EP2508462A1 - Extendible load bearing device - Google Patents

Abstract

The manual telescopic fork (1) is provided with an L-shaped fork arm (2) with a horizontal ground fork arm (10) and a vertical support part (11). The horizontal ground fork arm is provided with a box shaped fork extension (20) moving over the ground fork arm in longitudinal direction. The fork extension has an upper side (21) and two vertical sides (22). The arresting bolt has a tappet and a section. The section lies against the inner side of the fork extension while locking into the hole (25) in the fork extension by spring pressure.

Description

The invention relates to an extendable device for receiving loads. In particular, the invention relates to a manually telescoping fork for forklifts. Furthermore, the invention relates to a method for manually changing a telescopic fork.

Forklift trucks are widely used as universal industrial trucks. They are used to load or unload vehicles such as trucks or railway wagons. Another application is the storage or retrieval of goods in or from shelving systems. The loads are usually on pallets. These pallets are usually reusable transport pallets standardized in DIN EN 13698 Part 1 with a floor area of 0.96 square meters and the dimensions 1200x800x144 mm (Europool pallet or Euro pallet). These dimensions have been chosen so that 2 Euro pallets can be placed alongside each other or 3 Euro pallets across each other on the back of a lorry or in a railway carriage. For some time now, a plastic pallet with dimensions 1140 x 1140 mm, optimized for container dimensions, has established itself on the market. The tines of universal forklifts are tuned to these dimensions and usually 1 m to 1.20 m long. Furthermore, there are many other pallet dimensions that require adjusting the fork length for optimal load bearing.

If lorries or railway wagons are to be loaded or unloaded completely with pallets, the loading area must either be driven by a forklift or the loading or unloading must be done from two sides. In order to carry out the loading or unloading unilaterally in such a case, extensible forks are known. In the simplest case, an extendable fork extension is used to extend, which can extend a fork tines by up to 66%. The fork extension consists of a box profile, which is pushed onto the fork tines to be extended, the forks must be covered for reasons of stability to 60% of the total tine length. Such fork extensions are relatively heavy, so that in the usually manual plugging or unplugging large physical work must be done. In addition, the turning circle of a truck with attached fork extensions increases considerably. For flexible use, the fork extensions must always be carried as separate parts.

To avoid these disadvantages, telescopic forks are known. Such systems include a base fork tine and a telescoping outer fork tine. In hydraulically operated telescopic fork tines, a hydraulic cylinder drives the outer fork tines so that it can be extended and locked into any extension length within its stroke length. Locking is required to prevent a telescopic fork tine from going any further than intended. For example, the telescopic fork tines could hang on retraction of the fork after depositing a load on the remote pallet and continue to go unnoticed on. In the subsequent turning of the forklift, the long fork could damage goods.

If telescoping is rarely required, a manually telescopic fork can be provided for cost reasons. If the hydraulic locking device is integrated with a hydraulic telescopic fork, manual locking must be provided for a manually extendable telescopic fork.

Various locking systems are known in the art. For example, the EP 1 449 807 A1 a telescopically extendable fork prong, which has a the body completely or partially encompassing and with respect to this longitudinally displaceable adjusting body which is lockable in at least two relative positions on one or more locking element (e) on the inner body, via an externally accessible actuating element, a solution of Locking is possible. To actuate the actuator is pressed from the bottom of the adjusting body against spring pressure. There is a risk that a protruding part of the floor or shelf support on which the load is deposited, the actuator could press in and so could unlock the lock unintentionally.

The DE 197 29 124 A1 discloses a fork tine extension, which consists of a non-fixed to the base fork tines, the basic fork tine all-round component comprising the fork tine extension is pushed onto the base fork tines and slidable on this. The fork tine extension can be locked in at least one extended position and a position pushed in close to the fork back on the base fork tine. In one embodiment, the lock consists of a spring-loaded pin which is mounted in the basic fork tine, wherein it is aligned in at least one defined position of the fork tine extension with a bore in the side wall of the fork tine extension and retracts into this by the spring pressure.

In all known embodiments of manual telescopic fork tines, the telescoping pusher is locked via one or more locking pins by the bolts engage in an opening in the pusher. Due to the fact that there is a certain tolerance between the pushing part and the basic fork tine, the wall thickness of the pushing part has to be so strong that with a relative movement of the pushing part to the basic fork, the locking bolts still engage sufficiently to ensure a secure locking and to be able to absorb impact forces. This increases the weight of the extendable fork, which limits the payload of the forklift and makes adjustment of the fork extension more cumbersome. In addition, there is a step at the transition point between the basic fork tine and the telescopic part, which is the greater, the greater the wall thickness of the telescopic part. When the telescope part is extended, this can cause problems when retracting the fork under the dropped load. In particular, in transverse europallets boards are transverse to the forks direction at the bottom of the pallets, where the undersides of the forks can get stuck with the steps described.

The object of the invention is to provide a manually telescoping fork for forklifts, which avoids at least some of the disadvantages described.

According to the invention this object is achieved by a manually telekopierbare fork with the features of independent claim 1. Advantageous developments of the fork prong will become apparent from the dependent claims 2-9.

It is another object of the invention to provide a method for quickly and easily changing the length of the telescopic fork invention.

This object is achieved by a method according to claim 10.

According to the invention, the manually telescoping fork has an L-shaped fork with a horizontal base fork and a vertical support part, wherein the horizontal base fork prongs on at least three sides of a longitudinally forked over the fork prong, fork-shaped fork extension with at least one horizontal top and two vertical sides is and wherein this fork extension in at least one inserted and an extended position via at least one horizontally transversely introduced into a chamber in the base fork locking bolt, which can dive into corresponding, aligned in the retracted and extended position with the locking pin holes in a side wall of the fork extension and is loaded by a spring lockable, and wherein the locking pin has a cam and a shoulder, said paragraph when snapped into the bore in the fork extension over spring pressure on the inside of the fork extension and holds the cam pressed in the bore of the fork extension. Thus, the wall thickness of the fork extension can be kept to a minimum, which reduces the snagging of the fork extension on, for example, a transverse board of a pallet with the transition between the fork extension and fork prongs on the sides and the top of the fork. In addition, the weight of the entire device is minimized.

In a preferred embodiment, the fork tine extension additionally has a longitudinally open horizontal bottom so that the underside of the base fork tine is not completely enclosed by the fork tine extension, wherein the base fork tine in the area not covered by the fork tine extension has a continuous wear strip which is at least equal is like the wall thickness of the fork tine extension so that the wear strip is flush with or even protrudes over the fork tine extension. As a result, the risk of getting stuck to the fork extension on, for example, a transverse board of a pallet is further reduced.

It has proven to be advantageous that the fork extension has at least in the region of the lateral bores a bulge in the width direction, which may consist of a welded bar or a deflection of the side wall of the fork extension. This feature minimizes the risk that the locking pin will be inadvertently pressed when the forklift driver bumps against an obstacle with the fork tine.

In an advantageous embodiment, the locking pin on its first end side on a receiving bore for the spring, so that a buckling of the spring is avoided.

It has also proven to be advantageous that the second end face of the locking pin has an outwardly curved surface. When adjusting the fork extension must be moved, the locking pin presses with its second end face of the spring loaded against the inside of the fork tine extension. By the curvature of the surface of the second end face of the locking bolt, the friction between the locking pin and the fork tine extension is reduced, so that the fork tine extension can be adjusted more easily. The friction can be further minimized if, instead of the curved surface, a rotatable ball is provided on the second end side of the locking pin, with which the locking bolt can roll on the inside of the fork tine extension, if it is not engaged in a hole.

In a further preferred embodiment, a demountable cam is provided in the front region of the basic fork tine and a corresponding stop is provided in the rear region of the fork tine extension, so that slipping off of the fork tine extension is prevented.

The method according to the invention for changing the length of the telescopic fork prongs according to the invention provides for the detent pin 30 to be pressed in manually and then the fork tine extension 20 to move until the locking pin 30 engages in alignment with a bore 25 in the forks extension 20 in this and locks the selected fork length. The adjustment of the fork tine length is thereby carried out quickly and easily.

Further advantages, features and expedient developments of the invention will become apparent from the dependent claims and the following description of preferred embodiments with reference to the drawings.

• Fig. 1 eine Seitenansicht der manuell teleskopierbaren Gabelzinke im eingefahrenen Zustand
• Fig. 2 eine Seitenansicht der manuell teleskopierbaren Gabelzinke im ausgefahrenen Zustand
• Fig. 3 eine Ansicht der manuell teleskopierbaren Gabelzinke im ausgefahrenen Zustand von unten
• Fig. 4 einen Schnitt durch die die teleskopierbaren Gabelzinke an der Position der Arretierungsbolzen

From the pictures shows:

• Fig. 1 a side view of the manually telescopic fork in the retracted state
• Fig. 2 a side view of the manually telescopic fork in the extended state
• Fig. 3 a view of the manually telescopic fork in the extended state from below
• Fig. 4 a section through the telescopic fork at the position of the locking pin

Fig. 1 is a side view of the manually extendable telescopic fork prong 1 in the retracted state. The manually extendable telescopic fork tines 1 is usually used in pairs and can for example be attached to a movable load carriage of a truck or forklift. The forks 2 are usually L-shaped and have a vertical support member 11 with attached on the back side connecting elements 3, usually in the form of suspension hooks, which match the load carriage of the truck and an associated horizontal basic fork tines 10, which undercut a load and can be included. The vertical support member 11 may also be connected to a kind of prong adjustment or similar device.

For telescoping an adjustable fork tine extension 20 is movably connected to the horizontal base fork prong 10. The telescopic fork 1 is thus extendable in the longitudinal direction and thus extendable, the fork tine extension, the horizontal base prong 10 engages around at least on three sides and can be manually adjusted from a completely retracted position to a fully extended position. In the respective length position, the adjustable fork tine extension 20 is locked via a locking pin 30 with the fixed horizontal basic fork tine 10. If the telescoping fork is used in conjunction with an industrial truck such as a forklift, cargo with different load depths can always be picked up so that the load is always fully supported. Before a load is picked up, the driver of the truck descends and sets the commonly used as a pair of telescopic forks 1 in the correct length.

Because the adjustable fork extension 20 at least partially surrounds the fixed fork prongs 10, it has a larger cross-section than the basic fork prongs 10. The transition between adjustable tine extension 20 and fixed base fork tine 10 can cause problems in that when retracted from the pallet, the edge forming the transition hangs. When setting down the load and then retracting the telescopic fork, the edge on the underside of the fork tine extension 24 interferes the most as it sticks to the crossbars present on most pallets below the pallet.

In the figure, two holes 25 in the first vertical side 22 of the fork tine extension 20 can be seen, in which a locking pin 30 (see Fig. 4 ) can dive. To protect against unintentional pushing back of the latched into a bore 25 locking pin 30, but also to avoid chafing on the received pallets with the risk that there pallet material is rubbed off, the first vertical side 22 of the fork tine extension 20 bulges 26 in the region of the holes 25 on, as welded-on bars are executed. However, other embodiments for the bulge 26, for example in the form of a deflection, are conceivable.

Fig. 2 shows the manually telescoping fork tine 1 in a side view in the extended state. The fork extension 20 is maximally extended, so that there is still sufficient overlap between the horizontal base fork prong 10 and the adjustable fork extension 20.

Fig. 3 is a view of the manually telescopic forks 1 in the extended state from below. The basic fork prong 10 has on its side opposite the first side 12 underside a wear strip 15, the thickness of which is almost identical to the wall thickness of the fork tine extension 20. The fork extension 20 only partially encloses the underside of the base fork prong 10 leaving a longitudinal strip which is not covered by the prong extension 20. In this strip is the wear strip 15, which thus forms a smooth underside of the fork tine 2. The locking bar 15 can be made replaceable. Furthermore, a cam 18 in the front region of the basic fork tine 10 can be seen. This cooperates with stops 27 of the fork tine extension 20, so that the fork tine extension 20 can not be moved beyond this cam 18 addition. This ensures that even in the maximum extension position of the fork tine extension 20 sufficient coverage of the fork tine extension 20 with the basic fork tine 10 is present and the fork tine extension 20 can not be lost. The cam 18 is screwed to the basic fork prong 10 so that it can be unscrewed for disassembly of the forks extension 20. In addition to a screw and all other suitable releasable connections, such as a bolt with a bayonet connection, are conceivable.

Fig. 4 is a section through the telescopic fork 1 at the position of the locking pin 30. The locking bolts 30 are horizontal, each introduced from the side in the front region of the basic fork tine 10 in this. This position has the advantage that the load lying on the fork tine 2 can not accidentally press the locking bolt 30. In addition, this position is insensitive to dirt. A symmetrical arrangement of the locking pins 30 is shown.

About the double version impact forces on the forks extension 20 are always safely transmitted to the base fork prong 10. But it is also conceivable asymmetric arrangement by only one locking pin 30 is present in the basic fork prong 10, or by a plurality of locking bolts 30 are present, but which are installed at different positions in the basic fork prong 10. The basic fork prong 10 has a chamber 16 in which the locking pin 30 is mounted. The locking pin 30 can be made so relatively large, wherein in the middle of the base fork tine 30 is still sufficient material to ensure the carrying capacity. A spring 35 presses the locking pin 30 outward in the direction of the first vertical side 22 and the second vertical side 23 of the fork tine extension 20. For spring guidance, the locking pin 30 at its first end face 31, against which the spring 35 presses, a receiving bore 36 for the Spring 35 on. The second end face 32 of the locking bolt 30 has an outwardly curved surface. Thereby, the contact surface and thus the friction between the locking pin 30 and the inside of the first vertical side 22 and the second vertical side 23 of the fork tine extension 20 is minimized against which the locking pin 30 presses with its second end face 32 when the fork tine extension 20 is displaced. The total area of the second end face 32 is dimensioned so large that the locking pin 30 can be comfortably pressed manually and without having to use a tool. For example, the second end face 32 can be designed in the form of a spherical section, wherein the ball diameter is dimensioned such that the cam 33 can dip into the bore 25, which has a diameter of at least 20 mm, in particular at least 25 mm. The outwardly curved, in particular spherical shape of the second end face 32 has the further advantage that the locking pin 30 must be pressed less deeply to unlock the fork extension 20, as if the second end face 32 would have a flat surface. Once the locking pin 30 is pressed so far that the inner edge of the bore 25 of the fork extension extends beyond the edge of the second end face 32 of the locking pin 30, the fork tine extension 20 can already be moved. The further impressions of the locking pin 30 in the chamber 16 is done on further movement of the fork tine extension 20 on the inner surface of the first vertical side 22 and the second vertical side 23 of the fork tine extension 20. In another, not shown embodiment, the locking pin 30 instead of the outwardly curved surface on a rotatable ball on its second end face 32, whereby the fork tine extension 20 can be moved even easier.

The locking pin 30 has a cam 33 which is dimensioned so that it can dip into the bore 25 in a side 22, 23 of the fork extension 20. With a shoulder 34, behind the seen from the cam 33, the dimension of the locking pin 30 is greater than that of the cam 33, the locking pin 30 is retained in this case behind the vertical side 22, 23 of the fork extension 20, so that he does not Bore 25 can completely extend from the basic fork tine 10 and the fork tine extension 20. The chamber 16 in the basic fork tine 10 is at least the wall thickness of the fork tine extension 20 plus the necessary clearance between fork tine extension 20 and basic fork tine 10 deeper than the locking pin 30 is long. Thus, the locking pin can be pushed far enough into the basic fork prong 10 against the pressure of the spring 35 that it no longer engages in the fork tine extension 20. For optimum guidance, an additional guide bushing 17 can be mounted in the chamber 16.

By this construction, the wall thickness of the fork extension 20 can be kept to a minimum, whereby the transition between the base fork prong 10 and fork extension 20 is also kept minimal.

To change the length of the telescopic fork 1, the locking pin 30 is pressed manually and then the forks extension 20 is displaced until the locking pin 30 engages in alignment with a bore 25 in the forks extension 20 in this and locks the selected fork length. The adjustment of the fork tine length is thereby carried out quickly and easily.

The locking pins 30 can be made round or rectangular. In this case, the surface of the second end face 32, in the bore 25 in the first vertical side 22 or the second vertical side 23 of the fork tine extension 20 snaps into place, large enough to be pressed comfortably yet manually without having to use a tool can be pressed.

In addition to the in Fig. 1 and 2 shown positions "retracted" and "extended" any intermediate positions by introducing holes 25 in at least one of the vertical sides 22, 23 of the fork tine extension 20 at these positions conceivable, so that the fork tine extension 20 can be latched in any intermediate positions.

LIST OF REFERENCE NUMBERS

1

telescopic fork

2

forks

3

connecting element

10

Supporting fork

11

vertical support part

12

first side of the basic fork prong

13

second side of the basic fork prong

14

third side of the basic fork prong

15

wear strip

16

chamber

17

guide bush

18

cam

20

Fork extension

21

Top of the fork tine extension

22

first vertical side of the fork extension

23

second vertical side of the fork tine extension

24

Bottom of the fork tine extension

25

drilling

26

bulge

27

attack

30

locking bolt

31

first end face

32

second end face

33

cam

34

paragraph

35

feather

36

location hole

Claims (10)

A manually telescoping fork (1) comprising an L-shaped fork (2) having a horizontal base fork prong (10) and a vertical support portion (11), the horizontal base prong (10) being supported on at least three sides (12, 13, 14) of a box-shaped fork tine extension (20) slidable over the base fork prong (10) and comprising at least one horizontal top (21) and two vertical sides (22, 23), and wherein the prong extension (20) is in at least one retracted and extended position via at least one locking bolt (30) introduced horizontally transversely into a chamber (16) in the basic fork prong (10), having a first end face (31) and a second end face (32) opposite the first end face (31) inserted and the extended position with the locking pin (30) aligned bores (25) in a side wall (22, 23) of the fork tine Verlän (20) can be immersed and is loaded by a spring (35) on its first end face (31) can be locked,
characterized,
in that the locking pin (30) has a cam (33) and a shoulder (34), wherein the shoulder (34) rests on the inside of the fork tine extension (20) via spring pressure when latched in the bore (25) in the fork tine extension (20) and keeps the cam (33) pressed in the bore (25) of the fork tine extension (20). Manually telescoping fork (1) according to claim 1,
characterized,
in that the fork extension (20) additionally has a longitudinally open horizontal bottom (24), so that the underside (24) of the base fork prong (10) is not completely enclosed by the fork extension (20), wherein the base fork prongs (10) in the not area covered by the fork extension (20) has a continuous wear strip (15) which is at least as strong as the wall thickness of the fork extension (20), so that the wear strip (15) flush with the fork extension (20) or protruding beyond it. Manually telescoping fork (1) according to claim 1 or 2,
characterized,
that the fork extension (20) at least in the region of the lateral bore (25) has a bulge (26) in the width direction. Manually telescoping fork (1) according to claim 3,
characterized,
that the bulge (26) consists of a welded bar. Manually telescoping fork (1) according to claim 3,
characterized,
that the bulge (26) consists of a deflection of the first side wall (22) of the fork tine extension (20). Manually telescoping fork (1) according to one of the preceding claims,
characterized,
in that the locking pin (30) has a receiving bore (36) for the spring (35) on its first end face (31). Manually telescoping fork (1) according to one of the preceding claims,
characterized,
in that the second end face (32) of the locking pin (30) has an outwardly curved surface. Manually telescoping fork (1) according to one of Claims 1 to 6, characterized
in that the locking pin (30) has on its second end face (32) a rotatable ball, with which it can roll along the inside of the first vertical side (22) of the fork tine extension (20) when it does not locked in a hole (35). Manually telescoping fork (1) according to one of the preceding claims,
characterized,
in that a demountable cam (18) is provided in the front area of the basic fork prong (10) and a corresponding stop (27) is provided in the rear area of the fork prong extension (20). Method Changing the length of the telescopic fork of the invention according to one of the preceding claims, comprising the steps of: manually pressing the locking pin 30, and then moving the fork extension 20 until the locking pin 30 engages in alignment with a bore 25 in the fork extension 20 in this.

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