Two speed drive with oil shear electro clutch/brake

A two speed drive for an apparatus which uses DC electrically actuated oil shear brake/clutch units is disclosed. The two speed drive directly connects the output to a first input for high speed movement using a DC voltage coil to actuate the clutch/brake for low speed operation. The output is connected to a second input through a gearing system using another DC voltage coil to actuate the clutch/brake. The DC voltage coils provide a repeatable and variable acceleration curve for exact operation of the drive.

BACKGROUND OF THE INVENTION 
The present invention relates to drive systems. More particularly, the 
present invention relates to a two speed drive system using oil shear 
clutch/brake units for use on tool trays. 
Various drive systems have been developed which are capable of moving 
loaded tool trays or similar objects a specified distance in a specified 
amount of time. With the introduction of automatic equipment and automated 
assembly lines, the accuracy with which these objects need to be 
positioned has become tighter and tighter. 
A number of drive systems in use today rely on compressed air for 
actuation. Normally this compressed air is obtained from a central 
compressed air supply system which provides compressed air to all areas of 
the plant. The central system is prone to the problems of dirty air and 
inconsistent pressures due to the large volume of the system as well as 
the intermittent use by other areas throughout the plant. This lack of a 
clean and consistent supply of compressed air results in a drive system 
which is incapable of providing consistent acceleration and deceleration 
ramps which results in a loss of accuracy when moving the tool tray or 
similar object to its final position. 
Accordingly what is needed is a dependable drive system for a tool tray or 
other objects which is capable of delivering the tool tray to a specified 
location in a specified amount of time and with a specified accuracy on a 
repeatable basis. 
SUMMARY OF THE INVENTION 
The present invention provides the art with a two speed drive system which 
is capable of delivering a tool tray or other object to a specified 
position on a repeatable basis within the accuracy required by the machine 
tool builders to accommodate automization of lines. 
The present invention uses an integral design which puts all of the systems 
functions into one integral assembly. This results in a reduced number of 
parts in the system resulting in reduced downtime and an increase in the 
meantime between service. To eliminate the problems of dirty and 
inconsistent air, the present invention replaces air actuation with 
electric actuation. This provides a very consistent and repeatable 
operation with acceleration and deceleration ramps more consistent. By 
using electric actuation, the acceleration and deceleration ramps can 
easily be adjusted to accommodate various requirements. 
The reliability of the main drive motor of the two speed drive system is 
substantially enhanced in the present invention by having the main motor 
started in a no-load condition and having the main motor disconnected from 
the system during deceleration and final stopping. The reversing of the 
motor which is necessary for reverse movement of the tool tray or object, 
is also done under no-load conditions between cycles.

DETAILED DESCRIPTION OF THE INVENTION 
FIGS. 1, 2, 4 and 5 show a two speed drive designated by reference numeral 
10 in accordance with the present invention. The two speed drive comprises 
input shaft 12, housing assembly 14, clutch 16, low speed drive motor 18, 
motor brake 20, a first gear reduction unit 22, drive brake 24, output 
shaft 26 and a second gear reduction unit 28. 
Input shaft 12 is driven at one end 40 at a specified speed by a high speed 
drive motor (not shown). This motor can be connected to the input shaft 12 
by a flexible coupling, drive belts or any other connection means known in 
the art. Input shaft 12 is rotatably located in housing 14 by a set of 
roller bearings 42 and is rotatable about axis 38. The end of the input 
shaft 12 opposite the drive end 40 has a first cylindrical shaped chamber 
44 and a second cylindrical shaped chamber 46. First cylindrical shaped 
chamber 44 has a roller bearing 48 for supporting the output shaft 26 as 
will be explained later herein. Second cylindrical shaped chamber 46 has 
an interior surface which is adapted with a plurality of axially extending 
splines 49 which support a plurality of driving clutch plates 194 of the 
clutch 16 as will be explained later herein. 
Housing assembly 14 comprises a fan housing 60, a bearing seal housing 62, 
a bearing housing 64, a clutch control housing 66, a drive brake control 
housing 68 and a gear reduction housing 70. Fan housing 60 supports one of 
the two roller bearings 42 at one end and is adapted to be fixedly 
attached to the bearing housing 64 at the opposite end. The fan housing 60 
forms a cylindrical chamber 72. Disposed within the cylindrical chamber 72 
is fan 74. Fan 74 is fixedly mounted to input shaft 12 and rotates with 
input shaft 12 within cylindrical chamber 72. Fan housing 60 has a first 
plurality of apertures 76 which allow for the passage of cooling air 
pumped by fan 74. 
Bearing housing 64 is adapted at one end to be fixedly attached to the fan 
housing 60 and is adapted at the opposite end to be fixedly and sealably 
attached to the clutch control housing 66. Bearing housing 64 has a 
radially inwardly extending flange 80 located adjacent the end of bearing 
housing 64 adapted to mate with fan housing 60 which forms inner 
cylindrical surface 82. Inner cylindrical surface 82 supports the second 
of the two roller bearings 42 and forms a locating surface for bearing 
seal housing 62 as will be discussed later herein. The end of the bearing 
housing 64 which is adapted to mate with the clutch control housing 66 
forms a cylindrical chamber 84. Disposed within cylindrical chamber 84 is 
the second cylindrical chamber 46 located on the end of input shaft 12 as 
shown in FIG. 4. 
Bearing housing 64 has a second plurality of apertures 86 which allow for 
the passage of cooling air pumped by fan 74. The second plurality of 
apertures 86 cooperate with the first plurality of apertures 76 to create 
a path for air pumped by fan 74 to flow across bearing housing 64 and aid 
in cooling of oil disposed within cylindrical chamber 84. The bearing seal 
housing 62 is adapted to be fixedly and sealably attached to bearing 
housing 64 and is located by inner cylindrical surface 82. Bearing seal 
housing 62 locates seal 88 relative to input shaft 12. Seal 88 rides 
against input shaft 12 and seals the oil disposed in cylindrical chamber 
84 from entering cylindrical chamber 72. 
Clutch control housing 66 is adapted at one end to be fixedly and sealably 
attached to bearing housing 64 and is adapted at the opposite end to be 
fixedly and sealably attached to drive brake control housing 68. Clutch 
control housing 66 is annular in shape and defines a cylindrical chamber 
90 which is adjacent and open to cylindrical chamber 84. Disposed within 
the annular portion of clutch control housing 66 is coil cavity 92. 
Disposed within the coil cavity 92 is a DC voltage clutch coil 94. The DC 
voltage clutch coil 94 is provided with means to actuate the clutch 16 as 
will be explained later herein. Also disposed within the annular portion 
of the clutch control housing 66 are a plurality of spring bores 96. The 
plurality of spring bores 96 are circumferentially spaced and are located 
radially inward from cavity 92. Disposed within the plurality of spring 
bores 96 are a plurality of coil springs 98. 
A first annular pressure plate 100 is axially aligned with the annular 
clutch control housing 66 and is in contract with the plurality of coil 
springs 98. First pressure plate 100 is positioned such that it is capable 
of moving axially along axis 38. First annular pressure plate 100 defines 
inner cylindrical surface 102. Inner cylindrical surface 102 locates a 
roller bearing 104 which rotatably mounts a first activation means 106 
which is used to engage and release clutch 16 as will be described later 
herein. The plurality of coil springs 98 urge the first pressure plate 100 
and the first activation means 106 axially to the right as shown in FIG. 
1. In this position the clutch 16 is in the released position. Upon 
activation of the DC voltage clutch coil 94, the first pressure plate 100 
and the first activation means 106 are magnetically attracted and move 
axially to the left as shown in FIG. 1. The magnetic attraction of the DC 
voltage clutch coil 94 overcomes the spring force of the plurality of coil 
springs 98. In this position, clutch 16 is engaged. When the power to the 
clutch coil 94 is terminated, coil springs 98 urge the first pressure 
plate 100 to the right as shown in FIG. 1, releasing clutch 16. 
Drive brake control housing 68 is adapted at one end to be fixedly and 
sealably attached to the clutch control housing 66 and is adapted at the 
opposite end to be fixedly and sealably attached to the first gear 
reduction housing 70. Drive brake control housing 68 is annular in shape 
and defines a cylindrical chamber 110 which is adjacent and open to 
cylindrical chamber 90. Disposed within the annular portion of the drive 
brake control housing 68 is a coil cavity 112. Disposed within coil cavity 
112 is a DC voltage drive brake coil 114. The DC voltage drive brake coil 
114 is provided with means to activate the drive brake coil 114 as will be 
explained later herein. Also disposed within the annular portion of the 
drive brake control housing 68 are a plurality of spring bores 116. The 
plurality of spring bores 116 are also circumferentially spaced and are 
located radially inward from cavity 112. Disposed within the plurality of 
spring bores 116 are a plurality of coil springs 118. 
A second annular pressure plate 120 is axially aligned with the annular 
brake control housing 68 and is in contact with the plurality of coil 
springs 118. Second pressure plate 120 is positioned such that it is 
capable of moving axially along axis 38. Second annular pressure plate 120 
defines inner cylindrical surface 122 which locates a roller bearing 124. 
Roller bearing 124 rotatably mounts a second activation means 126 which is 
used to apply and release drive brake 24 as will be described later 
herein. The plurality of coil springs 118 urge second pressure plate 120 
and the second activation means 126 axially to the right as shown in FIG. 
1. In this position, the drive brake 24 is in the applied condition. Upon 
activation of the DC voltage brake coil 114, the second pressure plate 120 
and the second activation means 126 are magnetically attracted and move 
axially to the left as shown in FIG. 1. The magnetic attraction of the DC 
voltage brake coil 114 overcomes the spring force of the plurality of coil 
springs 118. In this position, the drive brake 24 is released. When the 
power to the brake coil 114 is terminated, the coil springs 118 urge the 
second pressure plate 120 to the right as shown in FIG. 1, applying the 
drive brake 24. 
Gear reduction housing 70 is adapted at one end to be fixedly and sealably 
attached to drive brake control housing 68 and adapted at the opposite end 
to be fixedly attached to the second gear reduction unit 28. In between 
the two ends of the gear reduction housing, a cylindrical chamber 130 is 
formed. The cylindrical chamber 130 is adjacent and open to the 
cylindrical chamber 110. The end of the brake control housing 68 which is 
adapted to be fixedly attached to the second gear reduction unit 28 has a 
radially inwardly extending flange 132 the end of which forms inner 
cylindrical surface 134. Inner cylindrical surface 134 supports roller 
bearing 136 which rotatably locates the output shaft 26 generally on axis 
38 as will be explained later herein. The radially inwardly extending 
flange 132 also forms inner cylindrical surface 138. Inner cylindrical 
surface 138 locates seal 140 relative to output shaft 26. Seal 140 rides 
against output shaft 26 and seals the oil disposed in the cylindrical 
chamber 130 from leaking out of the chamber. 
Gear reduction housing 70 also has a radially extending lobe 150. Lobe 150 
defines a lobe chamber 152 which is adjacent and connected to cylindrical 
chamber 130. The lobe chamber 152 is formed by wall 154 and plate 156. 
Plate 156 is an integral part and an extension of the end of the gear 
reduction housing 70 adapted to be fixedly attached to the second gear 
reduction unit 28. Plate 156 is adapted to be fixedly attached to the low 
speed drive motor 18 and has a cylindrical hole 158 through which drive 
shaft 230 of drive motor 18 is disposed. A seal 160 is provided between 
the cylindrical hole 158 and the drive shaft 230 for sealing the lobe 
chamber 152 from the low speed drive motor 18. 
The combination of lobe chamber 152, cylindrical chamber 130, cylindrical 
chamber 110, cylindrical chamber 90, and cylindrical chamber 84 define a 
sealed cavity 170 which is sealed from the outside by seal 88 on one end 
and by seals 140 and 160 on the other. Disposed within sealed cavity 170 
is a lubricating and cooling oil for the gears, bearings, brake and clutch 
drives. 
Output shaft 26 is rotatably mounted in roller bearing 136 located in gear 
reduction housing 70. Output shaft 26 is connected at one end to the input 
of the second gear reduction unit 28 and extends from the gear reduction 
unit 28 axially along axis 38 through the gear reduction housing 70, 
through the drive brake control housing 68, through the clutch control 
housing 66 and into the cylindrical chamber 84 of the bearing house 64. 
The end of the output shaft 26 located in cylindrical chamber 84 is 
rotatably mounted in the roller bearing 48 located in the input shaft 12 
as shown in FIG. 4. Located axially along the output shaft 26 are a clutch 
mounting area 180, a brake mounting area 182 and a gear mounting area 184. 
Clutch 16 comprises a clutch disk support member 190, a plurality of driven 
clutch plates 192 and the plurality of driving clutch plates 194. Clutch 
disk support member 190 is fixedly mounted to output shaft 16 in the 
clutch mounting area 180 such that it rotates with output shaft 26. The 
outer surface of disk support member 190 is provided with a plurality of 
axially extending splines 198 for connecting engagement with associated 
notches 200 in the inner periphery of the plurality of driven clutch 
plates 192. The plurality of driven clutch plates 192 are free to move 
axially along the splines 198. 
The plurality of driving clutch plates 194 are disposed interjacent or 
interleaved between the plurality of driven clutch plates 192 and are 
provided with notches 201 on their outer periphery for connecting 
engagement with splines 49 of input shaft 12. The plurality of driving 
clutch plates 194 are free to move axially along the splines 49. The 
driven clutch plates 192 and the driving clutch pates 194 are held in 
connecting engagement with splines 198 and splines 49 by abutment ring 202 
and the first activation means 106. 
In operation, coil springs 98 normally bias the first activation means 106 
to the right as shown in FIG. 1. Driving clutch plates 194 are free to 
rotate relative to the driven clutch plates 192 whereby input shaft 12 is 
free to rotate relative to output shaft 26. When DC voltage is applied to 
the DC voltage clutch coil 94, the driving clutch plates 194 and driven 
clutch plates 192 are clamped together between abutment ring 202 and the 
first activation means 106 by movement of the activation means 106 to the 
left as shown in FIG. 1. This causes the rotation of the output shaft 26 
by the input shaft 12. When the DC voltage is removed from the clutch coil 
94, the coil springs 98 separate the driving clutch plates 194 from the 
driven clutch plate 192 and the input shaft 12 is free to rotate relative 
to output shaft 26. 
Drive brake 24 comprises a brake disk support member 210, a plurality of 
rotating brake plates 212 and a plurality of reacting brake plates 214. 
Brake disk support member 210 is fixedly mounted to the output shaft 26 in 
the brake mounting area 182 such that it rotates with the output shaft 26. 
The outer surface of brake support member 210 is provided with a plurality 
of axially extending splines 218 for connecting engagement with associated 
notches 220 in the inner periphery of the plurality of rotating brake 
plates 212. The plurality of rotating brake plates 212 are free to move 
axially along the splines 218. Rotating brake plates 212 are held in 
connecting engagement with the splines 218 by abutment ring 222 and the 
second activation means 126. 
The plurality of reaction brake plates 214 are disposed interjacent or 
interleaved between the plurality of rotating brake plates 212. The 
interior surface of brake gear 244 is provided with a plurality of axially 
extending splines 245 for connecting engagement with associated notches 
247 in the outer periphery of the plurality of reaction brake plates 214. 
This plurality of reaction brake plates 214 are free to move axially along 
the splines 245. Reaction brake plates 214 are held in connecting 
engagement with the splines 245 by retaining means 222 and the second 
activation means 126. 
In operation, coil springs 118 normally bias the second activation means 
126 to the right as shown in FIG. 1. Reaction brake plates 214 and 
rotating brake plates 212 are clamped together between abutment ring 222 
and second activation means 126 by the spring force exerted by coil 
springs 118 thereby locking output shaft 26 to the brake gear 244. When DC 
voltage is applied to the DC voltage brake coil 114, second activation 
means 126 moves to the left as shown in FIG. 1. Rotating brake plates 212 
are thereby free to rotate relative to the reaction brake plates 214 
whereby output shaft 26 is free to rotate with respect to brake gear 244. 
When the DC voltage is removed from brake coil 114, coil springs 118 clamp 
together reaction brake plates 214 and rotating brake plates 212 by the 
spring force exerted by coil springs 118 thereby locking the output shaft 
26 to the brake gear 244. 
Low speed drive motor 18 is fixedly attached to plate 156 of radially 
extending lobe 150 of gear reduction housing 70. Low speed drive motor 18 
has drive shaft 230 located generally parallel to the axis 38 and 
extending from the interior of the lobe cavity 152 through the motor and 
into the motor brake 20. Motor brake 20 is of a design well known in the 
art and is connected to the driveshaft 230 such that when there is no 
power supplied to motor brake 20, the motor brake 20 is in the applied 
condition thus prohibiting driveshaft 230 from rotating. When power is 
supplied, motor brake 20 is released. Motor brake 20 and low speed drive 
motor 18 are electrically wired together such that power to drive the 
motor 18 and release of the motor brake 20 occurs simultaneously thus 
starting the motor 18 and releasing motor brake 20 at the same time. In 
the same manner, when power is cut to the motor 18, power to the motor 
brake 20 is also cut thereby applying motor brake 20 to stop driveshaft 
230. 
Driveshaft 230 extends into the lobe chamber 152 through cylindrical hole 
158 in plate 156 as described above. Seal 160 is positioned into 
cylindrical hole 158 and rides against driveshaft 230 for sealing the lobe 
chamber 152 from low speed drive motor 18. 
First gear reduction unit 22 comprises drive gear 240, intermediate gear 
242 and brake gear 244. Drive gear 240 is fixedly mounted to drive shaft 
230 of the low speed drive motor 18. Intermediate gear 242 is rotatably 
mounted on an axis generally parallel to axis 38 within lobe chamber 152 
as shown in FIG. 1. Intermediate gear 242 is meshed with drive gear 240 
and also with brake gear 244. Intermediate gear 242 can be of the compound 
gear design as shown in FIG. 1 or it can be a single gear depending upon 
the gear reduction ratio required. 
Brake gear 244 has a first cylindrical inner surface 250 for rotatably 
mounting brake gear 244 on output shaft 26 at gear mounting area 184. A 
second cylindrical inner surface 252 extends generally parallel to axis 38 
and forms an integral member of the drive brake as described above. Brake 
gear 244 is meshed with the intermediate gear 242. The gear reduction 
value of the first gear reduction unit 22 is a function of the numbers of 
teeth on drive gear 244, the plurality of number of teeth on intermediate 
gear 242 and the number of teeth on brake gear 244. 
Second gear reduction unit 28 comprises a double helical gear reduction 
unit whose design is well known in the art. The input to the second gear 
reduction unit 28 is from the output shaft 26. The output of the second 
gear reduction unit 28 is coupled by methods known in the art to the input 
member of a drive system, for example, to the pinion of a pinion drive 
system of a tool tray. 
The motion diagram in FIG. 3 represents a typical motion curve achievable 
with the two speed drive unit of the present invention. The motion diagram 
in FIG. 3 comprises five stages of motion, the initial acceleration stage 
300, the high speed linear travel stage 302, the high speed deceleration 
stage 304, the low speed linear travel stage 306, and low speed 
deceleration stage 308. 
The operation of the cycle begins with the high speed drive motor rotating 
at full speed in the correct direction driving input shaft 12. Clutch 16 
is in the released position and drive brake 24 is in the applied condition 
due to a lack of voltage being supplied to clutch coil 94 and brake coil 
114. Low speed drive motor 18 is stopped and motor brake 20 is in the 
applied condition. Output shaft 26 is held stationary by drive brake 24 
which reacts through first gear reduction unit 22, through low speed drive 
motor 18 to motor brake 20. 
Simultaneously, appropriate full power is provided to low speed drive motor 
18, motor brake 20 and main brake 24. Also simultaneously, an appropriate 
reduced voltage is applied to clutch 16. Low speed drive motor 18 rotates 
at full speed driving first gear reduction unit 22 due to the simultaneous 
release of motor brake 20 and drive brake 24. Output shaft 26 is not 
driven by low speed drive motor 18 at this point. 
The reduced voltage applied to clutch 16 begins to engage clutch 16 and 
drive output shaft 26. As the voltage to the clutch 16 is increased to 
full voltage, clutch 16 continues to engage until input shaft 12 is 
coupled to output shaft 26. This acceleration stage is designated by 
reference numeral 300 in FIG. 3. Because a DC voltage coil is used for 
clutch coil 94, it is possible to adjust the slope of the acceleration 
curve to suit a particular requirement. The rate of acceleration is 
controlled by the rate of increasing the DC voltage to clutch coil 94 from 
0 to full voltage. 
The high speed travel stage 302 occurs when the high speed drive motor is 
operating at full speed clutch 16 is engaged, drive brake 24 is released, 
low speed drive motor 18 is operating at full speed and motor clutch 20 is 
released. 
The high speed travel stage 302 continues until a deceleration limit switch 
(not shown) is tripped. At this point the appropriate DC voltage is 
disconnected from clutch 16 and an appropriate reduced voltage is applied 
to drive brake 24. The disconnecting of voltage to clutch 16 releases 
clutch 16 and input shaft 12 is free to rotate relative to output shaft 
26. The application of the reduced voltage to drive brake 24 begins the 
application of the brake and effects the deceleration of the tool tray as 
depicted by the deceleration stage 304 in FIG. 3. Brake coil 114 is also a 
DC voltage coil similar to clutch coil 94. Therefore, the slope of the 
deceleration stage 304 can be controlled by the rate of reduction of 
voltage to the brake coil 114. 
When the speed of output shaft 26 has been reduced to coincide with the 
speed of low speed drive motor 18, the dwell stage 306 shown in FIG. 3 is 
entered. The length of the dwell stage 306 is determined by the accuracy 
by which drive unit 12 can be decelerated during the deceleration stage 
304. During this dwell stage 306, output shaft 26 is driven by low speed 
drive motor 18 through first gear reduction unit 22, and through drive 
brake 24. 
The dwell stage 306 continues until a final limit switch (not shown) is 
tripped and the low speed deceleration stage 308 is entered. At this 
point, the power is disconnected from low speed drive motor 18, motor 
brake 20 and drive brake 24 bringing the output shaft to a stop. The cycle 
has now been completed and the unit is ready for the reverse cycle. For 
the reverse cycle, the high speed drive motor and low speed drive motor 18 
are reversed in direction. The operation of the two speed drive during the 
reverse cycle is identical to the above described cycle. 
By example, the motion diagram illustrated in FIG. 3 was achieved by 
utilizing a 20 HP, 1750 RPM high speed drive motor, a 2 HP 1750 RPM low 
speed drive motor 18, a first gear reduction unit 22 of 10.019 and a 
second gear reduction unit 28 of 14.339. The example presented was able to 
move a 25,000 pound tool tray 17 feet in 7 seconds with an index accuracy 
of +/-0.050 inches. 
While the above detailed description describes the preferred embodiment of 
the present invention, it should be understood that the present invention 
is susceptible to modification, variation and alteration without deviating 
from the scope and fair meaning of the subjoined claims.