Braking control apparatus for a vehicle

A braking control apparatus for a vehicle which locks and holds the brake pedal of the vehicle in a given depressed position. The apparatus is rendered inoperative when the vehicle is in such a condition that the locking and holding of the brake pedal is undesirable. When starting the vehicle, an accelerator pedal switch operatively connected to the accelerator pedal deenergizes an electromagnet for locking the brake pedal. With the brake pedal locked in any given depressed position, any further depression of the brake pedal results in deenergization of the electromagnet by the brake pedal switch operatively connected to the brake pedal. With the vehicle at rest, when the door is opened, the electromagnet is deenergized by a door switch. Also, during rapid braking of the vehicle, another brake pedal switch which is operatively connected to the brake pedal actuates a latching relay to deenergize the braking control apparatus.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to improvements in and relating to braking 
control apparatus for vehicles such as automotive vehicles. 
2. Description of the Prior Art 
It is troublesome for the driver of a vehicle to operate the hand brake or 
continuously depress the brake pedal to facilitate the driving operation 
of the vehicle when starting on a slope, prevent his vehicle at rest from 
colliding into the preceding vehicle from behind causing a double 
collision when his vehicle is collided from behind, prevent the vehicle 
from being moved forward due to a creeping phenomenon of the vehicle 
equipped with a torque converter and so on. As a means of overcoming these 
difficulties, a braking control apparatus has been proposed in the art in 
which once the brake pedal of a running vehicle has been depressed thus 
braking and bringing the vehicle to a stop, the brake pedal is locked in 
the depressed position by the energization of an electromagnet so that the 
depression of the brake pedal is maintained and thus the brakes continue 
to hold until the accelerator pedal is next depressed. While the 
conventional apparatus of this type has great advantages, it is 
disadvantageous in that when it is desired to depress further the brake 
pedal held in the previously depressed position by the electromagnet so as 
to apply the brakes harder, it is essential to depress the brake pedal 
against the electromagnetic force of the electromagnet thus requiring a 
considerably large amount of brake-pedal pressure. 
Another disadvantage in practical use is that if the driver who 
overestimates the braking action of this apparatus steps out of the 
vehicle without applying the hand brake, there is the possibility of a 
situation arising in which when any fault occurs in the electric system so 
that the energizing current to the electromagnet is interrupted or 
reduced, the braking of the vehicle is partially lost thus causing an 
unforeseen accident. 
Still another disadvantage is that when a fault occurs in the electronic or 
electric circuitry of the apparatus so that it can no longer perform the 
function of rendering the electromagnet inoperative during the time that 
the vehicle is in motion, the brake pedal will be locked in the depressed 
position by the electromagnet even when the vehicle is moving with the 
result that particularly when the brake pedal is depressed fully to 
rapidly brake the vehicle, even if the foot is lifted off the brake pedal, 
the rapid braking of the vehicle is maintained and thus the wheels remain 
locked giving rise to a very dangerous situation. 
SUMMARY OF THE INVENTION 
With a view to overcoming the foregoing difficulty, it is an object of this 
invention to provide a braking control apparatus wherein when the brake 
pedal is depressed again to increase the braking force, the energization 
of the electromagnet locking the brake pedal is interrupted or reduced to 
facilitate the depression of the brake pedal. 
It is another object of this invention to provide a braking control 
apparatus wherein there is provided a door switch which is operatively 
connected to the vehicle doors so that the opening of the door brings the 
door switch into operation to deenergize the electromagnet, whereby when 
the driver steps out of the vehicle, the locking of the brake pedal by the 
electromagnet is released automatically thus preventing the occurrence of 
any accident due to the driver's over-estimation of the ability of the 
apparatus. 
It is still another object of this invention to provide a braking control 
apparatus which is capable of preventing the occurrence of a dangerous 
situation in which when the vehicle is braked rapidly while it is moving, 
even if the foot is lifted off the brake pedal, the brakes continue to 
hold due to erroneous energization of the electromagnet. 
In accordance with this invention, there is thus provided a braking control 
apparatus for a vehicle which is capable of locking the brake pedal in any 
given depressed position, wherein the apparatus is rendered inoperative 
when the vehicle is in such a condition that the locking of the brake 
pedal is undesirable. Thus, the apparatus of this invention has a great 
advantage that driving safety of the apparatus is improved and the driving 
operation is made easier. 
Other objects, features and advantage of the present invention will become 
apparent from considering the following detailed description in 
conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Before describing the apparatus of this invention, the prior art braking 
control apparatus shown in FIGS. 1 through 7 will be described first. 
Referring to FIGS. 1 to 3, numeral 1 designates a brake pedal pivotable 
about a bolt 2 serving as a fulcrum, 3 a steering post, 4 a spring for 
returning the brake pedal, 5 a locking plate which is formed, as shown in 
FIGS. 2 and 3, into a flat shape on the whole having a part of its outer 
peripheral portion bent to form a bent portion whose part 5a in turn is 
secured to a metal mount 6. The metal mount 6 is fixedly mounted on the 
steering post 3 thus firmly holding the locking plate 5 in place on the 
vehicle body. Numeral 7 designates a bolt and a nut fastening the locking 
plate 5 to the metal mount 6. In FIG. 1, numeral 8 designates a cover 
screwed to the bent portion of the locking plate 5 and FIGS. 2 and 3 show 
the apparatus with the cover 8 taken away. Numeral 9 designates a forked 
connecting member having its forked end fitted on the brake pedal 1 and 
its base portion secured to a rod 10. As shown in FIGS. 2 and 3, the other 
end of the rod 10 is connected by a pin 13 to a rotary member 12 which in 
turn is movably mounted on a shaft 11 projected from the locking plate 5. 
Teeth 12a are formed on a part of the outer periphery of the rotary member 
12 and the teeth 12a are in mesh with teeth 15a of another rotary member 
15 which is movably mounted on a shaft 14 projected from the locking plate 
5. The teeth 15a are formed on a part of the outer periphery of the rotary 
member 15 and the rotary member 15 is provided with a cam portion 15b 
formed on its portion having no teeth. Numeral 16 designates an arm having 
its one end fixedly mounted on the rotary member 15 and its other end 
attached to an electromagnet 17 whose attracting surface is spaced away 
from the plane surface of the locking plate 5 by a certain gap. Numeral 18 
designates a spring for normally pressing the connecting member 9 against 
the brake pedal 1. Numeral 19 designates a microswitch fixedly mounted on 
a mounting plate 20 and its actuator is engaged with the cam portion 15 b 
of the rotary member 15 so as to be opened and closed in response to the 
rotary movement of the rotary member 15. The mounting plate 20 is provided 
with a slot 20a so that the mounting plate 20 is attached to the plane 
surface of the locking plate 5 and thus its position is adjustable within 
the extent of the length of the slot 20a. In FIG. 3, numeral 22 designates 
a manual locking lever which is rotatably mounted on a pin 23 projected 
from the locking plate 5 and the manual locking lever 22 is provided at 
its one end with a pawl 24 adapted for engagement with the teeth formed on 
a member (not shown) which is fixedly mounted on the rotary member 12 for 
rotation therewith and at its other end with a handle 25. As shown in FIG. 
4, the handle 25 is fitted on the lever 22 so as to be slidable in the 
lengthwise direction of the lever 22 (from side to side in the Figure) and 
it is also biased by a spring 26 to the right in the Figure. Also in FIG. 
4, the handle 25 is provided at its right end with a portion 25a having 
teeth inclined in one direction to engage with an inclined toothed portion 
25b which is formed on the end of the locking plate 5. With this 
construction, while, in FIG. 3, the lever 22 may be easily rotated 
counterclockwise about the pin 23 through the operation of the handle 25, 
the clockwise rotation of the lever 22 is normally prevented by the 
toothed portions 25a and 25b which are in mesh with each other. In FIG. 2, 
the manual locking lever mechanism and its associated parts are not shown 
for purposes of simplicity. The microswitch 19 is positioned so that when 
the brake pedal is depressed in excess of a predetermined amount, it is 
actuated and closed by the cam portion 15b of the rotary member 15. 
Referring now to FIGS. 5 and 6, numeral 27 designates a clutch pedal and a 
microswitch 28 is fixedly mounted on one side of a metal mount 29 attached 
to the steering post 3. A cam 31 having an arm 31a is rotatably fitted on 
a pin 30 projected from the metal mount 29 and the cam 31 is biased by a 
spring 60 so as to be normally pressed against the clutch pedal 27. A 
control cam 32 having a cam face 32a is attached by a bolt 61 to the other 
surface of the cam 31. The control cam 32 is provided with a hole which is 
engaged with the pin 30 and it is also provided with a curved slot 32a 
which is engaged with the bolt 61. Thus, by loosening the bolt 61, the 
control cam 32 may be rotated about the pin 30 through a certain angle. 
The cam 31 includes cam faces 31b and 31c adapted for engagement with the 
microswitch 28 and the height of the cam face 31b is selected equal to 
that of the cam face 32b of the control cam 32. Consequently, while, in 
the position of FIG. 5, the cam face 31b is engaged with the microswitch 
28 closing the latter, the cam face 31c engages with the microswitch 28 in 
response to a slight depression of the clutch pedal 27 thus opening the 
microswitch 28 and a further depression of the clutch pedal 27 brings the 
cam face 32b of the control cam 32 into engagement with the microswitch 28 
thus closing again the microswitch 28. 
In FIG. 7, numeral 33 designates a permanent magnet which is mounted on the 
shaft of the vehicle such as the propeller shaft for rotation in 
accordance with the rotation of the wheel, 34 a reed switch positioned 
adjacent to the permanent magnet 33 and having its one end connected to 
the positive terminal of a power source 37 through a diode 64, a resistor 
63, a main switch 35 and a key switch 36 and its other end grounded. The 
negative terminal of the power source 37 is also grounded. Numeral 38 
designates a relay, 39 a buzzer, 40 a switch operatively connected to the 
accelerator pedal (not shown) so that its contacts are opened in response 
to the depression of the accelerator pedal. 
Assuming now that the vehicle is in motion, the permanent magnet 33 is 
rotating and the reed switch 34 is turned on and off. Thus, when the reed 
switch 34 is turned off, a capacitor 65 is charged through the resistor 63 
and a diode 66, whereas when the reed switch 34 is turned on, the charge 
on the capacitor 65 is discharged through the reed switch 34 and the 
diodes 64 and 67, and this process is repeated. The AC component of the 
speed signal thus generated at the terminal of the capacitor 65 is 
rectified by the diode 66, smoothed out by a smoothing circuit comprising 
a resistor 68 and a capacitor 69 and then applied to the base terminal of 
a transistor 73 having connected thereto a base resistor 70, an emitter 
resistor 71 and a temperature compensating thermistor 72. Consequently, 
when the vehicle is in motion, the base current flows to the transistor 73 
so that the transistor 73 is turned on and the base current also flows to 
the following transistor 76 through its collector resistors 74 and 75 thus 
turning it on. When the transistor 76 is fully turned on, the voltage 
across a resistor 77 is increased and thus the final stage transistor 78 
is turned off. In other words, the transistor 78 operates as a phase 
inverting amplifier. Numeral 79 designates a biasing diode, 80 a capacitor 
connected in parallel with the coil of the relay 38. The coil of the relay 
38 is inserted in the collector circuit of the final stage transistor 78 
and the relay 38 has the common contact of its transfer contacts connected 
to the positive terminal of the power source 37 through the main switch 35 
and the engine key switch 36, the normally open contact connected to the 
electromagnet 17 and the normally closed contact connected to the buzzer 
39. Consequently, when the vehicle is in motion, the transistor 78 remains 
off and thus the electromagnet 17 is not energized. 
With the construction described above, the operation of the circuitry of 
FIG. 7 as a whole will now be described. 
When the brake pedal 1 is depressed, the brakes are applied so that the 
vehicle is slowed down and brought to a stop. During this deceleration 
operation, if the amount of the depression of the brake pedal 1 is less 
than a predetermined amount, the switch 19 remains off and the buzzer 39 
does not produce a buzzing sound. On the other hand, when the amount of 
the depression of the brake pedal 1 during the deceleration operation of 
the vehicle is greater than the predetermined amount, the switch 19 is 
turned on and the buzzer 39 produces a buzzing sound and the driver is 
informed of the fact that the depression of the brake pedal 1 has been 
positively accomplished. When the vehicle is brought to a complete stop, 
the reed switch 34 is no longer turned on and off so that the final stage 
transistor 78 is turned on and the relay 38 is energized. Consequently, 
while the transfer contacts of the relay 38 are changed from their 
illustrated positions, the circuitry is so constructed that the time of 
transfer of the contacts is slightly delayed from the time of complete 
stopping of the vehicle. In other words, the constant of the circuit 
including the capacitor 69 is selected so that after the vehicle has been 
stopped completely, the charge on the capacitor 69 is discharged through 
the base of the transistor 73 and thus the transistor 73 is turned on for 
a period of about 2 seconds, for example, and consequently at the 
expiration of about 2 seconds after the complete stopping of the vehicle, 
the relay 38 changes its position thus energizing the electromagnet 17. As 
a result, when the brake pedal 1 is depressed to an extent greater than a 
predetermined amount to decelerate the vehicle, the switch 19 is closed 
and thus the buzzer 39 continues to produce a buzzing sound until the 
lapse of about 2 seconds after the complete stopping of the vehicle, after 
which the electromagnet 17 is energized and attracted to the locking plate 
5 with the result that even if the driver lifts his foot off the brake 
pedal 1, the brake pedal 1 is continuously held in the previously 
depressed position and thus the brakes continue to hold. 
Next, to start the vehicle, the clutch pedal 27 is first depressed to the 
full extent. In this case, since the switch 28 remains closed as mentioned 
previously and the brakes still continue to hold. It is to be noted here 
that while there are instances where the switch 28 is opened during the 
time that the clutch pedal 27 is being depressed to the full extent as 
mentioned earlier, in this case the brakes continue to hold since the 
accelerator pedal is not depressed at all and the switch 40 remains closed 
thus energizing the electromagnet 17 continuously. Then, the shift lever 
(not shown) is operated and the accelerator pedal is depressed thus 
opening the switch 40. Thereafter, when the clutch pedal 27 is gradually 
released while depressing the accelerator pedal further, the switch 28 is 
also opened and the electromagnet 17 is deenergized thus causing the 
electromagnet 17 to lose its attractive power and thereby releasing the 
brakes. In this case, the amount of depression of the clutch pedal 27 is 
related to the operating position of the switch 28 in such a manner that 
the time of the clutch discs starting to meet coincides with the time that 
the switch 28 is opened and in this way the driving operation for starting 
the vehicle on a slope is facilitated. 
The size of the parts of the rotary members 12 and 15 and the arm 16 are 
selected so as to magnify the movement of the brake pedal 1 which is 
transmitted through the forked connecting member 9. 
In other words, these sizes are so selected that assuming that A represents 
the distance between the shaft 11 and the pin 13, B represents the 
distance from the shaft 11 to the pitch circle of the teeth 12a, C 
represents the distance from the shaft 14 to the pitch circle of the teeth 
15a and D represents the distance between the shaft 14 and the 
electromagnet 17 or the length of the arm 16, the following relation 
holds: 
EQU D.multidot.B &gt; A.multidot.C 
or 
EQU D &gt; A, B &gt; C 
in this way, it is possible to positively lock the brake pedal in its 
depressed position against its reaction force which is usually as large as 
20 to 30 Kg by means of a relatively small electromagnet. 
The manual locking mechanism shown in FIGS. 1 and 3 may be used in the 
following manner, namely, with the brake pedal 1 depressed and held in the 
depressed position by the electromagnet 17, by pulling the handle 25 
toward the observer in FIG. 1 so that the pawl 24 engages with the teeth 
formed on the member attached to the rotary member 12 for rotation 
therewith thus mechanically locking the rotary member 12, it is possible 
to cause the applied brakes to continue to hold even if the power source 
is disconnected. To release this mechanical lock, it is necessary to allow 
the handle 25 to slide upward while pulling it to the left in FIG. 4 
against the force of the spring 26. 
Next, the preferred embodiments of the invention will be described with 
reference to the accompanying drawings. 
Referring to FIG. 8, there is illustrated a first embodiment of the 
invention in which the invention is applied to the above-described braking 
control apparatus shown in FIGS. 1 through 7. In the Figure, the collector 
of the transistor 73 is grounded through a switch 141. The ends of the 
microswitch 28 operatively connected to the clutch pedal 27 and the switch 
40 operatively connected to the accelerator pedal which are not connected 
to the electromagnet 17, are connected to the junction point of the buzzer 
39 and the microswitch 19 as shown in the Figure. The junction point of 
the electromagnet 17 and the microswitch 28 and that of the electromagnet 
17 and the switch 40 are grounded through a pre-set resistor 143. The 
remainder of this embodiment is the same with the corresponding circuit 
construction of FIG. 7. As will be described later, the switch 141 is one 
whose contacts are closed in response to only a slight depression of the 
brake pedal 1. 
FIGS. 9 and 10 show the relationship between the switch 141 and the brake 
pedal 1. In the embodiments of this invention, the connection of the brake 
pedal with the rod differs from the connection of the brake pedal 1 and 
the rod 10 shown in FIGS. 1 to 3, namely, the base portion of a forked 
connecting member 145 is connected to a coupling member 110a which is 
attached to the right end of the rod 10, while the forked portion of the 
connecting member 145 is fitted on the brake pedal 1 and a metal plate 148 
is slidably fitted on the open end of the forked portion. Also a rubber 
box member 144 is fitted on the connecting member 145 opposite to the 
metal plate 148. The box member 144 is formed into a box shape with no 
lids and sides 144a of the box member 144 are thin and formed into a 
flexible shape. Numeral 143 designates a cover fastened to the metal plate 
148 by a rivet contact 141b. The box member 144 is held in place by nuts 
146 screwed onto the fork ends of the connecting member 145. Numeral 141a 
designates a rivet contact fixedly fitted in the central portion of the 
bottom of the box member 144 and connected by a wire 142 to the collector 
of the transistor 73 shown in FIG. 8. Numeral 147 designates a spring for 
biasing in such a manner that the contacts 141a and 141b are normally kept 
away from each other. The rod 10 is normally pulled to the left by another 
spring which is not shown, so that the left end of the contact 141b or the 
cover 143 is normally kept in contact with the forward end (the right end 
in the Figure) of the arm of the brake pedal 1. The resilience of the 
spring 147 and the sides 144a of the box member 144 are set to such values 
that while even a slight movement of the brake pedal 1 in the depressing 
direction brings the contacts 141a and 141b into contact with each other, 
any slight movement of the brake pedal 1 in the releasing direction causes 
the contacts 141a and 141b to separate from each other. This relationship 
may be easily established, although it is subject to the effects of the 
strength of the spring pulling the rod 10 to the left, the forces 
including the inertia force, the frictional force, etc., which are 
required for moving the electromagnet, etc., when pulling the rod 10 to 
the right, the restoring force or the inertia of the brake pedal, etc. The 
contacts 141a and 141b constitute the switch 141 and the contact 141b is 
grounded through the connecting member 145 or the brake pedal 1. Numeral 
149 designates a stopper for preventing the connecting member 145 from 
falling downwards and it is fixedly mounted on the brake pedal 1 by means 
of bolts and nuts. 
The operation of the first embodiment of the invention will now be 
described with reference to FIG. 8. 
With the vehicle in motion, when the brake pedal 1 is depressed, the 
contacts 141a and 141b are first brought into contact with each other and 
thus the switch 141 formed by these contacts is closed turning the 
transistor 76 on and the transistor 78 off. Consequently, even if the 
brake pedal 1 is depressed further so that the microswitch 19 is closed, 
the electromagnet 17 is not energized. When the vehicle is brought to a 
complete stop with the brake pedal 1 depressed to an extent greater than a 
predetermined amount, the speed signal from the reed switch 34 is 
terminated and the transistor 73 is turned off. After the vehicle has been 
brought to a complete stop, when the driver lifts his foot off the brake 
pedal 1, the switch 141 is opened so that the relay 38 is operated and the 
electromagnet 17 is energized thus locking the brake pedal 1 in the 
previously depressed position. More specifically, the apparatus of this 
invention operates as follows. When the foot pressure depressing the brake 
pedal 1 is reduced in an attempt to lift the foot off the brake pedal 1, 
the brake pedal 1 tends to return faster than the rod 10 so that the brake 
pedal 1 is separated from the cover 143 and the switch 141 is opened by 
the force of the spring 147, thus locking the brake pedal 1 in the 
previously depressed position by the electromagnet 17. Of course, the 
brake pedal 1 is locked in the position depressed greater than the 
predetermined amount and consequently the microswitch 19 remains closed. 
While this allows the brakes to continue to hold, if it is desired to 
apply the brakes more firmly, by depressing the brake pedal 1 harder so 
that the switch 141 is closed by the foot pressure and the relay 38 is 
deenergized, the brake pedal 1 may be easily depressed further with only a 
small amount of foot pressure. After the brake pedal 1 has been depressed 
harder, when the foot is lifted off the brake pedal 1, as mentioned 
previously, the switch 141 is instantly opened and the electromagnet 17 is 
energized thus locking the brake pedal 1 in the newly depressed position. 
The pre-set resistor 143 serves in such a manner that when the microswitch 
28 operatively connected to the clutch pedal 28 and the switch 40 
operatively connected to the accelerator pedal are both opened and the 
electromagnet 17 is deenergized, namely, when the vehicle is started, the 
electromagnet 17 is attracted with a weak force to the locking plate and 
in this way the striking sound due to the deenergization of the 
electromagnet 17 is reduced. The resistance value of the resistor 143 is 
suitably selected so as to prevent any possibility of the buzzer 38 being 
grounded through the switch 28 or 40 and the resistor 143 and caused to 
produce a buzzing sound while the vehicle is in motion. 
FIG. 11 is a circuit diagram of a second embodiment of the invention in 
which the speed detecting circuit is eliminated, wherein an amplifier A 
having transistors 204 and 205 for energizing the electromagnet 17 and a 
two-winding latching relay 250 for controlling the supply of current to 
the amplifier A are connected as shown in the Figure. In this second 
embodiment, the switch operatively connected to the accelerator pedal is a 
transfer switch 250 which is changed from the illustrated position in 
response to the depression of the brake pedal 1. 
With the main switch 35 and the key switch 36 closed, when the vehicle is 
started by depressing the accelerator pedal, the transfer switch 240 is 
changed from the illustrated position so that forward current flows to one 
coil 250a of the relay 250 and its contact 250c is changed from the 
illustrated position and latched in the newly assumed position. 
Consequently, the amplifier A is connected to the positive terminal of the 
power source 37. With the vehicle in motion, when the brake pedal 1 is 
depressed, the switches 141 and 19 of the same construction as the 
switches 141 and 19 of the first embodiment shown in FIG. 8 are closed. In 
this case, since the transistor 205 is turned off in response to the 
closing of the switch 141, the electromagnet 17 is not energized. When the 
driver lifts his foot off the brake pedal 1, the switch 141 is instantly 
returned into the position shown in FIG. 11. In this case, since the 
driver is not stepping on the accelerator pedal so that the switch 240 is 
placed in the position shown in FIG. 11, the electromagnet 17 is energized 
and the brake pedal 1 is locked in the previously depressed position. When 
it is desired to apply the brakes more hardly, the brake pedal 1 is 
depressed further so that the switch 141 is closed and the electromagnet 
17 is deenergized thus allowing the driver to depress the brake pedal 1 
easily. In the Figure, numeral 251 designates another microswitch which is 
operatively connected to the brake pedal 1 and disposed so that it is 
closed when the brake pedal 1 is depressed fully. Consequently, with the 
vehicle in motion, when the brake pedal 1 is depressed fully, the 
microswitch 251 is closed and reverse current flows in the other coil 250b 
of the two-winding latching relay 250, thus releasing the latch and 
deenergizing the relay 250. Consequently, the supply of power to the 
amplifier A is stopped and the electromagnet 17 is deenergized. The 
microswitch 251 is provided to prevent the risk of a situation arising in 
which when the running vehicle is braked hard, the brakes continue to hold 
and the wheels are locked. Numeral 239 designates a lamp for indicating 
that the electromagnet 17 has been energized. 
Next, a third embodiment of the invention will be described with reference 
to the drawings. FIG. 12 is a circuit diagram of the third embodiment in 
which the present invention is applied to the prior art braking control 
apparatus shown in FIGS. 1 to 7, wherein the collector of the transistor 
73 is connected to the ground through the switch 141. The collector of the 
transistor 73 is also grounded by way of a diode 305 and a door switch 
352. The door switch 352 is operatively connected to the doors so that it 
is closed when the door is opened. The junction point of the diode 305 and 
the door switch 352 is connected to the positive terminal of the power 
source 37 through a manual room light switch 353 and a room light 354. 
Connected in parallel with the electromagnet 17 is an indicator lamp 239 
having its one end connected to the normally open contact of the relay 38 
and its other end grounded through the pre-set resistor 143. The junction 
point of the electromagnet 17 and the pre-set resistor 143 is connected 
through the microswitch 19 to one ends of the microswitch 28 and the 
switch 40 operatively connected respectively to the clutch pedal 27 and 
the accelerator pedal and the other ends of the microswitch 28 and the 
switch 40 are grounded. In this embodiment, the buzzer 38 shown in FIG. 7 
is eliminated. The remainder of this embodiment is the same with the 
corresponding circuit construction of FIG. 7. The switch 141 is the same 
or equivalent to that used in the first and second embodiments shown in 
FIGS. 8 to 11. 
The operation of the third embodiment is as follows. With the vehicle in 
motion, when the brake pedal 1 is depressed, the contacts 141a and 141b 
are closed and the switch 141 comprised of these contacts is closed, thus 
turning the transistor 76 on and the transistor 78 off. Thus, even if the 
brake pedal 1 is depressed further so that the microswitch 19 is closed, 
the electromagnet 17 is not energized. When the vehicle is brought to a 
stop with the brake pedal 1 being depressed, the speed signal from the 
reed switch 34 is terminated and at the expiration of several seconds 
thereafter the transistor 73 is turned off. Thereafter, when the driver 
lifts his foot off, the switch 141 is opened so that the relay 38 is 
operated and the electromagnet 17 is energized, thus locking the brake 
pedal 1 in the previously depressed position. Namely, when the driver 
lifts his foot off the brake pedal 1, the brake pedal 1 tends to return 
faster than the rod 10 so that the switch 141 is opened by only a slight 
movement of the brake pedal 1 and thus the brake pedal 1 is locked in the 
previously depressed position. Of course, the microswitch 19 remains 
closed. While this causes the brakes to continue to hold, if it is desired 
to apply the brakes harder, the brake pedal 1 is depressed more hardly so 
that the switch 141 is closed in response to this brake-pedal pressure and 
the relay 38 is deenergized. Thus, the electromagnet 17 is deenergized 
allowing the brake pedal 1 to be easily redepressed further. After the 
brake pedal 1 has been depressed harder, when the driver lifts his foot 
off the brake pedal 1, the switch 141 is immediately opened and the 
electromagnet 17 locks the brake pedal 1 in the newly depressed position. 
This operation is the same with that described in connection with the 
first and second embodiments. 
In this condition, when the driver opens the door to step out of the 
vehicle, the door switch 352 is closed so that the transistor 76 is turned 
on and the transistor 78 is turned off. Thus, the relay 38 is deenergized 
and the electromagnet 17 is also deenergized thus releasing the brakes. 
The pre-set resistor 143 serves in such a manner that when the microswitch 
28 and the switch 40 are opened and the electromagnet 17 is deenergized, 
namely, when the vehicle is started, the electromagnet 17 is attracted 
with a weak force to the locking plate and in this way the striking sound 
due to the deenergization of the electromagnet 17 is reduced and the 
pre-set resistor 143 is of the same type as used in the first embodiment 
shown in FIG. 8. 
FIG. 13 is a circuit diagram of a fourth embodiment in which the speed 
detecting circuit is eliminated. More specifically, the mechanism of the 
circuit of FIG. 12 which deenergizes the electromagnet by the door switch 
is incorporated in the circuit of FIG. 11. An amplifier A' having 
transistors 204, 205 and 206 for energizing the electromagnet 17 and the 
two-winding latching relay 250 for controlling the supply of current to 
the amplifier A' are connected as shown in the Figure. In this embodiment, 
the amplifier A' and the two-winding latching relay 250 are the same with 
those shown in FIG. 11 except that the transistors 205 and 206 are 
connected in Darlington configuration to provide an improved amplification 
factor. Of course, these two transistors may be replaced with a single 
transistor as shown in FIG. 11. The switch 28 is of the same structure 
with that shown in FIG. 11. 
The operation of the fourth embodiment is as follows. With the main switch 
35 and the key switch 36 closed, when the accelerator pedal is depressed 
so that the vehicle is started, the transfer switch 240 is changed from 
the illustrated position and forward current flows in one coil 250a of the 
relay 250 thus changing its contact 250c from the illustrated position and 
holding it in the newly assumed position. Consequently, the amplifier A' 
is connected to the positive terminal of the power source 37. With the 
vehicle in motion, when the brake pedal 1 is depressed, the switches 141 
and 19 are closed so that the transistors 205 and 206 are turned off in 
response to the closing of the switch 141 and the electromagnet 17 is not 
energized. However, when the foot is lifted off the accelerator pedal 
deenergizing the swtich 240 and then the foot is lifted off the brake 
pedal 1 instantaneously deenergizing the switch 141, the electromagnet 17 
is energized and the brake pedal 1 is locked in the previously depressed 
position. When it is desired to apply the brakes harder, the brake pedal 1 
is depressed further so that the switch 141 is closed and the 
electromagnet 17 is deenergized thus allowing the driver to depress the 
brake pedal 1 easily. In the Figure, numeral 251 designates another 
microswitch which is operatively connected to the brake pedal 1 and 
disposed so that it is closed when the brake pedal 1 is depressed fully. 
As a result, with the vehicle in motion, when the brake pedal 1 is 
depressed fully, the microswitch 251 is closed and reverse current flows 
in the other coil 250b of the two-winding latching relay 250, thus 
releasing the latch and deenergizing the latching relay 250. Consequently, 
the supply of power to the amplifier A' is stopped and the electromagnet 
17 is deenergized. The microswitch 251 is provided to prevent the danger 
of the brakes applied hard on the running vehicle being allowed to 
continue to hold and thus locking the wheels. The operation of the door 
switch 352 which results in releasing the brakes will not be described 
since it is the same with that described in connection with the third 
embodiment shown in FIG. 12. 
Referring to FIG. 14, there is shown a fifth embodiment of the invention 
which is a slightly modified form of the fourth embodiment shown in FIG. 
13. This embodiment differs from the fourth embodiment of FIG. 13 in that 
the electromagnet 17 is energized by a relay 38' inserted in the collector 
circuit of the transistor 205 and the place of connection of the switches 
141 and 251 are slightly changed. The operation of this embodiment on the 
whole is the same with that of the fourth embodiment shown in FIG. 13 and 
the circuit construction of this embodiment may readily be understood from 
the Figure. Thus, they will not be described. In the case of a vehicle 
such as a torque converter-equipped vehicle having no clutch pedal, the 
switch 28 is not needed. 
FIG. 15 shows a sixth embodiment of this invention. In the embodiment, a 
single-pole double-throw type microswitch 19' is used instead of the 
single-pole single-throw type microswitch 19 of the fifth embodiment as 
shown in FIG. 14. The normally open contact of the microswitch 19' is 
connected to an electromagnet 17, while the normally closed contact 
thereof is connected to the negative terminal of one coil 250a of a 
latching relay 250. Further, in the embodiment a switch 400 is connected 
between the electromagnet 17 and the ground. The switch 400 is actuated in 
accordance with the positions of the shift lever of a vehicle, and, in 
this embodiment, it closes only when the shift lever is in the neutral 
position. 
In the Figure, the component elements designated by the same reference 
numerals as in FIGS. 12 and/or 13 are identical or equivalent in 
construction and function with the corresponding elements of FIGS. 12 
and/or 13. 
The sixth embodiment is intended to provide a better driving operation of a 
vehicle when, for example, the vehicle is climbing down on a steep 
downhill road. Namely, if an emergency brake is applied on such a downhill 
road, the microswitch 251 is closed and a reverse current flows in the 
other coil 250b of the latching relay 250, thus releasing the latch and 
deenergizing the latching relay 250, as mentioned earlier. Thereafter, in 
this embodiment, when the driver's foot is lifted off the brake pedal 1, 
the coil 250a of the relay 250 is energized by the actuation of the 
microswitch 19', whereby the relay 250 is latched. In other words, only if 
the driver's foot is lifted off the brake pedal after an emergency braking 
on a downhill road, the vehicle can start to climb down the downhill road 
by its gravity without necessitating the depressing of an accelerator 
pedal as in the other embodiments. Of course, in the embodiment the relay 
250 can be latched also by the depressing of the accelerator pedal. 
The switch 400 is provided to lead one terminal of the electromagnet 17 to 
the ground irrespective of the states of the switches 19, 28 and 240 when 
the shift lever is positioned neutral. 
The other operations of the sixth embodiment will not be described since it 
may readily be understood from the description of the other embodiments 
and figures. 
While, in some embodiments of the invention described hereinabove, a reed 
switch is used to constitute a part of the vehicle speed detecting means, 
of course the reed switch may be replaced with any other semiconductor 
switch such as a Hall device. Further, while the switch attached to the 
accelerator pedal, brake pedal and clutch pedal, respectively, comprises a 
mechanical switch using a coil spring, of course the switch may be 
replaced with any other solid-state switch such as a pressure sensitive 
diode switch or proximity switch.