GB2276852A

GB2276852A - Forklift truck with a driving wheel and lateral supporting wheels

Info

Publication number: GB2276852A
Application number: GB9405588A
Authority: GB
Inventors: Frank Soulas
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 1993-03-24
Filing date: 1994-03-22
Publication date: 1994-10-12
Anticipated expiration: 2014-03-22
Also published as: DE4309561C2; FR2703003A1; DE4309561A1; FR2703003B1; CA2012552A1; GB9405588D0; GB2276852B

Description

2276852 1 FORKLIFT TRUCK WITH A DRIVING WHEEL AND LATERAL SUPPORTING

WHEELS The invention concerns a forklift truck with a driving wheel and vertically adjustable supporting wheels distanced laterally from it. Such forklift trucks are used for example as low-lift trucxs or order picking trucks with the operator walking, sitting and standing. Often these trucks are tiller-guided. The stability of the forklift truck is improved by supporting wheels in the form of castor wheels distanced laterally from the driving wheel and which are usually suspended on springs or with a clearance in relation to the road surface so that the driving wheel has sufficient traction to propel and brake the vehicle even when the road surface is uneven. The supporting wheels only have a stability-increasing effect when the forklift truck tilts sideways more severely due to the distribution of the load as In this operating situation the spring preload is increased or the supporting wheel rests on a stop or there is no longer any clearance between the supporting wheel and,the road surface.

If the road surface is very uneven, supporting wheels can be provided without any clearance in relation to the road surface or with a greater spring preload. This improves the stability of the forklift truck. particularly when transporting loads with a high centre of gravity. It is easy to see that supporting wheels with a fixed vertical position have unsatisfactory properties in changing operating conditions. i.e. with varying road surfaces and Varying loads. Therefore, It has already been proposed that the supporting wheels be vertically adjustable in order to be able to adapt the forklift truck easily to varying conditions of use.

The underlying object of the present invention is to Provide a forklift truck of the kind dsecribed above. the supporting wheels of which are vertically adjustable simply and with minimal effort.

According to the invention this object is achieved in that the supporting wheels are each fixed In a mounting device pivotable about a horizontal axis, the axis of rotation of the supporting wheel 1 ".I 2 being in each case distanced from the horizontal axis and the mounting device being lockable in a plurality of rotational positions. Accordingly. the essential idea of the invention is to fix the supporting wheel eccentrically so that vertical adjustability Is obtained with the simplest means.

According to a second aspect of the invention, there is provided a castoring wheel unit for an industrial truck wherein a wheel axle is fixedly mounted between a pair of discs eccentric to the wheel axle, the discs being received in a castoring mounting for rotation relative to the mounting about the central axis of the discs, locking means being selectively operable to secure the discs against rotation relative to the mounting.

Particularly with a view to minimising production costs, it is expedient if the mounting device consists of two eccentric discs disposed on either side of the supporting wheel, each eccentric disc exhibiting a cylindrical collar which is pivotable in a bearing bore of a bracket, and the eccentric discs being in rotationally fixed connection with one another through the supporting wheel. The supporting wheel is adjusted vertically by turning the eccentric discs. Here, it is sufficient to turn one of the two eccentric discs with a suitable tool or possibly by hand, while the other eccentric disc is automatically entrained due to the rotationally fixed connection of the two eccentric discs.

The locking of the two discs against unintentional turning can be achieved in various ways. In one particularly advantageous variant the eccentric disc is lockable against turning in the bearing bore in a force- locking manner. For this, it is expedient if the eccentric.discs can be braced against one another.

This is advantageously achieved in that the supporting wheel exhibits an axle pin which is disposed with each of its ends in an eccentric bore of the eccentric disc and is embodied as a clamping element. This simultaneously allows the rotationally fixed connection of the two eccentric discs.

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b 1 3 Apart from this, at least one of the eccentric discs can be provided with a plurality of recesses which can be brought into operative connection with at least one locking device disposed in the bracket. In this case locking is achieved in a form-locking manner. The two possibilities can also be combined. Here, firstly, a precisely defined vertical setting can be achieved through the locking in the form-locking manner and then the locking can be strengthened and secured by subsequently bracing the two eccentric discs against one another.

According to one advantageous variant of the invention it is proposed that the mounting device is fixed to a first lever arm of a cranked lever, whose second lever arm is braced against an elastic component. Then. the vertical adjustment of the supporting wheel determines the pre-load with which this is pressed against the road surface.

Further advantages and features of the invention are explained in greater detail with reference to an exemplary embodiment shown diagrammatically in the accompanying Figures. in which:

Figure la shows a view of the front side of a forklift truck.

Figure 1b shows a side view of the forklift truck.

Figure lc shows a plan view of the forklift truck.

Figure 2a shows a side view of a supporting wheel of the forklift truck.

Figure 2b shows a view of the supporting wheel i'the direction of arrow IIb in figure 2a.

The forklift truck embodied as a tiller-guided electric lift truck shown in Figures la to lc has a driving part 1 with a tiller 2. a driving wheel 3 and two vertically adjustable supporting wheels 4 and 5 distanced laterally from the driving wheel 3. Hinged to the driving part 1 Is a liftable load part 6 with two load arms 8 and 9 provided with load rollers 7 and on which a battery box 11 is disposed. While the Invention is described with reference to a forklift truck, it will be understood that the invention is 1 4 applicable to other types of industrial vehicles and trucks, and the specification should be construed accordingly.

Figure 2a, in combination with Figure 2b, shows an arrangement of a supporting wheel 4 or 5, in which arrangement the vertical adjustability of the supporting wheel can be seen. The supporting wheel 4 or 5 is mounted at the free end of a pivotable lever arm 12. which in turn is mounted for swinging movement about a horizontal axis S in a castoring carrier 14 pivotable about a vertical axis V. The lever arm 12 has an upper extension 13i which engages with resilient elements 15 positioned between the upper extension 13 and the carrier 14 to resist upward swinging movement of the supporting wheel 4 or 5. The resilient elements 15 thus act as a suspension for the supporting wheel 4 or 5. Resilient components 15 may be, for example. rubber or plastic pads clamped between the upper extension 13 of the lever arm 12 and an abutment formed on a wall of the carrier 14, so that the supporting wheel 4 or 5 is sprung or can be pressed against the road surface under pre-load.

The lever arm is formed in two halves, with each of the two halves of the lever arm 12 forming a bracket 12a or 12b which has a circular bearing bore in which a cylindrical collar of a respective eccentric disc 16 or 17 is disposed. The eccentric disc 16 or 17 is rotatable about the axis of the bore of the bracket 12a or 12b to one of a number of rotary positions relative to the lever arm 12. The eccentric discs are lockable against turning in a force-locking manner. The collar formed on each eccentric disc 16 or 17 4 is preferably slightly tapered.

Each eccentric disc is itself formed with an axle bore to accept an axle pin 19 of the supporting wheel 4 or 5, the axle bore in the disc being eccentrically offset from the centre of the disc by a predetermined distance.

The supporting wheel 4 or 5 is mounted by means of a hub 18 on the axle pin 19. The two eccentric discs 16 and 17 are secured by bolts 20 and 21 to the ends of the axle pin 19, which Is received In the axle bores of the eccentric discs 16 or 17. The axle bores of the t 1 1 eccentric discs 16 or 17 are thus distanced from the horizontal axis H of the bearing bores of the lever arm halves 12a and 12b, so that rotation of the eccentric discs 16 and 17 relative to the lever arm halves 12a and 12b will cause the axis of the supporting wheel 4 or 5 to move round a circular path relative to the lever arm halves 12a and 12b. When the eccentric discs 16 and 17 are secured against turning about the horizontal axis H, the supporting wheel 4 or 5 is fixed and the axle pin 19 is locked against turning.

The co-axial bearing bores form a horizontal axis H about which the eccentric discs 16, 17 are pivotable. The axis of rotation R of the supporting wheel 4 or 5 is distanced from this horizontal axis H. Therefore, the distance of the supporting wheel 4 or 5 from the road surface F and the pre-load with which the supporting wheel is pressed against the road surface can be set by turning the eccentric discs 16 or 17. To set the supporting wheel 4 or 5 vertically, the screw 20 or 21 is slackened and one of the two eccentric discs 16 or 17 is turned by a certain amount. and the other eccentric disc is automatically turned with it due to the connection with the second eccentric disc through the axle pin 19 and the screws 20 and 21.

This rotation of the eccentric discs 16 and 17 relative to the lever arm halves 12a and 12b can be stepless, allowing infinite adjustment of the position of the axis of the supporting wheel 4 or 5 relative to the lever arm halves 12a and 12b, or may preferably be in steps. With vertical adjustability in steps, the result isa precisely definable clearance or a precisely definable pre-load between the supporting wheel and the road surface. To make this possible, at least one of the eccentric discs 16 or 17 is provided with recesses 22 in which a locking device 23 engages which can be fixed in the bracket 12a. After the eccentric disc is turned by the desired amount corresponding to a certain vertical setting, the locking device - in this example a pin 23 engaging in one of a number of cutouts 22 spaced round the periphery of the eccentric disc 16 is fitted and thus further turning of the eccentric disc 16 is 1 qTI 6 prevented. Then the two eccentric discs 16 and 17 are braced against one another. Provided the locking device 23 is made sturdy enough, this can also be provided as the sole locking device. or alternatively a locking device may be provided for each of the two eccentric discs 16 and 17.

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Claims

1. A forklift truck having a driving wheel and vertically adjustable supporting wheels disposed laterally in relation thereto, wherein the supporting wheels (4, 5) are each fixed in a mounting device pivotable about a horizontal axis (H), the axis of rotation (R) of the supporting wheel (4; 5) being in each case distanced from the horizontal axis (H) and the mounting device being selectively lockable in one of a plurality of rotational positions.

2. A forklift truck according to claim 1, wherein the mounting device consists of two eccentric discs (16, 17) disposed one on either side of the supporting wheel (4; 5), each eccentric disc (16; 17) having a cylindrical collar which is pivotable in a bearing bore of a bracket (12a; 12b), and the eccentric discs (16, 17) being in rotationally fixed connection with one another through the supporting wheel (4; 5).

3. A forklift truck according to claim 2, wherein the eccentric disc (16; 17) is lockable against turning in the bearing bore in a force-locking manner.

4. A forklift truck according to claim 3, wherein the eccentric discs (16, 17) can be braced against one another.

5. A forklift truck according to claim 4, wherein the supporting wheel (4; 5) has an axle pin (19) which is disposed with each of its ends in an axle bore of a respective eccentric disc (16; 17) the axle pin (19) acting as a clamping element.

6. A forklift truck according to one of claims 2 to 5, wherein at least one of the eccentric discs (16; 17) is provided with a plurality of recesses (22) which can be brought into operative connection with at least one locking device (23) disposed in the bracket (12a; 12b).

7. A forklift truck according to one of the preceding clairis, wherein the mounting device is fixed to a first lever arm (12) of a cranked lever, the second lever arm (13) of which is braced against an elastic component (15).

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8. A forklift truck according to any preceding claim, substantially as described herein.

9. A castoring wheel unit for an industrial truck wherein a wheel axle is fixedly mounted between a pair of discs eccentric to the wheel axle, the discs being received in a castoring mounting for rotation relative to the mounting about the central axis of the discs, locking means being selectively operable to secure the discs against rotation relative to the mounting.

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