Anti-theft system for use on a tractor/trailer land vehicle

An anti-theft system prevents release of the brakes of a tractor/trailer land vehicle after the manual brake control has been set and after the anti-theft system has been activated. With the anti-theft system activated, any attempt to release the brakes of the vehicle will not be successful and will activate an alarm. The anti-theft system cannot be activated until after the manually operated brake control has been activated. The anti-theft system can be applied to the brakes of either or both the tractor and/or the trailer of the vehicle.

TECHNICAL FIELD OF THE INVENTION 
The present invention relates to the general art of land vehicles, and to 
the particular field of anti-theft systems for use in land vehicles, 
specifically, tractor/trailer systems. 
BACKGROUND OF THE INVENTION 
As is well known, auto theft is a major problem in the United States and 
throughout the world. Most auto thefts occur when the vehicle is 
unoccupied and the owner is elsewhere. To combat this, the industry has 
proposed many different types of alarm and anti-theft systems. These 
systems range from simple mechanical locks which prevent mechanical 
operation of some element of the vehicle, such as the steering wheel, the 
brake pedals, the clutch or the like to audible and/or visible alarms and 
sophisticated tracking systems that are triggered when unauthorized use of 
the vehicle is attempted when the alarm or system is armed to systems for 
disabling some operation of the vehicle, such as the electrical system of 
the vehicle. 
While many anti-theft systems appear to be available for automobiles, the 
trucking industry has seen a dearth of anti-theft systems. To the 
knowledge of the inventor, the only system used for tractor trailer type 
trucks is a satellite tracking system that tracks merchandise and is not 
intended for use for preventing theft of the truck and/or trailer. 
Therefore, there is a need for an anti-theft system particularly adapted to 
preventing unauthorized use of a truck, such as a tractor-trailer type 
truck. 
However, while preventing theft of a truck, the system must permit safe 
operation of the vehicle and not interfere with such safe operation. Some 
anti-theft systems which disable an operating system of the vehicle could 
interfere with the safe, authorized operation of the vehicle. 
Therefore, there is a need for an anti-theft system particularly adapted 
for preventing unauthorized use of a truck, yet which permits safe 
authorized use of the truck. 
OBJECTS OF THE INVENTION 
It is a main object of the present invention to provide an anti-theft 
system particularly adapted for use on a tractor trailer type truck or 
such land vehicle. 
It is another object of the present invention to provide an anti-theft 
system particularly adapted for use on a tractor trailer type truck which 
prevents unauthorized operation of the truck. 
It is another object of the present invention to provide an anti-theft 
system particularly adapted for use on a tractor's trailer which prevents 
unauthorized operation of the trailer. 
It is another object of the present invention to provide an anti-theft 
system particularly adapted for use on a tractor trailer type truck which 
prevents unauthorized operation of the truck yet which will not interfere 
with the authorized use of the truck. 
SUMMARY OF THE INVENTION 
These, and other, objects are achieved by an anti-theft system which is 
specially adapted for use on land vehicles such as trucks, specifically 
tractor trailer type trucks. The present disclosure will be directed to 
trucks and tractor trailers, but this is intended to be a disclosure of 
the best mode and is not intended to be limiting. The system disables the 
brake system of the vehicle after that brake system has been activated to 
prevent rotation of at least one road wheel of the vehicle. The anti-theft 
system is connected with the brake system of the vehicle in a manner such 
that the anti-theft system cannot be activated until after the manual 
brake has been activated. 
Thus, the anti-theft system cannot be operated until after the manual brake 
has been activated, but will prevent de-activating the brake system until 
after the anti-theft system has been deactivated. This can be visualized 
as the following process: Activation of the anti-theft system requires 
first activating the manual brake system of the vehicle and then 
activating the anti-theft system; de-activation of the anti-theft system 
requires first de-activating the anti-theft system and then de-activating 
the manual brake system of the vehicle. 
However, once the anti-theft system is activated, the vehicle cannot be 
moved until the anti-theft system is de-activated. This can be visualized 
as an "ONLY IF" process: the anti-theft system can be activated "only if" 
the manual brake has been previously activated; whereas, once the 
anti-theft system has been activated, the vehicle can be moved "only if" 
the anti-theft system is de-activated before de-activating the manual 
brake of the vehicle. In this manner, the anti-theft system cannot be 
inadvertently activated during authorized operation of the vehicle. This 
is a safety feature of the present invention. 
A visible signal is placed in the vehicle and is activated when the 
anti-theft system is activated to indicate that the anti-theft system is 
active, and an alarm, such as a horn or siren, is connected to the 
anti-theft system to be activated when there is an attempt to de-activate 
the manual brake before the anti-theft system is de-activated. An 
alternative form of the invention has the anti-theft system connected to 
the trailer portion of the tractor-trailer vehicle as well as to the 
tractor portion of the vehicle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION 
As discussed above, the present invention is an anti-theft system 
particularly adapted for use on a tractor-trailer type land vehicle. The 
anti-theft system is enabled after the manual brake of the vehicle is 
activated to engage the brakes of the vehicle, and then activates an alarm 
if there is an attempt to disengage the manual brake without first 
disabling the anti-theft system. The anti-theft system cannot be activated 
until the manual brake is first engaged so the anti-theft system will not 
interfere with the authorized operation of the vehicle. The anti-theft 
system prevents disengagement of the brakes of the vehicle and can, if 
desired, activate an alarm as well. 
The brake system of a tractor trailer motor vehicle includes brakes that 
are spring biased into a wheel-stopping position and has an air system 
that counters this bias and prevents the brakes from moving into a wheel 
stopping position during operation of the vehicle. By way of example, 
reference is made to FIG. 1B which shows a brake mechanism B having a bias 
element, such as spring S in housing H. Wheel brakes are operated by 
element E which moves axially in directions C1 and C2, with direction C1 
applying the brake to stop rotation of the associated wheel. A diaphragm 
D1 co-operates with housing H to define a first air chamber A1 having an 
air inlet line MB1 fluidically connected to the manual brake of the 
vehicle, and a diaphragm D2 which co-operates with housing H to define a 
second air chamber A2 having a foot brake air input line FB1 fluidically 
connected thereto. Spring S biases diaphragm D1 in direction C1 and 
diaphragm D2 in direction C2 whereby the spring will move element E in 
direction C1 when fluid is removed from chamber A1 and element E will move 
in direction C2 when fluid is moved into chamber A2. Thus, when the manual 
brake is operated, fluid flows out of chamber A1 so the brake is applied 
when element E moves in direction C1, and when the foot brake is operated, 
diaphragm D2 will be moved in direction C1 against the bias of spring S to 
apply the brake. 
Operating the brakes, as by pressing on the foot pedal pressurizes air 
chamber A2 and moving element E of diaphragm D2 in direction C1 for 
overriding the bias of spring S for applying the brakes. Applying the 
manual brake (also known as the parking brake), vents the air pressure 
that is preventing the bias from moving the brakes into a wheel stopping 
configuration. As soon as the air line is vented, the bias of the brake 
system moves the brakes into the wheel stopping configuration. Releasing 
the brakes, as by releasing the foot pedal (which will release air 
pressure from chamber A2, and hence the spring), or releasing the manual 
brake (which will re-pressurize chamber A1 which re-pressurizes the brake 
system) releases the wheel or wheels. 
The present invention uses this feature of the tractor trailer vehicle to 
prevent unauthorized use of the vehicle. The present system places a port 
in the air line of the manual parking brake system and keeps that port 
closed until the anti-theft system is de-activated. In this manner, even 
if the brakes of the vehicle are released, air pressure to the brakes will 
not be re-established because the port blocks this air circuit. Thus, 
until the port is opened by deactivating the anti-theft system the vehicle 
cannot be moved because the brakes will remain engaged due to the bias of 
the brakes because air pressure that counters the bias cannot be applied 
to the brakes since the air pressure is blocked to chamber A1 to overcome 
the spring bias to release the brakes. 
The anti-theft system of the present invention also has a safeguard that 
prevents activation of the anti-theft system until after it receives a 
signal from the manual brake of the vehicle that the manual brake has been 
set. This prevents the system from malfunctioning into a brake applying 
configuration if the vehicle is being operated with the manual brake 
disengaged. 
More specifically, referring to FIGS. 1B-4, the air brake system 10 of the 
present invention includes a source of air 12 and an air-operated brake 
means 14 for stopping rotation of at least one motor vehicle road-engaging 
wheel. As shown in FIG. 1A and discussed above, the air-operated brake 
means 14 includes a spring-biased mechanism 16 that is biased to apply the 
brake to stop wheel rotation when the foot operated brake is pressed, 
and/or when the manual brake is actuated. This occurs by applying air 
against spring bias when the foot operated brake is activated, and 
removing the air that counters spring bias when the manual brake is 
actuated. Braking system 10 includes a manually-operated control means 
such as foot pedal 18 or manual parking brake 20 for releasing or applying 
air pressure in biased mechanism 16 as needed to set brake means 10 when 
activated. When brake means 10 is de-activated, as by releasing foot pedal 
18 or releasing parking brake 20, source of air pressure 12 is fluidically 
connected to biased mechanism 16 of brake system 10 to release or apply 
air pressure as necessary to the biased mechanism to work with the bias of 
the biased mechanism for releasing the brake means and permitting rotation 
of the wheel associated with the brake. While four brake/wheel 
combinations are shown in FIG. 1, more or less can be used as will occur 
to those skilled in the art based on the teaching of this disclosure. Each 
wheel/brake combination will operate and function as has been just 
discussed. 
Manually-operated control means 20 further includes a signal transmitter 22 
for emitting a signal 24 which can be an over-the-air signal or a closed 
signal, when manually-operated control means 18 or 20 is activated to set 
brake means 14 into a wheel rotation preventing configuration. The 
function of signal 24 will be understood from the following disclosure. 
A first fluid line 30 fluidically connects air source 12 to 
manually-operated control means 20 and a second fluid line 32 fluidically 
connects manually-operated control means 20 to biased mechanism 16 of 
brake means 10. Various valves and fittings are also included, but will 
not be discussed as they form no part of the invention. As discussed 
above, when brake means 20 is activated, air pressure from brake means 14 
is vented via relay valve R-14 and is thus withdrawn from application to 
brake means 14. This release of air pressure causes the spring biased 
mechanism in brake means 14 to apply the brakes to the wheel associated 
therewith. Releasing brake means 20 re-establishes the fluid path between 
air reservoir 12 and brake means 14 to re-apply air pressure to the brake 
means and to overcome the spring bias thereof and thus remove the brake 
from the wheel. 
Foot operated brake means 18 works in the manner discussed above. 
Therefore, the operation of foot brake means 18 will not be discussed. The 
fluid circuits for brake means 18 and 20 are shown in FIGS. 1, 2 and 3, 
and reference is made thereto for the details of the operation of the 
overall brake system. Those skilled in the art will understand such 
operation from these figures. 
The anti-theft system of the present invention uses the special operation 
of brake system 10 for its operation. Referring to FIG. 5 it can be 
understood that the anti-theft system of the present invention includes a 
control valve 40 fluidically located in second fluid line 32 in fluid 
series between manually-operated control means 20 and biased mechanism 16 
of air-operated brake system 14. Control valve 40 includes a vent port 42 
in second fluid line 32, a port-covering valve means 44 on second fluid 
line 32 for closing and opening vent port 42. A solenoid controlled 
mechanism 46 is connected to port-covering valve means 44 to move 
port-covering valve means 44 to a port opening position shown in solid 
lines in FIG. 5 when deactivated to a port closing position covering and 
closing port 42 when activated whereby air pressure cannot be applied to 
spring-biased mechanism 16 of the air-operated brake system through second 
fluid line 32 when port-covering valve means 44 is in the port closing 
position and air pressure can be applied to spring-biased mechanism 16 of 
brake 14 of air-operated brake system 10 through second fluid line 32 when 
port-covering valve 44 is in the port opening position. 
A remote control means 50 is used to activate mechanism 46 of control valve 
40 to close port 42 to prevent release of air-operated brake means 14 
after activation of manually-operated control means 20 into a 
brake-setting configuration even if manually-operated control means 20 is 
then moved back into a brake-releasing configuration and de-activates the 
mechanism 46 of control valve 40 to cover vent port 42 for releasing 
air-operated brake means 16 when manually-operated control means 20 is 
thereafter moved into the brake-releasing configuration. When port 42 is 
open to atmosphere, air pressure cannot be applied to chamber A1 to 
overcome the bias of mechanism 16 so the brakes remain applied to the 
wheels and rotation of those wheels is thereby prevented. 
Referring to FIGS. 5, 8 and 9, it will be seen that remote control means 50 
includes a electronically-operated means 52 for activating and 
de-activating the siren. A signal transmitter 53 connected to antenna 54 
which emits a signal 56 when remote control means 50 is activated. A 
signal receiver 58 is located in control valve 40 and is responsive to 
signal 56 emitted by the signal transmitter 53 in remote control means 50 
for activating mechanism 46 in control valve 40 to move port-covering 
valve 44 into the port closing position after manually-operated control 
means 20 has been activated. 
Remote control means 50 further includes a signal receiver 60 connected to 
transmitter/receiver antenna 54 and is responsive to signal emitted 24 by 
manually-operated control valve 20 when the manually-operated control 
valve is activated to permit activation of remote control means 50 and 
permit remote control means 50 to be operated for activating mechanism 46 
of control valve 40 whereby remote control means 50 will not be activated 
and thus cannot be operated until after manually-controlled means 20 has 
been activated into a brake setting condition. 
Referring more specifically to FIGS. 8 and 9 for details of the anti-theft 
system, the anti-theft system utilizes an electrical ignition circuit 
means for operating the motor vehicle, and further includes an audible 
alarm, such as horn 62, power means, such as vehicle battery 64, for 
powering alarm 62, and means 66 for connecting and disconnecting the 
ignition circuit means to power means 64, and an alarm circuit means 68 
for connecting alarm 62 to power means 64 when manually-operated control 
means 20 is operated while mechanism 46 of control valve 40 is in the port 
closing position. 
More specifically, alarm circuit means 68 a normally-closed 
pressure-sensitive switch 70 which, when activated, is biased onto a 
normally open position when manually-operated control means 20 is in 
position to apply air pressure to biased mechanism 16 of air-operated 
brake means 14 and which moves into a closed position for connecting power 
supply 64 to alarm 62 when manually-operated control means 20 is moved 
into a position to connect air source 12 to biased mechanism 16 of 
air-operated brake 14 after pressure-sensitive switch 70 is activated. 
Remote control means 50 is activated and de-activated by a remote control 
receiver, such as switch 52. As can be understood from FIG. 8, means 46 is 
operated via junctions 6 and 7 while pressure switch 70 is operated via 
junctions 8 and 12, with power being applied from source 64 via junction 
13. The exact circuitry used to make these connections will not be 
discussed since those skilled in the art will understand how to effect the 
wiring based on the disclosure of this invention. 
As can be understood from FIG. 8, horn 62 is connected to the remote 
control receiver via junction 2 and junction 1 is a ground junction so 
that when switch 52 is closed horn 62 is powered and is thus activated. 
Switch 52 is a momentary switch that will complete the circuit when 
actuated and will interrupt the circuit when released. As will also be 
understood, receiver 50 is connected to manual control 20 so the remote 
control is not operable until the manual control 20 is activated to set 
the brakes of the vehicle. Once the remote control is activated, pressure 
sensed by switch 70 will activate the alarm and element 44 will remain 
covering port 42 so air pressure cannot be applied to brake element 16. 
A visible signal 80 is located in the motor vehicle and is connected to 
remote control 50 via junction 9 to be activated when the remote control 
is activated and serve as a visible signal that the remote control is 
active. 
A flow chart for the operation of the system is shown in FIG. 7. Setting 
the manual brake 20 will activate the wheel brakes 14 by removing air 
pressure from biased elements 16 thereof. A signal is also generated for 
the remote control 50 so that remote control can be activated. The remote 
control is activated which moves element 44 from a port opening position 
to a port covering position so air pressure cannot be re-established to 
brakes 14. As soon as someone tries to release the brakes by moving the 
manually operated mechanism 20, switch 70 senses pressure in line 32; 
however, this pressure is not applied to the brakes because port 44 
remains closed. Thus, the brakes cannot be released. However, switch 70 
closes the circuit between power source 64 and siren 62 to activate that 
siren. 
When authorized use of the vehicle is to be made, the remote control is 
de-activated. Element 44 is then removed from port 42, and switch 70 is 
activated to the normally open position, also, switch PS-2 is activated 
removing the alarm from an activated condition. When manual control 20 is 
released, air pressure is established through line 32 to brakes 14 and the 
wheel brakes are released. 
Referring to FIGS. 1, 5, 6 and 9, it will be understood that the anti-theft 
system of the present invention can be used to protect against 
unauthorized movement of a trailer of the tractor/trailer combination. The 
anti-theft system used for the trailer is similar to the just-described 
system for the tractor. Therefore, the trailer system will not be 
discussed in great detail. It is noted that the trailer T has an 
air-operated brake means 14' for stopping rotation of at least one road 
engaging wheel of the trailer. The air-operated brake means 14' is 
fluidically connected to air source 12 via second fluid line 32 and 
manually-operated control means 20. Brake means 14' includes a biased 
element 16' that is biased against air pressure to apply braking pressure 
to the wheel of the trailer when air pressure is applied to the biased 
element and releases braking pressure from the wheel of the trailer when 
air pressure is released from the biased element. The remote control means 
50' receiver is associated with the trailer and includes a second 
normally-closed pressure-sensitive switch 70' fluidically connected to 
second fluid line 32 near brake means 14' for stopping rotation of the 
trailer wheel which, when activated, is biased onto a normally open 
position and when de-activated moves into a closed position for connecting 
power supply 64 to either alarm 12 or alarm 72' when manually-operated 
control means 20 is moved back to a position to be de-activated after the 
manually-operated control means and the remote control means have been 
activated. The remote control means 50' further has means, such as 
momentary switch 52' thereon for activating and de-activating the alarm 
siren 72 and 72'. 
It is understood that while certain forms of the present invention have 
been illustrated and described herein, it is not to be limited to the 
specific forms or arrangements of parts described and shown. Certain 
alternatives will occur to those skilled in the art based on the teaching 
of this disclosure, and these alternatives are intended to be within the 
coverage of this disclosure as well. However, the inventor can envision 
some cases where the foot pedal could be used as the key to the anti-theft 
system in the manner discussed above for the control 20. Accordingly, this 
form of the invention is intended to be covered by this disclosure and the 
following claims as well.