WO1999055997A1

WO1999055997A1 - Ladder combined with three different transport functions

Info

Publication number: WO1999055997A1
Application number: PCT/DK1999/000232
Authority: WO
Inventors: Henrik Lindberg
Original assignee: Henrik Lindberg
Priority date: 1998-04-28
Filing date: 1999-04-28
Publication date: 1999-11-04
Also published as: AU3516399A

Abstract

A ladder combined with three different transport functions which can be transformed into a trestle ladder, a long ladder, a sack truck and a vehicle to be used by craftsmen and storemen needing a simple assembly for many purposes. Two ladder sides (4 and 5) are held together in two pivotal joints (1 and 2) on the uppermost step (3) and are pivotally journalled about the axis of rotation S1, which can be locked by means of a biased clamp (12) secured to a locking piston. A blade (8) is hinged to the rear lowermost step and can also be used for securing the two ladder sides by virtue of its shape which can fasten the front lowermost step, and by means of a locking mechanism provided with a biased rocker arm (9) which presses the head of the rocker arm into one of two openings so as to fasten the blade along the ladder side or at an angle of 90°. The wheels can also be locked along the ladder sides and at an angle of 90° opposite the blade by means of a locking mechanism placed on a sleeve of the wheel suspension, said sleeve acting in the same manner as the locking means (9) with a biased rocker arm, (9a) of the blade. An additional wheel is mounted on the uppermost step and renders it possible to use the assembly according to the invention as a vehicle.

Description

1 Title: Ladder combined with three different transport functions.

Technical Field

The invention relates to a ladder combined with three different transport functions, said ladder comprising two ladder sides with a plurality of steps and secured in two joints which divide the uppermost step in such a manner that the joints can lock the ladder sides by employing a clamp for activating the locking mechanism, where a support member is mounted on the lowermost step and acts as a load-receiving member, and where two wheels are rotatably secured on lockable wheel suspensions.

Background Art

The individual components are not new per se. Thus ladders, trestle ladders, sack trucks and various embodiments of vehicles are known. The new concept of the invention is that these components are combined in a single device.

Thus the invention is based inter alia on the following known inventions:

The trestle ladder, viz. the double ladder, comprising two ladder sections arranged as an inverted V, whereby it is possible to place the ladder in an upright position without the use of a wall or the like for supporting said ladder.

The ladder is known in many different shapes, and particularly in form of models foldable in various ways into small sizes.

The sack truck, the two-wheeled vehicle with a load-receiving member (which is often also called: plate/spade/blade) mounted for allowing a lift and transport of small loads, such as sacks and boxes. The plate truck, viz. the small vehicle often provided with only two wheels placed below a plate in such a manner that it can be moved/transported sideways.

Various vehicles are, however, known which have combined some of these properties:

DE-PS No. 39 32 946 Al deals with a two- wheeled sack truck combined with a stepladder. The assembly is very complicated and comprises many parts and several longitudinal sections. In order to simplify the assembly, the present invention has chosen to use pipes for the steps instead of stair steps. Although a person stands in a more safe way on a stepladder, the present invention provides in addition a wide range of combination possibilities compensating for the said improved safety.

A combined ladder and sack truck has been described in DK-PS No. 148899 B, where a frame with two wheels has been equipped with a rather small frame as load-receiving member for a sack truck. The assembly is, however, particularly adapted for use on a boat because the rather small frame is shaped in such a manner that it can fix the ladder in a reliable position on a small boat.

An invention is described in PS No. 2333457, where said invention can be adapted to various types of vehicles, including a sack truck, but not to a ladder. The invention comprises two large wheels secured on a frame and a small undercarriage provided with two rotatable wheels.

Assemblies are furthermore known which have solved some of the same technical problems as the present invention:

DE-PS No. 4421 284 Cl, where a collapsible combined ladder comprises a joint and a locking mechanism which renders it possible to lock two or more ladder sections in several angles, including an angle rendering it possible to use the ladder sides as a trestle ladder. One of the problems of this joint is that it is difficult to pull out the clamp because it is not easy to grip about said clamp. Thus it is not possible to insert the fingers below the clamp, especially not when wearing working gloves, in order to get a good grip when said clamp is to be pulled out so as to loosen the joint. In addition, the joint is rather heavy and large due to its structure. The present invention has facilitated the introduction of the fingers below the clamp so as to ensure a good grip about said clamp in connection with a disengagement of the joint. Furthermore, the size of the joint has been reduced.

A German invention described in EP-PS No. 0 609 523 Al has also rendered it possible to lock a joint in such a manner that two step ladder sides can be secured in an inverted V. However, this joint only allows an interlocking when the ladder sides are arranged like a trestle ladder.

The Swedish PS-No. 8003489-5 describes a joint with a locking mechanism which is able to lock two ladder joints relative to one another in such a manner that they can be locked in several positions including the position wherein the ladder is in form of an oblong ladder of twice the length of the ladder sides and a trestle ladder. The latter is obtained by means of a circular joint with an inner gear wheel, whereby two biased sets of teeth are pressed towards the gear wheel and thus lock said gear wheel. A pressing of the two teeth against one another by means of two handles releases the locking mechanism. This structure is, however, apparently rather flimsy and is unlikely to stand up to a daily professional use. In addition, this locking mechanism is of a very large and heavy structure, cf. the drawings.

EP-PS No. 0 359 970 Al describes another embodiment of a joint with a locking mechanism for a combined ladder with two or more ladder sides. The joint presents a very complicated and detailed structure comprising many parts which must fit very accurately into one another. The joint can hardly be considered stronger than the weakest part. The structure of the above joints and locking mechanisms implies that a transverse chain or the like is superfluous for securing the ladder sides when said ladder sides are arranged as an inverted V. Thus it is avoided that the trestle ladder looks like an A.

Examples are also known of solutions permitting a locking of the wheel suspensions for two-wheeled vehicles, such as the EP-PS No. 0 399 364 describing a luggage van, but these solutions employ a locking of the wheels along the device for packing up the assembly to a minimum size. However, the present assembly employs the inturned wheels for establishing an assembly rendering it possible to transport for instance large plates one by one sideways.

Another assembly employing foldable wheels is described in DK-PS No. 167670 Bl . This publication describes a two-wheeled insert vehicle with two wheels suitable for transporting small loads for private use. This invention is characterised in that the wheels are fixed during the function of the vehicle because the spade used as load-receiving member is also used for securing the wheels at a 90° angle relative to the main frame of the vehicle. The wheels are rotatably journalled in bushings in such a manner that said bushings can rotate about a spindle corresponding to two pipes in the undercarriage of the assembly. The wheels can be released in their centre of rotation in order to fold the assembly by the spade being raised into a rest position followed by said wheels being turned inwards along the main frame.

Brief Description of the Invention.

For the assembling of these various components, the present invention provides various connections, joints, hinges and locking mechanisms in form of:

1) An assembly with a locking mechanism which can fix the ladder sides at several angles relative to one another, viz. 180° for the ladder, approximately 45° for the trestle ladder and 0° for the sack truck.

2) A wheel suspension with a locking mechamsm which can fix the two wheels in two positions, viz. 0 and 90° relative to the ladder sides.

3) A blade which can fix the two ladder sides due to a locking mechanism and its form and structure when the assembly is to be used as a sack truck.

The assembly is intended to solve the difficulties of the craftsman, especially the carpenter when he is to carry loads, such as also a heavy toolbox, machines, hand tool, waste and large wooden boards and plasterboards to the working site and subsequently to various locations at the site. Thus an assembly is provided which does not weigh much nor take up much room, and which can be used for several functions by way of simple manual adjustments, and which thus reduces the problems of bringing along and storing several different assemblies. In addition, the assembly according to the invention can be folded and thus of a reduced size in order to be placed for instance in the van of the craftsman. The assembly according to the invention can advantageously also be used in connection with for instance stock work.

The various joints and locking mechanisms are structured as durable as possible and so as to stand a daily professional use for many years. Reliability, simplicity and strength in the joints, the ladder sides and the locking mechanisms have thus been given a high priority.

Thus the invention provides a number of known components of the type indicated in the introduction by way of a simple manipulation of the invention.

This is according to the invention obtained by additionally using the attached blade for locking the two ladder sides by way of its structure, said blade being hinged to the rear lowermost step and shaped such that when lowered over the lowermost step of the front ladder side it fixes said step, a locking mechanism being able to lock said blade both along the ladder side and at a 90° angle relative to said ladder sides by means of a biased rocker arm which is mounted on said blade and presses against an opening in the inner pipe, where the locking mechanism is opened by way of a pressure on the rocker handle in such a manner that the head of the rocker arm slides into the next opening due to the spring effect, said opening being one of two openings, and whereby the wheel suspensions are locked by means of a biased rocker arm mounted on the uppermost portion of the sleeve, where said sleeve with the wheel suspension can be turned relative to said rocker arm in such a manner that said rocker arm can slide into an opening in the outer pipe, said opening corresponding to one of the two openings in the inner pipe, whereby the rocker arm can fix the wheels both along the ladder sides and at a 90° angle relative thereto, said wheels being able to rotate freely on the axes in both positions, and where the joints furthermore can be turned relative to one another by means of a particular clamp bolt which is provided with a biased locking piston secured to the clamp by means of a bridge in such a manner that an open resilient expansion ring arranged in a groove in said piston passes a corresponding groove in the cylinder of the piston when said clamp is subjected to a pull, whereby the clamp is kept outside the innermost disk until it is pressed by means of a spring into two of four openings in said innermost disk in such a manner that the ladder joints can be secured at three angles: 0, approximately 45 and approximately 180° .

As a result, it is possible to obtain the following assemblies by way of a specific number of manipulations of the invention:

1) A trestle ladder by arranging the two sides of the ladder at an angle of approxi- mately 45°, whereby the sides are locked by the locking mechanism in the joints arranged on the uppermost step which is shared by the ladder sides. A pull in the clamps of the joints renders it possible to release the locking mechanism and to alter the angle of the ladder sides. When the angle of approximately 45° has been reached, 7 the ladder sides can be locked by the clamps being pressed inwards.

2) A long ladder by arranging the two sides of the ladder in extension of one another at an angle of 180°, in which the joints again lock the ladder sides by means of the locking mechanism. The resulting ladder is of a length being twice the length of a ladder side.

3) A sack truck by putting down die blade and using the two wheels. The main function of the blade is to be a load-receiving member like in connection with other sack trucks. The blade has, however, in addition the particular function that by lowering said blade from vertical, viz. along the ladder side, into horizontal at a right angle relative to the ladder side, the two sides of the ladder are mutually locked and stabilize thus the function as a sack truck in such a manner that a strong surface is provided for the back of the sack truck. In order to maintain the angle of the blade in such a manner that the assembly does not tilt forwards at a forward pressure on the ladder sides, a locking mechanism is provided at the axis of rotation of the blade on the lowermost ladder step, said locking mechamsm also being used for unlocking said blade and raising said blade into a position along the ladder side, where said locking mechamsm locks the blade. The uppermost step of the ladder is provided with a handle of soft material, such as for instance rubber.

4) A plate vehicle or sack truck moving sideways for transporting plates etc by transforming the assembly according to the invention into a sack truck with the only difference therefrom that the wheels are inturned parallel to the ladder side where said wheels are locked by means of a locking mechanism. The resulting sack truck can be moved sideways with the result that large plates can be easily transported and handled. Thus when large plates are transported on an ordinary sack truck, a problem arises when passing narrow places, and the plate often blocks the view of the user.

5) A folded assembly in the rest position by turning the wheels inwards along the 8 ladder side, where said wheels are locked, and by turning the blade upwards and securing it. Thus a relatively small sized assembly is obtained which is suited for bringing along for instance in a van.

According to a particular embodiment of the assembly, a third rotatable wheel is secured to the uppermost step, whereby the assembly can be used as a vehicle, cf. Fig. 7, with one ladder side acting as a support and the other ladder side acting as a control frame with a handle for pulling the vehicle. In this function the locking of the joints of the ladder sides is not used whereby said ladder sides can be moved relative to one another. The extra wheel is shaped with a ball bearing in such a manner that the wheel can turn 360° whereby said wheel can be used for steering the vehicle when said vehicle is moved by means of the three wheels. Reference is made to a more detailed description of the wheel and the securing thereof to the assembly, said description being found in the list of Figures, Figs. 12 to 14.

According to a particular embodiment of the assembly, the bar (18) connecting the locking piston (19a) to the clamp (12) is shaped such that said bar does not extend directly from the outermost disk (11) to the centre of the clamp (12), but is instead shaped such that a bridge connects the portion of the bar just projecting from the outermost disk to the portion of the clamp just projecting from the said disk, whereby the clamp opening is not interrupted by a transverse bar. Thus it is possible to pro- vide a bridge in each side mating the clamp, and it is possible to use a thin disk for the bridge. The resulting structure is stronger and more durable the previously known. In addition, it is easy to introduce the fingers in the clamp, even when wearing working gloves.

Brief Description of the Drawings.

Fig. 1 is a perspective view of the assembly shaped as a sack truck, 9

Figs. 2 to 7 show the functions:

Fig. 2 illustrates the assembly according to the invention in form of a sack truck,

Fig. 3 illustrates the assembly according to the invention in form of a trestle ladder,

Fig. 4 illustrates the assembly according to the invention in form of a plate vehicle,

Fig. 5 illustrates the assembly according to the invention in form of a long ladder,

Fig. 6 illustrates the assembly according to the invention in form of a vehicle with an additional wheel,

Fig. 7 illustrates the assembly according to the invention in the folded state,

Fig. 8 is a side view of the joint, cf. the reference number 1 in Fig. 1,

Fig. 9 is a cross sectional view of the joint of Fig. 8 taken along the line A-A,

Fig. 10 shows the locking piston, cf. the reference number 19 in Fig. 9,

Fig. 11 shows the blade in the lowered state, where the position of the blade and the locking mechanism in the outermost positions is indicated by a dotted line in the Figure,

Fig. 12 is a front view of the wheel suspension, cf. the reference number 6 in Fig. 1 , where a thick line indicates the wheel in the locked state at an angle of 90 ° relative to the ladder side, and a thin line indicates said wheel in the locked position where it is closed to the ladder side, 10

Fig. 13 is a side view of the wheel suspension, where the wheel has not been drawn in,

Fig. 14 is a top view of the wheel suspension with a cross sectional view through the pipes of the ladder sides at XIV in Fig. 13, said wheel suspension again being indi- cated by a thick line in the perpendicular position and with a thin line in the parallel position,

Fig. 15 is a rear view of an additional wheel for transforming the assembly according to the invention into a pushcart,

Fig. 16 is a cross sectional view through Fig. 15, where the wheel and the lowermost portion of the fork carrying said wheel has been indicated by a dotted line in the drawing, and

Fig. 17 is a perspective view of the eccentric locking mechanism.

Best Mode for Carrying Out the Invention

Fig. 1 is a layout drawing of the assembly according to the invention, which is adapted to be used as a sack truck where the ladder sides 4 and 5 are assembled and locked in the joints 1 and 2, cf. also Figs. 8 to 10, while the blade 8 has been lowered. The particular function of the blade is that a lowering of said blade from vertical, viz. along the ladder side, downwards to horizontal at a right angle relative to the ladder side has the effect that the lowermost portion of the two ladder sides 4 and 5 are locked, which in turn stabilizes the sack truck function in such a manner that a strong surface is obtained for said sack truck. The blade is hinged by a pipe 22 on the lowermost step in the outermost, rear ladder side 21, said blade being able to be moved about in an axis of rotation on said lowermost rear step 21. The blade can be locked in the two positions by means of a locking mechanism 9, cf. also Fig. 11. 11

The ladder sides are secured due to the form of the blade 24. This blade is formed in such a manner that when lowered over the lowermost step 20 of the front, innermost ladder side said blade retains said step in a fixed manner.

Knobs 26 made of a moderately soft material, such as nylon, are mounted in the ends of the four pipes forming the side sections/sides of the ladder sides, and these knobs assist in fastening said ladder sides because the form of said knobs implies that they are only just in contact with one another when the ladder sides are being assembled. When the blade is used for assembling the ladder sides, these knobs are pressed together in such a manner that the ladder sides are kept together without play.

A further function of these knobs is to protect the base and the ladder sides against impacts and scratches.

An abutment 25 prevents the blade from moving backwards past the ladder side in such a manner that said ladder side cannot fall backwards.

A locking mechanism 9, cf. Fig. 1, is provided for locking the blade both along the ladder side and at an angle of 90° relative to the ladder sides. This locking mechanism 9 resembles a locking mechanism 9a used at die wheel suspension, and it comprises a biased rocker arm 27 fitting in an opening 27b in the blade 23 and the outer pipe 22. The head 28 of the rocker arm is shaped so as to fit in one of two openings 27d in the inner pipe 21. The rocker arm is secured to the blade in a hinge 27a.

A stepping on the rocker arm 27 has the effect that the head 28 thereof leaves the opening in the inner pipe 27d, whereby the blade can be lowered or raised by means of the foot. When the blade reaches its outermost position, the head 28 of the rocker arm can slide into the next opening in the innermost pipe and thereby lock said blade. A spring 27c presses the rearmost portion of the rocker arm upwards whereby the head 28 of said rocker arm is biased against the opening of the blade and diereby against the openings in the innermost pipe. The rocker arm 27 is furthermore shaped in such a manner that although a person has stepped thereon it continues to maintain a rather upward shape even though the rocker arm slides downwards together with the blade to which it is secured. When the blade is locked along the ladder side and it is desired to lower it, nothing but a pressing on the rocker arm is necessary whereby the blade slides downwards.

The uppermost step of the ladder 3 is provided with a handle of soft material, such as for instance rubber.

Fig. 3 illustrates the assembly according to the invention formed as a trestle ladder by the two sides of the ladder being arranged at an angle of approximately 45° . The sides are fixed in this position by two pivotal joints 1 and 2 secured to the uppermost ladder step 3. The angle is maintained in the joint by means of a locking mechanism.

Fig. 4 illustrates the assembly according to the invention formed as a plate vehicle by inturning and locking the wheels. The securing of one wheel suspension to the assembly and the locking mechanism are shown in Figs. 12 to 14. The wheel 40 is secured to a plate-shaped arm 43 mounted on a sleeve 42, said sleeve being pivotally journalled on the axis of rotation S3 in such a manner that the wheel can be turned inwards and outwards relative to the innermost ladder side 41.

The sleeve can be secured by means of a locking mechanism in two positions: at right angles to the ladder sides or parallel to said ladder sides. In the right-angled position, the wheels form part of the sack truck, whereas in the parallel position said wheels can function both for a reduction of the size of the assembly for storing purposes and for a particular sack truck moving sideways for carrying plates. Thus the wheels can turn freely on these axes in the two locked positions.

The locking mechanism retaining the sleeve with the wheel in the two positions 13 relative to the ladder side comprises a rocker arm 44 secured to a non-turnable sleeve 42' by two protruding legs 46 with an opening in each leg, whereby a pin 45 extending through the two openings fix the arm 44. Thus the rocker arm is pivotally journalled about the axis of the pin. The lowermost portion of the rocker arm is provided with a bending 47 of approximately 90° towards the sleeve 42, said bending fitting in an opening in the outer pipe sleeve 48. An opening 49 is provided in the inner pipe inside the sleeve, viz. one opening in the position of the wheel at an angle of 90° relative to the ladder side and an opening in the position of said wheel parallel to said ladder side. When the bending of the arm is placed in alignment with one of these openings, said bending can slide into the opening in the inner pipe and thereby lock the sleeve. A spring 49a presses against the uppermost portion of the arm 44 in such a manner that said arm is biased away from the sleeve, whereby the lowermost portion with the bending is pressed inwards towards the openings in the sleeve. In this manner it is possible by means of a foot to release the arm by a slight push, whereby the bending slides out of the opening in the inner pipe at the sleeve so that said sleeve can turn into the second position. Subsequently, the spring ensures that the bending of the arm slides into the next opening and there locks the wheel.

Fig. 5 illustrates the assembly according to the invention formed as a long ladder by arranging the two sides of said ladder in extension of one another at an angle of approximately 180° , whereby a ladder is obtained which is of a length twice the length of a ladder side. The joint is locked as described in connection with Fig. 1.

The locking mechanism of the joint 1 retaining the ladder sides in a turnable manner appears from Figs. 8 to 10, this joint being mirror-symmetrical with the second joint. This joint comprises two disks 10 and 11 kept together by means of a locking bolt 15. This locking bolt 15 acts as a shaft, and this bolt is non-tumably secured in the innermost disk 10, such as by means of a thread, the outermost portion of said bolt being kept at a distance from the outermost disk 11 by means of a number of disks 17, 17' and 17" of soft material, such as nylon. In this manner the outermost disk 14

11 is pivotally journalled about the locking bolt and die axis of rotation S2, said disks being kept together by the head of the bolt. The head of the bolt is significantly larger than the opening in the outermost disk 11 , and this shape of the bolt retains the outermost disk relative to the innermost disk without, however, preventing said outermost disk from turning relative to the innermost disk. According to the invention is is advantageous to place a sleeve 16 of for instance nylon between the outermost disk 11 and the locking bolt 15 so as to keep the bolt and the disk apart. Therefore the pivotal components of the joint should not touch one another directly so as to avoid wear, play and noise. The shaping of a track at 17" in one disk at the rim of said disk prevents dirt from penetrating into the joint.

A clamp 12 is mounted in extension of the outermost disk 11 and acts as a releasing means/handle for the locking mechamsm of the joint. The clamp extends through two openings 14 in the outermost disk 11 and is pressed by means of a spring 19b against the innermost disk 10. When the clamp is pulled out, it is kept out by means of a locking means 19 which can be released by a moderate pressure on said clamp. As a result, an alteration of the angle of from for instance 0° to 45 ° requires nothing but a pull in the clamp and a subsequent slight separation of the ladder sides followed by a pressing in of said clamp, said clamp automatically sliding into the next two openings when the ladder sides have reached an angle of 45 ° . The latter is obtained by the clamp when pulled out sliding a short distance into the outermost disk where it is locked. Subsequently, when the joint has been turned past the first openings it is possible to release the locking mechanism whereby the rounded ends of the clamp are pressed against the innermost disk until die next set of openings has been reached and said biased clamp slides into said openings.

Fig. 10 is a cross sectional view of die biasing and the locking means, where a piston 19a is secured to a bar 18 between the biased piston and die clamp. A spring 19b presses the piston and consequently die clamp towards the bottom formed by the material of the innermost ladder side. When the clamp is subjected to a pull, the 15 piston moves towards the spring until it reaches a groove in the cylinder 19e. The piston is provided with a corresponding groove 19d, in which an open resilient expansion ring is positioned, said expansion ring pressing against the outer side of the cylinder. When the two grooves 19e and d oppose one another, the ring expands into the outer groove with the result that the piston and consequently die clamp are secured. When die joint is to be locked, the clamp is subjected to a moderate pressure until the pressure of the expansion ring against the groove of the cylinder has been exceeded with the result that die piston 19a and the associated expansion ring 19c are pressed past the groove 19e in the cylinder.

Thus the joints can be turned freely without necessitating that the clamp is kept at a distance, and it is possible to choose when the clamp is to be biased in such a manner that it searches for the next set of openings in the inner disk whereby the joint is locked.

The four openings 13 in the innermost disk 10 imply together with the limitation of the assembly, viz. that said assembly cannot exceed a turning of 180°, that the ladder sides can be locked in three positions: 0° for the sack truck; approximately 45° for the trestle ladder; and approximately 180° for the long ladder.

Figs. 15 to 17 illustrate a particular embodiment of die assembly where a third wheel is secured to the uppermost step. As a result, die assembly can be used as a vehicle, cf. Fig. 6, with the inner ladder side 4 acting as a load-receiving member and the outer ladder side 5 acting as a steering frame for pulling or pushing the vehicle. The two ladder sides are not locked relative to one another. The blade can be locked to the ladder side used as a load-receiving member with die result tiiat a vehicle with a bottom is obtained. It is, however, also possible to lock the blade at an angle of 90° relative to the ladder side with the result that a vehicle witii a back supporting the load is obtained. 16

The wheel 50 is secured in a Y-shaped clamp 51 , whereby the axis 52 of the wheel is secured in pointed ends of the legs of the Y. A ball bearing 51 ' is mounted in the bottom of the Y, said ball bearing 51' being pivotally journalled about the axis of rotation S4 in such a manner that the clamp 51 is pivotal relative to an eccentric locking mechamsm. The latter eccentric locking mechamsm can secure the wheel suspension to the uppermost step 3 of the assembly according to the invention with the result iat the vehicle can be turned to the sides during the transport.

The eccentric locking mechamsm comprises a rocker handle 53 fixingly securing the wheel suspension about the uppermost step. In order to maintain the wheel at an angle of 90° relative to the inner ladder side used as a load-receiving member, said step is provided with a ridge 54 corresponding to a lowered groove 54' , such as a punched out oval opening, in the lowermost shell of the locking mechanism 55. The locking mechanism comprises two shells 55 and 55' formed as a pipe when held together. These shells are hinged 56 in one side in such a manner that the locking mechanism can be placed on the uppermost step and later on removed according to desire. In the other side these shells are provided with two oppositely directed lips 59 and 59' , which can be pressed together and secure the wheel by means of the rocker handle 53.

The rocker handle is provided with two hinges 57 and 57' on ie lower lip in such a manner that the portion of the rocker arm abutting the upper lip 59' fits in the lip when said handle in the open state is inserted in die hollow of the lip. For the sake of stability and durability this embodiment has been provided with two double hinges, but one or more than two hinges are also possible. The handle is secured to the hinges by means of a pin 58.

When the handle is closed, said handle tightens die two lips against each other witii the result that die shells are fastened to the pipe. The latter is carried out by the handle at the upper hinge 57' being shaped as an eccentric or oval cylinder in such 17 a manner that the smallest portion of the cylinder faces the upper lip 59' when the handle is open, and such that the largest portion of said cylinder faces said upper lip when the handle is closed. When the handle is closed, the size of the shells is slightly reduced or of the same size as the uppermost step with the result that die fastening is carried out, the previously described control means 54 and 54' stabilizing the wheel suspension and ensuring a keeping thereof at an angle of 90° relative to the outer ladder side forming the load-receiving member.

The rocker handle is shaped such diat in die tightened state it is positioned as close to die shells as possible.

Claims

18 Claims

1. A ladder combined with three different transport functions, said ladder comprising two ladder sides (4 and 5) with a plurality of steps and secured in two joints (1 and 2) which divide die uppermost step (3) in such a manner that me joints can lock the ladder sides by employing a clamp (12) for activating the locking mechanism, where a support member (8) is mounted on the lowermost step and acts as a load-receiving member, and where two wheels are rotatably secured on lockable wheel suspensions (6 og 7), c h a r a c t e r i s e d in that the attached blade (8) is used for locking the two ladder sides by way of its structure (24), said blade being hinged to the rear lowermost step (21) and shaped such that when lowered over the lowermost step (20) of the front ladder side it fixes said step, a locking mechanism (9) being able to lock the blade both along the ladder side and at an angle of 90┬░ relative to the ladder sides by means of a biased rocker arm (27) which is mounted on said blade and presses against an opening in an inner pipe (27d), where the locking mechanism is opened by way of a pressure on the rocker handle in such a manner that the head (28) of the rocker arm slides into die next opening due to the spring effect (27c), said opening being one of two openings, and whereby the wheel suspensions (6 and 7) are locked by means of a biased (49a) rocker arm (44) mounted on the uppermost portion of the sleeve (42'), where said sleeve with the wheel suspension (42) can be turned relative to said rocker arm in such a manner that said rocker arm can slide into an opening in the outer pipe (42), said opening corresponding to one (48) of the two openings (49) in the inner pipe (41), whereby the rocker arm can fix the wheels both along the ladder sides and at an angle of 90┬░ relative thereto, said wheels being able to rotate freely on the axes in both positions, and where the joints (1 and 2) furthermore can be turned relative to one another by means of a particular clamp bolt (15) which is provided with a biased (19b) locking piston (19a) secured to the clamp (12) by means of a bar (18) in such a manner that an open resilient expansion ring (19c) arranged in a groove in said piston (19d) passes a corresponding groove in the cylinder (19e) of the piston when said clamp is subjected to a pull, whereby the clamp is kept 19 outside the innermost disk (10) until it is pressed by means of a spring (19b) into two of four openings in said innermost disk in such a manner that the ladder joints can be secured at three angles: approximately 0┬░, approximately 45┬░ and approximately 180┬░ .

2. A ladder combined with diree different transport functions according to claim 1, c h a r a c t e r i s e d in that a third wheel is secured to the uppermost step in such a manner that the invention can be used as a vehicle, die wheel suspension being secured to the uppermost step of the assembly by means of an eccentric locking mechanism fastening the wheel suspension and keeping it stable by a ridge and a groove (54 and 54'), where the locking mechanism comprises two cylindrical shells (55 and 55'), which in one side are hinged (56) and in the other side are provided with two oppositely directed lips (59 and 59') which can be pressed togedier and secure the wheel by means of a rocker handle (53) hinged (57 and 57') to the lower lip in such a manner that the portion of the rocker handle abutting the upper lip (59') fits in the lip when the handle in the open state is placed in the hollow of die lip in such a manner that when the handle is closed said procedure tightens the two lips against one another, whereby the shells are fixed to the pipe, said rocker handle at the upper hinge (57') being shaped as an eccentric cylinder in such a manner that the smallest portion of the cylinder faces the upper lip (59') when the handle is open and the largest portion faces said lip when it is closed, whereby the handle in the closed state presses the size of the shells into a reduced size or the same size as the uppermost step with the result that the fastening is carried out.

3. A ladder combined wim tirree different transport functions according to one of the claims l or 2, c h a r a c t e r i s e d in that knobs of a moderately soft material are secured at die outermost rim of the four side members of the two ladder sides, whereby said knobs can assist in fastening the ladder sides when the blade according to claim 1 has been lowered. 20

4. A ladder combined with three different transport functions according to one of the above claims, characterised in that die bar (18) connecting the locking piston (19a) and de clamp (12) is shaped such mat said bar does not extend directly from the outermost disk (11) to the centre of die clamp (12), but instead is shaped wi a bridge connecting the portion of die bar just projecting from the outermost disk with de portion of said clamp only just projecting from the same disk, whereby the clamp opening is not interrupted by a transverse bar.