GB1582724A

GB1582724A - Brake

Info

Publication number: GB1582724A
Application number: GB24799/78A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-06-06
Filing date: 1978-05-31
Publication date: 1981-01-14
Also published as: AU3686078A; JPS5417248A; IT1095037B; SE405840B; DE2824595A1; IT7824259A0; CA1081204A; AU517332B2; FR2393758A1; BR7803599A; DD135893A5

Description

(54) IMPROVEMENTS IN OR RELATING TO A BRAKE (71) I, HANS INGEMAR REIMERTZ KARLSSON, a Citizen of Sweden, of Vintervagan 17, S-175 40 Jarfalla, Sweden, do hereby declare the invention for which I pray that a patent may be granted to me and the method by which it is to be performed to be particularly described in the following statement: The present invention relates to a brake, and more particularly to an automatically acting brake for hoisting apparatus.

It has been proposed to provide hoisting apparatus with automatically acting brakes to prevent a suspended load from falling down or being lowered at too great a rate, which can, of course, result in the load being damaged or someone standing close by being injured. In some of these proposed devices the brake means has consisted of an inertia-controlled brake disk which is rotatably mounted on a shaft.

The disk is axially displaceable on the shaft and is arranged for moving into a locking position, where the disk engages with a surface which is fixed in position in relation to the position of the shaft but which is not rotatable with the shaft, and also engages with a means rigidly attached to the shaft, thus braking or locking the shaft.

It has also been proposed to provide hoisting apparatus which comprises reversible rotatable shaft, a drum connected to the shaft and arranged for rotation when the shaft rotates, and on which a load carrying such as a cord or strap, means is wound up; and a spring connected to the shaft and arranged so that the spring is tensioned on rotation of the shaft in one direction while the load carrying means is extended, for subsequently providing a driving force causing rotation of the shaft in the opposite direction for subsequently rewinding the load carrying means on to the drum.

Hoisting apparatus of this kind is particularly suitable for suspending tools in working areas, for example, since the spring bias can be made to balance the weight of the tool so that it is kept at a predetermined height when it is suspended in the hoisting apparatus. It is easy to adjust the position in height of the tool merely by moving it upwards or downwards. The tool is kept in the position in which it is placed if the hoisting apparatus is so arranged that the tensional force provided from the spring is substantially constant, independent of the extent to which the load carrying means is withdrawn. With such a suspension, a tool can be easily handled and used while attached to the load carrying means of the hoisting apparatus.In many cases such a tool suspension is satisfactory, but there are occasions when it is necessary to release the tool from the suspension means so that the tool can be used in the most effective manner and for enabling all the necessary work operations to be performed. The drawback with the previously used hoisting apparatus of the type described above is that the load carrying means of the hoisting apparatus, usually a hoisting rope or cord, is completely wound up on the drum by the action of the spring when the rope is let go after releasing the tool. Since the hoisting apparatus is usually mounted at great height above the working area, it is difficult to group the hoisting rope once again for suspending the tool after the tool has been used.The hoisting rope must therefore be fastened down or retained at the working area in some way when the tool is detached from the rope, so that the rope is not wound up on the drum. This attachment or retention is often difficult to provide at the working area and makes the use of the tool more difficult.

The main object of the present invention is to provide an automatically acting brake means suitable for hoisting apparatus of the type described above which prevents the load carrying means being wound up in the hoisting apparatus on the drum of the hoisting apparatus, and which retains the load carrying means in the position in which it is when the tool or load is released from the load carrying means.

According to this invention there is provided automatically acting brake means for apparatus which comprises a reversible rotatable shaft, a drum connected to the shaft, arranged to rotate with the shaft and on which there is wound a load carrying means; and a spring connected to the shaft and arranged to be placed under tension when the shaft rotates in one direction during withdrawal of the load carrying means, for subsequently providing a driving force causing rotation of the shaft in the opposite direction for rewinding of the load carrying means onto the drum, the brake means comprising an inertia-controlled brake disk turnably mounted on the shaft, said disk being axially displaceable on the shaft and being arranged for coaction with a member which is fixed in position in relation to the position of the shaft, but which is not rotatable with the shaft, and with means fixed to the shaft for braking the shaft, the brake disk being arranged for displacement from a neutral position to a locking position when the brake disk is turned relative to the shaft during rapid rotation of the shaft in the direction corresponding to rewinding of the load carrying means, a spring being provided for subsequently returning the brake disk to the neutral position.

The invention also relates to apparatus incorporating such a brake means.

Since the brake means automatically retains the load carrying means as soon as a tool is taken away from the hoisting apparatus, no special measures are needed to be taken for retaining the load carrying means, and the tool can easily be resuspended in the hoisting apparatus at the place from which it was removed. An extremely substantial simplification of the handling and use of the tool is thus obtained.

In a further embodiment of the invention, the brake disk is arranged to be displaced to its locking position, also due to rapid turning of the shaft in the withdrawing direction, so that the load carrying means is locked or braked in the case where the load falls, or is lowered at too great a rate, which can occur due to the spring or some other part in the hoisting apparatus being broken, for example. Greater safety is hereby attained in using the hoisting apparatus.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described by way of example with reference to the accompanying drawings'in which: Figure 1 shows, partly in section, a hoisting apparatus with a brake means in accordance with the invention Figure 2 shows a side view along the line II-II in Figure 1 and Figure 3 corresponds to Figure 2 but illustrates a modified embodiment of the invention.

The hoisting apparatus shown in Figure 1 comprises a reversibly rotatable shaft 10 journalled in two bearings l3a, 13b which are mounted in two carrying plates 11, 12.

One end of the shaft 10 projects outside one plate 12, and this end of the shaft is provided with a drum 14, non-rotatably attached to the shaft by means of a locking pin 15, so that drum and shaft rotate together. The drum 14 is provided with two end walls 16, 17 between which a load carrying means 18, in this case a hoisting rope, is wound. The drum 14 is arranged in a casing 19 provided with a hole 20 in the lower wall thereof for withdrawal and retraction of the hoisting rope. At its free end the hoisting rope is provided with an eye 21, to which a tool or the like can be attached or from which the tool may be suspended. The portion of the shaft extending between the carrying plates is provided with a conical roller 22, which is nonrotatably attached to the shaft and thus turns with the shaft when the latter rotates.

A second shaft 23 is also rotatably mounted between the two carrying plates, the shaft being carried by two bearings 24, 25 which are attached to the plates. A second conical roller 26 is similarly non-rotatably attached to the shaft 23 for rotation with it. The conical rollers 22, 26 are arranged with their narrow ends facing in opposite direc tidns and, are each provided with a helical groove on their conical surfaces. The rollers are connected together by means of a tension cord 27, which is arranged to run in the helical grooves on the rollers. The cord is arranged to be wound up and unwound from one roller to the other when the hoisting apparatus is used. The rollers 22, 26 are fixed between the plates 11, 12 by means of spacing rings 22a and 26a, 26b respectively. One end of the shaft 23, which is at the opposite end to the said one end of the shaft 10, extends outside the plate 11 and is connected to a spiral spring 29 with the aid of an attachment means 28, non-rotatably fixed to the shaft.

The spring 29 is coiled a number of turns around the shaft 23 and at its outer end is attached to a spring housing 30 which surrounds the spring and which is attached to the plate 11.

The hoisting apparatus is so arranged that when the hoisting rope 18 is withdrawn from the drum 14, as the result of a downward tensional force applied to the rope, the first shaft 10 rotates and the tension cord 27 provided on the rollers 22, 26 is wound up on the lower roller in Figure 1 and simultaneously is unwound from the upper roller. The second shaft 23 thereby rotates causing the spring 29 to be tensioned. When the downwardly directed tensional force on the hoisting rope ceases, the hoisting rope can be rewound onto the drum by the spring bias generated, which provides rotation of the shafts and drum in the opposite direction (rewinding direction) to the withdrawing direction.As a result of the conical shape of the rollers, the effective tensional force provided by the spring when measured at the hoisting rope, in the rewinding direction will be substantially uniform, and will be independent of the extent to which the hoisting rope is pulled out. The function and advantages of the conical rollers are described in detail in the Swedish Published Specification 388,128.

The brake means in the hoisting apparatus comprises a brake disk 31 at the drum 14, said disk being mounted on the shaft 10 for rotation with the shaft but being movable axially along the length of the shaft and also being rotable to at least a limited extent, relative to the shaft. The disk may be moved axially between a position in which the disk is in engagement with the drum aiid a position in which the disk is in engagement with the end wall 32 of the casing 19 surrounding the drum.

The brake disk 31 is normally kept in engagement with the end wall 17 of the drum by means of a weak helical spring 34 arranged around the shaft 10, with one end engaging against a bushing 33 in the brake disk 31 and the other end engaging the end wall 32 of the casing 19. The brake disk 31 is provided -with four rivets 35, of which only two are shown in Figure 1.

The rivets have trunk heads 36, these being convex heads with less height than round heads. These heads 36 project from the face of the brake disk towards the drum 14.

For each of the rivet heads 36 there is a groove or recess 37 defined in the end wall surface of the drum for accommodating the rivet head. These grooves are shown in Figure 2, and each groove has a deep portion 38, the depth cif which is somewhat greater than the height of the rivet head 36 above the face of the brake disk, So that there is a space between the rivet head and the bottom of the groove when the head is in the deepest part of the groove, allowing the brake disk to abut the drum end wall.

In Figure 2, arrows A and B denote the direction of rotation of the drum for withdrawal of the hoisting rope (A) and rewinding it (B), respectively. The grooves 37 are substantially arcuate, with their centre of curvature at the axis of the drum, so that the grooves run substantially at right angles to the radius of the drum. The deep portion 38 of the grooves is at the forward end thereof, seen in the rewinding direction.

The rivet heads have a height above the face of the brake disk which is greater than the maximum distance between the brake disk 31 and the end wall 32 of the casing. Furthermore, the brake disk has a relatively large mass, so that it functions as an inertia-controlled means and does not immediately accompany the shaft on sud den turning of the latter. Thus there may be an anguiar displacement of the brake disk relative to the shaft.

The above described brake functions in the following way. When the hoisting rope is ,withdrawn from the drum, the brake disk accompanies the rotation of the drum and therefore does not affect withdrawal.

The brake disk is coupled to the drum by the rivet heads projecting into the grooves in the end wall of the drum, where they are kept in the deeper portions of the grooves, since the rear walls of the grooves, seen in the withdrawal direction, are relatively steep and therefore engage with portions of the rivet heads to function as driving surfaces. When, after a certain amount of extension and possible removal of the load, the hoisting rope is released, the drum will turn rapidly in the rewinding direction B due to the spring bias. By reason of its large mass and thus inertia, the brake disk will not accompany the drum but will turn on the shaft relative to the drum.The rear part of the grooves, seen in the rewinding direction, do not have a steep wall which can function as a driving surface, havinq instead a bottom, which Successively and with a slight incline approaches the surface on the drum end wall. With the turn of the brake disk relative to the drum, the rivet heads will slide on the bottom of the grooves, and thus the brake disk is displaced axially towards the end wall of the surrounding casing 1, the distance to this end wall being such that the brake disk will come into engagement with it before the rivet heads leave the grooves. When the brake disk comes into contact with the end wall, the drum is locked against fur there rotation because of friction, and thus no further rotation of the drum can take place.This locking takes places practically immediately after the hoisting rope has been released, since the drum only needs to turn through a very small angle for the brake disk to be put into engagement against the -end wall. The brake is re- leased by pulling the hoisting line out a small distance, so that the drum moves slightly in the withdrawing direction, whereby the brake disk is returned to the neutral position by the action of the weak helical spring. For rewinding the hoisting rope onto the drum, the rope must be moved slowly towards the drum, i.e. the rope must be braked manually during rewinding so that the existing friction between the brake disk and drum is sufficient to cause the brake disk to accompany the drum.

In the embodiment shown in Figure 3, the grooves 37 in the end wall 17a of the drum are so shaped that the deep portion 38a is in the middle of the grooves, and the grooves are successively shallower in both circumferential directions. Thus there will be greater safety in using the hoisting apparatus, since the drum will also be locked on rapid rotation in the withdrawing direction, since in such a situation the brake disk will also be displaced into engagement with the end wall of the casing.

The brake means otherwise functions in the way described above, but withdrawal of the hoisting rope must take place relatively slowly so that the brake disk is caused to accompany the rotation of the drum by the friction between the brake disk and the drum.

Although only two embodiments of the brake means according to the invention have been shown and described, it is obvious that many different embodiments are possible within the scope of the invention, as defined in the appended claims.

The hoisting apparatus does not need to include any conical rollers and the spring can be arranged to act directly on the shaft to which the drum for the hoisting rope is arranged. The hoisting rope can furthermore be replaced by a chain, a belt or strap. Mounting and suspension of the reversibly rotatable shaft can further be arranged in many different ways. The drum can be connected to the shaft by means of a transmission. The rivet heads on the brake disk can further be replaced by some other projection having another shape, and the projections can just as well be arranged on the drum, corresponding grooves being placed on the brake disk.

The precise shape and location of the grooves can also be varied.

The brake disk, on the side facing away .from the drum, can also be provided with a brake lining or teeth engaging respectively against a corresponding brake lining or against corresponding teeth on the end wall of the casing surrounding the drum.

The brake means can furthermore be so formed that in the case where locking or braking is intended to take place at speedy rotation in both directions, complete locking does not take place for rapid withdrawal, only severe braking being accomplished, so that a load hanging from a hoisting rope may only move downwardly slowly. This function is desirable if, for example, the spring or some other part in the hoisting apparatus should break. There is then risk for damage to the load and injury to persons if the load falls down, and neither is it expedient for the load to hang at some height in an unusable hoisting apparatus. In such cases it is an advantage if the load approaches the floor at a slow rate. This slow rate is provided by suitable balancing of the friction between the brake disk and the end wall and by a suitable rise in the bottom of the grooves in the drum end wall surface.For example, a sharper rise can give a less heavy bias of the brake disk against the end wall, so that the desired sliding between the brake disk and the end wall can be provided.

The brake means according to the invention can also be used in other hoisting apparatus than such intended for suspending tools, e.g. in roller blinds.

WHAT I CLAIM IS: 1. Automatically acting brake means for apparatus which comprises a reversible rotatable shaft, a drum connected to the shaft, arranged to rotate with the shaft and on which there is wound a load carrying means; and a spring connected to the shaft and arranged to be placed under tension when the shaft rotates in one direction during withdrawal of the load carrying means, for subsequently providing a driving force causing rotation of the shaft in the opposite direction for rewinding of the load carrying means onto the drum, the brake means comprising an inertiacontrolled brake disk turnably mounted on the shaft, said disk being axially displaceable on the shaft and being arranged for coaction with a member which is fixed in position in relation to the position of the shaft, but which is not rotable with the shaft, and with means fixed to the shaft for braking the shaft, the brake disk being arranged for displacement from a neutral position to a locking position when the brake disk is turned relative to the shaft during rapid rotation of the shaft in the direction corresponding to rewinding of the load carrying means, a spring being provided for subsequently returning the brake disk to the neutral position.

2. Brake means as claimed in claim 1 wherein the drum is attached to the reversibly rotatable shaft and wherein the means fixed to the shaft comprise one end wall of the drum, the brake disk being disposed adjacent to said end wall, the end wall and the adjacent face of the brake disk being so formed that the brake disk is displaced in an axial direction when the brake disk is turned about the shaft relative to the drum.

3. Brake means as claimed in claim 2, wherein in that the brake disk is provided with at least one projection projecting into a corresponding recess in the end wall of the drum, this recess having the form of a groove running substantially at right

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. that the existing friction between the brake disk and drum is sufficient to cause the brake disk to accompany the drum. In the embodiment shown in Figure 3, the grooves 37 in the end wall 17a of the drum are so shaped that the deep portion 38a is in the middle of the grooves, and the grooves are successively shallower in both circumferential directions. Thus there will be greater safety in using the hoisting apparatus, since the drum will also be locked on rapid rotation in the withdrawing direction, since in such a situation the brake disk will also be displaced into engagement with the end wall of the casing. The brake means otherwise functions in the way described above, but withdrawal of the hoisting rope must take place relatively slowly so that the brake disk is caused to accompany the rotation of the drum by the friction between the brake disk and the drum. Although only two embodiments of the brake means according to the invention have been shown and described, it is obvious that many different embodiments are possible within the scope of the invention, as defined in the appended claims. The hoisting apparatus does not need to include any conical rollers and the spring can be arranged to act directly on the shaft to which the drum for the hoisting rope is arranged. The hoisting rope can furthermore be replaced by a chain, a belt or strap. Mounting and suspension of the reversibly rotatable shaft can further be arranged in many different ways. The drum can be connected to the shaft by means of a transmission. The rivet heads on the brake disk can further be replaced by some other projection having another shape, and the projections can just as well be arranged on the drum, corresponding grooves being placed on the brake disk. The precise shape and location of the grooves can also be varied. The brake disk, on the side facing away .from the drum, can also be provided with a brake lining or teeth engaging respectively against a corresponding brake lining or against corresponding teeth on the end wall of the casing surrounding the drum. The brake means can furthermore be so formed that in the case where locking or braking is intended to take place at speedy rotation in both directions, complete locking does not take place for rapid withdrawal, only severe braking being accomplished, so that a load hanging from a hoisting rope may only move downwardly slowly. This function is desirable if, for example, the spring or some other part in the hoisting apparatus should break. There is then risk for damage to the load and injury to persons if the load falls down, and neither is it expedient for the load to hang at some height in an unusable hoisting apparatus. In such cases it is an advantage if the load approaches the floor at a slow rate. This slow rate is provided by suitable balancing of the friction between the brake disk and the end wall and by a suitable rise in the bottom of the grooves in the drum end wall surface.For example, a sharper rise can give a less heavy bias of the brake disk against the end wall, so that the desired sliding between the brake disk and the end wall can be provided. The brake means according to the invention can also be used in other hoisting apparatus than such intended for suspending tools, e.g. in roller blinds. WHAT I CLAIM IS:

1. Automatically acting brake means for apparatus which comprises a reversible rotatable shaft, a drum connected to the shaft, arranged to rotate with the shaft and on which there is wound a load carrying means; and a spring connected to the shaft and arranged to be placed under tension when the shaft rotates in one direction during withdrawal of the load carrying means, for subsequently providing a driving force causing rotation of the shaft in the opposite direction for rewinding of the load carrying means onto the drum, the brake means comprising an inertiacontrolled brake disk turnably mounted on the shaft, said disk being axially displaceable on the shaft and being arranged for coaction with a member which is fixed in position in relation to the position of the shaft, but which is not rotable with the shaft, and with means fixed to the shaft for braking the shaft, the brake disk being arranged for displacement from a neutral position to a locking position when the brake disk is turned relative to the shaft during rapid rotation of the shaft in the direction corresponding to rewinding of the load carrying means, a spring being provided for subsequently returning the brake disk to the neutral position.

angles to the radius of the drum and which has a deep portion and a portion of successively decreasing depth towards its rear end, seen in the direction corresponding to rewinding of the load carrying means.

4. Brake means as claimed in claim 2 or 3, wherein in that the brake disk abuts the end wall of the drum in the neutral position of the disk.

5. Brake means as claimed in claim 3 or 4, wherein the side face of the brake disk abuts the end wall surface of the drum and in the neutral position of the brake disk there is a space between the projection on the brake disk and the bottom of the corresponding recess.

6. Brake means as claimed in any of claims 3 to 5, wherein each recess in the end wall of the drum has a deep portion and portions of successively diminishing depth in both circumferential directions.

7. Brake means as claimed in any one of claims 3 to 6, wherein in that the brake disk has at least two projections and that these consists of trunk heads on rivets which are mounted on the brake disk.

8. Brake means ,substantially as herein described with reference to and as shown in Figures 1 and 2 of the accompanying drawings.

9. Brake means substantially as herein described with reference to and as shown in Figures 1 and 2 as modified by Figure 3 of the accompanying drawings.

10. Apparatus incorporating brake means according to any one of the preceding claims.