Apparatus for molding rigid structures from dry friction material

Apparatus for forming rigid structures such as disk brake pads from a dry mix of friction material includes a compression molding press, a friction material agitator and an improved mechanism for transporting friction material from the agitator to the press with friction material preform forming apparatus between the agitator and the press defining an intermediate portion of the improved transport mechanism.

This patent application, the parent application hereto which is United 
States patent application Ser. No. 637,914 which has issued as United 
States Pat. No. 4,003,498, and the parent application thereto, pending 
United States patent application Ser. No. 633,054, were all submitted by 
Edward Moneghan and assigned to Pennwalt Corporation. United States patent 
application Ser. No. 633,054 discloses and claims subject matter which is 
disclosed and claimed in pending United States patent application Ser. No. 
580,470, filed May 22, 1975, and now abandoned, by Frank Shelton and 
assigned by him to Maremont Corporation. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to apparatus for forming dry, high bulk, friction 
materials into rigid structures which are substantially immediately 
useable without further modification in applications requiring friction 
resistant structures. 
2. SUMMARY OF THE INVENTION 
Heretofore, it has not been known to provide apparatus for compression 
molding rigid friction material structures of the type set forth, 
including apparatus for progressively withdrawing mixed friction material 
from a remotely located supply and feeding it to a plasticizing screw 
along a closed path. Also unique is an agitator, suitable for progressive 
withdrawal of mixed friction material therefrom while agitating at least a 
portion of the remaining material. Further provided is apparatus, 
preferably a closed flexible auger, for progressively transporting the 
withdrawn friction material along a closed path to the plasticizing screw.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Reference is made to FIG. 1 wherein there is shown the apparatus for 
compression molding rigid bodies from friction material. Container 20 
containing the friction material recipe is mounted atop agitator 10 for 
release thereinto of friction material. Agitator 10 is connected to hopper 
48 of a stuffer 12 by feed means 22 through which the agitated mix of 
friction material recipe is transferred to stuffer hopper 48. Stuffer 
hopper 48 is mounted atop extruder 14 for delivery of mixed friction 
material recipe thereinto. Extruder 14 has preforming means 16 proximate 
one end thereof for receipt of partially plasticized friction material. 
Compression molding press 18 molds friction material preforms into the 
final molded product. 
Container 20 is mounted on agitator 10 for closed transfer of friction 
material recipe into agitator 10, without release of any dust or 
particulate matter into the atmosphere. Sealing means 26 at the juncture 
of container 20 and agitator 10 assures that no dust or fine particulate 
friction material escapes during transfer of the mixture from container 20 
to agitator 10. A suitable cover (not shown) may be used in place of 
sealing means 26 to close the open top of the agitator after the container 
is empty. 
Agitator 10 has therewithin a horizontal shaft 28 which has a plurality of 
fingers 30 extending radially therefrom. Horizontal shaft 28 is driven by 
motor 32, which is preferably an electric motor, through gear reduction 
means enclosed within housing 36. In FIG. 1, agitator 10 has been broken 
away to show horizontal shaft 28 and attached fingers 30. Agitator 10 has 
extending downwardly therefrom a duct 38 for guiding the mixed and 
agitated friction material recipe into a flexible feeder 22. Flexible 
feeder 22 has therein a flexible, continuous screw 40 of the auger type. 
Flexible screw 40 is driven by hydraulic motor 42 mounted at an end of 
flexible screw 40 remote agitator 10. Hydraulic motor 42 could equally 
well be mounted at the end of flexible screw 40 proximate agitator 10. 
Hydraulic motor 42 is mounted on a mounting bracket 43 affixed to stuffer 
hopper 48. Bracket 43, in addition to supporting hydraulic motor 42, 
encloses the end of flexible screw 40 from which transported friction 
material drops into stuffer hopper 48. A cover 47 covers the top of 
stuffer hopper 48 so no friction material can escape as it drops into 
stuffer hopper 48. 
Stuffer hopper 48 has been partially broken away in FIG. 1 to show a 
plunger 44 secured to the lower end of an upright, vertical shaft 46. 
Plunger 44 and shaft 46 reciprocate vertically, to stuff friction material 
in tapered stuffer hopper 48 through an orifice 49 into contact with 
rotatable plasticizing screw 52. Plunger 44 and shaft 46 are driven by an 
air cylinder 76 above stuffer hopper 48. 
The plasticizing apparatus, designated generally by arrow B, includes 
plasticizing screw 52 mounted for rotational motion within plasticizing 
screw housing 54. Plasticizing screw 52 is driven by a hydraulic motor 50. 
Screw 52, housing 54 and motor 50 are parts of extruder 14. Extruder 14 is 
mounted on a bed plate 68. 
At least one preform cup 70 is at the end of plasticizing screw 52 for 
receipt of at least partially plasticized material exiting screw housing 
54. An air cylinder 72 is above the juncture of cup 70 and housing 54. A 
housing 74 encloses a guillotine knife (not shown) which may be driven 
downwardly by air cylinder 72, between the preform cup and the 
plasticizing screw housing. This assembly is referred to as the preforming 
section. 
Molding press 18 has a base 56 upon which stationary platen 58 is mounted. 
Above stationary platen 58, on connecting guide posts 62, is a moveable 
platen 60. Mold halves, not shown, are disposed on the two platens. Rigid 
friction material bodies are formed in mold cavities defined by the mold 
halves when preforms of friction material are placed into the respective 
mold cavities, the mold halves are brought together, and heat and pressure 
are applied. Duct 64 is provided, adjustably affixed to one of guide posts 
62, for transferring molded rigid friction material bodies away from the 
press once molding is complete. A hydraulic cylinder contained in 
enclosure 66 provides vertical movement of moveable platen 60. 
Extending upwardly from a reciprocable piston in air cylinder 76 is rod 78 
which has selectably positionable upper and lower cam means 82 and 80 
affixed thereto. Upper cam means 82 actuates an upper limit switch L4, 
while lower cam means 80 actuates a lower limit switch L3. Upper and lower 
limit switches L4 and L3 are actuated by their respective associated cam 
means during reciprocation of rod 78. 
Reference is now made to FIGS. 2 and 3 wherein horizontal shaft 28 of 
agitator 10 is shown with a plurality of fingers 30, individually denoted 
30a, 30b and 30c, protruding therefrom in a radial direction, with ribbon 
31 helically formed about and affixed to the extremities of fingers 30c. 
Horizontal shaft 28 rotates in the direction shown by arrow E. Radially 
extending fingers 30a and 30b continuously agitate the friction material. 
Radially extending fingers 30c are each of different length and arranged 
extending from horizontal shaft 28 in order of decreasing length in the 
axial direction denoted by arrow F. Due to the helical shape of ribbon 31, 
as horizontal shaft 28 is rotated through friction material in agitator 
10, friction material in the neighborhood H of helical ribbon 31 is urged 
in direction F. Friction material remote from the helical ribbon, 
proximate fingers 30a, then moves in direction F, to fill the void created 
when material more proximate ribbon 31 has dropped through duct 38 for 
removal by flexible screw 40. 
Feeder 22 is provided with end sealing means 41 to close the lower end of 
flexible feeder 22 so no dust or friction material can escape. In the area 
of agitator 10 denoted by bracket G, equal length fingers 30a agitate the 
friction material and maintain it in a light, homogeneous condition. In 
the area denoted by bracket H, extended finger 30b, in combination with 
fingers 30c, serves to draw friction material from area G into area H. 
Reference is now made to FIG. 4 wherein there is shown an end view of 
horizontal shaft 28 with six equal length fingers 30a extending radially 
therefrom. Fingers 30a are closely spaced to the wall of agitator 10 to 
maintain substantially all the friction material within agitator 10 in an 
agitated, fluffed, homogeneous state. The direction of rotation of 
horizontal shaft 28 is denoted by arrow E". 
In FIG. 5, the direction of rotation of horizontal shaft 28 is shown by 
arrow E'". The projection of duct 38 is denoted 38'. As shaft 28 rotates, 
corkscrew-type motion of helical ribbon 31 results in friction material in 
agitator 10 gathering in the neighborhood of helical ribbon 31. Due to 
this action and the force of gravity, friction material falls downward 
into proximity with flexible screw 40 which removes the friction material 
from agitator 10 along a closed path. 
FIG. 6 is a diagram of electrical circuitry which controls feed of friction 
material from agitator 10 into stuffer hopper 48. P1 and COMMON are main 
electrical power lines. Switch L5 controls motor 32 and provides an 
electrical interlock whereby when agitator 10 is open, no mixing of 
friction material can take place. Line P2 provides power to the circuit 
elements when the apparatus is feeding friction material in an automatic 
mode, described below. Line P2 is in parallel with electrical circuitry 
controlling hydraulic drive motor 50 so automatic feeding of friction 
material cannot occur unless plasticizing screw 52 is rotating. Line P3 
provides power to feed friction material in a manual operating mode. Power 
to Line P3 is controlled by a manual switch not shown in the diagram. 
Element 92 is a material level sensing means in stuffer hopper 48. Upper 
and lower limit switches L1 and L2 are mechanically tied and are actuated 
by the presence of friction material in stuffer hopper 48. S1a is a pair 
of normally open contact points actuated by relay R1 while S3a is a pair 
of normally open contact points actuated by a time delay relay TDR2; S1a 
and S3a provide a holding circuit for TDR2. TDR2 is an "off time delay 
relay;" when TDR2 is energized, it immediately opens normally closed 
switch TDS2. The timer portion of TDR2 begins to time only when TDR2 is 
deenergized. Once the timer portion of TDR2 has timed out, TDS2 closes. 
The timing function of TDR2 does not affect conventional relay contact 
points S3a or S3b, both actuated by TDR2. Contact points S3a are normally 
open and close when TDR2 is energized while contact points S3b are 
normally closed and open when TDR2 is energized. The timing function of 
TDR2 is adjustable so the time TDS2 remains open, after TDR2 has been 
deenergized, can be varied. 
S1b is a pair of normally open contact points actuated by relay R1; S1b 
provides a holding circuit for R1. HS1, HS2 and HS3 are hand-actuated 
switches which are respectively normally open, normally closed and 
normally closed. These three switches allow hand control of TDR1 and C1. 
TDR1 is an "on time delay relay" with timing starting when TDR1 is 
energized. TDR1 opens normally closed pair of contact points TDS1 when it 
has timed out. Once de-energized, TDR1 allows points TDS1 to return to 
their normally closed position. Coil C1 controls air cylinder 76. When C1 
is energized, air is supplied to cylinder 76 causing a downward stroke of 
reciprocating plunger 44 and vertical rod 78. When C1 is de-energized, 
reciprocating plunger 44 and vertical rod 78 are returned to their 
starting position, where the downward stroke begins. 
S2a and S2b respectively are normally closed and normally open pairs of 
contact points actuated by relay R2. L3 and L4 are the lower and upper 
limit switches actuated by lower and upper adjustable cam means 80 and 82 
respectively. L3 is normally open and is closed only during contact with 
adjustable cam means 80; this contact defines the maximum downward travel 
of plunger 44. L4 is normally closed and is opened by adjustable cam means 
82 at the maximum upward travel of plunger 44. 
HS4 is a hand switch with four sets of contact points, two of which are 
normally open and two of which are normally closed. Hand actuation of HS4 
changes operation from manual to the automatic mode. HS6 is a hand switch 
for manual operation of hydraulic motor 42 which powers flexible screw 40. 
Coil C2 when energized actuates a conventional hydraulic valve which 
controls the flow of hydraulic fluid to hydraulic motor 42. HS5 is a 
normally open hand actuated switch. 
Operation of the Invention 
Friction material is fed at a controlled rate along a closed path to 
plasticizing screw 52 in FIG. 1. The closed path insures that the friction 
material will not escape to surrounding ambient air. Any such release of 
friction material would make the area unsuitable for workers. 
Feeding is initially accomplished by feeding material in agitator 10 into 
flexible screw 40 through duct 38. As horizontal shaft 28 rotates, it 
tends to keep the material agitated thereby preventing material from 
bridging above the pick-up area of flexible screw 40. Agitation also 
forces material in the agitator hopper from left to right in FIG. 1, into 
duct area 38. 
Flexible screw 40 is rotationally driven by hydraulic motor 42 and feeds 
friction material from duct 38 through flexible feeder 22 along a spiral 
path into stuffer hopper 48. 
Once friction material has been discharged into stuffer hopper 48, the 
material is then force-fed through orifice 49 into contact with 
plasticizing screw 52 by reciprocating plunger 44 with air cylinder 76. 
Horizontal shaft 28 and fingers 30 in agitator 10, flexible screw 40, 
stuffer hopper 48 and reciprocating plunger 44 function to feed friction 
material to plasticizing screw 52, through a closed system, at a rate 
suitable for operation of plasticizing screw 52. Accordingly, operation of 
horizontal shaft 28, flexible screw 40 and reciprocating plunger 44 must 
be coordinated to properly feed plasticizing screw 52. For plasticizing 
screw 52 to properly function, it must receive friction material at the 
rate at which screw 52 can carry friction material away from orifice 49 
through screw housing 54 for deposit into preform cup 70. Since friction 
materials are not free-flowing, these materials may "bridge" across 
orifice 49 thereby preventing plasticizing or extruding screw 52 from 
receiving any material. One function of reciprocating plunger 44 is to 
break any material bridging which occurs above orifice 49 and to stuff 
material down orifice 49 into contact with plasticizing screw 52. In this 
way, there is assurance that plasticizing screw 52 is receiving friction 
material at least as fast as plasticizing screw 52 can remove material 
from orifice 49. 
For reciprocating plunger 44 to properly function, the rate at which 
friction material is fed into stuffer hopper 48 must be precisely 
controlled. This feed rate must equal the rate at which plasticizing screw 
52 removes friction material from orifice 49. If the amount of material 
fed into stuffer hopper 48 is too small, too little material will move 
through plasticizing screw barrel 54, causing material in barrel 54 to 
become too hot. This is unacceptable since the temperature of material 
reaching preform cup 70 must be controlled to a close tolerance. If the 
temperature is too high, too much cure of the thermoset resin portion of 
the material will occur, making molding impossible. If too much material 
is fed into stuffer hopper 48, material will build up therein because 
plasticizing screw 52 will be unable to remove it quickly enough from 
orifice 49. This also is unacceptable because of the characteristic of 
friction material whereby the material will not flow vertically when such 
build-up begins. When too much material is fed in, reciprocating plunger 
44 only makes a hole through the built-up material and built-up walls of 
material do not collapse, an effect called "rat-holing". Any material in 
plasticizing screw barrel 54 overheats because insufficient material is 
present therein to dissipate the heat generated with the barrel. 
For controlling rate of feed of friction material to the plasticizing 
screw, three controls are provided. A first control is a valve controlling 
rate of flow in the hydraulic fluid line connected to hydraulic motor 42. 
This flow control is conventional, is preferably hand operated and is not 
shown in the drawings. It is preset for a given type of material which is 
fed into stuffer hopper 48. Normally once a proper setting is determined 
for this flow control it need not be further adjusted. This flow control 
adjusts the speed of hydraulic motor 42 thereby adjusting the speed at 
which flexible screw 40 rotates. The speed at which flexible screw 40 
rotates controls the rate of feed of friction material into stuffer hopper 
48. Unfortunately, due to the nature of friction materials, with their 
inconsistent, nonhomogenous make-up, a constant rate of feed of friction 
material into stuffer hopper 48 will not permit the degree of control of 
the amount of friction material in hopper 48 which is required for 
successful operation of reciprocating plunger 44. Accordingly, a second 
control is needed. 
The second control is a time control consisting of first time delay relay 
TDR1 controlling coil C2 which activates a conventional input electrical 
circuit, not shown, which serves to actuate a conventional hydraulic 
valve, not shown, which controls fluid flow to hydraulic motor 42. First 
time delay relay TDR1 actuates when reciprocating plunger 44 starts its 
downward stroke. Time delay relay TDR1 has associated therewith a preset 
time upon elapse of which, after actuation of TDR1, TDR1 is said to 
"time-out". When TDR1 times out, it opens TDS1 in the input circuit to 
coil C2 thereby closing the hydraulic valve, denying hydraulic fluid to 
hydraulic motor 42 thereby stopping rotation of flexible screw 40 and 
haulting feed of friction material into stuffer hopper 48. TDR1 can be set 
to a suitable time whereupon it will stop any over-feed of friction 
material. 
A third control used for control of the feed rate of friction material 
through orifice 49 to plasticizing screw 52 is level sensing means 92 
which senses the level of friction material in stuffer hopper 48. Level 
sensing means 92 is connected to electrical circuitry for control of 
hydraulic fluid to hydraulic motor 42. So long as the level of material is 
maintained below a critical high level is stuffer hopper 48, reciprocating 
plunger 44 will successfully stuff material through orifice 49 into 
proximity with plasticizing screw 52. 
Electrical power controlling feed of air to cylinder 76, feed of 
electricity to motor 32 and feed of hydraulic fluid to hydraulic motor 42 
is in parallel with electrical power controlling operation of screw motor 
50. Thus, only when plasticizing screw 50 is operative and rotating will 
friction material be fed from agitator hopper 10 through flexible feeder 
22 into stuffer hopper 48 through orifice 49 and into proximity with 
plasticizing screw 52. 
Level sensing means 92 in stuffer hopper 48 is a safety device which 
functions only upon failure of TDR1. During normal operation TDR1 serves 
exclusively to control operation of air cylinder 76, reciprocating plunger 
44 and vertical shaft 46. 
During normal automatic operation sequencing of TDR1 is as follows: 
Initially, assume plasticizing screw 52 is rotating thereby feeding 
partially plasticized material into preform cup 70. Air cylinder 76 is 
actuated thereby initiating downward travel of reciprocating plunger 44 
and rod 78. Upper adjustable cam means 80, slidably affixed to rod 78, 
moves downward unitarily with rod 78 thereby allowing limit switch L4 to 
trigger TDR1 by deenergizing R2 thereby allowing S2a to return to the 
normally closed state. This actuates the timer associated with TDR1. When 
reciprocating plunger 44 reaches the lower extremity of its travel, lower 
cam means 82 contacts limit switch L3 which energizes R2 thereby opening 
S2a and deenergizing C1 and TDR1. This reverses air flow into cylinder 76 
causing reciprocating plunger 44 to rise to its upper extremity where 
another reciprocation of plunger 44 is begun. Note that if TDR1 times out, 
reciprocating plunger 44 continues its downward travel; it does not stop 
upon completion of the preset time. TDR1 is to control operation of 
hydraulic motor 42, which drives flexible screw 40, not to control 
operation of reciprocating plunger 44. Either of two events makes the 
piston in cylinder 76 travel to its upper extremity whereupon it is ready 
to begin another downward stroke; these two events are (1) stopping 
plasticizing screw 52, which means preform cup 70 is full or (2) allowing 
reciprocating plunger 44 to reach a lower extremity of travel whereupon 
lower adjustable cam means 82 actuates bottom limit switch L3. If TDR1 
times out during a downward portion of a reciprocation of plunger 44, this 
signifies that friction or high bulk material is well packed below plunger 
44, in orifice 49 and in good contact with plasticizing screw 52. If 
reciprocating plunger 44 is contacting friction material in stuffer hopper 
48 when TDR1 times out, reciprocating plunger 44 does not stall because 
plasticizing screw 52 continues to rotate thereby continuously removing 
material from orifice 49; accordingly reciprocating plunger 44 continues 
to travel downwardly. If plasticizing screw 52 stops rotating due to 
shutoff of electrical power, consequent deenergizing of coil C1 causes 
reciprocating plunger 44 to return to its extreme top position to begin 
another downward portion of a reciprocation upon reconnection of 
electrical power to plasticizing screw 52. 
When the feeding mechanism is operated manually, power is supplied through 
line P3. Actuation of HS1 energizes C1, thereby causing reciprocation of 
the piston in air cylinder 76 with consequent reciprocation of plunger 44 
and actuation of TDR1. However actuation of TDR1 need have no effect on 
the feeding mechanism since TDS1 may be effectively bypassed by actuation 
of HS6. Assuming TDS2 is in its normally closed position, actuation of HS6 
actuates C2 which initiates operation of hydraulic motor 42, providing 
friction material to stuffer hopper 48. Similarly, manual actuation of HS5 
energizes electric motor 32 thereby rotating horizontal shaft 28 (assuming 
L5 is closed, indicating the cover interlock on agitator 10 is operative). 
When operating in the manual mode, level sensing means 92 and TDR2 are both 
operative from power supplied through line P1. This means that even in the 
manual operating mode, if stuffer hopper 48 becomes too full of material, 
TDR2 will be actuated, opening TDS2, stopping hydraulic motor 42 and 
halting feed of friction material into stuffer hopper 48. Level sensing 
means 92 and TDR2 operate in the same fashion when the feeding mechanism 
is in automatic mode since power is always supplied through line P1, no 
matter which mode of operation is used. 
Reference is again made to FIG. 6 for consideration of operation in the 
automatic feed mode. HS4 is a selector switch which the operator uses to 
select automatic or manual operation. In FIG. 6, HS4 is in position for 
manual operation. While operating in the automatic mode, HS4 is actuated, 
from the state shown in FIG. 6, thereby making circuits in reference lines 
11 and 13 and breaking circuits in reference lines 12 and 14. Referring to 
reference lines 1, 2, 3, and 4, so long as the level of friction material 
in stuffer hopper 48 is below that at which L1 is closed, L2 remains 
closed, energizing R1 which causes S1a and S1b to be actuated from their 
normally open positions to closed positions. Upon material in stuffer 
hopper 48 reaching the maximum allowable level, L1 closes, thereby opening 
L2. R1 remains energized due to closed S1b. Once L1 closes, TDR2 is 
energized since S1a is closed. Upon TDR2 being energized, S3a closes, S3b 
opens and TDS2 opens thereby halting feed of friction material by 
deenergizing coil C2 which controls hydraulic motor 42. TDS2 remains open, 
preventing feed of friction material, until TDR2 has been deenergized. 
TDR2 is deenergized when the level of material in stuffer hopper 48 drops 
and deactuates L2, and the timer portion of TDR2 times out. S3a and S3b 
respectively close and open immediately upon TDR2 energizing, since S3a 
and S3b are not connected to the timing function of TDR2. Once the level 
of friction material in stuffer hopper 48 has dropped below the maximum 
allowable level, L1 opens and L2 closes, energizing R1. This closes S1b, 
providing a hold circuit for R1. Upon L1 opening, TDR2 is no longer 
energized and S3b returns to its normally closed position. TDS2 returns to 
its normally closed state after the timing function of TDR2 has finished. 
TDR1 begins to time when it is energized with C1 which actuates a valve in 
an air line to cylinder 76. When C1 is energized, the piston in cylinder 
76 begins its downward stroke, causing plunger 44 and rod 78 to begin the 
downward portion of a reciprocation. TDR1 begins to time when plunger 44 
starts down. S2a is normally closed and is actuated by R2. When C1 is 
actuated and the piston in cylinder 76 begins downward travel, R2 is not 
energized and S2a is in its normally closed position. L4 is in its 
normally closed position, having closed immediately upon upper adjustable 
cam means 82 moving away from L4 upon downward movement of rod 78. Once 
the piston in cylinder 76 starts downward, it continues downward until 
lower adjustable cam means 80 closes normally open L3. This energizes R2 
thereby opening S2a and closing S2b. Closure of S2b provides a holding 
circuit which maintains R2 in the energized state. When S2a opens, C1 is 
de-energized thereby causing the piston in cylinder 76 to travel upwardly 
from its extreme downward position. TDR1 is also de-energized. The piston 
in cylinder 76 continues up until upper adjustable cam means 82 opens 
normally closed L4. This de-energizes R2, allowing S2a and S2b to return 
to their normally closed and normally open states respectively. When S2a 
closes, C1 is energized and the piston begins another downward stroke. 
Thus, once drive motor 50 for plasticizing screw 52 is actuated and HS4 is 
in position for automatic operation, the piston in cylinder 76 begins to 
reciprocate. 
Clearly, each time the piston in cylinder 76 reciprocates upon actuation of 
C1, TDR1 is also energized and begins to time. When TDR1 times out, 
normally closed TDS1 opens thereby deenergizing C2. This stops hydraulic 
motor 42, halting feed of friction material into stuffer hopper 48. TDS1 
closes when TDR1 is energized again at the start of another downward 
stroke of the plunger. TDS2 opens upon TDR2 being energized, remains open 
as TDR2 times after being deenergized and closes only when TDR2 times out. 
As noted above, TDR2 is only actuated when level sensor 92 senses that 
friction material has accumulated to the maximum allowable level in 
stuffer hopper 48. Thus, TDR1 and TDR2 together actuate C2 and control 
hydraulic motor 42. 
This operation is as follows: TDR1 is energized and begins to time each 
time plunger 44 initiates a downward stroke. If a reciprocation of plunger 
44 is completed before TDR1 times out, TDR1 initiates timing again upon 
the start of the next downward stroke of plunger 44. Energizing TDR1 on a 
second downward stroke of plunger 44 before TDR1 has timed out from the 
previous stroke of plunger 44 causes TDS1 to remain closed. In this 
condition C2 remains energized and hydraulic motor 42 continues to operate 
screw 40, continuing feed of friction material into stuffer hopper 48. 
Once stuffer hopper 48 becomes sufficiently full of material that a 
downward stroke of plunger 44 is impeded to the extent that a full 
reciprocation of plunger 44 exceeds the time to which timer portion of 
TDR1 has been set, TDS1 opens, halting feed of material into stuffer 
hopper 48. In such case, TDS1 remains open until TDR1 is again energized 
when plunger 44 has completed its downward stroke and has returned to its 
extreme upward position. Thus, when so much material has been fed into 
stuffer hopper 48 that plunger 44 requires an extended time to complete a 
single reciprocation, feed of material into stuffer hopper 48 is halted 
until plunger 44 has begun another downward reciprocation. 
If material in stuffer hopper 48 exceeds the maximum allowable level, 
thereby closing normally open L1 and energizing TDR2, TDS2 immediately 
opens, de-energizing C2, stopping hydraulic motor 42 and halting feed of 
friction material into stuffer hopper 48. TDS2 remains open so long as 
TDR2 is energized and after TDR2 is deenergized until TDR2 times out. Only 
after TDR2 times out does TDS2 close, thereby energizing C2, operating 
hydraulic motor 42 and feeding more friction material into stuffer hopper 
48. TDR2 does not start to time until it is deenergized by L1 opening due 
to drop of the level of friction material in stuffer hopper 48. The time 
interval to which TDR2 is normally set is sufficiently long to allow 
plunger 44 to perform at least a major portion of one reciprocation. Thus 
TDS2 once open does not close until the level of friction material in 
stuffer hopper 48 has dropped below the maximum allowable high level and 
plunger 44 has forced some friction material through orifice 49 into 
contact with plasticizing screw 52. In this way TDR1 and TDR2, by 
actuating TDS1 and TDS2 respectively, prevent the level of friction 
material in stuffer hopper 48 from exceeding the maximum allowable level 
at which rat-holing starts to occur and allow plunger 44 to stuff some 
material through orifice 49 before stuffer hopper 48 is again completely 
refilled. This is the process of "starve feeding" without which plunger 44 
cannot successfully feed friction material through orifice 49 into contact 
with plasticizing screw 52. 
Electric motor 32 driving horizontal rotating shaft 28 runs continuously 
when the feeding apparatus is operating in the automatic mode, so long as 
normally open L5 is closed by a cover or sealing means 26 at the top of 
agitator 10. Thus, material in agitator 10 is continuously mixed without 
regard to whether any material is being removed from agitator 10 by 
flexible screw 40. 
The molded rigid friction material bodies are ejected from molding press 18 
by suitable means at the termination of each cycle of the molding press. 
The friction material bodies fall through duct 64 for movement to curing 
ovens. 
The preferred embodiments for the apparatus have been described for the 
purpose of illustrating the function and structure of the present 
invention. However, the present invention is not to be deemed limited to 
the embodiments described herein. This invention includes all embodiments 
and modifications which are encompassed within the scope of the claims 
appended hereto.