IES75661B2 - A forklift truck - Google Patents

Description

A forklift truck This invention relates to a forklift truck, and in particular to a forklift truck for mounting piggy-back on a lorry, trailer or the like vehicle.

According to the invention, there is provided a forklift truck comprising:a chassis, the chassis being of C-shaped construction having a rear portion with a pair of spaced-apart arms extending forwardly of the rear portion, the chassis mounted on three or more wheels, with a front wheel mounted at an outer end of each arm of the chassis, steering means for turning at least one of the wheels f on command, drive means for driving one or more of the wheels, a telescopic boom having an inner end and an outer end, the inner end of the boom being pivotally mounted at an elevated position within the chassis and it is so shaped at this pivot position as to lie within the chassis in the retracted position with its boom inclined downwards, means for pivoting the boom on the chassis for raising and lowering the outer end of the boom, the boom comprising at least three complementary boom parts, namely, an inner boom part, a middle boom part and an outer boom part, the boom parts being slidably interengagable, operating means for moving the boom parts relative to each other comprising a pair of hydraulically operated rams, namely an inner ram mounted on the exterior of the inner boom part and connected to the middle boom part and an outer ram mounted on the exterior of the middle boom part and connected to the outer boom part, a fork carrier pivotally mounted at a free end of the outer boom part, the boom being operable to move the fork carrier between a retracted position behind the front wheels on an extended position in front of the wheels, levelling means operable in response to orientation of the boom on the chassis for maintaining the fork carrier in a substantially upright position at the free end of the outer boom part during pivoting of the boom.

Ideally with this construction of three complementary boom parts the middle section nests within the inner section to a position such that when fully retracted it lies adjacent the end of the inner boom section and the outer section nests within the middle boom section such that it lies adjacent the end of the middle boom section.

In one embodiment of the invention, means is provided for moving the fork carrier laterally relative to the chassis.

In a preferred embodiment, the fork carrier is slidably mounted at a free end of the outer boom part.

In a particularly preferred embodiment, a sliding pin is pivotally mounted on the fork carrier, the sliding pin slidably engaging within a support bushing mounted at a free end of the outer boom part, a side shift ram extending between the free end of the boom and the sliding pin, the side shift ram being operable to move the sliding pin through the bushing.

In another embodiment, a load support means is provided at an outer end of the boom, the load support means engagable with a load carrying platform traversed by the fork carrier in use.

In a further embodiment, the load support means is movable between a retracted stored position and an extended in-use position.

In a preferred embodiment, the load support means is a foot which is slidably engagable with the load carrying platform.

In a particularly preferred embodiment, the foot is slidably mounted in a complementary sleeve, ram means being provided for moving the foot through the sleeve between the retracted position and the extended position.

Conveniently, a detachable rubbing strip is mounted at a lower end of the foot.

In a preferred embodiment, the load support means is mounted on the fork carrier.

In another embodiment, an hydraulic fluid supply means is provided on the chassis for operation of the rams, the hydraulic fluid supply means being connected to rams at the outer end of the boom by flexible hydraulic fluid delivery pipes, said pipes passing through a tubular sleeve fixed to the outer boom part and extending rearwardly therefrom alongside the boom, the sleeve slidably engaging a support collar mounted on the middle boom part, the pipes passing around a guide on the chassis for folding the pipes into a tray mounted on the inner boom part when the boom is in a collapsed position.

The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which:Fig. 1 is a particular view of a forklift truck according to the invention; Fig. 2 is a side elevational view of a forklift truck; Fig. 3 is a rear elevational view of the forklift truck; Fig. 4 is a side elevational view of the forklift truck; Fig. 5 is a plan view of the forklift truck; Fig. 6 is a detail side elevational view showing an outer end of the boom; Fig. 7 is a view similar to Fig. 6 showing a fork carrier at an outer end of the boom in another position of use; Fig. 8 is a view similar to Fig. 6 showing the fork carrier in a further position of use; Fig. 9 is a detail perspective view showing a fork carrier mounted at the end of the boom; Fig. 10 is a plan view of the fork carrier mounted at the end of the boom; Fig. 11 is a view similar to Fig. 10 showing the fork carrier in one position of use; Fig. 12 is a view similar to Fig. 10 showing the fork carrier in another position of use; Fig. 13 is a front perspective view of the fork carrier; Fig. 14 is a front elevational view of the fork carrier; Fig. 15 is a detail side elevational view showing an outer end of the boom and fork carrier, in use; Fig. 16 is a plan view of a boom of the forklift truck; Fig. 17 is a detail side elevational view of a hydraulic pipe mounting arrangement at an inner end of the boom; Fig. 18 is a view similar to Fig. 17 showing the hydraulic pipes in another position of use; and Fig. 19 is a detail elevational view of portion of the boom.

Referring to the drawings, there is illustrated a forklift truck according to the invention, indicated generally by the reference numeral 1. The forklift truck 1 has a chassis 2 of C-shaped construction having a rear portion 2a with a pair of spaced-apart forwardly extending arms 2b. The chassis 2 is mounted on three wheels comprising a pair of spaced-apart front wheels 3 mounted at outer ends of the arms 2b and a centrally located rear wheel 4 mounted on the rear portion 2a, the wheel being steerable for turning the forklift truck 1. An engine 5 is mounted on the rear of the chassis 2 for driving an hydraulic pump to provide a pressurised hydraulic oil supply for driving the wheels 3, 4 through drive hydraulic motors located in each wheel hub and for powering various rams as will be described later. A telescopic boom 10 is pivotally mounted on the chassis 2. A fork carrier 11 is pivotally mounted at a free end of the boom 10 and supports lifting forks 12 at the outer end of the boom 10. The boom 10 is operable to move the fork carrier 11 between a retracted position between the arms 2b and behind the front wheels 3 (Figs. 4 and 5) and an extended position in front of the wheels 3 (Fig. 2).

Adjacent an inner end 14 the boom 10 is connected to a pivot pin 15 which is mounted between a pair of spacedapart A-frames 16 on the chassis 2. Boom lifting rams 17 extend between the chassis 2 and the boom 10 for raising and lowering the boom 10 on the chassis 2. As can be seen in Fig. 2, the boom 10 can be moved between a lowered position indicated at A in which the boom 10 is inclined downwardly with an outer end of the boom 10 below the pivot pin 15, through an intermediate position, indicated at B, and a raised position indicated at C in which the boom 10 is inclined upwardly supporting an outer end of the boom 10 above the pivot pin 15.

In this case, the boom comprises three complementary boom parts, namely, an inner boom part 20, a middle boom part and an outer boom part 22. Each boom part 20, 21, 22 is of rectangular section. The boom parts 20, 21, 22 are slidably interengagable, the outer boom part 22 being slidable within the middle boom part 21 which in turn is slidable within the inner boom part 20. An inner ram 24 extends between the inner boom part 20 and the outer boom part 21 and is operable for extension and retraction of the middle boom part 21 on the inner boom part 20. In similar fashion, an outer ram 25 is mounted between the middle boom part 21 and the outer boom part 22 for extension and retraction of the outer boom part 22 on the middle boom part 21.

Levelling means is operable in response to orientation of the boom 10 on the chassis 2 for maintaining the fork carrier 11 in a substantially upright position on the boom to keep the forks 12 in a horizontal load carrying position. The levelling means comprises a master ram 30 mounted between the chassis 2 and the inner boom part 20 and a complementary slave ram 31 mounted between the outer boom part 22 and the fork carrier 11. Figs. 6 to 8 show the sequence of movement of the fork carrier 11 relative to the boom 10 as the boom 10 is moved between the raised position (Fig. 6) and the lowered position (Fig. 8). As the boom 10 is lowered, a piston 33 extends into an associated cylinder 34 of the master ram 30 pumping hydraulic oil to the slave ram 31 thus extending a piston 35 of the slave ram 31 outwardly of a cylinder 36 of the slave ram 31. The reversed sequence occurs upon raising the boom 10 on the chassis.

Referring to Figs. 9 to 12, the mounting arrangement for the fork carrier 11 at the outer end of the boom 10 is shown in more detail. The fork carrier 11 has a front face 40 and a rear face 41. A pair of spaced-apart mounting brackets 42 extend outwardly of the rear face 41.

A pin 43 is rotatably mounted between the brackets 42. The pin 43 is slidably mounted within a support bushing 44 mounted at the free end of the outer boom part 22. A side shift ram 46 extends between the free end of the boom 10 and the pin 43, the ram 46 being operable to slide the pin 43 through the bushing 44 as shown in Figs. 11 and 12 for lateral movement of the fork carrier 11 at the outer end of the boom 10.

Referring to Figs. 13 to 15, a load support 50 is mounted at a front face 40 of the fork carrier 11. The load support 50 comprises a foot 51 which is slidably mounted within a complementary sleeve 52. A ram 53 extends between the fork carrier 11 and a lower end 54 of the foot 51 for raising and lowering the foot 51 on the fork carrier 11. A detachable rubbing strip 55 is mounted at a lower end 54 of the foot 51. In use, as shown in broken outline in Figs. 14 and 15, the foot 51 can be lowered by means of the ram 53 for engagement with a load carrying platform 57 such as the bed of a trailer or lorry to support a load carried on the forks 12. As the boom 10 is retracted, the foot 51 slides across the load carrying platform 57. Advantageously in this fashion, stability of the forklift truck 1 is maintained even when the boom is in the fully extended position.

Referring in particular to Fig. 1 and Figs. 16 to 19, the boom construction will be described in more detail. As previously described, a pressurised hydraulic oil supply is provided on the chassis and this is connected to rams at the outer end of the boom 10 by flexible hydraulic oil delivery pipes 60. These oil pipes 60 pass through a tubular sleeve 61 fixed to the outer boom part 22 by means of a sidewardly extending bracket 62. - An inner end of the sleeve 61 slidably engages a support collar 64 mounted on the middle boom part 21 by a hanger 65. Thus, the sleeve is supported generally parallel and alongside the boom 10. As shown in Figs. 17 and 18, the hydraulic oil pipes 60 at their inner end pass around a guide 67 associated with a tray 68 for folding the pipes 60 into the tray 68 when the boom 10 is in a collapsed position as shown in Fig. 17.

Fig. 19 shows the slide mounting of the boom parts. The outer boom part 22 slides within a bore 70 of the middle boom part 21. Arranged around the bore side walls are a number of slider pads 71 for sliding engagement with side walls of the outer boom part 22. These slider pads 71 are replaceable.

Referring to Fig. 1, stabiliser feet 80 are mounted at an outer end of each arm 2b of the chassis 2. The feet 80 can be vertically displaced between a raised stored position and a lowered ground-engaging position by means of rams mounted within a housing 81.

The invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail.

Claims (5)

1. A forklift truck comprising:a chassis, the chassis being of C-shaped construction having a rear portion with a pair of spaced-apart arms extending forwardly of the rear portion, the chassis mounted on three or more wheels, with a front wheel mounted at an outer end of each arm of the chassis, steering means for turning at least one of the wheels on command, drive means for driving one or more of the wheels, a telescopic boom having an inner end and an outer end, the inner end of the boom being pivotally mounted at an elevated position within the chassis and it is so shaped at this pivot position as to lie within the chassis in the retracted position with its boom inclined downwards, means for pivoting the boom on the chassis for raising and lowering the outer end of the boom, the boom comprising at least three complementary boom parts, namely, an inner boom part, a middle boom part and an outer boom part, the boom parts being slidably interengagable, operating means for moving the boom parts relative to each other comprising a pair of hydraulically operated rams, namely an inner ram mounted on the exterior of the inner boom part and connected to the middle boom part and an outer ram mounted on the exterior of the middle boom part and connected to the outer boom part, a fork carrier pivotally mounted at a free end of the outer boom part, the boom being operable to move the fork carrier between a retracted position behind the front wheels on an extended position in front of the wheels, levelling means operable in response to orientation of the boom on the chassis for maintaining the fork carrier in a substantially upright position at the free end of the outer boom part during pivoting of the boom.

2. A forklift truck as claimed in claim 1 wherein means is provided for moving the fork carrier laterally relative to the chassis.

3. A forklift truck as claimed in claim 2 wherein the fork carrier is slidably mounted at a free end of the outer boom part, and preferably a sliding pin is pivotally mounted on the fork carrier, the sliding pin slidably engaging within a support bushing mounted at a free end of the outer boom part, a side shift ram extending between the free end of the boom and the sliding pin, the side shift ram being operable to move the sliding pin through the bushing.

4. A forklift truck as claimed in any preceding claim wherein an hydraulic fluid supply means is provided on the chassis for operation of the rams, the hydraulic fluid supply means being connected to rams at the outer end of the boom by flexible hydraulic fluid delivery pipes, said pipes passing through a 5 tubular sleeve fixed to the outer boom part and extending rearwardly therefrom alongside the boom, the sleeve slidably engaging a support collar mounted on the middle boom part, the pipes passing around a guide on the chassis for folding the pipes into a 10 tray mounted on the inner boom part when the boom is in a collapsed position.

5. A forklift truck substantially as hereinbefore described with reference to the accompanying drawings. CRUICKSHANK & CO.,