DE29510702U1 - Track roller, in particular steering roller - Google Patents

Description

Castor, especially swivel castor

The invention relates to a castor, in particular a steering castor with a wheel fork, a running wheel and a locking device for blocking the running mobility of the running wheel and/or the pivoting mobility of the wheel fork, wherein the locking device has a foot lever and a brake lever having a braking section, which are each pivotally mounted and pre-tensioned into their release position, wherein the foot lever has an eccentric which interacts with an actuating section of the brake lever in a braking division.

A roller of this type is known from DE-PS 35 33 207. Here, a pivoted foot lever is provided, which has an eccentric-type actuating cam. The latter acts on a brake lever on the top, which is also pivoted. A basic position, i.e. a release position of the running wheel and the wheel fork, is supported by spring action. For this purpose, two springs are provided, one spring being a torsion spring which acts on the foot lever in the direction of the basic position or the loose position. A second spring is provided on the rocker-like brake lever, namely on the end of the swivel joint opposite the actuating section. For this purpose, a tongue is cut out of the brake lever, which is bent out to form a leaf spring-like return spring. The latter causes a spring preload of the brake lever in a basic position. The brake lever has means for blocking the running mobility of the running wheel and the pivoting mobility of the wheel fork. By operating the foot lever in a blocking position, the brake lever is moved via the eccentric that interacts with the actuating section

VGN: 251 712 21 792 Mü./Pa./üD 28.06.1995

tilted in such a way that a braking projection, which is arranged on the arm of the brake lever that has the actuating section, comes into contact with the running surface of the wheel and tooth segments on the free end opposite the actuating section enter into a corresponding locking toothing. The braking position is defined by an over-center position of the foot lever.

A roller of this type is also known from DE-PS 59 580. Here, the rotary mobility of the foot lever is provided by arranging the lever in a joint socket. The latter is formed by a spring-loaded brake lever on the trailing side of the roller. Here, too, the locking device is preloaded in the direction of a basic position, i.e. a loose position, for which a leaf spring is provided, which applies pressure to the brake lever accordingly. The brake lever is designed like a rocker, with a bar on the one hand of the swivel joint for engaging in a toothed fixed ball bearing shell and a braking section for applying pressure to the running surface of the wheel on the other. By operating the foot lever, the rocker-like brake lever is applied on the top in the area of the arm with the braking section, which pivots it into the corresponding braking position. This results in the bar simultaneously pivoting into the toothed ball bearing shell to block the swiveling mobility of the wheel fork, counteracting the force of the leaf spring. The braking position is also defined here by the over-center position of the foot lever. The latter does not have its own return spring.

The object of the invention is to provide a generic castor, in particular a swivel castor, with a locking device

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direction which is structurally simplified, without affecting the functional reliability of the castor or swivel castor.

The problem is solved by the invention specified in the main claim.

The subclaims represent advantageous further developments.

As a result of such a design, a generic castor, in particular a steering castor, is provided in a simplified design. This is achieved in that the eccentric moves the braking section, deflected via a rotary bearing of the brake lever, into the braking position by applying pressure to the actuating section from below. The foot lever and brake lever are rotatably mounted in the area of a roller housing between the wheel forks, the arrangement preferably being such that the running mobility of the wheel and/or the pivoting mobility of the wheel fork is provided in a basic position. The foot lever is arranged in such a way that its eccentric supports the actuating section of the brake lever. This basic position can be defined by a stop, for which purpose the foot lever has, for example, a stop shoulder which presses against the base of the wheel fork. Furthermore, the foot lever is preferably designed so that it protrudes from the roller housing on one side to form a foot actuating section. By applying pressure to this free end, the foot lever is rotated in such a way that the eccentric pushes against the actuating section of the brake lever from below and thus rotates the brake lever into a braking position. To block the running mobility of the wheel,

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the brake lever, which is preferably designed like a rocker, can have a brake projection arranged on the end area opposite the actuating section. This design of the locking device is preferred for soft wheel variants, in which in the blocking position the blocking projection of the brake lever engages deeply into the running surface of the wheel and presses it in accordingly. The blocking position is defined according to the invention by an over-center bearing of the foot lever and can only be released by force. In a preferred design, a blocking pin is provided on the actuating section of the brake lever to block the pivoting mobility. In a further design, two actuating sections are provided, which in a blocking position engage in a correspondingly shaped, fixed toothing of a ball bearing shell of a back bearing. The blocking pins can for example be molded onto the brake lever in the same material. Furthermore, these can also be formed by slots being formed on both sides of each blocking pin, whereby the area remaining between the slots is pressed out to form the pins. In order to keep the braking forces equal both in the direction of travel and against the direction of travel, it is also provided that the braking section acts on the wheel essentially in a vertical extension of the axis of rotation of the wheel. Contrary to the previously mentioned prior art, in which the locking device for blocking the wheel's mobility acts on the trailing side of the wheel, the invention stated preferably brakes above the wheel center. A further development solution is furthermore such that the brake lever is designed to run essentially straight in the longitudinal direction.

VGN: 251 712 21 792 Mü./Pa./UD 28.06.1995

This means that the brake lever can be manufactured in a simple manner. For example, such a brake lever can be a stamped part. However, it is preferred to design the brake lever in such a way that it is Z-shaped, whereby this Z-shape of the brake lever's length is only slightly indicated. A design is preferred in which the pivot bearing of the brake lever is provided in the middle section of the Z-shape. The areas extending from this section on both sides are designed as a braking section and as an actuating section. To increase the stability of the brake lever, it is proposed that the brake lever consists of a flat part with an angled edge. This can be manufactured in a technically simple manner. For example, the longitudinal edges of a stamped sheet steel part can be angled in such a way that a U-shaped brake lever is formed in cross-section. It is particularly advantageous that the angled edges are formed approximately in the middle of a hinge eyelet. The latter serve to pass through a rotational axis mounted in the fork legs of the wheel fork, around which the brake lever is pivotably mounted. To compensate for tolerances, it is also provided that the hinge eyelet is designed like an elongated hole. A design is preferred in which the hinge eyelet is designed with an open edge towards the top, i.e. towards the base of the fork. As already indicated, an advantageous design of the subject matter of the invention provides that the brake lever is U-shaped in the area of the hinge axis as well as in its braking section and in its actuation area, with U-legs pointing downwards. The clear distance between these U-legs is so

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dimensioned so that in a blocking position of the running mobility of the wheel these U-legs step sideways next to the wheel without touching it. It is also proposed that the foot lever and the brake lever are acted upon by a common spring. This means that in the simplest way both the foot lever and the brake lever are spring-loaded in a basic position, i.e. in a loose position. For this purpose it is proposed that the spring is a coil spring. Finally it is provided that the coil spring is mounted on a rotation axis of the foot lever by wrapping around it and one spring leg grips under the foot lever and a second leg running in the opposite direction grips under the brake lever. Due to this design as a coil spring, the two legs act in opposite directions. The foot lever is held in a basic position by means of one spring leg, in which it is supported by a stop, as already mentioned. Furthermore, the basic position of the brake lever is defined by the fact that both the blocking pin and the braking section are ineffective, whereby a stop limit can also be provided here. In a blocking position of the running mobility of the wheel and/or the swivel mobility of the wheel fork, the foot lever remains in an over-dead center position. To release this blockage, only a slight swiveling back of the foot lever is necessary, since after the over-dead center position is released, the coil spring comes into effect and moves the foot lever and the brake lever into the basic position. Due to the details of the invention described above, a locking device for castors, in particular swivel castors, is provided, which has few components that are also easy to manufacture. In addition, this locking device has low switching forces at high

VGN: 251 712 21 792 Mü./Pa./UD 28.06.1995

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braking forces. This is due to favorable lever arms. Preferred is a design with a combined blocking of the running movement of the wheel and the swiveling movement of the wheel fork. However, this design can be used equally advantageously for the individual case, for example for simply blocking the running movement or the swiveling movement of the wheel fork.

The subject matter of the invention is explained in more detail below using an exemplary embodiment illustrated in the drawing. It shows:

Fig. 1 A perspective view of a castor designed as a steering roller in a brake/rotation release position,

Fig. 2 the castor according to Fig. 1 in a
Front view,

Fig. 3 the section along the line III-III in Fig. 1,

Fig. 4 is a detailed view of a foot lever in a plan view,

Fig. 5 the section along the line V-V in Fig. 4, Fig. 6 the section along the line VI-VI in Fig. 4,

Fig. 7 a detailed view of a brake lever,
also in plan view,

Fig. 8 the section along the line VIII-VIII in
Fig.7,

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Fig. 9 the section along the line IX-IX in Fig. 8, Fig. 10 the section along the line X-X in Fig. 8, Fig. 11 the section along the line XI-XI in Fig. 8,

Fig. 12 is a perspective view corresponding to Fig. 1, but relating to the braking/rotation blocking position,

Fig. 13 is a representation corresponding to Fig. 2, but concerning the blocking position according to Fig. 12 and

Fig. 14 shows the section along the line XIV-XIV in Fig. 12.

Shown and described with reference to Fig. 1 is a castor 1, which can usually be assigned to an object, for example a piece of furniture, a shelf, a tripod, a scaffold or even a hospital bed.

The swivel castor 1 supports a running wheel 2. Its horizontal geometric axis x-x is offset from a geometric axis y-y, which allows the swivelling of the swivel castor 1 and thus extends vertically.

The horizontal axis x-x formed by a bolt 3 originates from the legs 4 of a wheel fork 5. Its upper fork base 6 forms a roller housing 7.

The fork base 6 of the wheel fork 5, which is designed as a ring part, is pivotally mounted between an upper ball bearing 8 and a lower ball bearing 9. The bearing

VGN: 251 712 21 792 Mü./Pa./UD 28.06.1995

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ring 10 of the upper ball bearing 8 forms with its periphery a mounting plate 11 for attachment to an object. The usual fastening holes are marked with the number 12.

The lower end of the roller housing 7 is formed by a lower bearing ring 13. The upper bearing ring 10 and the lower bearing ring 13 are centrally held, centered and secured against rotation relative to one another by a pin 14 screwed on both sides.

Between the fork base 6 and the circumferential surface 15 of the wheel 2, an intermediate space 16 is formed in which a locking device E is arranged.

Components of this locking device E are a foot lever 17, a brake lever 18 and a coil spring 19 acting on these two levers.

The foot lever 17 is shown in individual representations or sections in Figures 4 to 6. It is essentially made up of a smooth base plate 20 and a trigger section 21 extending from this plate 20, as shown in Figure 6, which is angled upwards and forms an angle alpha of 45 degrees to the plate. The trigger section 21 is formed by simply bending a free end of the base plate 20.

The free end region of the base plate 20 opposite the trigger section 21 is designed as a foot actuation section 22, the latter having a greater width than the base plate 20 in a projection of the foot lever 17 according to Figure 4. The transition

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from base plate 20 to foot actuation section 22 is softly rounded.

Starting from the transition area of the foot actuation section 22 to the base plate 20 up to the free end in the area of the trigger section 21, the foot lever 17 is U-shaped in cross section (see Fig. 5). The U-legs 23 formed here serve to increase the stability of the foot lever 17 and have holes 25 in the angled areas 24 assigned to the trigger section 21 for the passage of a hinge axis 26.

The mentioned areas 24 of the U-legs 23 in the area of the angled trigger section 21 also form an eccentric 27 that protrudes beyond the free end of the trigger section 21. The latter is designed in the form of a rib, with the edges of this rib being rounded.

Approximately in the middle of the foot lever 17 there is a stop rib 28 formed by a cut-out section that is angled upwards at a right angle.

The mentioned brake lever 18 is shown in Figures 7 to 11 in various representations and sections. It can be seen in particular from the longitudinal section in Fig. 8 that the brake lever 18 - viewed in the longitudinal direction - is essentially slightly Z-shaped. Here, starting from a uniformly formed central section 29, a blocking section 30 on the one hand and an actuating section 31 on the other hand are formed. The blocking section 30 is, as can be seen from Fig. 8, slightly bent upwards, enclosing an angle Beta to

VGN: 251 712 21 792 Mü./Pa./UD 28.06.1995

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the middle section 29 of approximately 12 degrees. The actuating section 31 is correspondingly angled downwards, whereby the angle Gamma enclosing the area between the actuating section 31 and the middle section 29 is equal to the angle Beta.

The brake lever 18 essentially consists of a flat part with an angle. In concrete terms, this means that the brake lever 18 is U-shaped in cross section, with U-legs 32 pointing vertically downwards from the longitudinal edges of the various sections 29 to 31. This design serves to increase the stability of the brake lever 18. In the area of the middle section 29, hinge eyes 32 in the U-legs 32 are formed, which are open at the top, i.e. in the direction of the middle section 29. A hinge axis 34 passes through these hinge eyes 33 when the brake lever 18 is in the installed position.

A braking section 35 is formed on the free end region of the blocking section 30. The latter has a semicircular shape in cross section, with the curve formed thereby pointing downwards.

In the area of the actuating section 31, stop shoulders 36 are formed in the respective gusset of the U-profile. These are formed by a cut-out, inwardly pressed section of the actuating section 31 (see Fig. 10).

Furthermore, blocking pins 37 are provided on the actuating section 31, which are also secured by corresponding free cuts and then pushed upwards.

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sections of the brake lever 18 are formed (see Fig. 11).

The structure of the brake lever 18 is designed symmetrically, wherein the axis of symmetry z-z in the installed position of the brake lever 18 is aligned in a projection perpendicular to the axis of rotation x-x of the impeller 2.

The blocking pins 37 are positioned in the area of the actuating section 31 in such a way that they enclose an angle delta of approximately 10 degrees to an imaginary axis aligned perpendicular to the axis z-z.

The width of the brake lever 18 measured perpendicular to the axis z-z is dimensioned such that the foot lever 17 can be accommodated in the space formed between the U-legs 32. The brake lever 18 thus has a greater width than the foot lever 17, at least in the area of the base plate 20.

The brake section 35 formed on the blocking section 30 has a smaller width than the actual brake lever 18. This width can, for example, correspond to the wheel width.

Figure 3 shows a sectional view of the installation state of the previously described individual parts in the intermediate space 16 of the wheel fork 5, namely in a position in which the wheel fork 5 and the impeller 2 are released.

As already mentioned, the foot lever 17 is mounted on a hinge axis 26 and the brake lever 18 on a further hinge axis 34. These hinge axes 26 and 34 are mounted in corresponding holes in the

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Wheel fork legs 4 and thus extend transversely between the legs 4 through the gap 16,

The arrangement is such that the hinge axis 34 of the brake lever 18 is positioned on the side of the pivot axis y-y facing the rotation axis x-x of the wheel 2 and the hinge axis 26 of the foot lever 17 is positioned on the side facing away from the axis x-x. In addition, the two hinge axes 26 and 34 are arranged offset from one another in terms of plane, in such a way that the hinge axis 26 of the foot lever 17 is at a lower level than the hinge axis 34.

In this position, the foot lever 17 engages under the actuating section 31 of the foot lever 18 in the area of its trigger section 21, whereby the trigger section 21 is surrounded by the U-legs 32 in the area of the actuating section 31. The free end section of the trigger section 21 acts on the underside of the actuating section 31.

The foot actuation section 22 protrudes freely from the gap 16 of the wheel fork 5 for actuation.

In this basic position, the brake lever 18 is positioned such that the middle section 29 is held approximately horizontally.

The brake lever 18 and the foot lever 17 are jointly acted upon by the coil spring 19, whereby the coil spring 19 is mounted on the hinge axis 34 of the foot lever 17, which is formed as a rotation axis, and wraps around it. Spring legs 38 and 39 extend from this coil spring 19 in opposite directions, whereby the spring leg 38 presses the foot lever 17 in the area of its

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release section 21 and the spring leg 39 engages under the brake lever 18 in the area of its blocking section 30.

Accordingly, the foot lever 17 and the brake lever 18 are always pre-tensioned in a release position, whereby in Fig. 3 the pre-tensioned direction of rotation of the foot lever 17 is marked with the arrow a and that of the brake lever 18 with the arrow b. From this it can be seen that the pivoting directions of the two levers are opposite.

The basic position shown is defined by a stop limit. This is formed by the fact that the foot lever 17 with its stop rib 28 comes into contact with the fork base 6 on the underside. A further pivoting of the foot lever 17 in the direction of arrow a is therefore not possible. Due to the opposite direction of action of the brake lever 18, the brake lever 18 is supported in the area of the actuating section 31 with its underside against the release section 21, which also defines this basic position.

In this position, the braking section 35 floats freely above the circumferential surface 15 of the impeller 2. Furthermore, the blocking pins 37 are located at a distance below the lower bearing ring 13 provided with a blocking gear ring 40.

In order to achieve a blocking position of the running mobility of the running wheel 2 and the pivoting mobility of the wheel fork 5, it is necessary to actuate the foot lever 17 in the area of its foot actuation section 22 in the direction of arrow P. This is preferably done by foot actuation.

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The resulting blocking position is shown in Figures 12 to 14.

By operating the foot lever 17 in the direction of arrow P, it is pivoted in the direction of arrow a', whereby the eccentrics 27 assigned to the release section 21 act on the underside of the actuating section 31 of the brake lever 18 in such a way that it pivots in accordance with arrow b'. The blocking position is fixed after an over-dead center position is exceeded.

In this position, the eccentrics 27 have come into contact with the stop shoulders 36 of the foot lever 18, which means that further pivoting of the foot lever 17 is not possible.

The pivoting of the brake lever 18 that accompanies the pivoting of the foot lever 17, in each case against the spring force of the coil spring 19, causes a displacement of the brake section 35 in the direction of the running surface 15 of the wheel 2 and the blocking pin 37 in the direction of the blocking gear ring 40. After reaching the blocking position, the blocking pin 37 engage in the gear ring 40 in such a way that the pivoting mobility of the wheel fork 5 is blocked.

As can be seen from Figure 14, the braking section 35 acts essentially in a vertical extension of the axis of rotation x-x of the impeller 2, whereby the braking section 35 slightly presses in the circumferential surface 15 of the impeller 2.

Because braking occurs above the wheel center, the braking forces are the same both in the direction of travel and against the direction of travel.

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It is also conceivable _{to have} a design in which the brake lever 18 is designed such that the brake section 35 merely blocks against the peripheral surface 15 of the wheel 2.

As already mentioned, the blocking position is self-locking. It can only be released intentionally by applying release forces in the direction of arrow P'. This can be done, for example, by pulling on the foot lever 17 on the underside of the foot actuation section 22 using the tip of the foot.

The activation of the actuation must only take place until the over-dead center position is undershot, since after this the restoring force of the coil spring 19 comes into effect, which in turn swings the two levers back into the basic position, i.e. into the loose position.

The locking device E shown can also be used perfectly with a wide variety of wheel diameters.

Preferably, the locking device E described comprises the combined blocking of the running mobility of the wheel 2 and the pivoting mobility of the wheel fork 5. However, the locking device E can be used equally advantageously for individual cases, for example for merely blocking the running mobility of the wheel 2 or the pivoting mobility of the wheel fork 5.

All disclosed features are essential to the invention. The disclosure of the application hereby also includes the disclosure content of the associated/attached prior art.

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The patent application documents (copy of the prior application) are included in their entirety, also for the purpose of incorporating features of these documents into the claims of the present application.

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Claims (12)

&idigr; * Claims 1. Castor, in particular a steering castor (1), with a wheel fork (5), a running wheel (2) and a locking device (E) for blocking the running mobility of the running wheel (2) and/or the pivoting mobility of the wheel fork (5), the locking device (E) having a foot lever (17) and a brake lever (18) having a braking section (35), each of which is pivotally mounted and pre-tensioned into its release position, the foot lever (17) having an eccentric (27) which interacts with an actuating section (31) of the brake lever (18) in a braking position, characterized in that the eccentric (27) moves the braking section (35) into the braking position by applying pressure to the actuating section (31) from below, deflected via a pivoting bearing of the brake lever (18). 2. Castor according to claim 1 or in particular according thereto, characterized in that a blocking pin (37) for blocking the pivoting mobility is provided on the actuating section (31) of the brake lever (18). 3. Roller according to one or more of the preceding claims or in particular according thereto, characterized in that the braking section (35) acts on the running wheel (2) essentially in a vertical extension of an axis of rotation (x). 4. Roller according to one or more of the preceding claims or in particular according thereto, characterized in that the brake lever (18) is designed to run essentially straight in the longitudinal direction. VGN: 251 712 21 792 Mü./Pa./UD 28.06.1995 5. Roller according to one or more of the preceding claims or in particular according thereto, characterized in that the brake lever (18) is Z-shaped. 6. Castor according to one or more of the preceding claims or in particular according thereto, characterized in that the brake lever (18) consists of a flat part having an angled edge. 7. Roller according to one or more of the preceding claims or in particular according thereto, characterized in that the bend forms a hinge eyelet (33) approximately in the middle. 8. Roller according to one or more of the preceding claims or in particular according thereto, characterized in that the hinge eyelet (33) is designed like an elongated hole. 9. Castor according to one or more of the preceding claims or in particular according thereto, characterized in that the brake lever (18) is U-shaped in the region of the hinge axis (34) as well as in its braking section (35) and also in its actuating section (31), with U-legs (32) pointing downwards. 10. Castor according to one or more of the preceding claims or in particular according thereto, characterized in that the foot lever (17) and the brake lever (18) are acted upon by a common spring. 11. Roller according to one or more of the preceding claims or in particular according thereto, characterized in that the spring is a helical spring (19). VGN: 251 712 21 792 Mü./Pa./UD 28.06.1995 12. Castor according to one or more of the preceding claims or in particular according thereto, characterized in that the helical spring (19) is mounted on a rotation axis (26) of the foot lever (17) by wrapping around the same and a spring leg (38) engages under the foot lever (17) and a second leg (39) running in the opposite direction engages under the brake lever (18). VGN: 251 712 21 792 Mü./Pa./UD 28.06.1995