GB2061105A - Castors - Google Patents

Abstract

In a lockable guide castor for supporting from a supporting surface such as a floor articles such as hospital beds and other furniture, appliances, and machines, in which the axle bearing cheeks of a supporting component swivellable around the longitudinal axis of a back bolt, support between them a swivel lever which has at least one locking means and which can be manipulated from the back bolt which is arranged to be vertically adjustable, the bearing cheeks are spaced only a small distance apart, they support the swivel lever near to the wheel axle, and they mount substantially centrically a wheel axle carrying a wheel at each of its ends. The swivel lever and the lower portion of the back bolt are disposed within the space bounded by the wheels and between the latter. The swivel lever has, as locking means, lobes which extend substantially parallel to the wheel axle and which can be applied against an internal ring-shaped area of the wheels which are essentially dish-shaped. The swivel lever preferably bears, under the influence of at least one spring, against a stop formed on at least one axle bearing cheek. The spring may be in the form of a swivellable leg spring resting on the wheel axle between the axle bearing cheeks. <IMAGE>

Description

SPECIFICATION Improvements in or relating to lockable guide castors The invention relates to a lockable guide castor for supporting from a supporting surface such as a floor, articles such as hospital beds and other appliances, and machines in which the axle-bearing cheeks of a supporting component swivellable around the longitudinal axis of a back bolt support between them a swivel lever which has at least one locking means and which can be manipulated from the back bolt which is arranged to be vertically adjustable.

Such a lockable guide castor is known for example, from Federal German Republic Gebrauchsmuster 7523 557. Its supporting component consists of a fork formed from sheet metal, the limbs of the fork, as bearing cheeks externally embracing a wheel and supporting it between them. The locking device is located between the central cross-piece of the fork of the supporting component and the tread of the wheel. It comprises a swivel lever, known as a brake flap, supported on the limbs of the fork, and which holds adjustably a brake member acting upon the wheel tread. At the upper side of the swivel lever there is a tooth construction which can cooperate with a peripheral tooth construction provided on a screw-on plate secured in position on the back bolt, as soon as the back bolt acts with positive pressure on the swivel lever and depresses it.At some spacing above the swivel lever, there is riveted to the fork limb a tongue-shaped plate, with which can be brought into engagement the plate secured in position on the back bolt and having the tooth construction. The back bolt is in the form of a rod of hexagonal section and is movably mounted in a hexagonal-section opening in a casing to be rigidly secured in a leg of the apparatus, the article of furniture, or the hospital bed. The casing in turn swivellably supports the fork-shaped supporting component through roller bearings. In order to lower the back bolt relative to the casing and thus also relative to the supporting component, there is provided a plate cam which acts upon the head at the upper end of the back bolt.If as a result of appropriate setting of the plate cam, the back bolt is located at its lowermost position, the toothed plate located on the end of said back bolt and having the tooth construction loads the swivel lever, meshes with the tooth construction on the latter and simultaneously presses the brake member against the wheel tread. In this way, by mutual meshing ofthe tooth constructions, the manoeuvrability of the guide castor is inhibited, as the rotatability of the wheel is arrested by pressing of the brake member on the wheel tread. If the back bolt is set slightly higher by turning of the plate cam, the swivel lever, under the action of a return spring, raises the brake body from the wheel tread, and the tooth constructions become disengaged.

The supporting component of the guide castor can now swivel, and the wheel can rotate. If, by appropriate adjustment of the plate cam, the back bolt is raised even further, the plate having the tooth construction positively engages, in one of two possible attitudes diametrally opposed relative to the supporting component with the further tongue hereinbefore referred to; a directional stabiliser becomes effective while the castor can move. In this way, for example, a hospital bed can be moved straight ahead in a predetermined direction, as a rule coinciding with the longitudinal direction of the bed.

In the known lockable guide castor, as with other known guide castors of the kind referred to hereinbefore, to an exceptional extent the arrangement and action of the swivel lever bringing about braking of the wheel is disadvantageous, particularly in the conventional use of the lockable guide castor on hospital beds. The wheel brake of course operates from time to time through application of pressure on to the wheel tread, so that impressions are continually left in said tread and are seldom fully effaced even in the case of very elastic material. As, with hospital beds the wheel brakes are often applied over long periods, a large number of indentations are formed in the wheel tread, and these lead to unsteady motion on movement of apparatus, articles of furniture, and particularly hospital beds or the like fitted with this guide castor.In addition, the wheel brake acting on the tread of the wheel contributes to quicker wear of the tread. In order to obtain the full braking action of the wheel brake, it is therefore necessary to adjust the brake member fairly frequently relative to the brake flap.

The problem with which the invention is faced is to improve a lockable guide castor for apparatus, articles of furniture, hospital beds orthe like of the kind originally stated, with regard to the arrangement of the swivel lever and the freedom, from servicing requirements of the wheel brake.

The invention solves this problem in that the bearing cheeks are spaced only a small distance apart, they support the swivel lever near to the wheel axle and they mount substantially centrially a wheel axle carrying a wheel at each of its ends, the swivel lever and the lower portion of the back bolt are disposed within the space bounded by the wheels and between the latter, and the swivel lever has as locking means lobes which extend substantially parallel to the wheel axle and which can be applied against an internal ring-shaped area of the essentially dishshaped wheels.

A series of extraordinary advantages are attained by means of the invention. By reason of the fact that the swivel lever, as a locking means, has lobes which extend substantially parallel to the wheel axle and which are applicable against an internal ring-shaped area of the dish-shaped wheels, there is provided a wheel brake which is not related to the degree of wear on the wheel treads. Such a wheel brake only needs adjustment when the brake surfaces have a certain degree of wear, purely as a result of their braking activity. As the wheel brake does not act upon the wheel tread, the swivel lever cannot leave in the latter any indentations leading to unsteady travel.By reason of the fact that the axle bearing cheeks are but a short distance apart from one another, support the swivel lever near to the wheel axle, and mount substantially centrically a wheel axle carrying a wheel at each of its ends, and because of the fact that the swivel lever and the lower portion of the back bolt are disposed within the space bounded by the wheels and between the latter, there is not only the possibility of designing a lockable guide castor according to the invention substantially more attractively, as no connector means at all, such as wheel axle, and the axle for supporting the swivel lever are any longer visible from the exterior, because these are fully concealed by the wheels, but in addition the possibility of making such a guide castor smaller as the space hitherto required for insertion of the locking device between the fork cross-piece of the supporting component and the wheel tread is gained. Instead of a small construction, wheels of greater diameter may be used for the same height, which can be more appropriate for optical and functional reasons. By reason of the fact that the bearing checks are a small distance apart from one another, the bearing axle for the swivel lever can be short, and the swivel lever itself can be very narrow. As in the lockable guide castor according to the invention forthe first time the space previously concealed by the wheel is now available for incorporation of a locking device, there is more freedom than hitherto in the design ofthe means for the locking device.

Further advantageous developments and special features of the lockable guide castor according to the invention will be apparent from the following description of two exemplified embodiments of the invention, with reference to the accompanying drawings, in which: Fig. lisa sectional elevation of a lockable guide castor according to a first embodiment, with the direction stabilised locked; Fig. 2 is a partial section along the line ll-ll in Fig. 1; Fig. 3 is a partial section similar to Fig. 1, with the locking device released; Fig. 4 is a partial section along the line IV-IV in Fig.

3; Fig. 5 is a view corresponding to Fig. 1 of a second embodiment of a lockable guide castor; Fig. 6 is a partial section along the line VI-VI in Fig.

5; Fig. 7 is a plan view according to the arrow VII in Fig. 6; and Fig. 8 is a part underneath plan, part cross-section along the line VIII-VIII in Fig. 5.

The guide castor 10 according to the first embodiment has a supporting component 12, swivellable around the longitudinal axis L of a back bolt 11, said carrier 12 in particular being a plastics injection moulding or a light metal die-casting. By means of a roller bearing 13 and a sliding bearing 14, using a sleeve 15, for example of polytetrafluorethylene, the supporting component 12 is arranged to rotate around a tubular case 16, which, as will be described in more detail hereinafter is fixed non-rotatable relative to the back bolt 11.

The tubular case 16 is fitted with a lower reduced portion 16a into a cylindrical socket in a bearing mounting 1 2a positioned vertically in the supporting component 12, and with a middle portion 16b ina hollow, in particular tubular leg 17 of an article such as a hospital bed and other furniture, an appliance, or a machine, and is secured in position thereon in all respects by a screw 18 the stem of which both passes through the leg 17 and engages in the tubular case 16. The lower portion 16a and the middle portion 16b of the tubular case 16 are penetrated byan axial fully-cylindrical bore 19, the diameter d of which is coordinated in the manner of a journal bearing, with the outside diameter of the back bolt 11, which in this region is also fully cylindrical.In order that the bore 19 may be bored and need not be tapped, the non-rotatable coordination between back bolt 11 and tubular case 16 takes place outside the limits ofthe bore 19, namely in the upper portion 16c of the tubular case 16. This portion section 16c is formed fork-shaped by having had taken out centrally therefrom by a side-milling cutter directed therealong in the drawing plane of Fig. 1, a section leaving a slot the internal unobstructed width whereof corresponds to the diameterd of the bore 19.There are thus formed upper portion 1 6c of the tubular case 16 two fork limbs 20 and 21 spaced apart from one another a distance equal to the diameterd of the bore 19: Aplate cam 23 is supported between these two fork limbs 20 and 21 on a manipulating axle 22 passing through the leg 17, the plate cam being connected to the axle 22 for housing therewith through levelled-off faced on each. The position of this plate cam 23 is secured at the upper side end thereof in the vertical direction by a capping member 26 of plastics material which is between the fork limbs 20 and 21 of the tubular case 16.At the lower side, the plate cam 23 contacts a head 28 which is non-rotatably connected with the upper end 1 1b of the back bolt, which is braced in relation to the tubular case by two compression springs 29. The head 28 has a somewhat T-shaped milled recess 30, while the upper end 1 1b ofthe back bolt 11 is provided with two somewhat tangentially arranged milled recesses 31 which are parallel to one another. In this way the head 28 can be joined at right angles to the plane of Fig. 1 ofthe drawings with the upper end portion 1 1b of the back bolt 11, by being pushed thereon. The head 28 is also held non-rotatably between the fork limbs 20 and 21, as the width thereof in to turn corresponds somewhat to the unobstructed inside measurement d of the fork legs 20 and 21 from one another (Fig. 2).

In this way the non-rotatable association of the back bolt 11 with the tubular case 16 is achieved without the necessity of having to provide bores the cross-section of which deviates from a circular shape. Thus no cross-sections need be tapped; all connections can be produced by boring or milling.

Back bolt 11 and tubular case 16 are adjustable in the vertical direction relative to one another, specifically the back bolt 11 is arranged to be vertically adjustable against the action of the compression springs 29 by appropriate setting ofthe plate cam 23.

The compression springs 29 are cased in blind holes 32 inside the middle portion 16b of the tubular case 16, and push with their respective upper spring ends below the lower surface of the head 28 ridigly connected with the upper portion 1 1b of the back bolt 11.

The supporting component 12 has two axlesupporting cheeks 33 and 34 (Fig. 4) preferably of the same material and integral therewith and extending parallel to and closely spaced from one another.

These cheeks have boreholes 35 as mountings for a wheel axle 36, which supports wheels 37, 38, one of each at its ends. The wheels 37,38 are somewhat dish-shaped in form and the open dished sides thereof face one another. The wheel hubs 39 are rotatably mounted independently of one another on the wheel axle 36. Each axle mounting zone, is concealed by a blind cap 40 inserted into the outer surfaces of the respective wheel 37 or 38. In the exemplary embodiment, moreover, the wheels 37 and 38 have tyres 47 of a plastics material having most effective running and wearing qualities.

Preferably in a likewise integral material relationship, the supporting component 12 has at the rear thereof a shield-like guard 42 overlapping the two wheels 37,38 at the top and circumferentially as far as the horizontal, and at the front a guard 43 extending generally vertically in this embodiment. The guards 42 and 43 at least approximately overlap the two wheels 37,38 widthwise as can be seen at the left-hand side of Fig. 4 with reference to the guard 43.

In the vicinity of the wheel axle 36, in the exemplary embodiment in Figs. 1 to 4, below the same, the bearing cheeks 33 and 34 support a journal pin 44 for the articulation of a swivel lever 45. This swivel lever is in the form of a two-armed lever. One arm 46 thereof serves to support it on the bearing cheeks 33, 34 with interposition at each cheek of a compression spring 48 which is fitted in a mounting 49 in the respective bearing cheek 33 or 34 and is supported on an abutment 50 jutting out somewhat parallel to the wheel axle 36, the abutment 50 being formed on the arm 46 of the swivel lever 45.

The other arm 37 of the swivel lever 45 has two locking means 51 and 52. The locking means 51 comprises two similar parts arranged symmetrically to the wheels 37,38 each as a wheel brake, and each consists of a lobe 53 engaging in the dish-shaped inner space of the respective wheel 37 or 38, somewhat parallel to the wheel axle 36, the outer surface 54 of said lobe 53 being cooperable as a friction brake with the rotating inner surface F of the respective wheel 37 or 38.

The locking means 52 is arranged centrally and is provided as an obstruction restraining the swivelling movement of the supporting component 12 relative to the back bolt 11. The locking means consists of an engagement part 55, upward-facing frontal area of which carries a tooth construction 56. The engagement part 55 is disposed beneath the back bolt 11 in the vertical projection of the latter. At the lower end 1 1a of the back bolt 11, there is secured fast against rotation a somewhat annular locking part 57 the downward-facing annular frontal area of which carries a tooth construction 58, which is complementary in form to the upwardly-facing tooth construction 56 on the engagement part 55.

The swivel lever 41 is fixed in the position shown in Fig. 1, loaded by compression spring 48, by an edge 59 of a bar 60 mounted on said lever butting against a vertically-extending edge 61 of one axle bearing cheek 33. Two bars 60 with edges 59 may be symmetrically arranged, so that a stop edge 61 is made available at each of the two bearing cheeks 33 and 34.

The arrangement part 55 is in the form of a component separate from the swivel lever 45 and connected with the arm 47 of the swivel lever 45 by a pin 62 which extends somewhat parallel to the wheel axle 36. The pin 62 may be immovably mounted on the arm 47, while the engagement part 55 has a vertically-elongated slot 63. Moreover, the engagement part 55 is mounted to move relative to the swivel lever 45 about the longitudinal axis of the pin 42. In this way the upper surface of the engagement portion 55 provided with the tooth construction 56, can always be horizontally oriented, irrespective of the swivelled position of the swivel lever 45 at any given time.

Moreover, the engagement part 55 rests with a lower surface 64 on the end surface 65 of an adjusting spindle 66 constructed as a bolt which cooperates for vertical adjustment with tapping (not shown) in an arm 47 of the swivel lever45. In this way the engagement part 55 may be elevated to cooperate with the locking part 57 in order to compensate in particular for wear of the wheel brake 54/55.

The locking part 57 is intended not only to be able to get into engagement by means of its tooth construction 58 with the tooth construction 56 of the swivel lever 45, but it also functions in the sense of a directional stabilizer. For this purpose, there are made in an upper region of the locking part 57, which otherwise has a circular periphery, two mutually-parallel flats 67 (Fig. 4), which can cooperate with corresponding edges 68 (Figs. 3 and 4) of a cut-away portion 69 within a plate 70 rigidly connected with the supporting component 12, as soon as the upper portion of the locking part 57 can enter into the two possible mutually overlapping positions of the edges 68 in the cut-away portion in the plate 70. These two positions are 180 out of phase with one another.Inasmuch as engagement is not possible, because the actual position to which the supporting component is turned does not allow corre lated engagement, the locking part 57 is situated nevertheless resiliently locked owing to the compressor springs 29 away from the lower surface of the plate 70, and instantly engages, upon swivelling of the supporting component with the cutaway portion 69 in the plate with positive interlocking, as soon as one of the two positions capable of locking and 1800 out of phase is reached.

The plate cam 23, turnable through the manipulating axle 22, has three portions 71, 72 and 73. The portions 71 and 72 are rounded somewhat bowl-like and are formed congruent to the convex arching of the surface of the head 28, while the third portion 73 is part of a circular cylindrical convex surface. The rounding of the portions 71 and 72 ensures a rest position. If, as shown in Fig. 1, the portion 71 is in pressure contact with the head 28, then the back bolt 11 is in its uppermost possible position. Here the locking part 57 is in a position in which it is capable of correlating with the cutaway portion in the plate 70, so that upon engagement of the two, as shown in Fig. 1, a deterioration of direction is fixed.As, however, the locking part 57 cannot yet act upon the locking means 52 provided on the swivel lever 45, and because the swivel lever 45 is held in its imperative position on account of the spring 48, the wheels 37 and 38 are free to rotate, so that the directionally stabilised castor can be rolled.

If the plate cam 23 is now turned a little counterstreamwise so that the control portion 71 disengages and the second control portion 72 is brought into operative position with the head 28, the back bolt 11 is moved a little downwards relative to the tubular case 16 and the supporting component 12. It then, together with the locking part 57 at its end, assumes the position according to Fig. 3. Here the locking part 57 is driven out of the castaway portion 69, without however, contacting the locking means 52 provided on the swivel lever 45. When the directional stabiliser is released, both the rotary movement of the wheels 37,38 and the guiding movement ofthe supporting component 12 around the longitudinal axis L are entirely free.

If the control disc is turned clockwise from its position in Fig. 1, or is turned counterclockwise from its position in Fig. so that the cylindrical control portion 73 comes into operative contact with the upper side of the head 28, the back bolt 11 is moved into its lowermost position. This position can thus be reached directly from either one or the two other positions. With this maximum downward movement, the tooth constructions 58 and 56 engage with one another, the swivel lever 45 at the same time being swivelled counterclockwise a small amount around its journal pin 44, until the brake surface 54 comes into contact with the wheel inner surface F.

The wheels 37,38 can now no longer rotate around wheel axle 36. Simultaneously, the swivellability of the supporting component 12 relative to longitudinal axis 11 is locked in that position which the castor occupies at the moment. Starting from this fully locked position, depending on the direction of turning of the manipulating axle 22, one of the two other possible positions may again be adopted.

The second embodiment 110 in accordance with Figs. 5 to 8 differs from the first embodiment 10 in accordance with Fig. 1 to 4 by the features hereafter explained. While in the first embodiment the plate cam 23 is an integral component part of the supporting component 12 already pre-assembled with the tubular case 16, in the second embodiment this plate cam 23 is omitted, and can be placed in position by the user, for example a hospital bed manufacturer, himself. The tubular case 116 in the second embodiment is in two parts, and is no longer directly introduced into the supporting component 12, but is connected fast against rotation by means of a tubular case 1 16a specially arranged in the supporting component 12.The two spiral springs 29 of the first embodiment are replaced by a single spiral spring 129 the turns of which concentrically surround the central longitudinal axis 1 of carrier bolt 11.

The second embodiment differs in another respect, namely that in the guide castor 110, the two-armed swivel lever 145 has the locking means 151 and 152 on one of the arms 146, While the formation of the locking means 52 and its arrangement on lever arm 147 is the same as in the previous embodiment, the locking means 151 differs in that it forms a form-locking brake. Instead of a friction surface 54, the locking means 151 has an external tooth construction 154 which cooperates with inner tooth constructions Z on the inner edges of each of the dished wheels 137, 138. The mounting of the swivel lever 145 is provided on a pin-shaped bearing axle 144 which is located above the wheel axle 36.The resilient restoration of the swivel lever 145 is taken care by an expanding spring 148 constructed as a leg spring, which is supported on the wheel axle 36 between the wheel bearing cheeks 133, 134. The end 148a of one leg is offset at 148b and the offset end 148b is engaged in a notch 149 within the lower edge of the axle-bearing cheek 133. The end 14 & of the other leg is positively supported below the left-hand arm 147 (in Fig. 5) of the swivel lever 145 by pressing thereagainst.

The spring-loaded end position of the swivel lever 145 is ensured by said lever 145 striking with a cam 160 at its upper side against the lower side of the plate 70. This positive stoppage could also be effected outside ofthe plate 70 on other areas fast with the supporting component. The operation of the locking device of the guide castor 1 takes place in fundamentally the same way as that of the locking device in the case of the castor 10. Reference can therefore be had to the description of the operation ofthe first embodiment. The reference numerals of the first embodiment have been adapted for parts similar in form, and, for parts functionally adapted to the second embodiment, the corresponding reference numerals have been increased by 100.

The invention is not restricted to the two embodiments given by way of example. Variations are possible within the scope of the invention as defined in the appended claims. In particular features of the two embodiments may be interchanged. The swivel lever 45 could be used with the spring 148 in the case of the guide roller 110 to name only one example from many.

Claims (12)

1. A lockable guide castor for supporting from a supporting surface such as a floor articles such as hospital beds and other furniture, appliances, and machines, in which the axle bearing cheeks of a supporting component swivellable around the longitud inal axis of a back bolt support between them a swivel lever which has at least one locking means and which can be manipulated from the back bolt which is arranged to be vertically adjustable, the bearing cheeks being spaced only a small distance apart, supporting the swivel lever near to the wheel axle and mounting substantially centrically a wheel axle carrying a wheel at each of its ends, the swivel lever and the lower portion of the back bolt being disposed within the space bounded by the wheels and between the latter, and the swivel lever having, as locking means, lobes which extend substantially parallel to the wheel axle and which can be applied against an internal ring-shaped area ofthe essentially dish-shaped wheels.

2. A lockable guide castor according to Claim 1, in which the swivel lever bears under the influence of at least one spring against a stop formed on at least one axle bearing cheek.

3. A lockable guide castor according to Claim 2, in which the spring is in the form of a swivellable leg spring resting on the wheel axle between the axle beating cheeks.

4. A lockable guide castor according to Claim 1, in which the swivel lever is in the form of a twoarmed lever.

5. A lockable guide castor according to Claim 4, in which one arm of the swivel lever carries the locking means while the spring is supported against the other arm.

6. A lockable guide castor according to Claim 4, in which one arm of the swivel lever carries a wheel brake as a locking means, and the other arm as a locking unit has an engagement part which can be engaged with the back bolt.

7. A lockable guide castor according to Claim 1, in which the swivel lever has an engagement part contactable by a fixed locking part on the back bolt, said engagement part being articulated to the swivel lever for movement about a spindle essentially parallel to the wheel axle.

8. A lockable guide castor according to Claim 7, in which the engagement part is arranged to be adjustable substantially longitudinally of the back bolt relative to the swivel lever.

9. A lockable guide castor according to Claim 8, in which the engagement part rests with positive pressure against the front end of an adjusting spindle screwed through the swivel lever.

10. A lockable guide castor according to Claim 1, in which the back bolt, in the region of its stem penetrating a tubular case connected to the supporting component for rotation relative thereto, has a cylindrical surface, the upper end of the tubular case contains a diametral forked slot into which extends non-rotatably a head which can be acted upon by a plate cam and is connected non-rotatably with the head of the back bolt.

11. A guide castor substantially as hereinbefore described with reference to Figs. 1 to 4 of the accompanying drawings.

12. A guide castor substantially as hereinbefore described with reference to Figs. 5 to 8 of the accompanying drawings.