This invention relates to a dump truck and in the preferred embodiment provides a dump truck with a self-loading ability - i.e. an ability to load material on to the truck using only the power of the truck to 5 effect loading.

According to one aspect of the present invention there is provided a dump truck comprising: a chassis, a sub-frame mounted on the chassis for pivotal movement relative to the chassis about a first

10 generally horizontal axis, the sub-frame having a front end and a rear end with the first generally horizontal axis located intermediate the front and rear ends; a bucket mounted on the sub-frame for pivotal movement relative to the sub-frame about a second

15 generally horizontal axis, the second enerally horizontal axis being located nearer the front end of the sub- frame than the first generally horizontal axis; a latch having an engaged position in which the bucket is latched to the sub-frame for movement therewith and a

20 dis-engaged position in which the bucket can pivot i f. relative to the sub-frame about the second horizontal ^r _r axis; and power operated means for pivoting the sub- frame relative to the chassis.

The preferred embodiment of the invention 25 provides a simple low cost dump truck which can be loaded

and unloaded using only the power of the dump truck. Because of the simple mechanical nature of the invention it lends itself particularly to a relatively small light-weight dump truck which nonetheless has the advantages of powered loading and unloading as outlined above.

The invention will be better understood from the following description of a preferred embodiment thereof, given by way of example only, reference being had to the accompanying drawings wherein:

Figure 1 is a schematic side elevation of a preferred embodiment of the invention;

Figure 2 is a schematic plan of the embodiment of Figure 1 ; and Figures 3 and 4 show schematically loading and emptying of the embodiment of Figures 1 and 2. Referring firstly to Figures 1 and 2 the preferred embodiment of the invention comprises a chassis 1 on which is mounted a sub-frame 2 for pivotal movement about a horizontal axis located intermediate the front end 3 and the rear end 4 of the sub-frame. A bucket 5 is mounted on the sub-frame for pivotal movement relative to the sub-frame about an axis 6 located at the front end 3 of the sub-frame. In its normal position the bucket 5 is upwardly open, i.e. the opening 7 of the bucket faces upwardly. Normally, the bucket 5 is latched to the sub-frame 2 by a latch S which normally adopts an engaged position in which the bucket 5 is locked to the sub-frame 2 for movement therewith. A double-acting hydraulic ram 9 extends between the sub-frame 2 and the chassis 1 for pivoting the sub- frame relative to the chassis between one extreme pivotal position (illustrated in Figure 3) and another extreme pivotal position (illustrated in Figure 1). The chassis is mounted on a pair of front wheels

10,11 which rotate about a common axis 12 located adjacent the first horizontal pivotal axis of the sub- frame 2, and a pair or rear wheels 15.16 which are castor mounted on the chassis 1. The front wheels 10,11 are independently drivable in either direction by a pair of hydraulic motors 13,14- Thus, by driving both motors 13)14 at the same speed and in the same direction the truck may be driven forward or backwards in- a straight line (according to the direction of rotation) and by driving the motors 13,14 a different speeds and/ or in different directions the truck may be steered. It will be noted that if the motors 13.14 are driven in opposite directions a very tight turning circle is obtained. Hydraulic power for the motors, 13,14 and the ram 9 is derived from a prime mover 17 of any suitable type - e.g. an internal combustion engine driven hydraulic pump. In the preferred embodiment, the prime mover 17 includes a mechanical and/or hydraulic power take-off to enable tools to be driven by the prime mover. A drivers seat IS is mounted on the chassis 1 enabling a driver to control the hydraulic functions of the truck via a bank of control valves 19 and to operate the latch 8 with his foot. Preferably, the truck includes means 20 to enable a tow-bar 21 to be connected to the chassis 1 and means 22 to enable road wheels 23 incorporating suspension units 24 to be mounted on the chassis 1. The arrange¬ ment ^" is such that with the road wheels 23 and tow-bar 21 mounted, and the tow-bar connected to a conventional tow hitch, the normal dump truck wheels 10,11,15,16 are clear of the ground, and the dump truck is supported on road wheels 23, thereby enabling the dump truck to be towed behind, e.g. a motor car as a two-wheeled trailer. In use, after delivery to a work site the tow-

bar 21 and road wheels 23 are removed and the truck is ready for use. In order to load materials into the truck the ram 9 is extended to bring the sub-frame 2 and bucket 5 into the configuration illustrated in Figure 3• In this configuration the lower face 25 of the bucket is substantially parallel to and adjacent the ground 26 upon which the truck is standing, and the truck may be driven into a heap of materials standing on-the ground to cause part of the heap to enter the bucket 5- The ram 9 may then be retracted to cause the portion of the load within the bucket to fall into the bottom of the bucket. If necessary, this operation may be repeated several times in order substantially to fill the bucket. When sufficient material is contained in the bucket the ram 9 is fully retracted to bring the sub-frame 2 and a bucket 5 into the position illustrated in Figure 1- whereby the dump truck may be driven to a dumping site. The ram 9 is then extended again to return the bucket to the position illustrated in Figure 3 _> and the latch 8 is tripped by the foot of the operator.

The ram 9 is again retracted, returning the sub-frame to the position illustrated in Figure 1 , but causing the bucket to pivot about the axis 6 to empty the load. When the ram has been fully retracted the sub-frame 2 and bucket 5 are in the configuration illustrated in Figure 4- In this con iguration, the entire contents of the bucket will be emptied. It will be noted in particular that in this configuration the lowest point 27 of the bucket is clear of the ground. The truck may then be reversed slightly from the dumping site, and the ram 9 extended to return the sub-frame and bucket to the configuration illustrated in Figure 3« This will cause the latch 8 automatically to assume its engaged position, whereupon retraction of the ram will return the bucket to the position illustrated in Figure 1, or to

some intermediate position if desired.

It will accordingly be noted that .the loading and unloading of the bucket may be effected using only the power provided by the prime mover 17, and in particular that the entire operation of the bucket is controlled by the single ram 9 and the latch 8. Because of the very simple nature of the controls involved, and the relatively few and inexpensive hydraulic components involved, the invention lends itself particularly to the construction of small light¬ weight dumpers - e.g. having a bucket capacity of approximately .23 m ³ and a pay-load of 200 Kg.