GB2069452A - Tractor and load lifting attachment combination - Google Patents

Abstract

A tractor is equipped with an auxiliary load supporting and lifting device 1 to enable the tractor to lift one end of a wheeled container 4 and thus permit it to be manoeuvred by the tractor. The device 1 has a mast structure 10, supported by spaced castor wheels 12 and includes a support arm 7 presenting an upwardly open hook 6 for engagement with a lifting bar 5 on the container 4 to provide for steering articulation between the load supporting device and the container. The device 1 is connected to lift arms 2 and crowd lever 3 of the tractor via a "quick fit" member 9. <IMAGE>

Description

SPECIFICATION Tractor and load lifting attachment combination The present invention relates to handling containers and in particular to moving very large containers, such as International standard freight containers and the like, through small distances without the use of cranes or specialised heavy duty transporters.

In particular the present invention relates to a transport system for handling containers, which in a loaded condition may weigh in excess of 20 tons (even in excess of 40 tons) in which the motive power is provided by the tractor unit of a shovel loader. A shovel loader comprises mechanism for imparting raising and tilting movements to a loading shovel. In the system of the present invention the loading shovel is detached from the tractor unit and is replaced by an auxiliary ground supported device which is pivotally connected to the lift arms and crowd lever of the tractor in the same manner as the bucket. In other words the auxiliary device is an implement which may be fitted in place of the standard bucket.The object of providing the auxiliary device is to allow one end of a container to be lifted and supported for transport without imposing loads on the axles, tyres and hydraulic system of the tractor of the same order as would be imposed if the end of the container had been lifted by the bucket support arms of the tractor, assuming the ability of the tractor vehicle to raise such load.

One particular problem to which the invention is directed is the handling of refuse containers at municipal and industrial refuse disposal sites. In general refuse containers are constructed in the same way in International standard freight containers. In addition they are fitted with small wheels adjacent each corner and have a lifting bar located on the centre line of the freight container at one or both ends to permit the container to be winched onto a specialised heavy duty transport vehicle, provided with deck channels and rear ramps to allow a container to be moved on and off the vehicle. The wheels on the containers are freely rotating but their axes are fixed so that they ride stably on the transport vehicle. Thus they can only be moved conveniently on the ground by raising one end.

On most large scale refuse disposal sites a shovel loader, usually a four-wheel drive shovel loader having centre pivot steering (steering by pivoting the frame approximately midway between fixed front and rear axles), is employed for handling refuse before or after treatment. While the tractor unit is capable of providing the tractive effort for moving a fully loaded refuse container, the rated load represented by a filled bucket would commonly be no more than 5 tons for a shovel loader operated in such environment. Thus it would be unacceptable to employ the lift-arms of the tractor to lift and support one end of the freight container for transport.In order to overcome this difficulty, according to the present invention, the shovel loader bucket is replaced by an auxiliary load supporting and lifting device, which comprises a mast structure, having a forwardly projecting support arm towards its upper end, the support arm having an upwardly open hook towards its forward end and the mast structure itself being supported by laterally spaced, freely rotatable castor wheels. The upwardly opening hook is shaped to engage with the lifting bar on the end of the container so that when the end of the container is lifted by means of the device the hook and lifting bar together form an articulation point between the tractor and the container while the load supporting device itself steers with the tractor.

It will readily be understood that when the crowd lever of the hydraulic system of the tractor is operated in such a manner as to tilt the mast structure backwards or forwards about the pivot which connects it to the lift arms of the tractor, an essentially vertical movement of the support arm of the auxiliary device will ensure. Thus the rearward movement of the crowd lever, as normally employed for tilting the bucket backwards to the travel position, will result in upward movement of the hook to engage under the lifting bar and impart lifting movement to the front end of the container.Then, by locking the crowd lever and allowing the lift arms to float, the weight, of the forward end of the container is supported on the castor wheels of the device, thus allowing the container to be manoeuvred either backwards or forwards by the tractor vehicle without imposing on the tractor vehicle the increased stresses which would occur during travelling if a large weight were supported directly upon the lift arms of the tractor.

Referring to the accompanying drawings:- Figure 1 shows a shovel loader, fitted with the auxiliary device of the present invention, approaching a container, preliminarily to lifting one end, Figure 2 shows the auxiliary device in the travel position with one end of the container supported on it, Figure 3 shows a side view of the mast structure (without wheels) and Figure 4 shows an end view of the mast structure.

In Figure 1 the container hoist device 1 is shown as pivotally connected to the lift arms 2 and crowd lever 3 of a shovel loader and approaching one end of a container 4 for engagement with an existing container lift bar 5.

In Figure 2 the mast of the container hoist device has been tilted backwardly towards the shovel loader to raise the front end of the container by engaging the hook 6 of the support arm 7 under the lift bar 5. This enables the container 4 to be manoeuvred by forward or rearward movement of the shovel loader. This combination is particularly useful in that it allows the container to be manoeuvred into a building which may have a relatively narrow entrance.

It should be noted in Figures 1 and 2 that the crowd lever 3 and lift arms 2 are pivotally connected to a transverse "quick fit" member 9 which is arranged for engagement in a conventional manner with co-operating members of a shovel loader bucket to permit quick connection and quick release of the bucket which moves with the member 9, when attached to it.

The mast structure 10 is pinned to the member 9 at 11, in the same manner as a bucket. The wheels 12 are mounted in castors 14 which are free to rotate about generally vertical axes in relation to the mast structure 10.

The mast structure 10 is illustrated in greater detail in Figures 3 and 4. The mast comprises a generally triangular frame formed of a transverse member 1 5 connected to vertical members 1 6 which receive the castor members 1 4 and are connected at their upper ends to inclined frame members 17, joined at their apex to a vertical frame member 18. The support arm 7 is welded to and extends forwardly from the vertical member 18. The members 17 support a cross tube 19 carrying downwardly facing hook members 20 arranged for engagement with the members 9 to provide a quick connection therewith. Apertured lugs 21 are secured to the transverse frame member 15 for connection to the member 9 at 11.

The "quick fit" connection of the mast structure to the member 9 by hooks 20 and pins 11 is an essentially conventional quick fit arrangement for securing an implement and could be replaced by "quick fit" arrangements of other design. It would also be possible, although less convenient, to connect arms 2 and crowd lever 3 directly to the mast by means of upper and lower pivot pins.

There are two different modes of operating the device illustrated in the drawings. In one mode of operation the operator drives the machine forwardly to bring the hook 6 beneath the lifting bar 5 and then sets the lifting jack controls at the float position and operates the crowd jack 24 to tilt the mast structure rearwardly, thus bringing it to an upright position at which the bar 5 is cradled in the hook 6. In moving the mast structure to the upright position it pivots about the pivot 11 and this is accompanied by forward rolling movement of the wheels 12 and some upward movement of the lift arms 2, dependent upon the amount of compression of the tyres under the imposed load.

When the mast has reached the upright position the crowd jack control is placed in the "hold" position thus effectively locking the lever 3 and the lift arms 2 in relation to one another. In an alternative mode of operation the crowd jack control is placed in the "float" position and the hoisting of the container is achieved by driving the machine forwardly to bring the bar 5 into contact with a surface 25 which extends upwardly above the forward part 26 of the hook 6. Forward movement of the tractor then swings the mast into the upright position by reason of the resistance to movement of the container. On reaching the upright position the crowd jack control is again set at the "hold" position.

After lifting the forward end of the container by either modes of operation it is possible to travel the device in either forward or rearward directions.

The surface of the hook 6 is preferably rounded so as to permit easy articulatory movement between the support arm 7 and the bar 5. Thus steering is eased, particularly when the tractor is pushing the container. To avoid damage to the container in this mode of travel a pair of springloaded bumpers 27 extend forwardly from the structure and are arranged to operate limit switches which actuate warning lights to warn the driver that the angle between the tractor and the container is approaching the permissible limit.

Although the invention has been described in terms of a combination of a shovel loader and auxiliary hoisting device, the auxiliary hoisting device may be employed with any vehicle provided with a member analogous with member 9, arranged for tilting movement and up and down movement. For example the auxiliary device could be connected to a tilting carriage of rough terrain lift truck, such as described in Patent Application No. 7919157.

The auxiliary device -- tractor combination has been described in terms of moving a specialised wheeled container provided with a lifting bar at one or both ends. However it could be employed to skid non-wheeled containers of other designs, provided that such are provided at one end with an analogous fitment to the lifting bar to permit that end of the container to be supported by the lift arm and to articulate in relation to the lift arm.

Claims (8)

1. An auxiliary load supporting and lifting device for adapting a tractor, having forwardly extending lift arms and crowd lever or like means for imparting raising and lowering movement and tilting movement to an implement supported forwardly of said tractor, to raise one end of a container to permit movement thereof by the tractor, said auxiliary device comprising a mast structure carried on spaced, self-steering wheels at the lower end of the mast structure, said mast structure having a forwardly extending arm providing an upwardly open hook at a location forward of said wheels for engagement with a horizontal bar-like member at one end of the container and means for connecting the mast structure to said lift arms and crowd lever or the like means of said tractor to enable the tractor to control the inclination of the mast structure to bring said hook into and out of engagement with said bar-like member and raising and lowering said one end of said container.

2. A device as claimed in claim 1 wherein the hook has relieved side edges to facilitate steering articulation between said mast structure and said container.

3. A device as claimed in claim 1 or 2 including a pair of bumpers arranged on the front of the mast structure, to limit the degree of steering articulation between the container and the mast structure.

4. A device as claimed in claim 3 wherein the bumpers are spring loaded and arranged to operate limit switches connected to actuate a warning that the steering articulation has reached the permitted limit.

5. A tractor in combination with a wheeled auxiliary load supporting and lifting device enabling the tractor to raise one end of a container, the auxiliary device comprising a mast structure carried by a pair of spaced self-steering ground support wheels and including a forwardly extending arm presenting an upwardly open hook forwardly of said wheels for engagement with a lifting point on the container; said tractor being connected to the mast structure by poweroperated linkage means for tilting said mast backward and forward.

6. The combination as claimed in claim 5 wherein the tractor includes at least one lift arm and at least one crowd lever for imparting tilting movement to said auxiliary device.

7. The combination as claimed in claim 6 wherein the mast structure is connected to the lift arm(s) and the crowd lever by a quick fit connection.

8. The combination as claimed in any of claims 5 to 7 in which the tractor is of the centre-pivot steering type.