GB2085103A

GB2085103A - Roller for a Manually Movable Trolley

Info

Publication number: GB2085103A
Application number: GB8130325A
Authority: GB
Original assignee: SCHULTE SOEHNE KG A
Current assignee: SCHULTE SOEHNE KG A
Priority date: 1980-10-08
Filing date: 1981-10-07
Publication date: 1982-04-21
Also published as: DE3138135A1; FR2491398A1; FR2491398B1; GB2085103B; DE3138135C2; CH635034A5

Abstract

Such roller has two independently rotatable running discs (6) with rims (7) designed to engage in longitudinal grooves (10) in an inclined conveyor belt, and an annular brake ring (8) which surrounds with clearance a cylinder (5) seated non- rotatably on a spindle (3), against which cylinder (5) the brake ring (8) is pressed with a frictional (e.g. Figures 1-3) positive connection (Figure 5) when the outer periphery of the brake ring (8) is seated on (a) rib(s) (11) of the conveyor belt since rib is greater than r-t (see Figure 3), to brake the roller. So long as roller is rolling on a flat floor, the brake ring (8) will hang on the cylinder without touching the cylinder (5) (Figure 1). In modifications:- the cylinder and the brake ring engage by V-shaped groove and rib (Figure 4); the ring is centered with respect to spindle by balls (Figures 6,7); the brake ring has a laterally extending flange (Figure 8) at its outer periphery. <IMAGE>

Description

SPECIFICATION Roller for a Manually Movable Trolley The invention relates to a roller for a manually movable trolley, particularly a shopping trolley, to be capable of being automatically braked while being conveyed on an inclined conveyor belt having a longitudinally grooved surface.

The roller comprises two independently rotatable running discs, each provided with a rim to engage in a respective groove in the conveyor belt, and a brake member which, when the rims are so engaged, is seated on at least one rib of the conveyor belt.

German Patent Specification 26 56 322 describes a roller of this kind with a brake member, the salient feature of which is that the brake member is fixed positively and rigidly to a roller mounting member between the two running discs. The roller carrying member is not constructed in the usual way, as a fork engaging around the roller, but instead extends between the discs so that the discs are exposed and unprotected from the outside. This construction also has the disadvantage that in the event of a change to conventional rollers the old roller and fork are useless.

It has also been proposed to provide a fork of conventional shape, and a supporting member seated non-rotatably on a spindle between the running discs, while the actual brake member is fixed to the supporting member at the bottom.

The torque applied to the supporting member by the braking action has to be introduced positively, e.g. via squares and square holes, first to the spindle and then to the fork. Thus the roller again cannot be fitted indiscriminately into any fork.

According to the invention, there is provided a roller for a manually movable trolley, to be capable of being automatically braked while being conveyed on an inclined conveyor belt having a longitudinally grooved surface, comprising two independently rotatable running discs, each provided with a rim to engage in a respective groove in the conveyor belt, and an annular brake ring which, when the rims are so engaged, is seated on at least one rib of the conveyor belt provided between the respective grooves and which is located between the running discs and has an outside diameter less than the outside diameters of the rims, the brake ring surrounding with a clearance a cylinder which is disposed nonrotatably between and coaxially with the running discs and the sum of the effective radius of the cylinder and the effective radial dimension of the annular ring being greater than the radius of each rim less the possible depth of engagement of the rims in the grooves.

To improve the frictional engagement it may be provided that, on their cooperating faces, one of the cylinder and the ring has a circumferentially extending groove of V-section therein and the other has a rib of V-section to engage in the groove.

In one advantageous embodiment of the invention, the outer peripheral surface of the cylinder and the inner periphery surface of the ring are toothed with a different number of teeth to one another, which teeth can roll over one another and can be engaged and disengaged by relative movement in a radial direction.

In another embodiment the roller includes means for centering the ring with respect to the roller spindle when the rims are no longer engaged in the grooves in the conveyor belt. Such means may comprise balls distributed evenly in a circle around the roller spindle and loosely located in apertures extending right through the ring, the balls projecting from the ring on both sides and being guided in grooves provided each in a respective one of the discs, concentric with the respective disc and on the side thereof facing the ring, the flanks of the grooves being resiliently deformable at least at one side.

Advantageously the ring has a laterally extending flange at its outer periphery, the width of the flange being nearly equal to the distance between the rims.

A roller according to the invention can be fitted in any one of many existing kinds of fork without observing any particular angular position, and the cylinder can be prevented from co-rotating simply by clamping friction at the prongs of the fork.

Even occasional accidental turning of the cylinder would not greatly affect the operation of the brake. A further advantage is that the brake member is loaded evenly over its whole periphery, and its life expectancy therefore can be much greater than that of the prior art brake member, which has a relatively small braking surface.

The invention is diagrammatically illustrated by way of example with reference to the accompanying drawings, in which: Figure 1 shows a roller according to a first embodiment of the invention, supported on a level floor, in a longitudinal section perpendicular to the plane of the surface; Figure 2 shows the roller of Figure 1 again in longitudinal section, supported on a grooved conveyor belt; Figure 3 is a diagrammatic side elevation of the roller of Figures 1 and 2, supported on an inclined conveyor belt, showing the geometrical relationships and the application of forces; Figure 4 is a longitudinal section through a second embodiment of a roller according to the invention, supported on a grooved conveyor belt, including a brake ring with an internal profile and a cylinder with an external profile;; Figure 5 is a longitudinal section through a third embodiment of a roller according to the invention supported on a grooved conveyor belt with a toothed brake ring and cylinder; Figure 6 is a longitudinal section through a fourth embodiment of a roller according to the invention, supported on a level floor, with balls of an axial bearing extending through apertures in the brake ring, between running discs; Figure 7 shows the same roller as Figure 6 but supported on a grooved conveyor belt; and Figure 8 shows a fifth embodiment of a roller according to the invention where the brake ring has an external flange.

In the example shown in Figures 1 to 3, a fork having a pair of prongs 1 joined by a web 2 mounts a spindle 3. The fork for the sake of simplicity is shown as a trestle type roller fork, although it could equally be a pivoting roller fork.

The spindle 3 extending between the prongs 1 of the fork is prevented from dropping out by screws 4 and prevented from turning by the frictional clamping action of the screws 4. The spindle 3 is fixed to or integral with a coaxial cylinder 5, and a respective running disc 6 with a rim 7 is mounted rotatably on the spindle at each side of the cylinder 5. An annular brake ring 8 surrounds the cylinder 5, with a clearance. The size of the brake ring 8 is such that the sum of its radial dimension b and the radius r of the cylinder 5 is a greater than the radius R of the rim 7 of each disc 6 minus the depth t of grooves 10 in a conveyor belt on which the roller is intended to be used.

So long as the roller illustrated in Figure 1 is rolling along a flat floor 9, the brake ring 8 will hang on the cylinder 5 without touching the floor 9. As shown in Figure 2, however, as soon as the rims 7 engage in respective grooves 10 of the conveyor belt (here thought of as being horizontal), a portion on the outer periphery of the brake ring 8 will be seated on a rib 11 of the conveyor belt, while a portion of the inner periphery of the brake ring 8 will bear against the cylinder 5. This will clearly cause the roller to be braked. If, as in Figure 3, the conveyor belt is inclined at an angle a, then the two points of contact will no longer be on the same radius line of the cylinder 5, since the weight G acts vertically and the reaction force K must act along the same vertical line for reasons of equilibrium.It can easily be seen that, at the position of contact between the cylinder 5 and the brake ring 8, the tangent which determines the frictional relationship is at an angle p to the horizontal, p being larger than zg. With a given co-efficient of friction it is not a but p that determines whether the desired braking action takes place. The relationship between p and a can be influenced by the choice of rand b, although the fulfilment of the frictional condition can also be influenced by other measures.

As shown in Figure 4, the frictional force can be increased by providing the cylinder 5' with a Vshaped groove 12 and the brake ring 8' with a Vprofile 13 fitting into the groove.

As illustrated in Figure 5, the frictional connection may be replaced by a positive connection, by providing the periphery of the cylinder 5" with teeth 14 and the brake ring 8" with a larger number of teeth 15 than the number of teeth 14 and adapted to roll over the teeth 14.

Engagement between the teeth need not satisfy the strict conditions for power transmitting teeth, but it should be noted that engagement can be brought about and terminated by radial displacement, possibly through constructing the teeth with straight flanks and with a large enough flank angle, e.g. 450.

In the examples so far illustrated the brake member 8 does not participate in the turning of the running discs when rolling. Nevertheless it is evenly loaded at its periphery, since it is turned through a small angle towards the cylinder 5 at the beginning of each braking process, before full braking is obtained. Figures 6 and 7 show an example where balls 17, 17' are provided in apertures 16 16' extending right through the brake member 8"', the balls projecting from the brake member on both sides and being guided in circumferential grooves 1 8 in the adjacent faces of the discs 6'.When the braking process is initiated, the ball 17 at the lower part of the ring 8"' is moved radially inwards and the flanks 19 of the grooves 1 8 are resiliently deformed, while the ball 1 7' at the upper part of the ring 8"' is not moved because of the clearance provided in the aperture 16'. As soon as the roller is rolling along a level surface again the flanks 19, acting through the ball 17, push the brake member 8"' back to the central position, after which it participates in the rotation of the running discs 6'. However, both flanks of the grooves 1 8 could be resiliently deformable, in which case the balls 17, 17' would have less clearance within the apertures 16, 16'.

The embodiment with balls is advantageous chiefly because the running discs 6' can be supported against one another by the balls 17, 17'.

In the above examples, the brake member is seated only on the middle rib of the three ribs of the conveyor belt between the rims. As shown in Figure 8, wear can be reduced by providing the outer periphery of the brake ring 8'n with a surrounding flange 20, the width of the flange almost filling the gap between the rims 7.

Claims

1. A roller for a manually movable trolley, to be capable of being automatically braked while being conveyed on an inclined conveyor belt having a longitudinally grooved surface, comprising two independently rotatable running discs, each provided with a rim to engage in a respective groove in the conveyor belt, and an annular brake ring which, when the rims are so engaged, is seated on at least one rib of the conveyor belt provided between the respective grooves and which is located between the running discs and has an outside diameter less than the outside diameters of the rims, the brake ring surrounding with a clearance a cylinder which is disposed nonrotatably between and coaxially with the running discs and the sum of the effective radius of the cylinder and the effective radial dimension of the annular ring being greater than the radius of each rim less the possible depth of engagement of the rims in the grooves.

2. A roller according to claim 1, wherein, on their cooperating faces, one of the cylinder and the ring has a circumferentially extending groove of V-section therein and the other has a rib of V section to engage in the groove.

3. A roller according to claim 1, wherein the outer peripheral surface of the cylinder and the inner periphery surface of the ring are toothed with a different number of teeth to one another, which teeth can roll over one another and can be engaged and disengaged by relative movement in a radial direction.

4. A roller according to claim 1, including ,means for centering the ring with respect to the roller spindle when the rims are no longer engaged in the grooves in the conveyor belt.

5. A roller according to claim 4, wherein said means comprise balls distributed evenly in a circle around the roller spindle and loosely located in apertures extending right through the ring, the balls projecting from the ring on both sides and being guided in grooves provided each in a respective one of the discs, concentric with the respective disc and on the side thereof facing the ring, the flanks of the grooves being resiliently deformable at least at one side.

6. A roller according to any one of claims 1 to 5, wherein the ring has a laterally extending flange at its outer periphery, the width of the flange being nearly equal to the distance between the rims.

7. A roller for a manually movable trolley substantially as hereinbefore described and illustrated with reference to the accompanying drawings.