throbber
Feb. 24,1970
`
`'
`
`K. F. u‘firflsav
`
`,
`
`3,497,266
`
`-
`Filed March 8, 1968
`
`CONTROfl-FOR ELECTRIC BRAKE
`-
`
`'
`2 Sheets-Sheet 1
`
`a_
`
`\§
`
`
`
`TOWlNG
`VEl-HCLE
`
`,_....—____.
`
`
`
`420
`
`M\
`0'0 \
`450 5 A25 §
`
`INVENTOR
`KENNETH F. UMPLEBY
`
`ka~$éwga¢raam
`
`ATTORNEYS
`
`Curt - Exhibit 1006 - 1
`
`Curt - Exhibit 1006 - 1
`
`

`

`Feb. 24, 1970
`
`‘ K. F. UMPLEBY
`, COfiTR‘OL‘FOR ELECTRIC BRAKE
`
`"
`
`3,497,266
`
`Filed “arch 8. 1968
`
`2 Sheets—Sheet 2
`
` iiju5
`
`VOLTAGE
`
`TIM:
`
`3‘76. 5a,
`
`V0LTAGE
` VOLTAGE
`
`
`
`INVENTOR
`KENNETH F. UMPLEBY
`
`wig-ah. gubfim
`
`'ATTORNgxs
`
`Curt - Exhibit 1006 - 2
`
`Curt - Exhibit 1006 - 2
`
`

`

`United States Patent Office
`
`3,497,266
`Patented Feb. 24, 1970
`
`5
`
`ABSTRACT OF THE D 巧CLOSURE
`The energizing coil of an electric brake in a towed
`vehicle such as a trailer or the like is energized by pulsat-
`ing direct current. The duty cycle or pulse-width ratio of
`the energizing current is controlled by a free-running
`multivibrator which, in turn, is hand-controlled by the
`driver in the towing vehicle. The hand control can,
`be overridden by an auxiliary hydraulic cylinder and
`cable system operated by the hydraulic braking system
`in the towing vehicle. The multivibrator circuitry pro-
`vides an initial sur.ge current to the electric brake coils
`when the electric brake is first energized.
`
`10
`
`15
`
`20
`
`25
`
`35
`
`55
`
`60
`
`65
`
`CONTROL F謂霊晋TRにBRAKE
`
`Kenneth F. Umpleby, Ann Arbor, Mich., assignor to
`Motor Wheel Corporation, Lansing, Mich., a corpora.
`tion of Ohio
`Filed Mar. 8, 1968, Ser. No. 711,564
`mt. CI. B60t 7/20
`
`U .S. Cl. 303-3
`
`16 Claims
`
`2
`18 to an auxiliary fluid cylinder 22 mounted on a master
`cylinder 24 by a Y fitting 26. Master cylinder 24 is part
`of the conventional hydraulic brake system in the towing
`vehicle to operate the towing vehicle brakes 28 in re-
`sponse to actuation of a foot pedal 30. Fitting 26 is
`mounted directly on cylinder 24 in place of and inter-
`changeably with a stop light switch which would other-
`wise be normally mounted on conventional master cyl-
`inders. The stop light switch 32 is then mounted on one
`arm of fitting 26. In general, the electric brakes 10, 12
`can be hand operated 'by the driver via controller 18 but
`manual operation of the controller 18 can・be overridden
`via cable 20 and cylinder 22 in response to actuation
`of brakes 28 when pedal 30 is depressed.
`Referring more particularly to circuit 16, 'battery 14
`is the towing vehicle battery and the positive terminal of
`battery 14 is arranged to be connected through a normally
`closed switch 40 (FIGS. 1 and 2) and a lead 42 to the
`emitter 44 of an output switching transistor 46. Switch 40
`is also mechanically coupled to controller 18 as indicated
`by dashed lines in FIG. 1. The collector 48 of transistor
`46 is connected in series with parallel-connected energiz-
`ing coils 50, 52 in brakes 10, 12, respectively, and then
`to ground 54. The transistor 46 is controlled by a free-
`running multi-vibrator 56 comprising first and second
`Objects of the present invention include providing an
`transistors 58, 60. The collector 62 of transistor 58 is
`electric brake system particularly adapted for a towed
`connected in series with three resistors 63, 64, 65 to lead
`vehicle wherein a manually operated control for the
`42, and the emitter 64' is connected to .ground. A capaci-
`electric brakes can be overridden by operating the brakes
`tor '66 is connected in series with a resistor 68 between
`of the towing vehicle by an improved arrangement that
`30
`ground and the junction between resistors 64, 65. Tran-
`is simple in construction, economical to manufacture,
`sistor 60 has its collector 70 connected in series with re-
`easily installed on towing vehicles having hydraulically
`sistors 72, 74 to lead 42 and its emitter 75 connected in
`operated brakes of conventional construction and operates
`an emitter-follower configuration to the base 76 of a
`safely without likelihood that failure in hydraulic 'brakes
`drive transistor 77. The collector outputs of transistors
`in the towing vehicle will be caused 'by failure in the
`58, 60 are cross-coupled in a generally conventional
`overriding arrangement.
`manner by means of capacitors 80, 84. Capacitor 80 is
`Other objects, features and advantages of the present
`connected between the base 82 of transistor 60 and the
`invention will become apparent in connection with the
`junction of resistors - 63, 64, and capacitor 84 is con-
`following description, the appended claims and the ac-
`nected between the junction of resistors 72, 74 and the
`companying drawings in which:
`40
`'base 86 of transistor 58. Resistors 63, 72 prevent excessive
`FIG. 1 illustrates an electric brake for a trailer or the
`reverse bias voltages.
`like wherein the electric brake is remotely and hand con-
`The bias circuit for the base-emitter circuits of transis-
`trolled by the driver in a towing vehicle;
`tors 58, 60 includes a potentiometer 90 having its wiper
`FIG. 2 is a fragmentary view partly in section and
`91 electrically connected to lead 42 and mechanically
`illustrating an auxiliary hydraulic cylinder and cable sys-
`45
`coupled to the controller 18 as indicated by dashed lines
`tern interconnecting the hydraulic braking system of the
`in FIG. 1. One terminal 93 of potentiometer 90 is con-
`towing vehicle to the electric brake control;
`nected to base 86 through a resistor 94 and the other
`FIG. 3 shows one type of electric brake usable with
`potentiometer terminal 95 is connected to base 82 through
`the brake control system of the present invention;
`serially connected resistors 96, 98. Resistor 98 is ad-
`FIGS. 4a and 4b show waveforms illustrating low duty-
`50
`justable to balance the braking action of brakes 10, 12
`cycle operation and high duty-cycle operation, respec-
`with the braking action of brakes 28 and adjust the sensi-
`tively, of the brake controller circuit of FIG. 1;
`tivity for manual operation of controller 18.
`FIG. 5 shows a waveform illustrating operation of the
`Transistor 77 drives the base 100 of transistor 46 via
`brake controller circuit in FIG. 1 in a modified embodi-
`resistors 102, 104. The emitter-collector circuit of tran-
`ment of the present invention wherein the electric brake
`sistor 46 is connected in series 'with the paralleled coils
`control circuit is under the control of a pressure-sensitive
`50, 52. A silicon diode 110 is connected between ground
`resistor directly responsive to operation of the hydraulic
`54 and the collector 48 of transistor 46 across the naral-
`brakes of the towing vehicle; and
`leled coils 50, 52. Diode 110 is poled to block current
`FIGS. 6a and 6b show waveform illustrating voltages
`therethrough when transistor 4'6 is conducting and to
`appearing in the circuit of FIG. 1 upon actuation of the
`provide a return path for circulating currents from
`electric 'brake controller to provide a momentary high
`coils 50, 52 when transistor 46 is switched off. Coils
`power to the electric brake.
`50, 52 are also arranged to be connected directly across
`Referring more particularly to FIG. 1, the electric
`battery 14 through a normally open switch 112, by-
`brake system generally comprises a pair of electromag-
`passing circuit 16.
`netic brakes 10, 12 (FIGS. 1 and 3) which are arranged
`A variable resistor 114 is also shown in FIG. 1 in
`to be energized from a battery 14 'by the control circuit
`dotted lines connected between potentiometer terminal
`designated generally at 16. In the preferred embodiment,
`95 and lead 42 to illustrate an alternative embodiment
`brakes 10, 12 are mounted on the wheels of a towed
`of the present invention. Resistor 114 is a pressure sen-
`vehicle such as a trailer and the like. Control circuit 16
`sitive resistor whose value changes in response to fluid
`is actuated via a manually operated controller 18 mounted
`70
`in the towing vehicle at a location convenient for opera-
`pressure applied thereto. In the alternative embodiment,
`tion by the driver. A flexible cable 20 connects controller
`resistor 114 is mounted directly on fitting 26 in place
`
`Curt - Exhibit 1006 - 3
`
`

`

`3,497,266
`
`5
`
`10
`
`4
`3
`Brake drum 162 and disc 160 rotate with the wheel of
`of cylinder 22 to respond to variations in brake fluid
`the vehicle on which they are installed whereas pin
`pressure in the master cylinder 24.
`180 and the associated support structure for shoes 168,
`Referring more particularly to FIG. 2, the controller
`169 and lever 181 are mounted stationary relative to the
`18 comprises a housing 120 which is mounted by suit-
`drum.
`able means (not shown) on the dash board, underneath
`The function and operation of the control for the
`the instrument panel, of the towing vehicle. Alterna-
`electrically operated brake described hereinabove and for
`tively, housing 120 cou'd be mounted at other conven-
`the circuit 16 can be best understood in connection with
`ient locations in the towing vehicle such as on the steer-
`the waveform-s shown in FIGS. 4-6. With control arm
`ing column. A control lever 122 integral with a shaft 124
`is pivotally mounted at 126 on housing 120. The free
`122 in its raised "fully off" position engaging switch 40,
`end of lever 122 projects outwardly through the front
`switch 40 will be open and hence no power from battery
`of housing 120 for hand actuation of the electric brakes
`14 is applied to circuit 16. When it is desired to actuate
`10, 12. An integral crank arm 128 on shaft 124 is dis-
`brakes 10, 12, the operator moves lever 122 downwardly
`posed at approximately a right angle to lever 122 to
`causing arm 128 to disengage from switch 40 whereupon
`project upwardly as viewed in FIG. 2. Switch 40 (FIGS.
`switch 40 closes to energize ' control circuit 16. Simultane-
`1
`D
`1 and 2) is mounted on housing 120 to be actuated by
`ously, the wiper arm 91 is moved from its extreme left-
`arm 128 to an open positi,on when arm 128 is in the
`hand position on potentiometer 90 toward the right as
`position illustrated in full lines in FIG. 2 which corre-
`viewed in FIG. 1. Disregarding for the moment the effect
`sponds to a condition when brakes 10, 12 are "fully off."
`of capacitor 66 when switch 40 first closes, one of the
`Arm 128 and lever 122 are urged toward the "fully off"
`20 transistors 58, 60 will conduct initially and establish
`position by a spring 130. Switch 40 limits pivotal move-
`free-running operation of the multivibrator 56 with tran-
`,ment ・ of arm 128 at the off position although other suita-
`sistors 58, 60 being rendered alternately conducting via
`ble stop means may be used. Switch 112 (FIGS. 1 and
`the conventional cross coupling through capacitors 80,
`2) is mounted on case 120 for engagement by lever 122
`84. When transistor 60 conducts, transistor 77 is rendered
`when lever 122 is moved downwardly to the position
`25 conductive l with the emitter , current of transistor 60
`illustrated in dotted lines which corresponds to a "fully
`driving transistor 77 into saturation. Conduction of tran-
`on" condition of brakes 10, 12. The components of cir-
`sistor 77 provides current drive via resistor 104 to tran-
`」 sistor 46 to render transistor 46 conducting and thereby
`cuit 16 are also mounted within housing 120 and the
`wiper arm 91 of potentiometer 90 is connected directly
`connect coils 50, 52 across battery 14. Energization of
`to shaft 124 so that rotation of shaft 124 in response
`30 coils 50, 52 actuates brakes 10, 12.
`to pivotal movement of lever 122 varies the poとentiom-
`In general, the braking force applied by the brakes
`eter setting.
`10, 12 depends primarily on the setting of potentiometer
`Cylinder 22 is mounted directly on fitting 26 by a
`91, the values of resistors 94, 96 (together with resistor
`suitable fitting 134 at the inlet end of cylinder 22. Cyl-
`98) and the timing capacitors 80, 84 and also on the
`inder 22 comprises a piston 136 having a suitable seal
`35 values of resistors 63, 64, 65 and resistors 72, 74. For a
`(not shown), commonly an 0 -ring or a cup seal. Piston
`small displacement of lever 122, wiper 91 will be moved
`136 is actuated from right to left as viewed in FIG.
`just slightly from the terminal 93 and in this position the
`2 in response to hydraulic fluid pressure increases at the
`time constants for capacitors 80, 84 are such that during
`master cylinder 24 when pedal 30 is operated. A spring
`each cycle or repetition period of multivibrator 66, tran-
`seat 140 is integrally connected to piston 136 for co-
`sistor 60 conducts for a short time by comparison to the
`movement therewith and a compression spring 141 is
`time during which transistor 58 conducts. Hence the
`mounted between seat 140 and the opposite end wall
`pulse width ratio for the multivibrator output is low and
`143 of the auxiliary cylinder 22 to bias piston 136 in
`correspondingly the duty cycle at coils 50, 52 is low.
`a direction toward the right as viewed in FIG. 2 in the
`The waveform for the voltage output applied to coils
`absence of hydraulic pressure at the inlet of cylinder 22.
`550, 52 from source 14 during low duty-cycle operation
`45
`Cable 20 is a Bowden-type cable having an inner con-
`corresponding to low braking force is shown in FIG. 4a.
`trol wire 144 movable longitudinally inside an outer
`FIG. 4a can also be considered as representing the pulse
`sheath 146. Wire 144 has one end secured in a boss
`train developed by multivibrator 56. With wiper 91 posi-
`142 on seat 140 as by a crimped or soldered connection.
`tioned at or near the potentiometer terminal 93, a train
`Sheath 146 extends through the end wall 143 of cylinder
`of pulses 200 will be applied to coils 50 from battery 14.
`22 and is secured therein by suitable means such as sol-
`During each cycle T of the multivibrator 56 the duration
`dering or an appropirate fitting. The other end of the
`t2 of each pulse 200 is small compared to the off time t3
`sheath 146 is detachably mounted on the rear wall of
`and hence the average D .C. power applied to coils 50, 52
`housing 120 and the other end 149 of the wire 144
`over several cycles will be low as indicated by the level
`extends into housing 120 and passes freely through a
`204 (FIG. 4a). During the off time t3, diode 110 prevents
`55
`small aperture 150 in the arm 128. A flanged ferrule
`the voltage across coils 50, 52 from exceeding the supply
`154 is secured on wire 144 as by crimped or soldered
`voltage of battery 14 due to the inductive loading effect
`connection. Ferrule 154 is located at an appropriate point
`of coils 50, 52, or stated differently, when the fields in
`on wire 144 so as to be disposed just behind arm 128
`coils 50, 52 collapse, diode 110 provides a return path
`when arm 128 is in its raised, "fully off" position with
`for circulating current through coils 50, 52 during the off
`no fluid braking pressure applied to piston 136.
`60
`time of transistor 46. With the electrical and mechanical
`By way of further disclosure, one of the brakes 10
`time constants of coils 50, 52 and brakes 10, 12 longer
`is shown in greater detail in FIG. 3 to illustrate one
`than the cycle time T of multivibrator 56, the operation
`type of brake which may be operated by a brake con-
`of coils 50, 52 is as though the coils were supplied by the
`trol circuit of the present invention, but it is to be under-
`average D.C. voltage level 204.
`stood that the control circuit and braking system may
`65
`As higher braking forces are required, lever 122 is
`be used with other types of electric brakes. Disc 160 is
`moved further downwardly in turn moving the wiper 91
`located adjacent a brake drum 162 having a rim 164
`further to the right as viewed in FIG. 1. The time con-
`engageable with linings 166, 167 mounted respectively
`stant for capacitor 84 is increased, increasing the "off
`on conventional brake shoes 168, 169. Brake shoes 168,
`time" of transistor 58. Simultaneously the time constant
`169 are retained by springs 170, 171, 172 and their lower
`70
`for capacitor 80 is decreased, increasing the "on time"
`ends 173, 174 are connected together by the usual ad-
`of transistor 60 by an equal amount so that the frequency
`justable linkage 176. The upper ends 177, 178 of brake
`shoes 168, 169 abut an operating cam 179 on a 一 pin
`or cycle time T of the multivibrator 56 does not change.
`180 affixed to a pivotal lever 181 to which a puck 182
`FIG. 4b illustrates the pulses 210 applied to coils 50, 52
`(FIQS, 1 a nci 3) is sttachcd by rneans of a pin 183.
`from battery 14 when control lever 122 is moved to an
`75
`
`50
`
`40
`
`Curt - Exhibit 1006 - 4
`
`

`

`3,497,266
`
`1 5
`
`6
`5
`10, 12 are actuated upon application of the car brakes
`extreme lower position just prior to engagement with
`28 is controlled through the brake controller 18 in syn-
`switch 112. The cycle time T of multivibrator 56 remains
`chronism with and in proportion to the amount of brak-
`the same whereas the "on time" t4 of transistor 60 is sub-
`ing effort being applied to the car brakes 28. When pedal
`stantially greater than the "on time" t2 (FIG. 4a) at low
`30 is released, spring 141 forces piston 136 back to its
`duty-cycle operation. Hence FIG. 4b illustrates a high
`5
`original "fully off" position and spring 130 returns lever
`duty-cycle operation providing an apparent average D .C.
`122 back to its "fully off" position. The lost motion con-
`voltage level 206 substantially higher than the correspond-
`nection between wire 144 and arm 128 allows the con-
`ing level 204 during the low duty cycle.
`troller 18 to be manually actuated by lever 122 without
`Maximum braking forces are applied when lever 122
`affecting the car brakes 28 since arm 128 slides freely
`is moved to its lower-most position engaging with and
`1 0
`
`along the free end 149 of the wire.
`actuating switch 112 to connect coils 50, 52 directly
`Resistor 98 varies the "off tim?." of transistor 60 and
`across battery 14. Switch 112 also provides a safety
`incidentally varies the frequency for a given setting of
`feature in the event that the remaining portion of control
`potentiometer 90. Resistor 98 is used to adjust the sensi-
`circuit 16 should fail.
`tivity of the trailer brakes 10, 12 for manual operation
`With respect to actuation of brake 10, when coil 50
`
`and the resistor or a variable tap thereon is accessible to
`is energized puck 182 is magnetically attracted against
`the driver. At all settings of resistor 98 the brake response
`the rotating disc 160. Assuming disc 160 is rotating
`to actuation of lever 122 is linear over the operating
`clockwise as viewed in FIG. 3, the frictional forces
`range of the lever and the lowest achievable duty cycle
`exerted by disc 160 on puck 182 swings lever 181 on pivot
`20 remains substantially constant. Stated differently, resistor
`shaft 180 to the left as viewed in FIG. 3. This pivotal
`98 changes the slope of the straight line response for
`movement of lever 181 rotates the operating cam 179
`braking forces versus displacement of lever 122, but the
`which in turn operates the upper ends of shoes 168, 169
`response curve always starts at or near zero. Although
`so that the shoes move outwardly to engage linings 166,
`a rough balance between the braking effort at the brakes
`167 with drum 162. The shoes are shown in an operated
`25 28 and the brakes 10, 12 is obtained by selection of
`position in FIG. 3. As the pulse width ratio for the multi-
`spring 141, a finer balance is obtained by adjusting re-
`vibrator output is increased, the corresponding increased
`sistor 98. Hence the same control circuit 16 can be used
`duty cycle or apparent D .C. level of the current in coil
`with various different types of trailers and various dif-
`50 forces puck 182 harder against disc 160, thus increas-
`ferent loads. The resistor 98 is not varied during braking
`ing the frictionally induced torque in lever 181 and
`30 operations.
`thereby moving puck 182 and lever 181 farther to the
`Attention is now directed to FIG. 5 in connection with
`left which in turn further increases the applied braking
`the operation of the alternative embodiment wherein re-
`forces.
`sistor 114 replaces cylinder 22 and cable 20. Operation
`Referring back to the initial energization of the con-
`of the foot pedal 30 and the corresponding increase in
`trol circuit 16 and the effect of capacitor 66, just prior
`35 pressure in master cylinder 24 decreases the value of re-
`to closure of switch 40 there is no charge on capacitor
`sistor 114. The connection of resistor 114 in the control
`66 but upon closure of switch 40 the voltage at the junc-
`ture between resistors ・ 64, 65 rises instantaneously to a
`circuit 16 is such that variations in resistor 114 affect
`both the frequency and the duty cycle or pulse width
`value determined by the values of resistors 65, 68. The
`ratio for multivibrator 56. Hence with increased pressure
`effect of capacitor 66 as it charges exponentially to a
`40 in cylinder 24 and a corresponding decrease in the value
`voltage determined by the average current in transistor
`58 and the value of resistor ・ 65 is shown in FIGS. 6a and
`of resistor 114, voltage pulses 222 - are applied to coils
`50, 52. By comparison to FIG. 4a, the frequency of
`/,. In FIG. 6a the time at which the switch 40 closes is
`pulses 222 is increased over that of pulses 200 and the
`designated t5 and the charging of capacitor 66 is illus-
`"off duty cycle" in FIG. 5 would be decreased for the
`trated by the voltage curve 212. The effect of capacitor
`same setting of potentiometer 90, in turn increasing the
`66 is to initially increase the frequency of multivibrator
`
`4 5
`apparent voltage to the level 224.
`56 as illustrated by the higher frequency pulses 214 (FIG.
`It will be apparent from the foregoing description that
`6b). The increase in frequency has the corresponding
`the electric brake control of the present invention can
`effect in coils 50, 52 of increasing the apparent D .C.
`achieve smooth and accurate control over a wide range
`level as indicated at 216. As the frequency decreases to a
`of braking forces. Duty cycles from five percent to ninety-
`steady state value when capacitor 66 is fully charged, a
`5
`0
`five percent can be achieved in economically practical
`lower average voltage level 218 is provided. The higher
`controls. The frequency of operation of multivibrator 56
`level 21l6 may be required in certain brake systems to
`remains essentially constant during adjustment of wiper
`assure that puck 182 is quickly and firmly brought into
`91. The controller output voltage applied to coils 50, 52
`contact with plate 160. However, it should be understood
`is essentially independent of the load presented by the
`that in other applications the initial surge feature is not
`
`5 5
`coils, either due to the variation in the braking forces or
`required, and hence capacitor 66 and resistor 88 can be
`to using different types of coils. The output voltage ap-
`omitted and a single resistor used in place of resistors
`plied to the coils is determined primarily by the voltage
`64, 65.
`at source 14 when transistor 46 is saturated. There is
`With respect to operation of the brakes 10, 12 in re-
`little, if any, heat dissipated by the circuit 16 and most
`sponse to actuation of the foot brake pedal 30, piston
`
`6 0
`of the energy dissipation occurs during switching of tran-
`140 is moved from right to left as viewed in FIG. 2
`sistor 46 resulting in high electrical efficiency and mini-
`against the pressure of spring 141 by an increase in fluid
`mum drain on battery 14. The solid state circuitry and
`pressure in the master cylinder 24 upon operation of foot
`operation of the potentiometer 90 at low-level signals
`pedal 30. The resulting movement of wire 144 pushes
`achieves very reliable operation.
`ferrule 154 against the crank arm 128 to thereby pivot
`6
`5
`The mechanical coupling from the master cylinder to
`arm 128, shaft 124 and lever 122 from the "fully off"
`the controller 18 via the auxiliary cylinder 22 and cable
`position toward the "fully on" position. The constants
`20 provides a very simple construction that is easily in-
`of spring 141 are selected to correlate the rotation in
`stalled in the hydraulic brake system of the towing vehi-
`arm 128 as a result of given brake pressures with the
`cle, especially in combination with the particular con-
`variation required at potentiometer 90 to balance the
`0
`7
`trol circuit described. The system can be operated either
`brakes 28 with brakes 10, 12. The maximum displace-
`with or without the interconnecting cable system and the
`ment of spring seat 140 and wire 144 is also chosen to
`cable system can be readily added without major dis-
`correspond to the maximum travel of lever 122 to just
`assembly of the controller 18 and without any modifica-
`bring lever 122 into engagement with switch 112 and
`actuate the switch. Hence the degree to which the brakes
`75 tion in the control circuit 16. The auxiliary cylinder 22
`
`Curt - Exhibit 1006 - 5
`
`

`

`3,497,266
`
`8
`7
`ing system, and stop means on said cable adapted to
`and the cable 20 are rugged enough to provide safe
`engage said crank arm when said cable is displaced in
`operation of both brakes 28 and brakes 10, 12. It is un-
`response to fluid pressure in said hydraulic braking system
`likely that the brakes 28 will fail due to failure in the
`and to thereby pivot said arm toward a "fully on" position.
`auxiliary cylinder and cable system.
`8. The combination set forth in claim 7 wherein said
`It should be understood that the control for electric
`stop means is disposed at one side of said crank arm,
`brakes has been described hereinabove for purposes of IJ
`said cable passes freely through said aperture and extends
`explanation and illustration and is not intended to mndi-
`outwardly from the other side of said crank arm so
`cate limits of the present invention.
`that when said lever is manually moved toward its "fully
`I claim:
`on" position said crank arm pivots on said shaft and slides
`1. In combination with a towed vehicle and a towing in
`longitudinally along said cable toward the free end thereof
`vehicle wherein the towing vehicle is equippet with a
`while said cable is stationary.
`hydraulic braking system and the towed vehicle is
`9. The combination set forth in claim 7 wherein said
`equipped with electrically operated brakes operatively
`circuit means comprises a first normally closed switch
`connected to a source of electrical energy and wherein an
`to connect said source to said circuit to thereby energize
`electric brake controller is mounted in said towing vehicle i
`5
`said circuit and wherein said switch is arranged and dis-
`for manual actuation by the operator of said towing
`posed in said controller for actuation to an open position
`vehicle, circuit means actuated by said manually operable
`when said lever is in said "fully off" position to discon-
`means to vary the electrical energy applied to said elec-
`fleet said circuit from said source.
`trically operated brakes, transducer means having a fluid
`inlet and an output member movable in response to pres- 2
`10. The combination set forth in claim 7 comprising
`0
`sure variations at said inlet, said transducer means being
`second circuit means for directly connecting said electric
`located remote from said controller and being operatively
`brakes to said source, a normally open switch in said
`connected to said hydraulic braking system of said towing
`second circuit means and operative to normally disconnect
`vehicle so that variations in the hydraulic pressure in said
`said electric brake from said source, and wherein said
`braking system impart a corresponding movement to said 2
`switch means is arranged and disposed in said controller
`output member, and a mechanical coupling connected
`for actuation to its closed position in response to move-
`between said transducer output member and said man-
`ment of said lever to a "fully on" position.
`ually operable controller to mechanically actuate said
`11. The combination set forth in claim 8 wherein said
`controller in response to fluid pressure variations in the
`cable comprises an outer sheath and an inner wire opera-
`hydraulic braking system of said towing vehicle and there-3
`tively disposed inside said sheath for movement longi-
`by vary the electrical energy applied to said electrically
`tudinally therein, one end of said sheath is fixedly mounted
`operated brakes.
`on said controller and the opposite end of said sheath
`is fixedly mounted on said cylinder and said inner wire
`2. The combination set forth in claim 1 wherein said
`is connected at one end' to said piston and at its other
`mechanical coupling comprises a flexible cable connected
`end to said crank arm, said cable being a compression
`at one end in said controller unit and at the other end 3
`cable such that when fluid pressure causes motion of said
`to said transducer means.
`piston, said piston pushes said inner wire and said inner
`3. The combination set forth in claim 2 wherein said
`wire in turn pushes said crank arm.
`transducer comprises a first hydraulic cylinder, said out.
`12. The combination set forth in claim 2 wherein said
`put member comprises a piston mounted in said cylinder
`circuit means includes a potentiometer to cause varia-
`and movable from a first position toward a second posi- 4
`tions in current through said coil and wherein said po-
`tion in response to fluid pressure increases in said hy-
`tentiometer is connected to a shaft rotatably mounted in
`draulic brake system, and wherein a spring is mounted
`said controller, a hand-operated member to rotate said
`in said cylinder to urge said piston toward said first
`shaft, and wherein said cable is operatively connected to
`position.
`said shaft to rotate said shaft in response to fluid pres-
`4. The combination set forth in claim 3 wherein said4
`sure variations at said transducer means.
`hydraulic braking system includes a master cylinder and
`13. The combination set forth in claim 12 wherein
`said first cylinder is mounted directly on said master
`said means operatively connecting said cable to said shaft
`cylinder.
`comprises a lost-motion connection operable to permit
`5. The combination set forth in claim 1 wherein said
`manual actuation of said hand-operated member without
`circuit means to vary said current in said electric brakes5
`actuating said cable.
`comprises impedance means having a variable tap, said
`14. In combination with a hydraulic braking system,
`controller comprises hand-movable means mechanically
`an electrically operated brake system operatively con-
`connected to said tap to vary the same, and wherein said
`nected to a source of electrical energy, said electrically
`mechanical coupling between said transducer and said
`operated brake system including an electric brake con-
`controller is connected in said controller to actuate said5
`troller mounted for manual actuation by the operator of
`mechanical coupling between said hand movable means
`said hydraulic braking system, circuit means actuated by
`and said tap.
`6. The combination set forth in claim 1 wherein said
`said manually operable means to vary the electrical en-
`ergy applied to said electrically operated brake system,
`controller comprises a housing, a shaft pivotally mounted
`transducer means having a fluid inlet and an output mem-
`on said housing, a lever integral with said shaft and pro- 6
`0
`ber movable in response to pressure variations at said
`jecting outwardly therefrom through said housing to be
`inlet, said transducer means being operatively connected
`accessible by the operator of said towing vehicle, and
`to said hydraulic braking system so that variations in the
`a crank arm integral with said shaft for co-movement
`with said lever arm, said transducer means comprises a
`hydraulic pressure in said braking system impart ' a cor-
`hydraulic cylinder, said output member comprises a pis- ,
`responding movement to said output member, and a me-
`5
`ton mounted in said cylinder, and wherein said mechanical ー
`chanical coupling connected between said transducer out-
`coupling between said transducer means and said con-
`put member and said manually operable controller to
`troller comprises a flexible cable connected at one end
`mechanically actuate said controller in response to fluid
`to said piston and at the other end to said crank arm.
`pressure variations in the hydraulic braking system and
`7. The combination set forth in claim 6 wherein said '
`thereby vary the electrical energy applied to said electri-
`0
`cranK arm nas an aperture tneretnrougn anti wnerein saia
`cally operated brakes.
`other end of said cable passes through said aperture,
`15.

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