US2799411A - Dual loaders - Google Patents

Description

July 16, 1957 D. w. J. HARROWELL ETAL 2,799,

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mum. LOADERS Filed Jan. 3, 1955 4 Sheets-Sheet 4 United States Patent DUAL LOADERS Douglas William James Harrowell, Rickmansworth, and

Albert Frederick John Pink, Ashford, England, assignors to W. E. Bray & Company Limited, Feltham, England, a British company Application January 3, 1955, Serial No. 479,608

(Ilaims priority, application Great Britain April 1, 1954 3 Claims. (Cl. 214-140 This invention relates to bulk loaders, i. e., self-propelled vehicles having a bucket carried at the end of lift arms which pivot about a horizontal axis on the vehicle so that the bucket may be lowered to ground level for loading by driving it, by moving the vehicle itself, into a bulk supply of material, and subsequently may be raised to a convenient height for discharging.

In present day loaders the lift arms are usually raised and lowered by a main hydraulic ram or rams and the bucket tilted and discharged by secondary hydraulic rams.

In certain circumstances of loading and discharging, it is desirable for the bucket to be capable of discharge at either end of the vehicle and the object of this invention is to provide an arrangement of and actuating mechanism for the lift arms which will permit of discharge of the bucket both at the front and rear of the loader.

In order to be able to load and unload at the same end of a loader it is necessary that the bucket should be clear of that end of the vehicle both at ground level where it is loaded and at discharge level where it is to be positioned over say the sides of a lorry or dumper. It is usual therefore in order to avoid unnecessarily long lift arms in such loaders, to pivot the lift arms on the vehicle at a point roughly midway in height between ground level and the normal discharge level.

Where the bucket is also to be discharged at the other end of the vehicle it is again necessary that it should be capable of being swung on the lift arms into a position where it is clear of that end of the vehicle, and to reach this position from the loading position, the lift arms must be swung through an angle of between approximately 150 and 180 The present invention therefore provides a bulk loader in which the lift arms are capable of being swung from a loading position at one end of the vehicle through a discharge position at the same end of the vehicle to a discharge position at the opposite end of the vehicle, the lift arms being operated through a member pivoted on the vehicle the effect of which is to multiply the angular movement of the lift arms under the control of the main ram or rams.

Preferably the lift arms are pivoted at a fixed point on the vehicle and are each actuated by a power operated lever also pivoted at a fixed point on the vehicle and linked to the arm, the distance between the point of linkage and the pivot on the lever being greater than the corresponding distance on the lift arm, the linkage providing the necessary degree of lost motion between the lever and lift arm.

The linkage may comprise a member pivoted at one end on the lever and at the other end on the lift arm so that in combination with the lever it forms a toggle joint be tween the chassis of the vehicle and the lift arm to the centre of which joint the force exerted by the main ram may be applied.

In one construction in accordance with the invention 2,799,411 Patented July 16, 1957 1 ram is preferably provided and conveniently the depending arm is of arcuate shape to permit movement of the toggle linkage to a position where it lies above the pivot of the lift arm and in which position the pivotal centres of the jack with the arcuate lever of the toggle link and of the link arm with the lift arm are substantially in alignment but have not reached dead central position so that on the return stroke of the ram, the lift arm can be swung back to its forward operating position.

In the first discharge position at the loading end of the vehicle the contents of the bucket are discharged by operation of the secondary rams and in the second position the bucket is self-discharging. Single acting rams may be used to raise the lift in conjunction with a suitable mechanical means to return the lift arm over centre on the return stroke.

The invention is illustrated in the accompanying drawings in which:

Figure 1 is an elevation showing a tractor fitted with a bucket and lifting mechanism in accordance with a preferred embodiment of the invention.

Figure 2 is an elevation of an enlarged scale showing an alternative form of linkage and of the mounting for the jack.

Figures 3, 4 and 5 are views in elevation of alternative forms of linkage and mountings for the jack for use on a bulk loader in accordance with the invention.

Referring more particularly to Figure 1 of the accompanying drawings there is shown a tractor having a. chassis C fitted with an internal combustion engine or other prime mover driving ground wheels W. It will be understood that while we have shown a wheeled tractor the invention is equally applicable to a tractor having endless tracks.

Mounted on thechassis C usually at a point intermediate the front and rear ground wheels is a main boom indicated generally at M, pivotally fixed to the forward ends of which is a bucket B. The main boom M, which usually includes two lift arms, there being one lift arm at each side of the chassis, is raised and lowered by means of hydraulically operated jacks J hereinafter termed the main jacks. Movement of the bucket B is independently controlled by means of a secondary ram or jack A, of which preferably there are two for operation in conjunction with the main jacks.

In the embodiment shown in Figure l the main boom M is mounted to fulcrum about a point P on a superstructure 3 only one of the lift arms, namely that on the near side of the vehicle being shown. The bucket B is provided with lower spaced lugs 4, the spacing of which corresponds to that of the lift arms and by means of which it is mounted to pivot about pins 5 carried at the forward ends of the lift arms. The secondary jacks A which are anchored to brackets 8 on the lift arms each include a ram 6 pivotally connected at 7 to the bucket. In Figure 1 the forward discharge position for the bucket B and lift arms when the latter have been raised after loading the bucket is shown in dotted lines. For discharging the bucket at the rear, the pivotal movement of the lift arms is continued to the position shown in dot and dash lines.

As previously stated the lift arms are actuated when being raised and lowered by means of the main hydraulic rams J: the cylinder of each ram is pivotally fixed to the chassis at a point X, conveniently to the rear of the wheel axis, the ram being connected at a point Y to one end of an arcuate load lever which functions as a multiplying lever. Arcuate lever 10 at its opposite end has a fulcrum point S on the superstructure 3. A link 11 connects the load lever 10 to the lift arm, one end being pivoted on the lift arm at point Q and the other end being pivoted on the load lever at point R. It will be seen from the drawing that the distance between the pivotal centres SR of the load lever 10 is greater than the distance between the centres PQ of the lift arm and consequently movement of the load lever 10 through an angle of about 80 results in movement of the lift arm through an angle of approximately 160'.

By making use of a load lever 10 which is curved it is possible for the line PR to pass beyond the fulcrum P of each lift arm without the lever itself actually doing It will be seen that the pivotal point Y in the fully extended position of the ram 9 reaches a point Y and that the line of the jack XY which, when extended, assumes the position XY' does not pass beyond the centre P about which the boom pivots. This is essential to the operation of the linkage since if the line XY is allowed to pass over the centre P, when it is desired to recover the boom by withdrawing the ram, the pull exerted on the boom would be in the wrong direction and recovery would be impossible.

By suitable arrangement of the centres PQRS, it is possible to arrange for the main jack to exert an effective moment (leverage) of force about the pivotal point P of the boom sufiicient always to control the boom and the load in the bucket over an angle of approximately 180'.

In the arrangement shown, the wide angle of movement of the lift arms from the front loading position to the rear discharge position is achieved by arranging the pivotal points on the chassis so that the distance SR is greater than the distance PQ. The lever 10 and link 11 function as a form of toggle joint operated by the hydraulic ram 1.

In the loading position the bucket may be tilted upwardly as shown to the position in dotted line in order to crowd it full, the tilting operation being carried out by means of the secondary or crowding ram or rams 6. In the forward discharge position, the bucket may be tilted downwards from the upper position shown to the lower position so as to discharge the contents, this operation again being carried out by means of the secondary ram or rams 6. In the rear discharge position, the angle of the bucket is such that automatic discharge is achieved, the bucket being shaped so as to provide a chute for directing the contents clear of the vehicle on arrival of the lift arms in their rear angled position.

In the modified arrangement shown in Figure 2, the link between the lift arm and the arcuate lever arm 10 is replaced by a lost motion slot 12 in a plate 12 forming part of or attached to the underside of the lift arm, the lever having a fulcrum pin 13 which corresponds to the fulcrum point R for engagement in the slot. This arrangement is mechanically equivalent to that shown in Figure 1 except that the lost motion line in Figure 1 represented by the path of point R with respect to point Q, is not straight as in Figure 2, but is arcuate and of a radius equivalent to'the length of the link member.

The arrangement shown in Figure 3 is a modified form of the linkage shown in Figures 1 and 2 but with the difference that the lever arm by which motion is transmittedfrom the main jack I to the boom consists 'of a two armed lever mounted to pivot about a fulcrum as on the chassis, one arm 29 being connected at 30 to the ram of the main jack and its other 31 through a link 33 to the main boom. It will be seen that the arm 31 and link 32 likewise operate in the manner of a toggle. It should be understood that, if desired, the position of the main jack may be reversed as shown in dotted lines at J.

Referring now to Figure 4 there is shown a linkage arrangement similar to that of Figure 3 but the pivotal connection of the main jack and the lever arm indicated at 31 and the fulcrum of the latter is reversed. As shown in Figure 4 the lever arm 35 has a fulcrum S on the main chassis while the ram of the main jack is pivotally connected at 36 to the lever arm but otherwise the operation remains substantially the same as that described in Figure 3. ln this arrangement, shown in Figure 4, the operation of the main jack causes the upper end of the lever 31' to swing to the rear across the pivot point P and so raise the main boom from the loading position to either of the two discharge positions, the rear discharge position of the main boom being shown in dotted lines.

Figure 5 shows a further modification of the invention inwhich instead of anchorage for the main boom being a point fixed on the chassis, it is provided by a stop link 40, the link 40 itself having a fixed fulcrum 41 and providing a fulcrum 42 at its other end for the main boom which, for convenience, is provided with a rearward extension 43, to which the ram of the main jack is pivoted at 44. 45 indicates a stop bracket on the chassis of the vehicle so as to limit the angular movement of the lever arm 40. During the initial withdrawal of the ram to raise the main boom the latter swings about the fulcrum 41 and moves in unison with the load lever 40 until such time as the lever 40 is arrested by encountering the stop plate 45. It will be seen that during the initial movement of the ram, i. e. when the latter is withdrawn to raise the main boom, that this will result in a movement of the lever arm 40 about its fulcrum 41 (the boom moving with it) until it is arrested by engagement with the stop bracket 45. During this time the parts will have moved to the position shown in broken lines. When the main boom is in this position indicated by the reference M it corresponds to the forward discharge position for the bucket. Continued movement of the ram will result in the main boom swinging about the fulcrum 42 whose position is now indicated by the reference 42' i. e. the effective, pivot for the main boom has been transferred from 42 to 42', the effect of which is to multiply the angular movement of the lift arm.

We claim:

1. In a bulk loader vehicle capable of discharging material at either the front or the rear of the vehicle, a lift arm pivoted on each side of said vehicle for swinging movement about a horizontal axis; a bucket pivotally mounted on the ends of the lift arm remote from said axis; hydraulic means for controlling pivotal movements of said bucket with respect to said lift arms; a power lever pivoted on each side of the vehicle at a point spaced from the pivotal connection of the adjacent lift arm; a linkage on each side of said vehicle connecting the adjacent power lever. and lift arm, the distance between the pivotal connection of each of said power levers to the vehicle and the pivotal connection to the associated linkages being greater than the distance between the pivotal connection of each of said lift arms to the vehicle and the pivotal connection of the linkages to the associated lift arms, so that angular movement of the levers produces greater angular movement of the lift arms; and operating means for imparting angular movement to the power levers to move said lift arms and said bucket from the loading position to either discharge position and return.

2. A construction as set forth in claim 1 in which in one of said discharge positions a line joining the pivotal connections of said power levers to said vehicle and the pivotal connections of said power levers to their associated linkages is at one side of the point of pivotal connection of said lift arms to said vehicle, and in which in the other discharge position said line is at the other side of said point.

3. A bulk loader as claimed in claim 2 in which each 2,498,144 of the power levers is shaped so that the lever itself does 2,529,338 not cross over said point. 2,533,000 2,571,113 References Cited in the file of this patent 5 UNITED STATES PATENTS 458,913 2 I 2,105,329 Orlowsky Jan. 11, 1938 320:727

2,427,968 Hoover Sept. 23, 1947 Thomas Feb. 21, 1950 Hoover Nov. 7, 1950 Hoar et al. v Jan. 16, 1951 Crosby Oct. 16, 1951 FOREIGN PATENTS Canada Aug. 16, 1949 Germany Nov. 12, 1951

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