DE9108969U1 - Braked swivel castor - Google Patents

Description

'ernstr. 21
5400 KOBLENZ

Description^

The invention relates to a braked castor, with a castor housed in a fork pivotably mounted in a bearing about an approximately vertical axis, the castor axis being arranged at a distance from the axis of rotation of the fork, with a brake rocker arranged between the fork legs, which is pivotably mounted between the fork legs and has an engagement section facing the castor, which comes into braking engagement with the outside of the castor when the brake rocker is pivoted, with a directional lock for locking the fork in the steering position on the trailing side of the castor.

Castors are used to make a wide variety of transport trolleys or frames mobile. In order to achieve mobility, it is important that the fork in which such castors are mounted can rotate easily so that the frames or transport trolleys can be easily maneuvered in the smallest of spaces and that the roller in the fork can rotate easily. For example, such trolleys should fill corners and angles in storage rooms, parcel rooms, supermarkets or in road or rail vehicles as precisely as possible and thus save space. To do this, they must be able to be moved there.

The easy mobility of the frames or trolleys fitted with castors is, however, a major nuisance once these devices have been parked. They must then remain stationary instead of moving easily in all directions. With heavily loaded trolleys,

This can become a serious safety issue even on level ground, not to mention the associated handling problems.

For this reason, braked castors have become known, for example according to the generic term GM - 74 39 939, in which the castor can be braked and the swiveling mobility of the fork of the castor can be locked at the same time. This is done using a brake arm that is operated by a foot lever. This is located on the swiveling part of the fork that is far from the fork bearing, the trailing side of the castor. When the foot lever is operated, the castor is simultaneously braked and the swiveling mobility of the fork is locked by means of the brake arm. The fork is locked by an angled bar on the brake arm that engages in a toothing on the fixed inner part inside the fork bearing.

This locking mechanism has the disadvantage that relatively large forces act on the fork locking mechanism because the locking elements for the fork, the teeth on the fixed inner part within the fork bearing and the angled bar engaging in it are arranged relatively close to the rotation axis of the fork. The twisting torques, on the other hand, act with a larger lever arm, the distance between the roller axis and the fork axis. Furthermore, the locking mechanism of the roller cannot be operated centrally by a rod for several swivel castors at the same time because the brake arm is operated on the trailing side on the swivel castor side. The trailing side and with it the operating lever for the roller braking and swivel locking each swivel around the fork axis at will, so that this must be searched for. This

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The known, combined locking devices are only suitable for foot operation. They are not accessible for rod operation or pressure medium operation.

At the same time, the locking fork and the braking of the castor cannot be operated independently and centrally by a rod for several castors at the same time.

Another disadvantage of the known swivel castor is that the actuating end (foot lever) of the brake or locking arm, its swivel bearing and the braking surface are located relatively close to one another and on one side of the fork of the swivel castor, namely the forward side. This means that considerable forces must be applied during the braking process in order to achieve sufficient braking effect, with part of the braking force automatically being used up by the fork lock and the forces not being able to be dosed independently of one another in any way. In addition, with the known braked swivel castor, a long actuating path must first be covered before the brake takes effect.

Furthermore, a swivel castor has become known from the utility model 91 03 536.8, which has a significantly improved directional lock, which consists of a rigidly connected to the mounting plate of the swivel castor and by means of a

a stationary pressure cylinder that can be pressurized with a pressure medium, in which a piston that can be set under the pressure of the pressure medium is arranged so that it can be displaced longitudinally against the pressure of a return spring, which carries a piston rod, the free end of which emerges through an opening in the pressure cylinder and acts as a locking bolt

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is designed. When actuated, this locking bolt either engages in a locking hole on the castor fork or the mounting plate or can be moved to an unlocking position. This castor, whose directional lock can be advantageously activated by central actuation, does not, however, have a braking device for the castor.

The aim of the innovation is, based on the state of the art mentioned at the beginning, to create a swivel castor that has a simple braking device that can be operated independently of the steering fork locking mechanism, is easy to operate and achieves optimum effectiveness. In addition, it should also be suitable for being operated centrally by a rod or a pressure medium.

This task is solved by an independent brake swing (brake lever) working from a directional lock, which extends around a pivot line (bearing bolt) between the fork arms on the rear side of the castor and parallel to the castor axis, that an actuating part (actuating bolt) movable transversely to the brake swing (brake lever) is arranged in the vertical pivot axis of the castor, which can be pressed against an actuating point on the side of the brake swing (brake lever) opposite the pivot line (bearing bolt) in such a way that the latter can be pressed with its engagement section against the castor into braking engagement, and that a spring is arranged between the castor fork and the brake swing (brake lever) and pivots the latter away from the castor with the engagement section, and that the actuating point on of the swivel line

(bearing pin) remote side of the engagement section is arranged at a distance from it.

The actuating bolt, which is mounted in the vertical swivel axis of the fork and acts on the brake arm, enables central actuation of the steering roller lock by means of a rod or a pressure medium due to its fixed position in the rotation axis of the fork. The steering roller fork can now swivel as desired, the actuation for the castor brake always remains in the same place. At the same time, there is enough space to retain the well-known and proven directional lock.

According to the invention, the brake lever is now extended beyond the engagement section, so that the distance between the actuating point and the pivot line is greater than that between this and the engagement section, and thus a lever ratio is effective, due to which the braking force effective between the engagement section and the roller is considerably greater than the actuating force applied to the brake lever by the actuating part at the actuating point.

Thus, according to the invention, a braking device is provided which is considerably smoother than that of the known swivel castor and nevertheless provides a high braking force.

In order to achieve a particularly long brake lever, it is basically possible to arrange the swivel line in front of or behind the roller; in this case the brake lever overlaps or surrounds the roller.

However, such a design would require a considerably longer roller fork; for this reason, it is particularly advantageous in the swivel castor according to the invention to arrange the swivel line between the roller and the fastening plate.

The pivot line does not have to be fixed relative to the roller fork, but can be formed by the generatrix of a curve along which it moves when the brake lever is pivoted.

According to the invention, the brake lever

Axle stubs aligned on both sides

which are seated in bearing bores that are made in the fork I leg I.

This design is on the one hand particularly simple, on the other hand the swivel bearing is protected from dirt by the fork I legs I, so that it remains smooth during the service life of the fixed castor according to the invention and therefore requires only a relatively low force from the spring, which in turn means that the entire brake is smooth. This is especially true if, as mentioned below, the spring loading the brake lever is quite strong because it also has to lift a brake rod into its ready position.

The actuating part can basically be designed as the end of a rocker arm or the piston of a pressure cylinder; according to the preferred embodiment of the invention, however, the actuating part is designed as an actuating bolt which is slidably guided in a sliding guide that passes through the fastening plate.

91 08 369.

In principle, it is also possible to assign a separate return spring to the actuating bolt, whereby an end stop can then also be provided for the brake lever, which holds it in its ready position.

According to the preferred embodiment of the invention, however, it is particularly advantageous that the brake lever, when loaded by the spring, in turn raises the actuating bolt, which can be moved upwards and downwards in its longitudinal direction, into its ready position, or pushes back an actuating part that may also be arranged diagonally or horizontally; this not only saves another spring, but also makes the entire mechanism smoother, since when two springs are coordinated, a slightly increased restoring force must always be accepted in favor of operational safety.

According to the preferred embodiment of the invention, however, it is particularly advantageous to use a wound leg spring as the spring, as is used in a similar form in clothespins, and to arrange it with its wound section on the leg axis.

This creates a reliable spring mount without any additional design or even an additional part, which is sufficient even for a spring as strong as is required when it has to press the entire brake linkage into the ready position together with the actuating bolt.

It is basically possible to design the spring as a tension spring, which is in some ways even advantageous, since the pivot axis can then be brought up to the vertical edge of the roller fork, which results in a particularly long brake lever and thus a high transmission of the actuating force.

According to the preferred embodiment of the invention, however, it is particularly advantageous to design the leg spring as a compression spring that engages between the extension of the brake lever and the fastening plate. This avoids the structurally complex engagement of these two elements that is required with a tension spring.

According to the invention, however, it is particularly advantageous to form the leg spring from two adjacent partial springs that are wound in opposite directions, so that their two leg ends acting on projections (riveted bolts) arranged on the inside of the fork leg I &eegr; lie next to each other at the same height. These leg ends are held securely on the projections (bolts) by collars.

The other leg ends of the two springs are connected to one another by a cross wire which is supported under the brake arm in a transverse groove formed for this purpose and thus keeps the two partial springs at a distance and also fixes their position. This arrangement achieves a considerable saving in space in the vertical direction, which leads to extremely short actuation paths for the brake in the braking device according to the invention.

What is particularly important, however, is that any transverse forces acting in a direction other than in a radial plane to the pivot line of each of the partial springs cancel each other out due to their opposing design. This means that no force occurs that, for example, presses the brake lever against the inner surface of a fork leg and thus causes friction and impairs the smooth operation of the brake mechanism.

The brake lever can be designed as a solid component or in a box construction for the purpose of special bending rigidity.

According to the preferred embodiment of the invention, the brake lever is designed like a U-beam, whose U-recess, delimited by two side legs I η, is open at the bottom. This design gives the brake lever a high degree of flexural rigidity.

The side legs can extend over the entire length of the brake lever with a constant height, as with a U-beam, but according to the invention they are preferably triangular, with the greatest height of the side legs being in the area of the pivot axis. The side legs extend beyond the engagement section. A side leg thus begins where a high bending moment sets in on the brake lever and increases in height as the bending moment increases. This design prevents the brake lever from springing back under load and thus lengthening the actuation path. The entire actuation path is thus used to bring the engagement section closer to the roller, so that a particularly large lifting ratio can be selected for the brake lever.

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can, since no significant lost motion occurs when converting the actuation path into the braking path.

The brake lever can be designed as an investment casting

but is preferably as a bent sheet metal part

which further simplifies the structure.

The engagement section can be designed according to the outer contour of the roller and adapted to it; thus, in the case of a roller with flat tapered rim edges, the engagement section can have a rectangular or trapezoidal recess which clamps itself onto the rim edges after only a small pressure force is applied.

According to the preferred embodiment of the invention, however, the engagement section is adapted to a roller, as shown in the above-mentioned publications, with an approximately circular cylindrical running surface against which the engagement section can be pressed. This has crossbars protruding towards the roller, so that when the brake is actuated, not only is a friction force created between the outer circumference of the roller and the engagement section, but these parts also hook into one another when the crossbars are pressed into the flexible material of the running surface of the roller. The braking effect is thus further improved for a given braking force and the brake therefore operates even more smoothly.

According to the design according to the invention, the brake rocker (brake lever) is cranked in the area of the spacer of the spring in such a way that a part of it surrounds the outer circumference of the brake roller with a small, tangential distance and

at the same time, it is located a short distance below the actuating plate of the roller fork when the brake is in the release position, while the other part of the brake lever is located a short distance from the actuating bolt and runs approximately parallel to the actuating plate. The advantage of this design is that it also ensures extremely short actuating paths for the brake. Furthermore, it ensures that if for any reason the force introduced into the brake lever via the brake rod at the actuating point is unusually high, so that the brake lever tends to give in to this load, it then immediately rests against the outer circumference of the roller and thus cannot be subjected to any further load, which could otherwise possibly cause it to bend.

Preferably, the surface of the actuation point facing the actuating part of the brake rocker (brake lever) is designed so that it extends transversely to the actuating direction of the actuating part; transverse forces that could load the actuating part transversely to its direction of movement cannot be applied to the actuating part, which can therefore be constructed less rigidly and thus more simply. Due to the absence of friction caused by such transverse forces that inhibits the movement of the actuating part, the brake arrangement according to the invention is even smoother.

Depending on the available actuation path, the permissible tolerances and the required path of the engagement section, which depends on the flexibility of the running layer of the roller, the transmission ratio of the brake lever according to the invention can be optimized.

In order to achieve a particularly smooth-running brake, in an advantageous embodiment of the invention, the distance between the center of engagement of the actuating part at the actuation point and the center of engagement of the engagement between the engagement section and the roller should be at least as large, preferably twice as large or possibly even larger than the distance between the latter center of engagement and the pivot line. A double distance has proven to be particularly useful, whereby a tripling of the braking force is achieved, compared to the actuating force. A larger distance can be even more advantageous up to a limit dependent on the boundary conditions described above (actuation path, necessary path of the engagement section, tolerances).

The invention is explained in more detail below using an exemplary embodiment shown in the drawing. It shows:

Fig. 1 - an embodiment of a swivel castor according to the invention, cut lengthwise, brake arm released,

Fig. 2 - the inventive design of the

Castor wheel according to Fig. 1 cut lengthwise, brake arm in braking position and

Fig. 3 - an inventive design of the swivel castor according to Fig. 1 and 2 in front view.

The drawings show in Fig. 1 to 3 a steering roller 1 with a roller 2, which is in a roller fork 3

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is housed. The roller fork 3 consists of two parallel, vertical forks 3a, which are connected to one another on their top by a fastening plate 3b. As can be seen from Fig. 1 and 2, the roller fork 3 is made particularly simply and robustly from a punched and bent sheet metal part. It is mounted on a fork bearing 7 between two ball rings 4 and 5 so that it can rotate about a vertical axis 6. As is sometimes usual with such swivel casters, the swivel axis 6 of the roller fork 3 is at a certain distance from the roller axis 8 so that a stable steering behavior of the swivel caster 1 is established when the swivel caster 1 is in operation. In Fig. 1, an arrow is marked at 9, which indicates the trailing side.

The ball races 4 and 5 hold the roller fork 3 between the fork bearing 7 and a cover 11 held by a short bearing screw 10. The bearing screw 10 is penetrated by an actuating bolt 12. The actuating bolt 12 is mounted in the bearing screw 10 and can be moved axially in the bearing screw 10 without friction loss. In Fig. 1, the actuating bolt 12 is pressed upwards so that it emerges above the bearing screw 10. It can be pressed down there by a rod or by another actuating device.

A brake arm (= brake lever) 13 is arranged between the two fork legs 3a of the steering roller I I engabe I 3. It has legs 13b bent downwards at one end, which are attached to the side and with which it is pivotably mounted on the trailing side of the steering roller on the steering roller I I engabe I 3 by means of bearing bolts 15 arranged at the same height and which

together with the longitudinal plate 13a of the brake swing arm (brake lever 13) form an inverted U-cross section. The horizontal connecting line running through the middle of the two bearing bolts 15 forms the pivot line around which the brake swing arm (brake lever 13) can pivot.

The other end of the brake swing arm (= brake lever) 13 lies a short distance below the bearing screw. When the actuating bolt 12 in the bearing screw is pressed down by an actuating device (not shown) and emerges on the underside of the bearing screw 10, it actuates the brake swing arm (= brake lever) 13 by rotating the brake swing arm (= brake lever I) 13 around its bearing bolts and pressing the brake swing arm (= brake lever I) 13 downwards.

In Fig. 2, an actuated position of the brake rocker (= brake lever) 13 is shown. An engagement section 16 located between the bearing end with the bearing bolt 15 and the actuating end of the brake rocker (= brake lever) 13 applies braking force to the circumferential surface of the roller 2. The engagement section 16 is equipped with braking ribs 17 in order to improve the contact with the circumferential surface of the roller 2.

If the actuating bolt 12 is pressed downwards, it presses the brake rocker (= brake lever I) 13 downwards until the engagement section 16 engages the running surface of the roller 2 and brakes it. In this case, the distance between the vertical running through the center of the roller axis 8, i.e. through the engagement center of the engagement section 16, and the

The center axis of the actuating bolt 12 is approximately &zgr;white&eegr; ha Lbtimes as large (55 mm) as the distance between the vertical and the pivot line (bearing bolt 15) (22 mm). The pressure force with which the engagement section 16 is pressed against the running surface of the roller 2 is therefore approximately three times the actuating force applied downwards by the actuating bolt.

The brake rocker (= brake lever I) 13 is pressed into its released position by a spring 24. The spring is made up of two leg springs that are connected to one another by a spacer 25. The two leg springs are each supported with their free leg ends 24a, which are bent at an angle towards the roller axis 8, on projections 26 (e.g. riveted bolts) that are arranged on the inside of the fork legs 3a below the engagement section 16, close to the vertical line running through the center of the roller axis 8.

The two spring arms 24 are each wrapped with one turn around the riveted bearing pin 15 (= pivot pin).

The other leg of the leg spring 24 runs diagonally upwards and merges into the spacer 25, which forms the cross connection to the opposite leg spring and keeps the brake rocker (brake lever) 13 at a distance from the roller 2. With this spacer 25, the spring 24 rests under the brake rocker in a convex curve formed by the cranking of the same, whereby it holds the spring securely in position and transfers its restoring force linearly and evenly to the brake rocker (= brake lever I) 13.

A vertically operating directional lock 18 is arranged on a trailing-side, plate-shaped extension 27 of the upper bearing shell of the roller ring 4 of the fork bearing 7. For this purpose, the lower bearing shell of the roller ring 4 of the fork bearing 7 is also extended to form a trailing-side inlet plate 23 for a locking bolt 19 that is slidably guided in a sleeve 21.

The locking bolt 19 tapers conically towards its locking end and forms a cylindrical locking end 19a with a smaller diameter. The sleeve 21, in which the locking bolt 19 is guided so as to be longitudinally displaceable, is welded to the extended, upper bearing shell of the roller ring 4. Between the sleeve 21 and a projection 19b on the locking bolt 19, an annular space 28 is formed in which a spiral spring 20 is held and the locking bolt 19 with its locking end 19a in a matching recess 23a in the egg n I on &rgr; la11e 23, which in the embodiment is formed by a protrusion of the roller fork 3 on the rear side in the area around the recess for the roller, which is produced during the punching process. The locking bolt 19 can be moved into a raised unlocking position by applying a pulling force against the force of the spring 20, for which purpose the locking bolt 19 transitions into a lifting rod 22 at the end remote from the engagement and protruding above the sleeve 21.

The locking end 19a of the locking bolt 19 protruding downwards from the sleeve 21 falls into the recess 23a in the roller fork 23 when the fork is in the appropriate position and thus fixes the roller fork 3 in a specific pivoting position relative to the fork bearing 7.

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ALL individual and combination features presented in the claims, the description and/or the drawings are considered essential to the invention.

The scope of protection of the invention extends not only to the features of the individual claims, but also to their combination.

The invention is not limited to the embodiment shown and described. Rather, this represents only an advantageous embodiment.

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Claims (12)

Braked swivel castor with a castor housed in a fork that is pivotable about an approximately vertical axis mounted in a bearing, the castor axis being arranged at a distance from the rotation axis of the fork, with a brake rocker arranged between the fork legs, which is pivotably mounted between the fork legs and has an engagement section facing the castor, which comes into braking engagement with the outside of the castor when the brake rocker is pivoted, with a directional lock for steering locking of the fork on the trailing side of the swivel castor, characterized in that that a brake arm (brake lever 13) which works independently of a directional lock and which can be pivoted about a pivot line (bearing pin 15) extends between the fork arms (3a) on the trailing side of the steering roller and parallel to the roller axis (8), that an actuating part (actuating bolt 12) that is movable transversely to the brake rocker (brake lever 13) is arranged in the vertical pivot axis (6) of the steering roller, which can be pressed against an actuating point on the side of the brake rocker (brake lever 13) opposite the pivot line (bearing bolt 15) in such a way that the latter can be pressed with its engagement section (16) against the roller (2) in braking engagement and that a spring (24) is arranged between the roller fork (3) and the brake rocker (brake lever 13) and pivots the latter with the engagement section (16) away from the roller (2) and that furthermore the The actuation point is arranged on the side of the engagement section (16) remote from the pivot line (bearing pin 15) and at a distance from it. 2. Castor according to claim 1,
characterized, that the pivot line (bearing pin 15) is arranged between the roller (2) and the fastening plate (3b) connecting the upper ends of the fork legs (3a). 3. Castor according to one of claims 1 or 2, characterized in that that the pivot line is formed by the imaginary center axis of two bearing bolts (15) with which the brake rocker (brake lever 13) is pivotably attached to the fork arm (3a). 4. Castor according to one of claims 1 to 3, characterized in that that the actuating part is designed as an actuating bolt (12) which is guided in a sliding bore which passes through the bearing screw (10) of the castor (1) and is movable in its longitudinal direction. 5. Castor according to claim 1 to 4, characterized in that the brake rocker (brake lever 13) and spring (24) are designed in such a way that the actuating bolt (12) is pressed back into its sliding bore by the actuating point so that the actuating bolt (12) is pushed back into its starting position in the released position. 6. Castor according to one of claims 1 to 5, characterized in that that the spring (24) is designed in the form of two connected leg springs, which are seated by a spacer (25) on both sides of the brake rocker (brake lever 13), which form compression springs which, by means of their free leg ends (24a) directed obliquely towards the pivot axis 6, are supported on projections (26) which are in the area below the engagement section (16) of the brake rocker (brake lever 13) are arranged inside the fork legs (3a), and that the spacer (25) is supported at the point under the brake rocker (brake lever 13) where it is bent downwards and that furthermore the spring (24) is wound from wire. 7. Castor according to one of claims 1 to 6, characterized in that the brake rocker (brake lever 13) is designed as an elongated part with a substantially U-shaped cross-section, with a longitudinal plate (13a) and two side legs (13b), that the two side legs (13b) are penetrated by the pivot line (bearing pin 15) and have bearing holes which are pivotably seated on the bearing pin (15), and that the engagement section (16) is arranged on the side of the longitudinal plate 13a) facing away from the pivot line (bearing pin 15). 8. Castor according to claim 7,
characterized, that the side legs (13b) of the brake arm 91 OB9S9. (brake lever 13) seen in the direction of the pivot line (bearing pin 15), each have a substantially triangular cross-section, with the base running along the longitudinal plate (13a), the pivot line (bearing pin 15) sitting approximately on the inner center point and the legs intersecting the base at the end of the extension or at the end of the engagement section (16) apart from the pivot line (bearing pin 15). 9. Castor according to one of claims 7 or 8, characterized in that that the brake arm (brake lever 13) is designed as a bent sheet metal part. 10. Castor according to claim 9,
characterized, that the longitudinal plate (13a) on the The engagement section (16) has protruding engagement strips (17) extending approximately parallel to the pivot line (bearing pin 15) and which are embossed from the opposite side of the longitudinal plate (13a). 11. Castor according to one of claims 7 to 10, characterized in that that the longitudinal plate (13a) of the brake rocker (brake lever 13) in the released position between the side legs (13b) of the brake rocker (13) in the area between the side legs (13b) runs just below and parallel to the fastening plate (3b) or the inlet plate (23) and essentially horizontally and the longitudinal plate (13a) in the area of the actuation point behind the opposite crank is essentially horizontal and parallel and just below the nut of the bearing screw (10) of the swivel castor
extends when the brake arm
(Brake lever 13) is in the release position. 12. Castor according to one of claims 1 to 11, characterized in that that the distance between the actuation point and the engagement section (16) of the brake rocker (brake lever 13) is at least as large and
preferably about 2 1/2 times as large as the distance between it and the pivot line between the bearing pins 15.