TECHNICAL FIELD OF THE INVENTION

This invention relates to off-road dump trucks of the kind which include a wheeled chassis supporting a forward-facing drivers seat and an hydraulically operated open-box bucket which is mounted in front of the drivers seat and hinged to the chassis to deposit material in front of the vehicle. For convenience, such vehicles will be referred to herein simply as dump trucks.

BACKGROUND

Dump trucks are often used on construction sites for transporting loose material such as sand, gravel or soil. In most cases the material carried in the dump truck is loaded in a heap, so that when it is tipped out of the bucket onto the ground it lands in a heaped condition, highest in the centre of the truck and shallower towards the sides. To some extent it is possible to use the bucket as a levelling device, enabling the material to be spread over an area, but the deposited material is not evenly distributed, often requiring additional levelling of the material.

This also raises safety issues where the truck moves over the dumped material, particularly if the material is being deposited on sloping ground. The wheels of the truck can often create deep ruts in which they can become stuck, and it has been known for trucks to slip and overturn when attempting to get out of deep ruts. Another safety consideration is the levelling of the truck before unloading. If the truck is not supported on relatively stable and horizontal ground, the sudden change of weight and balance due to movement of the bucket and dumping of the material can cause the truck to slide, or even turn over.

It is known to provide a dump truck with a blade as well as a bucket. For example, US 3 866 342 proposed attaching a blade in front of the bucket so that the vehicle can be used as a snow plough. In US 2 878 598 a demountable bulldozer blade can be attached to the loader arms which hold the bucket in a raised position, whilst in US 2001/0037588 A1 a grading blade can be releasably mounted inside the bucket.

FR 1 478 535 A discloses another dump truck in which a grading blade is mounted on arms which are pivotally mounted beneath the bucket. The arms are connected to the bucket by links so that when the bucket is tipped by means of an hydraulic ram the blade is automatically lifted clear of the ground. The links can also be disconnected from the bucket and secured to the chassis so that the blade is fixed in a raised position during rotation of the bucket.

Yet another arrangement is disclosed in GB 2 305 640 A, in which the blade is mounted in front of the driver and the bucket is mounted at the rear.

In all of these earlier proposals the blade is of limited use during discharge of material from the bucket. Tipping and levelling must be conducted as separate operations, which is both time consuming and potentially dangerous. The present invention seeks to provide a new and inventive attachment which overcomes or alleviates the abovementioned problems without impeding the normal functions of the truck.

SUMMARY OF THE INVENTION

The present invention proposes a dump truck provided with a nudge blade which extends between the tipped bucket of the dump truck and the ground, and the nudge blade can be adjusted in height, independently of the bucket, by means of an hydraulic system.

The nudge blade may be removably mounted on a carrier secured to the chassis of the truck. The carrier may be pivotally mounted on the front axle of the dump truck.

The carrier preferably comprises a carrier bar and a pair of rearwardly extending arms which are pivotally secured to the front axle. The arms may have open front ends for receiving mounting posts secured to the nudge blade, and the mounting posts may be secured within the arms by means of removable pins. The open ends of the arms are preferably provided with removable plugs. The carrier may be provided with means for stowing the plugs when the blade is attached.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings:

Figure 1 is a general side view of a dump truck of the kind with which the present invention is concerned;

Figure 2 is a plan view of the front end of the dump truck showing the vehicle fitted with a nudge blade in accordance with the invention;

Figure 3 is an exploded perspective view of the nudge blade;

Figure 4 is a detail of the mounting arrangement for the nudge blade;

Figure 5 is a side view of the nudge blade in a raised position, and

Figure 6 is a side view of the nudge blade in its lowered operative position.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring firstly to Fig. 1, the invention is applicable to light off-road dump trucks of the kind shown. The truck has a chassis 1 supported on tyred wheels 2, at least two of which are driven and steerable from a forward- facing drivers seat 3 by means of a steering wheel 4. The driver will often be seated in the open, although the vehicle may be equipped with a roll bar 5, or even a small drivers cab (not shown). At the front of the vehicle, an open-topped bucket 6 is pivotally mounted on the chassis 1 , usually provided with an hydraulic system which allows the driver to tip the bucket 6 in a controlled manner using lever 7, and thereby dump the contents of the bucket in front of the vehicle.

Referring to Fig.s 2 and 3, in accordance with the present invention a carrier bar 10 is attached to the chassis 1 by means of brackets 11. Each bracket includes a vertical back plate 12 which is removably bolted to the front axle mountings of the vehicle, with a pair of forwardly projecting pivot plates 13 and 14. For convenience the back plate 12 and one pair of pivot plates 13 and 14 are omitted in Fig. 3. Opposite ends of the carrier bar 10 are welded to box-section stub arms 15 and 16, the rear ends of which are pivotally secured between the plates 13 and 14 by aligned horizontal pivot pins, indicated at 17 and 18. In the middle region of the carrier bar 10, an hydraulic cylinder 19 is pivotally connected to the carrier bar between upstanding lugs 20 and 21 , the upper end of the cylinder 19 being pivoted to a U-shaped bracket 22 fixed on the chassis 1 (Fig. 2). The cylinder 19 can be hydraulically operated from the drivers position by means of a separate control lever 8 (Fig. 1), thereby allowing the carrier bar 10 to be raised and lowered in a continuous controlled manner.

The front ends of the stub arms 15 and 16 remain open, but they can be temporarily closed to stop material entering the stub arms by means of close fitting blanking plugs 25, as shown in Fig. 4. The plugs are temporarily secured by L-pins 26 which pass through aligned apertures 27 and 28 in the respective stub arm and plug, retained if necessary by a spring R-clip 29. When the plugs 25 are removed from the stub arms 15 and 16 they may be temporarily stowed in sockets 30 and 31 fixed to the rear of the carrier bar 10 (Fig. 2), again retained by the L-pins 26 and R- clips 29 if desired. Continuing to view Fig.s 2 and 3, a nudge blade 35 can be mounted on the carrier bar 10, to extend across the width of the truck between the outer faces of the front wheels 2. In vertical cross section, viewed from the front of the vehicle, the nudge blade is preferably of generally concave shape. The nudge blade is mounted by a pair of rearwardly-projecting posts 36 and 37 (shown separately in Fig. 3 for illustration purposes only) which can be slid into the open ends of the stub arms 15 and 16 and secured by D-pins 38 and 39 inserted through the arms and posts.

Fig. 5 shows the nudge blade 35 in its raised position, the cylinder 19 having been operated to raise the carrier bar 10 and blade 35 clear of the ground. It will be noted that the blade 35 does not impede the tipping of the bucket 6, as indicated in dashed outline. The dump truck can thus be used as normal even when the nudge blade it fitted. However, during a tipping operation the driver can operate the control lever 8 to lower the nudge blade as shown in Fig. 6, so that the blade is now positioned close to the ground extending up to the bottom edge of the bucket 6, when tipped, in a substantially vertical plane. In this position, forward movement of the truck allows the blade 35 to level the tipped material, before of after the tipping of the material, substantially reducing the formation of ruts beneath the wheels 2 and generally allowing a more even distribution of material to be achieved.

The material tipped from the bucket 6 is kept completely level throughout its width by the action of the nudge blade levelling the dumped material as the truck moves towards it. In addition, the outside areas of the strip of tipped material is compacted by the wheels of the dump truck. Consequently, the tipped material is completely level and compacted when tipping is complete. The precise operating height of the nudge blade 35 can be set by the lever 8, according to the nature of the work being undertaken.

Whilst the above description places emphasis on the areas which are believed to be new and addresses specific problems which have been identified, it is intended that the features disclosed herein may be used in any combination which is capable of providing a new and useful advance in the art.