The invention has been developed primarily in connection with a tandem combination of wheeled machines (comprising a foremost machine and a rearmost machine) for use in agriculture, with the foremost machine being intended to be coupled at its forward end with the rear of the propelling vehicle and the rearmost machine being coupled at its forward end to the foremost machine, to be towed behind the foremost machine.

The invention is particularly suitable for application to a tandem combination of a baler (which comprises the foremost machine) and a bale wrapper, which comprises the rearmost machine. The combination can therefore be towed behind a tractor in order to carry out two separate operations on a mown or cut crop lying on the ground e. g. grass, namely to pick-up the crop and form it into a bale in the baler, and then to transfer the bale to the bale wrapper which then applies stretch-film wrapping around the bale prior to discharging the wrapped bale.

The invention is applicable to balers of any suitable type, including balers for forming bales which are 1) of rectangular cross section and 2) of circular cross section i. e. so called"big bales"or"round bales". Balers for forming cylindrical bales of circular cross section can be of the fixed chamber type or variable chamber type, as will be well known to those of ordinary skill in the art.

Bale wrappers used in the combination can be of the rotating turntable type, or of the orbiting satellite type.

Balers and bale wrappers are well known in agriculture, and need not be described in detail herein.

It is already known to provide a trailed combination of a baler and a bale wrapper (see for example W090/14756), and in which each wheeled component of the combination has a chassis or frame supported by a respective wheel set, and with the bale wrapper being towed behind the baler via a tow bar or other pivoted connection. A tractor towing the combination therefore is able to manoeuvre the combination in a field, with the forward end of the baler pivoting relative to its connection with the tractor, and the forward end of the bale wrapper pivoting relative to its connection to the rear of the baler.

However, while the two pivot connections allow the combination to be manoeuvred in a field when necessary, this gives difficulty in designing a suitable transfer mechanism to transfer a formed bale from the baler to the bale wrapper.

A satisfactory design of transfer mechanism would have to be able to transfer the bale to a usual bale-receiving table of the bale wrapper, despite variation in relative inclination of the longitudinal axes of the baler and the bale wrapper caused as the result of turning movements of the tractor and the trailed combination. Clearly, when the tractor and the towed combination carries out a turning manoeuvre, the axes of the tractor, the baler and the bale wrapper will no longer be generally parallel to each other (as will arise during normal forward travel without steering of the tractor), and therefore this will inhibit smooth transfer of any bale from the baler to the bale wrapper.

The invention, in a particularly preferred development, seeks to overcome this problem by providing a control mechanism which seeks to maintain generally parallel relationship between the longitudinal axes, despite pivoting of the baler relative to the tractor (propelling vehicle) during steering movement of the tractor.

By provision of such a control mechanism, the axis of the bale wrapper can be located generally parallel to the axis of the baler at all times, and therefore this simplifies' the transfer of the bale from the baler to the bale wrapper.

However, while the invention is particularly applicable to a towed combination of a baler and a bale wrapper, it should be understood that the principles of the invention may also be applied to other towed combinations in which it is desirable to maintain parallel (or co-axial) relationship between the longitudinal axes of the foremost and rearmost wheeled components of the combination. By way of example only, the foremost and rearmost wheeled components may comprise a bale wrapper and a following self-loading trailer.

According to a first aspect of the invention, there is provided a tandem towable combination of a foremost wheeled device and a rearmost wheeled device, the foremost device being intended to be towed behind a propelling vehicle, and the rearmost device being intended to be towed behind the foremost device, and each device having a wheel-supported frame with a generally longitudinally extending axis, and in which the combination comprises: a first forward towing hitch for coupling the frame of the foremost device pivotally to the rear of the propelling vehicle so that the axis of the frame can adjust its inclination relative to the travelling direction of the propelling vehicle during turning movement of the propelling vehicle and the combination; a second towing hitch for coupling the frame of the rearmost device pivotally to the rear of the foremost device; a control device which is responsive to pivotal adjustment of the axis of one of said devices (a) relative to the propelling vehicle or (b) relative to the other of said devices, during movement of the combination; and, a steering mechanism on a first of said devices which is operative to adjust the inclination of the axis of said device; in which the control device is coupled with the steering mechanism and is operative to make compensating adjustment of the steering mechanism, as a consequence of adjustment of the axis of said one device, in order that the combination can follow a required path.

According to a second aspect of the invention there is provided a tandem towable combination of a foremost and a rearmost wheeled device, the foremost device being intended to be towed behind a propelling vehicle, and the rearmost device being intended to be towed behind the foremost device, and each device having a wheel-supported frame with a generally longitudinally extending axis, and in which the combination comprises: a first forward towing hitch for coupling the frame of the foremost device pivotally to the rear of the propelling vehicle so that the axis of the frame can adjust its inclination relative to the travelling direction of the propelling vehicle during forward turning movement of the propelling vehicle and the combination; a second towing hitch for coupling the frame of the rearmost device pivotally to the rear of the foremost device; a control device responsive to pivotal adjustment of the axis of the frame of the foremost device; and a steering device coupled with the wheel set of the rearmost device and operative to adjust the steering angle of the wheel set in order to adjust the inclination of the axis of the frame of the rearmost device: in which the control device is coupled with the steering device and is operative to make compensating adjustment of the steering device in order to maintain the axis of the frame of the rearmost device substantially parallel with the axis of the frame of the foremost device.

Accordingly, by the invention, it is possible to maintain the axes of the foremost and rearmost devices generally parallel to each other, despite turning manoeuvres applied to the combination by the propelling vehicle.

Effectively, the frames of the foremost and rearmost devices are maintained substantially rigid, and pivot as a single unit about the first forward towing hitch which couples the frame of the foremost device pivotally to the rear of the propelling vehicle.

In practice, there may be some small pivotal adjustment of the axis of the frame of the rearmost device, relative to the axis of the frame of the foremost device, as the compensating adjustment of the steering device takes place.

The foremost and rearmost devices therefore are maintained in substantially parallel alignment, despite turning movements applied to the combination by the propelling vehicle, and this facilitates easy transfer of material being handled by the foremost device to the rearmost device, or facilitates operations of any transfer mechanism effective between the foremost and the rearmost devices.

In a particularly preferred embodiment of the invention, the foremost device comprises a baler and the rearmost device comprises a trailing bale wrapper apparatus.

The combination therefore can be towed behind e. g. a tractor, in order to pick-up already mown grass, and the baler forms the grass into a tightly packed bale, and which is then transferred to a table of the bale wrapper, which then carries out a bale wrapping operation, prior to discharge of the wrapped bale. Therefore, in a single pass of the combination, two separate operations can be carried out, namely picking-up and forming a bale, and subsequent wrapping of the bale.

The baler may be of any suitable type, including a baler for forming bales of rectangular cross section, or cylindrical bales of circular cross section. The bale wrapper can be of the rotating turntable type, or can have a fixed table, and one or more orbiting satellite dispensers of stretch film. For particularly high speed wrapping operation, a bale wrapper could be of the rotating turntable type, plus one or more orbiting satellite film dispenser reels.

The invention may be applied to other types of machines used in agriculture in combination, such as a trailed combination of a bale wrapper and a shelf-loading trailer.

The control device (which is responsive to pivotal adjustment of the axis of the frame of the foremost device) can be any suitable mechanical, electromechanical or hydraulically operated mechanism. In a preferred arrangement, the control device includes a monitoring device which detects pivotal adjustment of the axis of the frame of the foremost device from a neutral or datum position, and an actuator device may be provided which is controlled by the monitoring device and which is coupled with the steering device so as to make any necessary compensating adjustment of steering device to maintain the axis of the frame of the rearmost device substantially parallel with the axis of the frame of the foremost device.

Alternatively, the monitoring device may be arranged to monitor relative pivotal adjustment between the axis of the frame of the foremost device and the axis of the frame of the rearmost device.

The actuator may comprise a mechanical arrangement of connecting rods or the like, providing mechanical feedback to the steering device. Alternatively, the steering device could be controlled by other means, such as electric or hydraulic actuation.

Preferred embodiments of the invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic plan view of a first embodiment of tandem towable combination according to the invention coupled to the rear of a tractor, and showing the tractor and the combination undergoing turning movement, in which the combination comprises a foremost device in the form of a baler and a rearmost device in the form of an orbiting satellite bale wrapper; Figure 2 is an isometric view showing in more detail how the trailed combination follows the turning movement of the tractor; Figure 3 is a further isometric view from an opposite side, also showing how the combination follows the turning movement of the tractor; Figures 4 to 6 are similar views of a modified embodiment of the invention; and, Figures 7 to 10 are views of a further embodiment of the invention.

Referring now to Figures 1 to 3 of the drawings, the illustrated example of tandem towable combination to which the invention may be applied is designated generally by reference 10, and comprises a foremost device 11 which is coupled at its forward end with the rear of a propelling vehicle 13 e. g. an agricultural tractor, and with a rearmost device 12 being coupled at its forward end to the foremost device 11 to be towed behind it.

In the illustrated example, the foremost device 11 comprises a baler, and the rearmost device 12 comprises an orbiting satellite type of bale wrapper. The baler and the bale wrapper can be of any suitable type, and as will be well known to those of ordinary skill in the art, balers can be of the type suitable for forming rectangular cross section bales, or cylindrical bales of circular cross section. The bale wrappers can be of the rotating turntable type, the orbiting satellite type, or combination of rotating turntable and orbiting type.

The combination 10 comprises two devices (11 and 12) each having a wheel-supported frame, with a respective wheel set, which in the illustrated arrangements comprises a single axle set of wheels 14 for the baler 11, and a single set of steerable wheels 15 for the bale wrapper 12. The forward end' of the frame of the bale wrapper 12 is coupled to the rear of the baler 11 via a towing hitch 16 which comprises a draw bar which is pivotally connected at its forward end to the frame of the baler 11. The baler 11 is pivotally coupled at its forward end with the rear of the tractor 13 via towing hitch 17.

The combination 10 can be towed directly behind the tractor 13 during operation, and may be used therefore to carry out three separate operations on a crop already lying on the ground e. g. mown grass, or straw. The combination can pick up the crop lying on the ground, transfer it to the baler 11 and form it into a bale of suitable cross section, and then transfer the formed bale (by any suitable means not shown) to the bale wrapper 12, which then applies stretch film wrapping to the bale prior to discharge of the wrapped bale. The bale may be discharged by the baler 11 onto the ground, to be directly in the path of travel of the bale wrapper 12, and which may be provided with any suitable pick- up mechanism to transfer the bale onto the usual bale wrapping table of the bale wrapper 12. Alternatively, some suitable transfer mechanism could be provided in order to transfer the bale directly from the bale forming chamber of the baler 11 to the table of the bale wrapper.

However, during movement across a field with a crop lying on the ground, turning manoeuvres of the tractor and the combination will be necessary from time to time, and the control mechanism which will now be described is constructed and operated to have the function of making compensating adjustment of the steering angle of the steerable wheels 15 so as to maintain the axis of the frame of the bale wrapper 12 generally parallel with the axis of the frame of the baler 11, despite the application of turning manoeuvres to the combination by the tractor 13.

Thus, the baler 11 can follow the turning movements of the tractor 13, as shown in Figure 1, generally in the manner of any trailed vehicle. However, although there is a pivot coupling between the frame of the bale wrapper 12 and the baler 10, which permits limited pivoting movement, in practice the baler 11 and bale wrapper 12 form a composite unit, with a common longitudinal axis i. e. the unit effectively comprises a rigid-coupled assembly.

This is achieved, as can be seen in Figure 1, by automatic feedback adjustment of the steering angle of the wheels 15, so as to maintain the longitudinal axis of the bale wrapper 12 generally parallel (or coincident in some circumstances) with the longitudinal axis of the baler 11.

A control device is therefore provided (not shown) which is arranged to respond to pivotal adjustment of the axis 18 of baler 11 relative to that tractor axis, and which is coupled with a steering device (not shown) controlling the steering angle of the steerable wheels 15, in order to maintain the axis 19 of the frame of bale wrapper 12 generally parallel with the axis 18 of the baler 11.

The control device may include any suitable form of monitoring device, which monitors angular adjustment of the axis 18 relative to the tractor 13 during turning manoeuvres, and which can then trigger operation of a suitable actuator device (not shown) which is coupled with the steering device and which causes suitable compensating adjustment of the steering angle of the wheels 15 to maintain the axes 18 and 19 generally parallel. Figures 2 and 3 are isometric views, showing how this is achieved, whereby the combination 10 of wheeled devices 11 and 12 effectively form a unitary assembly which turn together about the pivot connection of the forward hitch 17 to the rear of the tractor 13.

The actuator to operate the steering device can take any suitable form, including mechanical rod linkage, electric actuation or hydraulic actuation.

The invention can be applied to other types of towable combination, e. g. a bale wrapper followed by a self loading trailer.

However, while the preferred arrangement of the control device is such that it can monitor deviation between the axis of the propelling vehicle and the axis 18 of the foremost device 11, it should be understood that it is within the scope of the invention for other arrangements of control device to be provided. Thus, the control device could be arranged at any convenient position in order to minor deviation between the axis 18 of the foremost device 11 and the axis 19 of the rearmost device 12, and then to provide a feedback signal which applies necessary adjustment to the steering angle set by the steerable wheelset 15 of the rearmost device 12, in order to maintain a generally parallel relationship between the axes 18 and 19, during turning movements of the combination 10 by the propelling vehicle (tractor) 13.

A modified embodiment of the invention is shown in Figures 4 to 6, and which is generally similar to the first described embodiment. The towed combination is designated generally by reference 10a, and foremost device lla is coupled to the rear of the tractor 13 via forward pivot hitch B, and rearmost device 12a is coupled to the rear of foremost device lla via rigid cranked towbar 16a and forward pivot hitch A.

Figure 4 to 6 show the compensating adjustment of the steerable wheels of the rearmost device 12a, during turning of the combination 10a by the tractor 13, in order to maintain the axes of the foremost and rearmost devices generally parallel.

A control device is provided in order to monitor deviation between the axis of the tractor 13 and the foremost device lla, to provide compensating adjustment of the steering mechanism of the rearmost device 12a.

Alternatively, the control device can monitor any deviation between the axes of the foremost and rearmost devices, in order to provide suitable compensating feedback signals to an actuator which operates the steering mechanism.

Referring now to Figures 7 to 10, this shows a further embodiment of the invention, designated generally by reference 110, and which comprises propelling vehicle 113, foremost wheeled device 111 and rearmost wheeled device 112, which in the illustrated embodiment comprise a baler and a bale wrapper. However, in this embodiment, although devices 111 and 112 each comprise again frames supported by a wheelset, in which embodiment the wheelset 115 of the foremost device 111 (the baler) are steerable wheels, whereas the wheels of the rearmost device 112 (the bale wrapper) have a fixed axle.

By provision of suitable monitoring devices (to monitor deviation of the axis from a predetermined datum), plus feedback control to a steering mechanism, the combination 110 can be caused to move along any required path, as set by a pre-programmed controller (not shown), depending upon the required mode of operation.

As described earlier, one of the modes of controlled adjustment is such that the control device makes compensating adjustment of the steering mechanism in order to maintain the axis 19 of the frame of the rearmost device 12 substantially parallel with the axis 18 of the frame of the foremost device 11 during forward turning movement of the combination by the propelling vehicle 13.

A second mode of controlled adjustment which may be set on the programmed controller is such that the control device makes compensating adjustment of the steering mechanism in order to control reverse steering movement of the combination.

A third mode of controlled adjustment is such that the control device makes compensating adjustment of the steering mechanism in order that, during turning movement of the combination, the wheels of the rearmost device 12,112 substantially follow the path of the wheels of the foremost device 11,111, to enable tighter turns to be negotiated e. g. when leaving a field entrance onto the public highway.

In preferred embodiments of the invention, the steering mechanism comprises any suitable linkage controlling the steering angle of adjustable steering wheels of the wheelset of one of the vehicles. However, other arrangements of steering mechanism may be provided e. g. provision of one or more separate steerable wheels. A further alternative is to provide a drawbar type of steering mechanism, in which the forward end of the drawbar is transversely adjustable to exert a steering action.

There have been referred to above three possible modes of operation of the towed tandem combination which can be achieved, and a detailed table of adjustments and control parameters is set out below, by way of example only, in the preferred application of the invention to a towed combination of a baler and a bale wrapper. These parameters are set out by way of example only, and are not intended to be limiting to the claimed protection.

Different possible steering systems for wrapper baler combinations.

Definitions: K-constant, different size in defined actions A-angle between tractor and baler B-angle between baler and wrapper C-angle of wrapper wheels D-angle of baler wheels Wheels steering Actions Monitoring Inline Track following Backwards Steering on Between tractor C=K*A C=K*A C=K*A wrapper-wheels and baler + wrapper wheel angle Between baler and B minimized by C=K*B C=K*B wrapper + wrapper changing C wheel angle Between baler and B minimized by B minimized by wrapper only chancing C changing C opposite direction of inline Steering on Between tractor D=K*A D=K*A D=K*A baler-wheels and baler + baler wheel angle Between baler and B minimized by D=K*A D=K*A wrapper + baler changing D wheel angle Between baler and B minimized by B minimized by wrapper only changing D changing D opposite direction of line