BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a recovery machine, and more particularly to a friction brake for a recovery machine, which is capable of applying a varying braking force according to the speed of a tensioning machine and reducing weight of the recovery machine.
Description of the Related Art
Fig. 1 illustrates the procedure for recovering a guide rope and a conventional line using a recovery machine so as to install a new line such as an optical communication line and an electric transmission line between power transmission towers or exchange an conventional line with a new one.
The recovery machine 10 recovers a guide rope 30 and a conventional line 40 as follows. The guide rope 30 and the conventional line 40 are installed at positions downwardly spaced a predetermined distance from supporting rollers 20 installed to a new line 50. The guide rope 30 and the conventional line 40 are drawn using the force of a tensioning machine 60 at one side of the power transmission tower. At this time, the guide rope 30 and the conventional line 40 are drooped down. If excessively drooped down, the guide rope 30 and the conventional line 40 may come in contact with a power transmission line to which power is applied, causing electric accidents.
Here, in order to solve the above problem, there has been developed a hydraulic recovery machine for recovering a guide rope and a conventional line without excessive droop by giving a predetermined braking force to a lower roller using a force of a hydraulic pump when the guide rope and the conventional line are pulled. Configuration and principle of such a hydraulic recovery machine are disclosed in Korean Patent Publication No. 10-2004-17258.
In order to ensure an optimized recovery speed, the recovery speed should be increased when the recovery machine advances in a horizontal direction or at an

upwardly inclined slope. However, the hydraulic recovery machine cannot change its recovery speed according to a slope.
In addition, the above hydraulic recovery machine always grips a new line with a tension over 20 kgf so as to give a braking force at a maximum slope angle, thereby causing serious abrasion on the upper and lower rollers. That is to say, frequent exchange of the upper and lower rollers is required due to continuous friction between the new line and the upper and lower rollers. In addition, an exchanged new line is apt to be damaged due to excessive tension of the upper and lower rollers.
Meanwhile, the hydraulic recovery machine has a heavy hydraulic cylinder to endure a hydraulic pressure, and its size is also big. This increases the weight of the recovery machine, which is inefficient in terms of mechanical performance and costs.
SUMMARY OF THE INVENTION
The present invention is designed to solve the problems of the prior art, and therefore it is an object of the present invention to provide a friction brake for a recovery machine, which is capable of giving a varying braking force according to a tensioning speed and making the recovery machine have less weight.
In order to accomplish the above object, the present invention provides a friction brake for a recovery machine, which is used for exchanging a conventional line with a new line by means of a construction method using supporting rollers and gives a braking force to a lower roller with a circular groove in a side thereof, the friction brake including: a brake frame configured to surround both sides of the lower roller of the recovery machine and having a guide hole in one side thereof; a brake bar positioned in the brake frame and configured to surround both sides of the lower roller, brake pads being mounted to both ends of the brake frame; an elastic member installed between the brake frame and the brake bar; and a guide bar having one end positioned out of the brake frame and to which a rope ring connectable to a line or a rope is mounted, and also having the other end extended into the brake frame through the guide hole and coupled to the brake bar.

Preferably, the brake bar is elastically biased by means of the elastic member so that the brake pads are contacted with a side of the circular groove of the lower roller to cause friction.
More preferably, metal lining is treated on the side of the groove of the lower roller contacted with the brake pads by friction.
In another aspect of the present invention, there is also provided a friction brake for a recovery machine, which is used for exchanging a conventional line with a new line by means of a construction method using supporting rollers and gives a braking force to a lower roller with a circular protrusion on a side thereof, the friction brake including: a brake frame configured to surround both sides of the lower roller of the recovery machine and having a guide hole in one side thereof; a guide bar having one end positioned out of the brake frame and to which a rope ring connectable to a line or a rope is mounted, and also having the other end extended into the brake frame through the guide hole and to which a brake pad is mounted; and an elastic member installed between the brake frame and the brake pad.
Preferably, the brake pad is elastically biased by means of the elastic member so as to be contacted with the protrusion formed on a side of the lower roller to cause friction.
More preferably, metal lining is treated on the side of the protrusion of the lower roller contacted with the brake pad by friction.
A friction brake for a recovery machine, which is used for exchanging a conventional line with a new line by means of a construction method using supporting rollers and gives a braking force to a lower roller with a circular groove in a side thereof, the friction brake comprising: a brake frame configured to surround both sides of the lower roller of the recovery machine and having a guide hole in one side thereof; a brake bar positioned in the brake frame and configured to surround both sides of the lower roller, brake pads being mounted to both ends of the brake frame; an elastic member installed between the brake frame and the brake bar; and a guide bar having one end positioned out of the brake frame and to which a rope ring connectable to a line or a rope is mounted, and also having the other end extended into the brake frame through the guide hole and coupled to the brake bar.

BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and aspects of the present invention will become apparent from the following description of embodiments with reference to the accompanying drawing in which:
Fig. 1 is a schematic view showing a recovery machine of the prior art, which recovers a guide rope and a conventional line;
Fig. 2 is a perspective view showing a friction brake for a recovery machine according to an embodiment of the present invention, which is installed to a recovery machine having a lower roller with a circular groove formed in a side thereof;
Fig. 3 is a plane view showing the friction brake for a recovery machine of Fig. 2;
Figs. 4 and 5 are side views illustrating operation of the friction brake for a recovery machine of Fig. 2;
Fig. 6 is a perspective view showing a friction brake for a recovery machine according to another embodiment of the present invention, which is installed to a recovery machine having a lower roller having a circular protrusion formed on a side thereof;
Fig. 7 is a plane view illustrating the friction brake for a recovery machine of Fig. 6; and
Figs. 8 and 9 are side views illustrating operation of the friction brake for a recovery machine of Fig. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Hereinafter, preferred embodiments of the present invention will be described in detail referring to the accompanying drawings. Prior to the description, it should be understood that the terms used in the specification and appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present invention on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation. Therefore, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the invention, so it

should be understood that other equivalents and modifications could be made thereto without departing from the spirit and scope of the invention.
Figs. 2 and 3 show a friction brake for a recovery machine according to an embodiment of the present invention, which is installed to a recovery machine having a lower roller with a circular groove on its side.
The friction brake 100 for a recovery machine according to this embodiment includes a brake frame 120, a brake bar 140 to which brake pads 144 are installed, an elastic member 160 for elastically biasing the brake bar 140, and a guide bar 180 coupled to the brake bar 140.
The brake frame 120 is configured to surround both sides of a lower roller 190. A guide hole 122 is formed in one side of the lower roller 190 so as to guide the guide bar 180.
The brake bar 140 is positioned in the brake frame 120 and configured to surround both sides of the lower roller 190 in order to give a braking force to the recovery machine. The brake pads 144 are formed on both ends of the brake bar 140. The brake pads 144 are positioned in circular grooves 192 formed in both sides of the lower roller 190.
The elastic member 160 is installed between the brake frame 120 and the brake bar 140.
Preferably, the brake bar 140 is elastically biased by means of the elastic member 160 so that the brake pads 144 are contacted with sides of the grooves 192 of the lower roller 190, causing friction. That is to say, the brake pads 144 give a frictional force to the recovery machine due to frictional contact with the sides of the grooves 192 formed in the lower roller 190.
The guide bar 180 is extended from outside of the brake frame 120 to inside thereof and coupled to the brake bar 140. In addition, a rope ring 182 connectable to a line or a rope is mounted to one end of the guide bar 180, which is positioned out of the brake frame 120.
Now, operation of the friction brake for a recovery machine according to a preferred embodiment of the present invention, configured as mentioned above, is described.

While a conventional line or a guide rope connected to the rope ring 182 of the friction brake 100 is recovered, a tensioning machine (not shown) is not always operated at the same speed.
If the tensioning machine operates at a low speed, as shown in Fig. 4, the guide bar 180 having the rope ring 182 pulls the brake bar 140 with a weaker force, so the brake bar 140 is elastically biased by means of the elastic member 160. The brake pads 144 installed to both ends of the elastically biased brake bar 140 are contacted with the sides of the grooves 192 formed in the lower roller 190, thereby causing friction. That is to say, as the frictional force of the brake pads 144 with respect to the sides of the grooves 192 of the lower roller 190 becomes stronger, the speed of the recovery machine is lowered.
In case the tensioning machine operates at a high speed, as shown in Fig. 5, the guide bar 180 having the rope ring 182 pulls the brake bar 140 with a stronger force, so the brake bar 140 is pulled forward beyond the elastic force of the elastic member 160. A frictional force of the brake pads 144 installed to both ends of the forwardly pulled brake bar 140 with respect to the sides of the circular grooves 192 formed in the lower roller 190 becomes weak. That is to say, since the frictional force of the brake pads 144 with respect to the sides of the grooves 192 of the lower roller 190 is weakened, the speed of the recovery machine is increased.
Figs. 6 and 7 show a friction brake for a recovery machine according to another embodiment of the present invention, which is installed to a recovery machine having a lower roller with a circular protrusion on its side. In Figs. 6 and 7, the same reference numeral as in Figs. 2 and 3 is used for the same component.
Referring to Figs. 6 and 7, the friction brake 100' for a recovery machine according to this embodiment includes a brake frame 120', a guide bar 180' to which a rope ring 182 and a brake pad 144' are mounted, and an elastic member 160 for elastically biasing the brake pad 144'.
The rope ring 182 is mounted to one end of the guide bar 180', positioned out of the brake frame 120', so as to be connectable to a line or a rope. The brake pad 144' is mounted to the other end of the guide bar 180', which is extended inside through a guide

hole 122' of the brake frame 120'. The elastic member 160 is installed between the brake frame 120' and the brake pad 144'.
Preferably, the brake pad 144' is elastically biased by means of the elastic member 160 and contacted with a circular protrusion 194 formed on the side of the lower roller 190' to cause friction. That is to say, the brake pad 144' gives a frictional force to the recovery machine by means of frictional contact with the circular protrusion 194 formed on the lower roller 190'.
Now, operation of the friction brake for a recovery machine according to this embodiment, constructed as mentioned above, is described.
In case the tensioning machine operates at a low speed, as shown in Fig. 8, the guide bar 180' having the rope ring 182 pulls the brake pad 144' with a weaker force, so the brake pad 144' is elastically biased by means of the elastic member 160. The elastically biased brake pad 144' is contacted with the side of the circular protrusion 194 formed on the lower roller 190', causing friction. That is to say, since the frictional force of the brake pad 144' with respect to the side of the protrusion 194 of the lower roller 190' becomes stronger, the speed of the recovery machine is lowered. In case the tensioning machine operates at a high speed, as shown in Fig. 9, the guide bar 180' having the rope ring 182 pulls the brake pad 144' with a stronger force, so the brake pad 144' is pulled forward beyond the elastic force of the elastic member 160. The frictional force of the forwardly pulled brake pad 144' with respect to the side of the circular protrusion 194 formed on the lower roller 190' becomes weaker. That is to say, since the frictional force of the brake pad 144' with respect to the side of the protrusion 194 of the lower roller 190' is weakened, the speed of the recovery machine is increased.
As mentioned above, if a recovery speed caused by the tensioning machine is slow, the elastic member 160 elastically biases the brake pad 144, 144' to be contacted with the lower roller 190, 190' and cause friction therebetween, thereby giving a strong braking force. That is to say, in case the recovery machine advances in a downwardly inclined direction, the strong braking force applied to the recovery machine may prevent the conventional line or the guide rope from being drooped though the recovery machine moves at a low speed. In addition, though the recovery machine stops on a downward

slope, it may be prevented that the conventional line and the guide rope are drooped, by setting an initial braking force of the recovery machine to 20 kfg or above. To the contrary, as the recovery speed is increased by means of the tensioning machine, the guide bar 180, 180' overcomes the elastic force of the elastic member 160, lowering the frictional force of the brake pad 144, 144' with respect to the lower roller 190, 190', thereby lessening the braking force. That is to say, since the braking force is weak when the recovery speed caused by the tensioning machine is high, the friction of the upper and lower rollers with respect to a new line is decreased, thereby reducing abrasion of the upper and lower rollers and preventing damage of the new line.
In addition, metal lining is preferably treated on the sides of the groove 192 and the protrusion 194 of the lower roller 190', which are contacted with the brake pad 144, 144' by friction. This treatment using metal lining may reduce abrasion of the friction portion.
As a result, since the braking force of the recovery machine to which the friction brake 100' is mounted is varied according to the recovery speed of the tensioning machine, abrasion of the upper and lower rollers 190, 190' may be minimized, and thus maintenance costs are reduced.
Meanwhile, the friction brake 100, 100' of the present invention is structurally simple and small rather than a conventional recovery machine, so it is efficient in terms of mechanical performance and its installation costs may also be reduced.
The present invention has been described in detail. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
APPLICABILITY TO THE INDUSTRY
As mentioned above, the friction brake for a recovery machine according to the present invention gives the following effects.

First, since the braking force is varied according to the recovery speed of the tensioning machine, abrasion of the upper and lower rollers is minimized and a new line is not damaged, thereby reducing costs for maintenance.
Second, the friction brake of the present invention, and thus the recovery machine, has a lighter weight, so mechanical performance is improved and installation costs are reduced.

WE CLAIM;
1. A friction brake for a recovery machine, which is used for exchanging a
conventional line with a new line by means of a construction method using supporting rollers
and gives a braking force to a lower roller with a circular groove in a side thereof, the friction
brake comprising:
a brake frame configured to surround both sides of the lower roller of the recovery machine and having a guide hole in one side thereof;
a brake bar positioned in the brake frame and configured to surround both sides of the lower roller, brake pads being mounted to both ends of the brake frame;
an elastic member installed between the brake frame and the brake bar; and
a guide bar having one end positioned out of the brake frame and to which a rope ring connectable to a line or a rope is mounted, and also having the other end extended into the brake frame through the guide hole and coupled to the brake bar.
2. The friction brake for a recovery machine according to claim 1,
wherein the brake bar is elastically biased by means of the elastic member so that the brake pads are contacted with a side of the groove of the lower roller to cause friction.
3. The friction brake for a recovery machine according to claim 1,
wherein metal lining is treated on the side of the groove of the lower roller contacted with the brake pads by friction.
4. A friction brake for a recovery machine, which is used for exchanging a
conventional line with a new line by means of a construction method using supporting rollers
and gives a braking force to a lower roller with a circular protrusion on a side thereof, the
friction brake comprising:
a brake frame configured to surround both sides of the lower roller of the recovery machine and having a guide hole in one side thereof;
a guide bar having one end positioned out of the brake frame and to which a rope ring connectable to a line or a rope is mounted, and also having the other end extended into the brake frame through the guide hole and to which a brake pad is mounted; and
an elastic member installed between the brake frame and the brake pad.
5. The friction brake for a recovery machine according to claim 4,
wherein the brake pad is elastically biased by means of the elastic member so as to be contacted with the protrusion formed on a side of the lower roller to cause friction.
6. The friction brake for a recovery machine according to claim 4,
wherein metal lining is treated on the side of the protrusion of the lower roller contacted with the brake pad by friction.