Emergency brake

A brake having first and second brake support means; a brake shoe mounted on each support means intermediate the ends of each support means, each support means pivotably being mounted at one end to a fixed frame, a first spring means mounted to the other end of the second support means biasing the first and second support means, and thus the brake shoes toward each other in a braking action. First actuating means are connected to the second support means and act against the first spring means to maintain the brake shoes in a non-braking position and selectively operable to release the first spring means. A third brake support means is pivoted to one of the first and second brake support means, the third brake support means being also connected to one of the brake shoes. Second actuating means are connected between the third support means and the one of the first and second support means, the second actuating means selectively being operable to move the brake shoes to a braking position independently of the first spring means.

This invention is directed to an improved brake. 
The invention is particularly directed to a solenoid-type brake used on 
winches, which brake is provided with a back-up system in case of failure. 
Solenoid-type brakes on winches are well known. These brakes use current, 
supplied to the winch motor, to operate a solenoid which deactuates the 
winch brake. When the winch motor is stopped, the solenoid is 
automatically cut-off to thereby actuate the winch brake. 
These brakes however have no provision to apply a braking load to the winch 
if the solenoid fails. No simple and effective emergency brake is provided 
to brake the winch in the event the solenoid jams or breaks. 
It is therefore the purpose of the present invention to provide a 
solenoid-type brake having emergency braking means if the main solenoid 
fails. It is also the purpose of the present invention to provide this 
emergency braking in a simple and inexpensive manner. This is done by 
utilizing many of the original brake components in the emergency brake, 
with some modification, thus avoiding the use of an entirely separate 
back-up braking system. 
According to the present invention, there is provided a brake having first 
and second brake support means; a brake shoe mounted on each support means 
intermediate the ends of each support means, each support means being 
pivotably mounted at one end to a fixed frame, a first spring means 
mounted to the other end of the second support means biasing the first and 
second support means and thus the brake shoes toward each other in a 
braking action. First actuating means are connected to the second support 
means and act against the first spring means to maintain the brake shoes 
in a non-braking position and are selectively operable to release the 
first spring means. A third brake support means is pivoted to one of the 
first and second brake support means, the third support means being also 
connected to one of the brake shoes. Second actuating means are connected 
between the third support means and the one of the first and second 
support means, the second actuating means selectively operable to move the 
brake shoes to a braking position independently of the first spring means. 
According to a further aspect of the invention there is provided a means 
for self-correcting the air-gap or space e between the brake lining 17 of 
each of the brake blocks 15 and the brake drum 19 when the space e becomes 
wider than the necessary distance due to the wear of the linings 17. 
The brake may further comprise a limit switch for operating an alarm signal 
when the brake linings are worn to a dangerous limit. 
The brake may further comprise an additional security system for permitting 
the smooth and progressive braking of the shaft to be braked in the event 
of a current failure, thus permitting the smooth normal ascending or 
descending movement of a load.

The improved brake 1 shown in the figures is generally employed to brake 
the shaft 3 of a winch 5 in a crane 7. A cable 9 is wound about winch 5 
and a motor (not shown) operates winch 5 to rotate it in either direction 
to wind or unwind cable 9 on or off the winch and thus raise or lower a 
load 11 carried by cable 9. 
The brake 1, known in the prior art and as shown in FIGS. 2 and 3, has a 
pair of opposed brake shoes 13. Each brake shoe comprises a brake block 15 
and a brake lining 17. The brake shoes 13 are adjacent a brake drum 19 
mounted on shaft 3. One brake shoe 13 is pivotably mounted to first brake 
support means 21, intermediate its ends 23, 25, by a pin 27. This first 
support means 21 comprises a pair of spaced-apart strip members 28. The 
other brake shoe 13 is also pivotably mounted to second brake support 
means 29, intermediate its ends 31, 33, by a pin 35. This second support 
means 29 comprises a channel member 36. The ends 23 of support strips 28 
are pivotably attached by a pin 37 to a post 39 forming part of the frame 
of the crane 7. The end 31 of channel member 36 is also pivotably attached 
by a pin 41 to post 39. 
A spring 43 normally biases the upper ends 25, 33 of support means 21, 29 
toward each other about pins 37, 41 thus causing brake shoes 13 to bear on 
drum 19. The spring 43 is mounted about a rod 45. The rod 45 extends 
generally transversely to support means 21, 29 and has one threaded end 47 
passed transversely through a block 49 which is pivotably mounted between 
strips 28 near their upper end 25. A pair of nuts 51 are threaded on the 
end 47 projecting through block 49. The rod 45 passes freely through an 
enlarged hole 53 in the upper end 33 of channel 36 and projects a 
considerable distance from it. This end of the rod carries a circular disc 
57. The rod 45 projects axially from the center of the disc 57. A second 
circular disc 59 is loosely mounted on the projecting portion of rod 45 
adjacent channel 36. Spring 43 is mounted on rod 45 between discs 57, 59. 
A bracket 61 projects from the back of disc 57. The bracket 61 is pivotably 
connected by a pin 63 to one end 65 of a bellcrank 67. The bellcrank 67 is 
pivotably connected, intermediate its ends 65, 69, by a pin 71, to a pair 
of arms 73 extending laterally from channel 36. The other end 69 of 
bellcrank 67 is pivotably connected to a rod 75 projecting from a solenoid 
77. The solenoid 77 is mounted on a bracket 79 attached to support means 
29. 
In operation, the solenoid brake 1 is activated when the motor operating 
the winch 5 is on. When activated, the rod 75 is extended, rotating 
bellcrank 67 clockwise as seen in FIG. 3 and tending to move support means 
21, 29 apart, and thus moving the brake shoes 13 off drum 19 and 
compressing spring 43 between discs 57, 59. When the winch motor is turned 
off, solenoid 77 is deactivated and spring 43 is now operable to move 
support means 21, 29 via the linkage of bellcrank 67, arms 73, and rod 45, 
toward each other thus applying brake shoes 15 onto drum 19 to thereby 
brake winch 5. 
The structure described above is known in the art. In accordance with the 
present invention, an improved solenoid brake 1 is provided in case 
solenoid 77 fails. The improved brake 1 has third brake support means 101 
which comprises a pair of lever arms 103 pivotably mounted at their lower 
end 105 by pins 107 on strips 28 between their lower end 23 and pivot pin 
27 holding brake shoe 13. The short lower end 105 of arms 103 is 
substantially aligned with strips 28. The arms 103 have a longer upper 
portion 109 which diverges away from strips 28. 
In the vicinity where portions 105, 109 of arms 103 meet, bolt 27, 
connecting block 15 to strips 28, passes through arms 103 thereby 
connecting them to block 15 as well. 
To provide for relative movement between arms 103 and strips 28, the strips 
28 are provided with a lost motion connection with bolt 27. More 
particularly, strips 28 are each provided with arcuate slots 115 with the 
center for their radius "R" of curvature, being pins 107. A sliding 
substantially rectangular block or connector 117 is mounted in each slot. 
Bolt 27 passes through a bore 119 in blocks 117 as shown in FIG. 6. Each 
block 117 also has a cylindrical projecting collar 121 mounted in a 
circular bore 123 in arms 103. The bolt 27 passes through collar 121 and 
bore 119 in each block 117 on the arms on each side of block 15. 
Actuating means 131 are connected to the free ends 133, 25 of arms 103 and 
strips 28 respectively, for moving the ends away from each other. These 
actuating means 131, in one embodiment as shown in FIGS. 2 to 5, comprise 
a solenoid actuated spring 135. The spring 135 can be mounted about a 
solenoid rod 137 within a split cylindrical casing 139. One section 141 of 
the casing 139 is pivotably connected between the free ends 133 of arms 
103 by bolts 143. The rod 137 passes axially through the end wall 145 of 
casing 139 and a bolt 147 is threaded onto the end of rod 137 projecting 
from wall 145. 
The other section 149 of split casing 139 is connected to a block 151, (see 
FIG. 2) which is pivotably connected by bolt 153 between, and to the ends 
25 of strips 28. A solenoid 155 is attached to block 151 and solenoid rod 
137 extends through block 151 into solenoid 155. 
In operation, solenoid 155 is normally actuated thus drawing rod 137 to the 
right as viewed in the Figures, keeping spring 135 compressed, and blocks 
117 to the right in arcuate slots 115. This position is maintained 
regardless of whether solenoid 77 is actuated. However, if there is a 
failure in solenoid 77 so that the brake will normally not work, the 
solenoid 155 can be quickly deactuated by the operator. Spring 135 then 
expands as shown in FIG. 5 moving the ends 133, 25 of arms 103 and strips 
28 apart. In effect, arms 103 pivot about pin 107 away from strips 28, and 
carry brake block 15 with them to brake on drum 19. Strips 28 at the same 
time move clockwise, thus, via rod 45, bellcrank 67, arms 73, and channel 
36, pulling opposed brake block against drum 19 also. It is thus seen that 
the emergency solenoid 155 employs at least part of the original linkage 
system in applying the brakes. 
Instead of a solenoid actuated spring 135 for moving the arms 103, the 
brake can employ fluid pressure means 201 as shown in FIG. 7. In this 
embodiment, a cylindrical casing 203 is mounted between the ends 204, 25 
of arms 205 and strips 28 respectively. A first, movable rod 209 projects 
through a central collar 211 in one end 213 of casing 203 and has its 
projecting end 214 passed through a block 215 which is pivotably mounted 
by pins 217 (one only shown) between arms 205. The projecting end 214 is 
threaded and nuts 219 are threaded on the end 214 on either side of block 
215. The other end 221 of rod 209 is attached to a plate 223 which, in 
turn, lies adjacent to, and is fixed to, a flexible membrane 225 which 
divides the casing into two cylindrical chambers 227, 229. A compression 
spring 231 is located in chamber 229 about rod 209 between plate 223 and 
end wall 213 of casing 203. 
An inlet port 233 is provided in the other end wall 235 of casing 203. A 
hose, 237, directing pressurized fluid can be connected to port 233 which 
communicates with chamber 227. 
A rod 239 extends from the center of the other end wall 235 of casing 203 
and is attached to the ends 25 of strips 28 in the same manner that rod 
209 is attached to arms 205. 
In operation, when the solenoid 77 of the brake fails, fluid under pressure 
is admitted through port 233 into chamber 227 and the casing 203 is pushed 
to the left, against the spring 231 as viewed in FIG. 7. This pivotally 
moves the ends 25 of strips 28 away from the ends of arms 205 causing the 
brake to be applied. When emergency braking is no longer required, the 
chamber 227 is vented through line 237 and spring 231 returns the casing 
203 to the position shown in FIG. 7 thus allowing the strips and arms to 
move toward each other thereby releasing the brakes. 
Referring to FIG. 8, the self-correcting means 301 is shown as comprising 
two rods 303 and 305, one of the rods 303 having one of its ends pivotally 
connected by means of a pivot 307 to the end 33 of the channel member 36, 
the other end of the rod 303 being provided with a unidirectional 
self-adjusting element 311 which makes it possible to rod 303 to be 
displaced in one direction only, namely in the direction indicated by 
arrow A in FIG. 8. The unidirectional self-adjusting element 311 prevents 
the back displacement of rod 303 from a determined position, in a 
direction opposite to the direction shown by arrow A. 
In the same way the second rod 305 has one of its ends pivotally connected 
by means of bolt 153 to the ends 25 of strips 28. The other end of rod 305 
is provided with a unidirectional self-adjusting element 313 identical to 
the unidirectional self-adjusting element 311 of rod 303. Each of the 
unidirectional self-adjusting elements 311 and 313 is provided with a ring 
element 315, both of the ring elements being pivotally mounted with a 
certain clearance e' about a shaft 317. The clearance e' that the ring 
elements 315 have with the shaft 317 is equal to the air-gap e provided 
between the linings 17 and the brake drum 19. This clearance e' is 
important to the proper operation of the unidirectional self-adjusting 
elements 311 and 313 as will be explained in later paragraphs. 
As in the case of rod 303, rod 305 can be displaced only in one direction 
i.e. according to arrow B and once in such a displaced position it is 
firmly gripped by the unidirectional self-adjusting element 313 and cannot 
be displaced backward without the release of release means 319 explained 
later. 
In operation, when the brake linings 17 are worn, it is evident that the 
air-gap e between the linings 17 and the shaft 3 becomes wider. However, 
due to the presence of the self-correcting means 301 such an air-gap e is 
automatically adjusted to the desired distance every time that the linings 
are brought together to brake the shaft 3. In fact, when the linings 17 at 
each side of shaft 3 are brought towards each other rods 303 and 305 are 
displaced according to arrows A and B, respectively, due to the moving 
towards each other of the support means 21 and 29, respectively. Now, 
supposing that, in a first stage, the lining elements 17 are not worn and 
are in their braking position, i.e. they are in contact with the brake 
drum 19, the air-gap e does not exist anymore. This air-gap e being equal 
to the clearance e' between the ring elements 315 and the shaft 317, each 
rod 303 or 305 with its unidirectional self-adjusting element is moved 
forwardly according to arrows A or B by a distance e' and not more than 
this clearance e' because they are prevented of doing so by the fact that 
the linings cannot move further towards each other due to the presence of 
brake drum 19. However, in a second stage, if linings 17 are worn, it is 
evident that the air-gap e becomes wider on each side of the brake drum 
19. In such a case for the linings 17 to come into contact with the brake 
drum 19 the rods 303 and 305 are displaced according to arrows A and B, 
respectively, more than the width of air-gap e or the clearance e'. Such 
an additional displacement is possible due to the presence of the 
unidirectional self-adjusting elements 311 and 313 on each rod 303 and 
305, respectively. Thus, it is evident that in such an operation the rods 
303 and 305 of the self-correcting means 301 are displaced first by the 
amount of the clearance e' or air-gap e and then by the amount of the 
width of the worn portions of the linings 17. Now, when the braking 
operation is stopped and the linings 17 are displaced back to their 
non-braking position, the additional displacement of rods 303 and 305 
cannot be moved back in directions opposite to arrows A and B, 
respectively, due to the presence of the unidirectional self-adjusting 
elements 311 and 313 as above explained. This additional displacement 
actually corresponds to the worn portions of the linings 17 and when the 
brake linings 17 are back to their normal non-braking positions, the 
distance or air-gap e between these linings 17 and the brake drum 19 is 
automatically adjusted to its initial value by the clearance e' which, as 
above explained, is equal to the air-gap e. 
If the linings are further used, rods 303 and 305 are further displaced 
unidirectionally according to arrows A and B, respectively, thus providing 
for the worn portions of the lining. Once they have been displaced in the 
unidirectional permitted direction, they cannot be displaced back to their 
initial position and therefore the worn portions are thus compensated. 
In order to prevent the total wearing of the linings 17 without noticing 
it, there is provided a limit switch 321 consisting of two parts, a first 
part 323 being connected to the first support means 21 and a second part 
325 being connected to the second support means 29. When the linings 17 
are worn to a dangerous limit, during a braking operation when the support 
means 21 and 29 are inclined towards each other, part 323 of the limit 
switch 321 comes into contact with part 325 and operates an alarm signal. 
As a further precaution, there is provided for the entire system of the 
brake as shown in the embodiment of FIG. 8 an additional security system 
comprising an auxiliary motor 327 connected to a flywheel 329. The 
flywheel 329 is connected to an alternator 331 which is itself connected 
by means of a relay 333 to the solenoid 155. Supposing that the current 
fails in the power source and therefore the solenoids 77 and 155 are both 
deactivated; without the presence of an additional security system like 
the one above explained, the brake blocks 15 are suddenly brought against 
the brake drum 19 thus abruptly braking the shaft 3. It will be 
appreciated that such an abrupt and sudden braking may cause damage to the 
cable 9 and break it under the jolting of heavy loads carried by cable 9. 
With the presence of the additional security system as above explained 
when the current is cut the auxiliary motor 327 is stopped along with the 
main motor activating the solenoids 77 or 155. However, the flywheel 329, 
due to its stored energy, operates the alternator 321 which by means of 
the relay 333 automatically enters into action and activates the solenoids 
155 for a certain amount of time, lets say a few minutes, depending of the 
flywheel used, for permitting the smooth normal ascending or descending 
movement of the load 11 and the progressive deceleration thereof, thus 
providing a smooth landing of the load carried by the cable 9. It is 
evident that after a certain amount of time the energy stored by the 
flywheel 329 is consumed and the brake linings are again applied against 
the brake drum. The same additional security system as shown in FIG. 8 
can, of course, also be employed in the embodiments of FIGS. 1 to 7.