FORCE TRANSMITTING ASSEMBLY
BACKGROUND OF THE DISCLOSURE
The present disclosure relates in general to a force transmitting assembly and
in particular to an annular brake or clutch assembly with a floating housing to
transmit force to retain the shaft against rotation when employed as a brake or to
transmit rotation when employed as a clutch.
The term force transmitting assembly as employed herein is intended to refer
to an assembly capable of functioning as either a clutch or a brake. These* types of
assemblies are also referred to herein as a clutch-brake assembly. While the
present disclosure is particularly suited for use as a brake assembly and will be
described in detail with reference to that application, it should be immediately
apparent that it is equally capable of functioning as a clutch, a brake, or more simply
referred to as a force transmitting assembly. The term force transmitting assembly
will be used herein interchangeably with the term annular brake assembly
Known clutch-brake assemblies have previously been connected with a shaft
to control power transmission. These known clutch-brake assemblies have been
utilized in association with can-making machines, press drives, and shear drives, as
well as other machines. Known clutch-brake assemblies are disclosed in U.S.
Patent Nos. 5,046,593; 5,257,684; 5,577,581; and 6,637,568.
When machines have different operating characteristics, the force
transmitting capability of a clutch-brake assembly must correspond to the operating
characteristics of the machine with which the clutch-brake assembly is utilized.
Thus, a first machine may require the transmission of relatively large forces to rotate
a shaft and to retain the shaft against rotation, yet another machine may require
smaller forces to rotate the shaft and retain the shaft against rotation. Accordingly
the size and torque of these devices will vary with application.
[0005] While the annular brake assembly of the present disclosure may be used in
any application that requires a braking force, it is particularly suited in industrial
applications as a brake for each of the electric motors in an electric dragline or
shovel in the mining and construction industries. In these types of applications,
rotors are continuously accelerating in one direction, stopping and accelerating in
the opposite direction. The rotors are rotating back and forth with the motor shafts

during operation. Lower inertia value of rotating components means faster cycle
time which means more production.
Thus, there still exists a need for a brake assembly that can minimize inertia
and maximize torque in these and other applications.
BRIEF SUMMARY OF THE DISCLOSURE
The present disclosure relates to a force transmitting assembly which
minimizes inertia and maximizes torque. Friction material is in contact with
substantially all of the working surface of a rotor in order to optimize the torque-to-
inertia ratio. The friction material may be mounted on pressure plates clamping on
the rotor, or alternatively mounted on the rotor itself. The force transmitting
assembly includes an axially moveable housing attached to a stationary mounting
flange. A central opening through the mounting flange and housing receives a driven
shaft. The housing contains a rotor fixedly attached to the shaft. The housing
includes front and rear annular pressure plates with friction surfaces disposed on
each side of the rotor. The housing further includes an annular piston fluidly
movable in a first direction relative to the front annular pressure plate for releasing
the driven shaft for rotation. The piston is further axially movable in a second
direction to compress the front and rear annular pressure plates against the rotor for
braking action.
In one embodiment a plurality of springs urge the piston in the second
direction relative to the front and rear annular pressure plates for braking action.
Other embodiments may include other biasing devices to move the annular piston in
the second direction such as a pneumatic or hydraulic piston and cylinder
The various features of novelty which comprise the present disclosure are
pointed out with particularity in the claims annexed to and forming a part of this
i
disclosure. For a better understanding of the instant disclosure, reference is made
to the accompanying drawings and descriptive matter in which a preferred
embodiment is shown and described.
BRIEF DESCRIPTION OF THE DRAWINGS
The fpregoing and other features of the invention will become more apparent
upon a consideration of the following description taken in connection with the
accompanying drawings wherein:

1 is an elevated perspective view of an annular brake assembly
according to the present disclosure;
Fig. 2 is a sectional view of the annular brake assembly of Figure 1;
Fig. 3 is an exploded view of the annular brake assembly of Figures 1 and 2;
Fig. 5 is a partial sectional view of the annular brake assembly;
Fig. 6 s a perspective view of the rotor with the friction material disposed
thereon;
Fig. 7 is a partial sectional illustrational view of the rotor fixedly mounted on
the shaft of a motor; and
Figs. 8A-8C illustrate other embodiments of the rotor.
DETAILED DESCRIPTION
An annular fcrgke assembly, generally designated 20, shown in Figure 1 is
operable between a first disengaged condition or non-braking mode and a second
engaged condition or braking mode. When the annular brake assembly 20 is in the
disengaged condition, the brake assembly 20 releases frictional force from a driven
shaft. When the brake assembly 20 is in the second engaged condition, the brake
assembly 20 is effective to retain the shaft against rotation.
The annular brake assembly 20 according to the present disclosure
addresses several shortcomings with the prior art brake assemblies. In particular,
the prior art brake assemblies utilize splined hubs to provide axial freedom for the
rotor on the shaft. As the splines wear, the disk becomes imbalanced and exhibits
other wear problems. The splined hubs are expensive to manufacture and replace
besides presenting issues with the down time involved in the repair process.
[0021] In contrast to these prior art devices, the annular brake assembly 20 of the
present disclosure employs a rotor fixedly attached to the driven shaft as will be
described in much greater detail later herein. The structure of the brake assembly
20 according to the present disclosure further allows the friction material to be
replaced without complete disassembly as in the prior art brake assemblies.
[0022] First referring to Figure 1, the annular brake assembly generally designated
20 comprises an axially moveable housing 22 with a limited range of axial movement

connected to a stationary mounting flange 24. Mounting flange 24 is attached to the
frame of a motor or machine, such as a press machine, for example. The housing
22 and mounting flange 24 have a central opening 26 for receiving a rotatable shaft
28 (shown in Figure 7) driven by a motor 30 or other machine. The housing 22
includes axially moveable front and rear annular pressure plates 32, 34 with friction
surfaces situated on each side of a rotor 36 for applying and releasing a clamping
load on the rotor 36. Rotor 36 is fixedly connected to the shaft 28 and rotates
therewith. An array of helical coil springs 38 are employed to actuate an annular
piston 40 into the braking mode which applies force to the pressure plates 32, 34 for
a clamping load against the rotor 36. Annular piston 40 is disposed within a cylinder
or cover member 42 in an arrangement that forms an annular fluid chamber 43
constructed to receive a pressurized fluid of a variable volume that moves annular
piston in the first direction as shown in Figure 2 by arrow A. A plurality of radial
passages 46 in the outer regions of the.cylinder 42, piston 40, front, and rear
pressure plates 32, 34, and the mounting flange 24 are axially aligned to receive
guide rods 44 with threads at each end and fasteners 45 connect and hold these
components together. The term "floating housing" as employed herein is intended to
refer to the axially moveable components of housing 22 which are the front and rear
annular pressure plates 32, 34, the array of helical coil springs 38, the annular piston
40, and the cylinder 42. Another embodiment of the present disclosure may include
air or hydraulic pressure to apply the clamping force on the rotor and utilizing the
array of springs to disengage or release the clamping force. This embodiment may
be utilized in automotive, truck or other vehicle applications.
[0023] Rotor 36 has a generally cylindrical form and preferably includes a centrally
located hub 48 with a bore 50 for positioning on shaft 28. Hub 48 may be an integral
part of rotor 36 and cast as one piece together, or separately attached with fasteners
to rotor 36. Rotor 36 rotates with shaft 28 relative to the components of the housing
22 which are axially moveable in a limited range. Rotor 36 has a planar surface on
each side making up a working surface area for frictional engagement. In one
embodiment, the bore 50 in hub 48 is tapered and is received on a correspondingly
tapered shaft 28 from the motor 30 as best illustrated in Figure 7. The rotor 36 is
held firmly in place to the shaft 28. A suitable fastener, like a nut 51 or a similar
locking device is threaded on the end of the shaft 28. An alternate embodiment
includes retaining the rotor 36 with a known keyless locking bushing or nut to a

PCT/IB21

Straight shaft 28, Turning next to Figures 8A through 8C, there are depicted various
embodiments of the rotor 36 designated 136, 236, and 336. Rotor 136 includes an
annular gap 138 with reinforcement ribs 140. Gap 138 and reinforcement ribs 140
dissipate generated heat from the braking action and prolongs the operating life of
the rotor. Rotor 236 has a solid metal construction with a plurality of openings 238
therethrough used to cool and to allow debris and gases to escape from the braking
action. Rotor 336 combines the features of rotor 136 and rotor 236 by providing
both the annular gap 338 and the plurality of openings 340 with the supporting ribs
342 to allow debris and gas to escape and heat dissipation during the braking mode.
[Q024j?n the embodiment shown in the Figures, when there is fluid pressure on the
annular brake assembly 20, the brake is in the disengaged condition. A suitable
fluid for pressurizing the brake assembly includes air conducted from a fluid source,
such as an air compressor (not shown), a device well known in the art. The air
passes through a. solenoid operated valve similar to that described in U.S. Patent
6,637,568, which is owned by the assignee of the present invention and hereby
incorporated by reference, into fluid connectors 52 on cylinder 42 which are in fluid
communication through passages 54 with a variable volume annular fluid chamber
43 as best seen in Figure 2. As chamber 43 is filled with pressurized air, the front
annular pressure plate 32 moves with the cylinder 42 in a first direction as seen by
arrow A. This is the non-braking mode or condition and the rotor 36 freely rotates
with shaft 28. As cylinder 42 moves in the direction of arrow A, the pressure plate
32 which is attached pushes against the array of helical coil springs 38 and the
annular piston 40. This releases any clamping load on the rotor 36 from the front
annular pressure plate 32. Simultaneously, when the air pressure is being applied,
the annular piston 40 causes the rear annular pressure plate 34 to move against the
mounting flange 24 releasing the clamping load on the rotor 36 by the rear annular
pressure plate 34. In this mode of operation, the brake assembly 20 is in the
disengaged condition or non-braking mode. When the air pressure is evacuated
from chamber 43, springs 38 apply force to the piston 40 and front pressure plate 32
causing them to move in the second direction as seen by arrow B thereby applying
force to the rear pressure plate 34 resulting in both plates 32, 34 placing e clamping
load on or compressing the rotor 36 for the braking action or braking mode. The
brake assembly 20 is now in the engaged condition or braking mode. As mentioned

earlier, other embodiments can reverse this by making the air or hydraulic pressure
apply the braking force and the springs releasing the braking force.
[0p2SjXlthough the annular brake assembly 20 may be associated with press
forming machines or electric draglines, it is contemplated that the brake assembly
will be utilized in association with other known machines requiring acceleration and
deceleration of components of the machine and relatively high disengaging and
engaging frequencies functioning either as a clutch, a brake, or both. Other
machines with which the brake assembly 20 may be associated with, for example,
include a press machine, and/or shear drive. The machines may be single stroke or
continuous-running machines. Other examples include automotive applications,
metal stamping machines, wire processing machines, thread rolling machines,
veneer-cutting machines, bottle sorting machines, paper processing machines or
textile machines. Of course, it should be understood that the brake assembly 20
may be associated with many other known types of machines if desired.
[$M>2t>lThe annular brake assembly 20 as seen in Figs. 2 and 3 basically comprises
a mounting flange or base member 24, a housing 22 with the aforementioned
components, and a rotor 36. The housing 22 includes the front and rear annular
pressure plates 32, 34, one pressure plate on each side of the rotatable rotor 36, the
array of springs 38, annular piston 40, and the cylinder or cover member 42. Aside
from the rotor 36, these items make up the components of the housing 22 and are
interconnected and in alignment with the mounting flange 24 with guide rods 44 and
coaxially disposed clamp tubes 56 mounted in passages 46 on the outer edges of
the components. It should be immediately apparent that the annular brake
assembly 20 may be modified in alternate embodiments that can include a brake
disc or a clutch disc in order to function as either a clutch or a brake. The rotor 36 is
freely rotatable relative to the housing 22.
[OpjWICylindrical clamp tubes 56 positioned coaxially over the guide rods 44 are
arranged to have one end 58 of the clamp tube 56 abut the rear annular pressure
plate 34. The diameter of the passage 46 in the front annular pressure plate 32 is
sized slightly larger than the passage 46 in the rear annular pressure plate 34 so as
to slidably receive the clamp tube 56 therein. The opposite end 60 of the clamp tube
56 abuts against the annular piston 40 as best seen in Figure 2. Return springs 62
are coaxially disposed on the clamp tubes 56 between the pressure plates 32, 34
and exhibit a spring force to facilitate and assist the axial movement of the pressure

plate 32 and to cause the axial movement of pressure plate 34 when the brake
assembly is in the disengaged condition. The spring constants of the return springs
62 and the coil springs 38 can be adjusted using relatively thick turns of wire or
alternatively thinner wire to enable the desired amount of application force and
return force to be used for the axial movement of the pressure plates 32, 34 in
association with machines having different force or torque requirements.
[0P28JThe mounting flange 24 is cast as generally one cylindrical piece of metal and
includes a plurality of passages 46 on its outer radial region. The passages 46 in the
mounting flange 24 preferably include a stepped bore 64 with a decreasing
diameter. Fastener collars 66 which threadably receive the guide rods 44 include a
cap portion 68 for limiting the axial movement of the guide rods 44 within the
stepped bores 64 a distance in both directions A and B sufficient to provide the
clamping force on the rotor 36 and to release the clamping force . A cylindrical
central opening or passage 26 extends through the mounting flange 24 for receiving
the shaft 28.
[QPZfJTha metal housing 22 includes front and rear annular pressure plates 32, 34
each cast as one generally cylindrical piece of metal. The pressure plates 32, 34
have a friction surface side disposed on the opposite sides of the rotor 36. Each
friction surface side of the pressure plates 32, 34 includes a plurality of generally
trapezoidal shaped indentations 70 radially arranged around the pressure plates 32,
34 with preferably each indentation including a retaining channel 71 within the
indentation 70 for slidably receiving and holding correspondingly shaped friction
pads 72. The generally trapezoidal shaped friction pads 72 are sized to slip within
the openings 76 between the clamp tubes 56 for easy replacement without
disassembling the brake assembly 20. The friction pads 72 are of a composite
construction supported by a metal backing plate 74. The backing plate 74 may
include openings 78 at an upper end for securing the friction pads with fasteners to
mating openings 73 in the pressure plates 32, 34. The friction material making up
pads 72 may include radially extending or annular grooves 75 to remove debris and
particulates as well as function as visual indicators of wear. The front and rear
annular pressure plates 32, 34 as best seen in Figure 2 are disposed on each side
of the rotor 36 in an arrangement that places the friction pads 72 on opposite sides
of the rotor 36 and preferably cover at least approximately fifty percent of the
working surface area on each side of the rotor 36 and more preferably at least

approximately sixty-five percent of the working surface area on each aide of the rotor
36. Even still more preferably an embodiment can cover approximately seventy-five
percent of the working surface area on each side of the rotor 36. The fric:ion
material substantially covers the entire working surface area of the rotor 36. The
working surface area is the available planar rubbing area on each side of the rotor
from the outer diameter of the hub. Another embodiment of the present disclosure
may include placing the friction pads 72 on both sides of the rotor 36 rather than on
the pressure plates 32, 34 as shown in Figure 6. Passages 46 are located in the
plurality of shoulders 80 located on the outer radial edge of the front annular
pressure plate 32 and are aligned with the passages 46 in the radial portion of the
rear annular pressure plate 34 and those in the mounting flange 24. Passages 46
are sized to receive the guide rods 44. The diameter of the passages 46 in the rear
annular pressure plate 34 has a size that accommodates only the diameter of the
guide rods 44 whereas the diameter of the passages 46 in the front annular
pressure plate 32 are sized to accommodate the cylindrical clamp tubes 56 coaxially
positioned over the guide rods 44. One end 58 of the clamp tubes 56 abuts the rear
annular pressure plate 34 and the other end 60 of the clamp tubes 56 abuts the
annular piston 40. Return springs 62 are coaxially disposed on the clamp tubes 56
and facilitate the axial movement of the pressure plates 32, 34 in the engaged and
disengaged conditions.
[0J)36JThe housing 22 further includes an array of helical coil springs 38 constructed
in a manner described in detail in U.S. Patent Application Serial No. 11/590,199 filed
October 31, 2006, which is owned by the assignee of the present invention and
hereby incorporated by reference. No detailed explanation of these springs is
necessary here. Alternate embodiments may include any resilient biasing valves
operable to axially move annular piston 40 in the first and second directions, for
example, electrically actuated or hydraulically actuated solenoid valves (not shown).
[pjD317the housing 22 also includes the annular piston 40 which is generally
cylindrical and may be cast as one piece of metal. Shoulders 84 on an outer radial
edge of piston 40 have passages 46 aligned with the passages 46 in the shoulders
80 of the front annular pressure plate 32, and passages 46 in the rear annular
pressure plate 34 and mounting flange 24. Passages 46 in the annular piston 40,
like the passages 46 in the rear annular pressure plate 34, have a diameter that
accommodates the diameter of the guide rods 44, but not the clamp tubes; 56.

Annular piston 40 includes a cylindrically shaped raised central portion 86
constructed to hold and retain the array of helical coil springs 38 as best shown in
Figures 2 and 5. Annular piston 40, like pressure plates 32, 34 and mounting flange
24, includes the centrally located opening 26 for accommodating the rotatable shaft
28.
[Q032]The cylinder or coyer member 42 has a generally cylindrical shape and may
be cast as one piece of metal. Cylinder 42 has a plurality of fluid connectors 52 on
its front constructed for attachment to a pressurized fluid source, like air, for
example. Fluid connectors 52 fluidly communicate through fluid passages 54 with
the annular fluid chamber 43 for pressurization and evacuation. Cylinder 42 has a
centrally located annular recess 88 with a lip 90 extending slightly radially inward.
Lip 90 is attached with fasteners 92 to the front side of the front annular pressure
plate 32. Stepped channel 94 on the back side of the cylinder 42 slidably engages
the walls 87 of the raised portion 86 of the annular piston 40 to form the variable
annular fluid chamber 43.
[0033]The force transmitting assembly 20 of the present disclosure finds many
applications where force is necessary to engage or disengage a flywheel or rotatable
shaft. Advantageously, the force transmitting assembly 20 provides an axially
moveable housing with a fixed rotor 36 attached to a stationary mounting flange 24.
The structure of the present disclosure eliminates the need for axial freedom of
splined rotors that wear, cause imbalance, and are expensive to replace and
manufacture. A significant advantage of the structure of the present disclosure is
the maximization of torque and the minimization of inertia by having the friction
material of friction pads 72 cover substantially all of the rotor surface 36.
[0034]The foregoing is illustrative of the present disclosure and is not intended to be
construed as limiting thereof. Although a few exemplary embodiments of this
disclosure have been described and shown, those skilled in this art will readily
appreciate that many modifications are possible without departing from the novel
teachings and advantages of this disclosure:--Accordingly, all such modifications are
intended be included within the scope of this disclosure as defined in the claims and
their equivalents.

We Claim:
Claim 1. An apparatus for transmitting force to a shaft, comprising:
a mounting flange having a central opening which receives the shaft;
a rotor having a radial working surface and a centrally located opening fixedly
mounted on the shaft and rotatable therewith;
a front and a rear pressure plate disposed on opposite sides of said rotor and
moveably attached to said mounting flange, said front and rear pressure plates
being axially moveable relative to said mounting flange in a first direction lor
releasing a clamping load on said rotor and in a second direction for applying a
damping load on said rotor;
a piston moveably connected to said front pressure plate, said piston being
axially moveable in said first and second directions; and
a cylinder connected to said front pressure plate and axially moveable
therewith, said cylinder having an annular channel constructed for engagement with
a raised portion of said piston together forming a variable volume fluid chamber,
said cylinder and said piston being axially moveable in the first direction under the
influence of fluid pressure applied to said cylinder and piston from the volume fluid
chamber to press said front pressure plate against an urging counterforce for
releasing the clamping load of said front and rear pressure plates against said rotor,
said piston being movable in the second direction to press a friction surface on said
front and rear pressure plates against said rotor for applying the clamping load on
said rotor.
Claim 2. An apparatus as set forth in claim 1 further comprising a plurality of
friction pads on said friction surface of said front and rear pressure plates sufficient
to substantially cover said working surface of said rotor.

Claim 3. An apparatus as set forth in claim 1 further comprising an array of
helical coil springs disposed between said piston and said front pressure plate for
supplying the urging counterforce for the clamping load on said rotor.
Claim 4. An apparatus as set forth in claim 1 wherein said mounting flange, said
rotor, said front and rear pressure plates, said piston, and said cover have a
generally annular shape and a centrally located opening for receiving the shaft
Claim 5. An apparatus as set forth in claim 1 wherein said mounting flange, said
front and rear pressure plates, and said piston are interconnected with guide rods
through aligned passages on an outer edge.
Claim 6. An apparatus as set forth in claim 5 further including a plurality of
clamp tubes eoaxially situated on said guide rods between said rear pressure plate
and said piston for facilitating the application and release of the clamping force on
the rotor.
Claim 7. An apparatus as set forth in claim 1 further including return springs
eoaxially disposed on said clamp tubes between said front and rear pressure plates
for assisting release of the clamping force on said rotor.
Claim 8. An apparatus as set forth in claim 1 further including a hub fastened to
said rotor for receiving the shaft.
Claim 9. An apparatus as set forth in claim 2 wherein each of said friction pads
have generally a trapezoidal shape removably attached to said front and rear
annular pressure plates.
Claim 10. An apparatus as set forth in claim 1 further comprising a plurality of
friction pads disposed on said rotor.

Claim 11. An apparatus as set forth in claim 2 wherein each of said friction pads
have generally a trapezoidal shape and are removably attached to said rotor.
Claim 12. An apparatus as set forth in claim 1 wherein said rotor comprises an
annular rotor with an annular gap with reinforcement ribs.
Claim 13. An apparatus as set forth in claim 1 wherein said rotor comprises an
annular rotor with a plurality of openings therethrough.
Claim 14. An apparatus as set forth in claim 1 wherein said rotor comprises both
an annular gap with a reinforcement ribs and a plurality of openings therethrough.
Claim 15. An apparatus as set forth in claim 7 further comprising a plurality of
generally trapezoidal shaped friction pads each sized to be removably replaced
through openings between said clamp tubes.

A force transmitting assembly transmits force to engage
and disengage a driven shaft. When the force
transmitting assembly is engaged, front and rear
annular pressure plates (32, 34) frictionally retain a
rotor (36) fixedly mounted on the shaft and stops
rotation of the shaft. The force transmitting assembly
maximizes torque and minimizes inertia by providing
friction surfaces with friction material (72)
substantially engaging the entire working surface of
the rotor 36. The force transmitting assembly includes
an axially moveable housing attached directly to a
mounting flange.