Land vehicles – Wheeled – Articulated vehicle
Reexamination Certificate
2001-02-23
2003-03-18
Morris, Lesley D. (Department: 3611)
Land vehicles
Wheeled
Articulated vehicle
C172S439000
Reexamination Certificate
active
06533307
ABSTRACT:
TECHNICAL FIELD
Apparatus for transferring load between a towing tractor and a towed above ground implement.
BACKGROUND ART
At present problems are often encountered when tractors are used for towing above ground implements such as seed drills, scoops, large trailers and cultivating discs. In general, these problems arise due to the tractor and/or towed implement encountering:
Obstructions e.g. rocks
Muddy or wet ground
Hills or hollows
The above situations cause problems as they can adversely affect the traction of the tractor's driving wheels and render the towing of such implements a dead weight dragging operation.
The above difficulties are currently overcome by using tractors which have:
Ballast added; or
Increased horse power/weight; and/or
Four wheel drive; and/or
Dual wheels.
However, as will be appreciated the above remedies suffer from either increasing the cost of the tractor required to perform the job, or adding time and effort to the job due to having to add ballast to the tractor.
In relation to underground working implements such as ploughs and rotary hoes, the above mentioned difficulties for towed implements have been overcome by the implementation of a hydraulic draft control system associated with the three-point linkage of a tractor. The draft control system operates by either raising or lowering the implement depending on whether its effective load has bee increased or decreased. By this means, the draft control system is able to transfer load (weight) between the implement and tractor to maintain the desired degree of wheel slippage.
It would therefore be an advantage if there could be provided some means by which the draft control system already present on many tractors could be utilised in the towing of above ground implements also.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.
DISCLOSURE OF INVENTION
According to one aspect of the present invention there is provided apparatus for transferring load between:
a towing tractor which includes:
a) a three-point linkage which includes three linkage arms; and associated hydraulic draft control system; and
b) a tow-bar; and
a towed above ground implement which includes a draw-bar which attaches to the tow-bar of the tractor,
characterised in that the apparatus includes a shock absorber which is:
(i) directly or indirectly connected at one end thereof to at least the two lower arms of the tractor's three-point linkage, and
(ii) at the other end thereof is connected either directly or indirectly to the draw-bar of the towed implement in a manner that allows the draft control system of the tractor to be activated so as to transfer load between the tractor and the implement, as is required to maintain the desired wheel slippage of the tractor's traction axle whilst towing the implement.
According to one aspect of the present invention there is provided apparatus for transfering load between:
a towing tractor which includes:
a) a three-point linkage which includes three linkage arms; and associated hydraulic draft control system; and
b) a tow-bar; and
a towed above ground implement which includes a draw-bar which attaches to the tow-bar of the tractor;
characterised in that the apparatus includes a shock absorber which is:
i) directly or indirectly connected to the three arms of the tractor's three-point linkage, and
ii) at the other end thereof is connected either directly or indirectly to the draw bar of the towed implement in a manner that allows:
the shock absorber to experience a force which is forward of the towed implement; and
the draft control system of the tractor to be activated so as to transfer load between the tractor and the implement, as is required to maintain the desired wheel slippage of the tractor's traction axle whilst towing the implement;
such that load from the towed implement can be transferred to all the wheels of the tractor.
According to another aspect of the present invention there is provided a method of transferring load between:
a towing tractor which includes:
a) a three-point linkage which includes three linkage arms and associated hydraulic control system; and
b) a tow-bar; and
a towed above ground implement which includes a draw-bar which attaches to the tow-bar of the tractor;
the method characterised by the steps of:
(i) directly or indirectly connecting a shock absorber to at least the two lower arms of the tractors three-point linkage, and
(ii) connecting the opposite end of the shock absorber to the draw-bar of the towed implement in a manner that allows the draft control system of the tractor to be activated, and
(iii) tensioning the shock absorber by raising or lowering the tractor's three-point linkage arms so as to enable the transfer of load between the tractor and the implement, such as required to maintain the desired wheel slippage of the tractor's traction axle while towing the implement.
According to a further aspect of the present invention there is provided a method of transferring load between:
a towing tractor which includes:
a) a three-point linkage which includes three linkage arms and associated hydraulic control system; and
b) a tow-bar; and
a towed above ground implement which includes a draw-bar which attaches to the tow-bar of the tractor;
the method characterised by the steps of:
(i) directly or indirectly connecting a shock absorber to the three arms of the tractors three-point linkage, and
(ii) connecting the opposite end of the shock absorber to the draw-bar of the towed implement in a manner that allows:
the shock absorber to experience a force which is forward of the towed implement; and
the draft control system of the tractor to be activated, such that load from the towed implement can be transferred to all wheels of the tractor, and
(iii) tensioning the shock absorber by raising or lowering the tractor's three-point linkage arms so as to enable the transfer of load between the tractor and the implement, such as required to maintain the desired wheel slippage of the tractor's traction axle while towing the implement.
It is envisaged that the towing tractor may be any tractor with the characteristics referred to above.
The towed above ground implement may include:
Trailers
Scoops
Seed drills
Cultivating discs
However, this list should not be seen as limiting as the present invention may also be applied to other implements which are attached to the tow-bar of the tractor.
The shock absorber may come in a variety of different forms.
In general, the shock absorber should be capable of supporting a 3-4 ton load.
In some embodiments the shock absorber may be a gas strut or hydraulic ram.
In other embodiments the shock absorber may be a helical spring or other resilient-type member/device.
In preferred embodiments the shock absorber may be a leaf spring.
For ease of reference only, the shock absorber will now be referred to as being a leaf spring. However, it should be appreciated that the principles stated for this embodiment may also have general application to other embodiments where the shock absorber is not a leaf spring.
The leaf spring may be connected to at least the two lower arms of the tractor's three-point linkage in a variety of different ways.
In general, the leaf spring may be attached to these arms via a mounting-frame which connects to the terminal ends of the tractors linkage arms.
In preferred embodiments, the mounting-frame may connect to all three arms of the three-point linkage.
In some preferred embodiments, the leaf spring may be pivotally attached to the mounting-frame so as to allow for any lateral movement of the towed implement. In general, the applicant has found this is best achieved by having the leaf spring pivot along the same axis, as that which the draw-bar of the implement pivots with respect to the tow-bar of the tractor.
In other preferred
Greer Burns & Crain Ltd.
Morris Lesley D.
Winner Tony
LandOfFree
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