Tractor front loader

In front loaders designed for drive-in attachment to tractors, two telescopic struts are pivotable between a stowed retracted position alongside the boom assembly which carries the bucket; a first deployed extended position for supporting the rear end of the detachable main portion of the loader, aided by auxiliary struts, when it is not attached to the tractor; and a second deployed extended position, in which the struts engage with abutments on the sub-frame which carries both the boom assembly and the hydraulic cylinders for pivoting the boom assembly and are secured to said cylinders, for locking the boom assembly in its fully raised position whilst the detachable main portion is attached to the tractor.

BACKGROUND OF INVENTION 
This invention relates to a tractor front loader, and more particularly to 
a front loader designed for drive-in attachment to a tractor, that is to 
say to a front loader having brackets adapted to be permanently secured to 
a tractor and engageable with a detachable main portion of the loader 
which is adapted to be supported when not in use at the required height 
for drive-in attachment. 
When not in use, the detachable portion is supported at its front end by 
its bucket whilst its rear end is supported by two struts which are 
disposed at respective sides of said portion and hitherto have simply been 
pivotable between a stowed position and a deployed support position. 
The object of the present invention is to utilise the support struts to 
better effect. 
SUMMARY OF INVENTION 
According to the invention, in a front loader designed for drive-in 
attachment to a tractor, comprising front and rear bracket means adapted 
to be permanently secured to the tractor frame, a sub-frame adapted to be 
temporarily secured to the bracket means, a loader boom assembly pivotably 
mounted on the sub-frame, a loader bucket or the like pivotably mounted on 
the boom assembly, and hydraulic piston-and-cylinder assemblies for 
selectively pivoting the boom assembly and the bucket, two support struts 
disposed at respective sides of the boom assembly are pivotable between a 
stowed position, a first deployed position in which they support the rear 
end of the sub-frame at drive-in height when it is not attached to the 
tractor, and a second deployed position in which they lock the boom 
assembly in its fully raised position whilst the sub-frame is attached to 
the tractor.

DESCRIPTION OF PREFERRED EMBODIMENT 
Referring now to FIG. 1 of the drawings, a front loader designed for 
drive-in attachment to a tractor includes a front attachment bracket 
indicated generally at 10 comprising two side plates 11 interconnected 
near their upper ends by a transverse bar (not shown) and welded at their 
lower ends to a basically U-shaped ballast-weight carrier 13 the arms of 
which are adapted to be permanently secured by set-screws at 14 near the 
front of the tractor frame 15 at each side thereof; and two rear 
attachment brackets 16 adapted to be permanently secured by set-screws at 
17 near the mid-point of the length of the tractor frame 15 at each side 
thereof. 
Referring now to both FIGS. of the drawings, a detachable main portion of 
the loader includes a sub-frame indicated generally at 18 adapted to be 
temporarily secured to the brackets 10 and 16 which is substantially 
U-shaped in plan view and comprises two elongated side members 19 
interconnected at their front ends by a radiator guard 20. A loader boom 
assembly indicated generally at 21 comprising two parallel booms 22 of 
shallow inverted V-shape interconnected between their apices and front 
ends by two cross-members 23 and 24 has the rear ends of its booms 22 
pivotably mounted about a common transverse axis 25 on the upper ends of 
respective pedestals 26 secured by welding to the rear ends of the side 
members 19 of the sub-frame 18, and the boom assembly 21 is pivotable 
relative to the sub-frame 18 by two hydraulic piston-and-cylinder 
assemblies 27 each of which is pivotally connected between the lower end 
of one of the pedestals 26 and a stiffening plate 28 welded to the apex of 
the associated boom 22. A loader bucket 29, or a similar tool such as a 
manure fork, is pivotably mounted about a common transverse axis 30 on the 
front ends of the booms 22, and is pivotable relative to the boom assembly 
21 by two hydraulic piston-and-cylinder assemblies 31 each of which is 
pivotally connected between the rearmost cross-member 23 and a hole in a 
lug 32 near one side of the bucket 29, the common axis 33 of the holes in 
the lugs 32 being spaced from but parallel to the pivot axis 30 of the 
bucket 29. The sub-frame 18 locates on the front bracket 10 by means of 
two horizontal ribs (not shown) fixed to and projecting laterally outwards 
from the respective side plates 11 and each engageable between upper and 
lower forwardly converging guides 37 and 38 respectively which are fixed 
to and project laterally inwards from the adjacent side of the radiator 
guard 20, and also by means of two wedges (not shown) secured to and 
projecting laterally outwards from the respective side plates 11 and each 
engageable with one of two mutually forwardly converging plates 40 secured 
to and projecting laterally inwards from the respective sides of the 
radiator quard 20. Either the plates 40 or the associated wedges are made 
adjustable in a fore-and-aft direction. The upper part of each rear 
bracket 16 is substantially U-shaped in plan view, with a rear wall 41 and 
two mainly parallel side walls 42, and the lower rear corner of each 
pedestal 26 of the sub-frame 18 is secured within the upper part of the 
associated rear bracket 16 by an easy-release attachment pin 43 with a 
hand-grip 46 and an associated eccentric bush 47 with a handle 49 which 
form the subject of our U.S. patent application Ser. No. 502,051. 
A telescopic support strut indicated generally at 58 is pivotably mounted 
on each stiffening plate 28, just forward of the point of connection to 
said plate of the associated piston-and-cylinder assembly 27, and 
comprises inner and outer members 59 and 34 respectively adapted to be 
releasably locked together by a pin 60 in each of its extended and 
retracted positions. The outer member 35 has a foot 57 welded to its free 
end, and pivotably mounted on it near said end is an auxiliary strut 35 
which can be secured in contiguous parallel inoperative relationship 
thereto as shown in FIG. 1 by passing a linch-pin (not shown) through a 
diametrical hole 61 in a peg 62 welded to the auxiliary strut 35 and 
adapted to project through a hole in the outer member 34. Each support 
strut 58 can occupy three positions. Its stowed position shown in broken 
lines in FIG. 1 is in retracted condition along the underside of the 
forward part of the associated boom 22, where it is secured by a pin 63 
passing through aligned holes in the outer member 34, the auxiliary strut 
35 and a pair of lugs 64 welded to said boom. Its first deployed position 
shown in FIG. 2, in which its foot 57 contacts the ground in order to 
support the rear end of the detacheable main portion of the loader at 
drive-in height whilst said portion is not attached to the tractor and the 
front end of said portion is supported by the lowered bucket 29 or the 
like, is in extended condition at an angle of, say, 40.degree. to the 
forward part of the associated boom 22, to which it is secured by removing 
the linch-pin associated with the peg 62 welded to the auxiliary strut 35 
and pivoting said strut to a poaition in which its free end can be 
connected to the lugs 64 welded to said boom by the pin 63 used to secure 
the support strut 58 in its stowed position. Its second deployed position 
shown in full lines in FIG. 1, in which its foot 57 engages an abutment 65 
at the lower front corner of the associated pedestal 26 in order to lock 
the boom assembly 21 mechanically in its fully raised position whilst the 
detachable main portion of the loader is attached to the tractor, is in 
extended condition closely adjacent the underside of the associated 
piston-and-cylinder assembly 27, to which it is secured by passing a 
linch-pin (not shown) through a diametrical hole 66 in a peg 67 welded to 
the outer member 34 and adapted to project through a hole in a U-shaped 
member 68 welded to the cylinder of said assembly.