GB2271977A - Bale lifter - Google Patents

Abstract

A bale lifter 11 comprises two arms 12 which are pivotable about a horizontal axis 15. Lifting forks 14 are attached to swing arms 12 and extend horizontally from the arms. The distance between the forks 14 may be varied by means of the hydraulic ram 13. The fork arm 14 is tilted with a 'V' shape clamping tube which comprises a top portion (17 Fig 2) made from a relatively light gauge tube and a lower portion (18) formed from a relatively heavy gauge tube, providing self alignment to the vertical. The lifter incorporates a stop 20 to aid bale positioning when a bale is released. <IMAGE>

Description

BALE LIFTER This invention relates to a bale lifter which is adapted for attachment to a propelling vehicle, and which is capable of engaging with a bale and of transporting the bale to a required unloading station, and of stacking the bale at the unloading station.

The invention has been developed primarily in connection with the transportation of substantially cuboidal bales of long stem agricultural materials, such as straw, hay, or partly dried grass. Such bales are usually referred to as square bales and are formed by balers which pick up the material lying on the ground, compress the material into substantially cuboidal form, apply chord or other wrapping around the cuboidal form to maintain its shape, and then discharge the bale rearwardly onto the ground.

These bales are of substantial size and typically can weigh up to half a metric tonne, and therefore present considerable handling problems.

In the case of unwrapped bales, eg of straw or hay, it is known to use spike type loaders which have a spike which is driven into an end face of the bale lying on the ground, or in a stack. The loaders can then be raised in order to lift the bale, and then the bale can be transported to a required unloading point, eg onto a trailer or onto a stack of bales.

These spike type loaders are robustly constructed and work reasonably well, but are inappropriate for use in transporting wrapped bales, since the impalement of the bale by the spike would puncture the film wrapping which would be very undesirable.

Bales are wrapped with plastics film wrapping in order to exclude the bales material from contact with water from the atmosphere, in the case of wrapped straw or hay, and in the case of wrapped bales of grass, the wrapping is applied around the bales in order to exclude both water and oxygen from the surrounding atmosphere, so that the grass can mature to form silage.

In the case of wrapped bales having dry matter or with damp baled material, the avoidance of any puncture in the film wrapping is essential to prevent deterioration in the quality of the baled material. Therefore, spike type loaders are unsatisfactory for use with wrapped bales, although some farmers use them and then apply sticker patches over any punctures produced.

Known bale lifters comprise at least two arms spaced apart from one another and mounted on the rear of a vehicle such as a tractor. The arms typically comprise rollers having a small cross sectional diameter. The rollers engage on either side of the bale slightly underneath the bale, and thus allow the bale to be lifted up.

A problem with using such bale lifters with the square type bales is that due to the fact that the sides of the square bale are substantially upright, it is not easy to engage the bale at a point underneath the bale. In addition, the small cross sectional diameter of the arms exerts large pressure on the square bales, which causes the wrapping to be punctured.

According to the present invention there is provided a bale lifter adapted to be mounted on a propelling vehicle comprising: a mounting portion adapted to mount the lifter on the propelling vehicle; a support carried on the mounting portion; and at least two generally parallel bale lifters mounted at spaced apart positions on the support, in order to define bale lifting forks; wherein the support is pivotably mounted on the mounting portion for movement about a substantially horizontal pivot axis, whereby the distance between the bale lifting forks may be varied, and in which at least one lifting fork comprises a contact portion extending from the at least one fork, and being substantially wider than the at least one fork, which contact portion is pivotable about an axis which is substantially parallel to the fork.

The forks are adapted to engage opposite sides of a bale particularly a square bale. Although the sides of the square bale are substantially upright, typically, the sides will slope inwards towards the bottom of the bale. The forks are adapted to engage towards the bottom of the bale at the point where the sides begin to slope inwards. When the forks engage part of the bale, the support will push the forks against the sides of the bale and exert a pressure on the bale. Because the side of the bale slopes inwards towards the bottom of the bale, a top side of the contact portion will make contact with the bale before the bottom of the contact portion. Due to the fact that the contact portion is pivoted, the contact portion will pivot relative to the arm in order that it is substantially in contact with the whole of the side of the bale.The pressure exerted on the side of the bale is thus reduced due to the large contact area with the bale. The wedge effect thus produced is known as the KEYSTONE effect.

Preferably, the bale lifter further comprises biasing means for biasing the contact portion in a position substantially in the same plane as the arm. This means that when not in use the contact portion will always return to a substantially vertical position in which it is lying in the same plane as the fork ready for the next use.

Advantageously, the contact portion comprises a tubular closed loop attached to the fork and pivoted about an axis collinear with the fork.

Conveniently, a bottom portion of the contact portion is heavier than the top of the contact portion which biases the contact portion in an upright position.

Preferably, the support comprises two swing arms, each of which arms is pivotably mounted on the mounting portion.

Each swing arm is attachable to a bale lifter. Movement of one or both swing arms results in the distance between the bale lifters being varied.

Advantageously, the bale lifter further comprises restricting means for restricting the movement of at least one arm.

Conveniently, the bale lifter comprises moving means for moving the lifting forks outwardly, or inwardly, as desired.

When using a bale lifter according to the present invention to stack a bale adjacent to other bales, it is desirable to ensure that any gap between adjacent bales is as small as possible.

When using the bale lifter according to the present invention it is possible that a gap may be left between adjacent bales, which is substantially equal in size to the cross sectional width of a bale lifting fork. The gap is undesirable because it promotes possible wind and vermin damage.

The restricting means are preferably positioned on the mounting portion of the bale lifter, in a position such that when one of the bale lifting forks is moving in an outward direction in order to release the bale, its movement is restricted due to the fact that the lifting fork will abut with the restricting means.

In use, a bale which has been lifted by the bale lifter, and is to be stacked is placed by the bale lifter in a position as close as possible to an adjacent bale. The lifting forks are then caused to move in an outward direction by the moving means, in order to release the lifting forks from the bale. A first lifting fork which is positioned in the gap between adjacent bales, is unable to move due to the limited dimensions of the gap in which it is positioned. The second lifting fork however is free to travel to an outward position. However, during the outward movement of the second arm, the arm will abut with the restricting means before it reaches its maximum outward position.Further force applied to the lifting forks by the moving means in order to attempt to cause each fork to move in an outward direction, results in the first arm pushing against the adjacent bale, and thus closing the gap between that bale and the bale which was stacked before it. The operation may be repeated on each bale.

Preferably the moving means comprises a hydraulic ram connected to each of the lifting forks, which hydraulic ram causes the lifting forks to move outwardly or inwardly, depending on whether the bale is to be engaged or released.

Embodiments of the invention will now be further described by way of example only with reference to the accompanying drawings in which: Figure 1 is a schematic representation of a bale lifter according to the present invention; Figure 2 is a more detailed representation of a lifting fork forming part of the bale lifter of Figure 1.

Figure 3 is a schematic representation of a second embodiment of the invention.

Referring to the Figures, a bale lifter according to the present invention is designated generally by the reference numeral 10. The bale lifter is mounted on a propelling vehicle such as a tractor (not shown) by a mounting portion 11.

Attached to the mounting portion 11 is a support comprising two swing arms 12, which are pivotable about a respective substantially horizontal axes 15. Lifting forks 14 are attached to the swing arms 12 and extend substantially horizontally from the swing arms. The distance between the forks 14 may be varied by means of the hydraulic ram 13.

Referring to Figure 2, a fork arm 14 is shown in more detail.

The fork arm 14 comprises a contact portion 15 mounted on the fork 14. The contact portion 15 comprises two 1800 return bend portions 16, a top portion 17 made from a relatively light gauge tube, and a lower portion 18 formed from a relatively heavy gauge tube.

In use, the propelling vehicle will move towards the bale which is to be lifted. On approaching the bale the distance between the two arms 14 may be varied appropriately to suit the dimensions of the bale to be lifted. When not in contact with the bale, the contact portion 15 of each arm 14 will remain substantially upright due to the fact that the lower portion 18 of the contact portion 15 is heavier than the top portion 17.

When the forks 14 have been appropriately positioned on either side of the bale, the support portions 12 are pivoted in order to bring the forks 14 in contact with the bale. Typically, the sides of the bale which engage with the forks 14 curve inwardly towards the bottom of the bale. It is at this point that the fork 14 is engaged with the bale. The lower portion 18 of the contact portion 15 will thus engage with a lower sloping inward portion of the bale. Due to the fact that the contact portion 15 is pivoted about the arm 14. The contact portion 15 will also slope inwardly at substantially the same angle as the bale, in order that the entire contact portion 15 is in contact with a portion of the bale. This has the result of securely engaging the bale between two spaced apart forks 14.It also has the advantage that the pressure exerted on the bale by the forks will be spread across a fairly large contact area and will thus reduce damage to the wrapped bale.

Referring to Figure 3, a second embodiment of the invention is shown. Equivalent parts to the embodiment shown in Figures 1 and 2 have been given corresponding reference numerals.

The bale lifter 10 further comprises restricting means 20 in the form of a bar extending from the mounting portion 11.

In use, when it is desired to release a bale which is being carried by the bale lifter 10 onto a stack, the hydraulic ram will apply pressure to each of the lifting forks 12, 14 in order to cause each arm to move in an outward direction, such that the bale may be released. Before causing the arms to move, the bale is positioned adjacent a stacked bale, such that one of the arms 14 is positioned in a gap between the adjacent stacked bale and the presently carried bale. Activation of the hydraulic ram attempts to cause both of the arms to move in an outward direction. However, because of the positioning of the first arm 14, in the gap between the adjacent bales that arm is unable to move. Therefore the force exerted on both of the arms 14 results in the second arm only moving it in an outward direction. The restraining means 20 is positioned such that before the second arm 14 has reached an extreme outward position, it abuts with the restraining means 20, and thus is unable to move outwardly any further. Further pressure applied on the arms by means of the hydraulic ram 13 therefore causes the first arm 14 to push against the previously stacked bale.

The direction of force on the previously stacked bale causes it to move towards the bale which was stacked before it, and thus closes the gap between it and the bale which was stacked previously.

The operation may be repeated successively as further bales are stacked.

Claims (10)

1. A bale lifter adapted to be mounted on a propelling vehicle comprising: a mounting portion adapted to mount the lifter onto the propelling vehicle; a support carried on the mounting portion; and, at least two generally parallel bale lifters mounted at spaced apart positions on the support, in order to define bale lifting forks; wherein the support is pivotably mounted on the mounting portion for movement about a substantially horizontal pivot axis, whereby the distance between the bale lifting forks may be varied, and in which at least one lifting fork comprises a contact portion extending from the at least one fork, and being substantially wider than the at least one fork, which contact portion is pivotable about an axis which is substantially parallel to the fork.

2. A bale lifter as claimed in Claim 1 further comprising biasing means for biasing the contact portion in a position substantially in the same plane as the arm.

3. A bale lifter according to Claim 1 or Claim 2 wherein the contact portion comprises a tubular closed loop attached to the fork and pivoted about an axis collinear with the fork.

4. A bale lifter as claimed in any one of the preceding claims wherein a bottom portion of the contact portion is heavier than the top of the contact portion which biasing contact portion in an upright position.

5. A bale lifter as claimed in any one of the preceding claims wherein the support comprises two swing arms, each of which arms is pivotably mounted on the mounting portion.

6. A bale lifter as claimed in any one of the preceding claims further comprising restricting means for restricting the movement of at least one arm.

7. A bale lifter as claimed in any one of the preceding claims comprising moving means for moving the lifting forks outwardly, or inwardly as desired.

8. A bale lifter as claimed in any one of the preceding claims wherein the restricting means are positioned on the mounting portion of the bale lifter, in a position such that when one of the bale lifting forks is moving in an outward direction in order to release a bale its movement is restricted due to the fact that the lifting fork will abut with the restricting means.

9. A bale lifter as claimed in any one of the preceding claims comprising a hydraulic ram connected to each of the lifting forks, which hydraulic ram causes the lifting forks to move outwardly or inwardly depending on whether the bale is to be engaged or released.

10. A bale lifter substantially as hereinbefore described with reference to the accompanying drawings.