CA2847791A1

CA2847791A1 - Brake test apparatus

Info

Publication number: CA2847791A1
Application number: CA2847791A
Authority: CA
Inventors: Paul Tonello
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-03-28
Filing date: 2014-03-28
Publication date: 2014-09-09
Anticipated expiration: 2034-03-28
Also published as: CA2847791C

Abstract

A. brake testing apparatus for testing automatic pressure released spring operated brake systems on a vehicle having a main pressure line for releasing the brakes ,and having a bleed solenoid valve in the pressure line and an orifice operable to gradually "bleed" down pressure and simulate a brake pressure fault, a brake warning light responsive to a drop in pressure, an emergency brake light operable to indicate emergency application of the brakes, a bleed line connection in the charge line connected to the brakes, electrical connections connecting the bleed solenoid to a control cable connection mounted in the vehicle; and, a portable control device connectable with the control connections and incorporating at least one switch for operating the bleed solenoid.

Description

7`1111, FIELD OF THE INVENTION
The invention relates to Automatic Brake Applicator systems (ABA) required on mining equipment in Ontario according to the Occupational Health and Safety Act R.R.O. 1900 Reg. 854, Part V and similar statutes in many other countries and jurisdictions. ABA
systems are in use in various different forms on mobile equipment.
BACKGROUND OF THE INVENTION
An A.B.A. system is a fail-safe emergency brake system usually consisting of hydraulic and electrical components arranged in such a way that they will automatically apply a spring applied ¨ hydraulically released brake (SAHR), in the event of specific system failures. System triggers include failure in main electrical power, automatic transmission pressure failure, accumulator pressure failure, (SAHR brake pressure failure), and engine oil pressure failure. The systems that are integral to maintaining control on the moving vehicle should be checked regularly so that they ensure that an operator can maintain control, and also to ensure that they function as an automatic application in the case of emergency.
As with all safety systems, the A.B.A. system needs to be tested and confirmed that it is functioning correctly. Given the differences in manufacturers and complexity of some vehicles, and the need to ensure that the pressure switch may be set to the right pressures, that it has become more difficult for technicians to understand each unique A.B.A. and independently test each safety feature.
Also, an ABA Relay is used if you lose transmission or accumulator pressure or engine oil pressure. This will lose power to the ABA relay and result in dropping latch on the relay and also lose power to the solenoid and thus applying brakes.
Fail safe SAHR emergency brake systems typically have springs which apply the brakes and utilize stored hydraulic energy, via a pressure accumulator type device, to hold the mechanical friction components of a vehicle brakes in a released position.
Conventionally, the operator would apply the brake through a service brake pedal, or the application of the emergency brake button. This would open an electrical circuit that is maintaining power to a hydraulic solenoid or relay, that is providing a path between the accumulator and the SAHR brake. With the power to the solenoid removed, the brake pedal and the SAHR brake hydraulics maintaining the SAHR
brake in the released position are removed, therefore allowing the springs to cause the mechanical friction components to engage and stop the vehicle. The core system that maintains and controls the SAHR brake is called the "Charge Circuit". The charge circuit maintains the pressure for the whole brake circuit. Release pressure is usually regulated through the service brake pedal.
While the various above features are described in relation to a hydraulic pressure operated system, it will be appreciated that there are other ABA systems incorporating other forms of fluid medium, such as pressurized nitrogen in some cases, and in other cases provide a reduced pressure functioning in the same way as the pressure of the hydraulic or nitrogen system. The accumulator stores more energy for more brake applications. For the purpose of this discussion, the word pressure is deemed to relate to both positive pressure such as in the hydraulic or nitrogen systems.
A.B.A. ¨ Pressure Monitoring and Testing The charge circuit of an emergency brake system is monitored for pressure in three

2 locations with three different pressure sensors, namely;
Impending Brake Pressure Sensor (Impending Brake), indicates when the brakes will be coming on.
Accumulator Pressure Sensor (Accumulator Sensor). This puts the brakes on at a certain pressure.
Secondary Brake Pressure Sensor (Brake Pressure Sensor). This controls the brake light, and turns the brake button light out.
The impending brake sensor and accumulator sensor are on the charge circuit main line and the brake pressure sensor. The brake pressure switch is in the same line as the Accumulator.
The accumulator and impending pressure sensors (typically pre-set switches) monitor the charge circuit, ensuring enough stored hydraulic is available to maintain a fully released SAHR brake. The roles of these sensors are to both indicate to the operator the state of the pressure and to automatically apply the brakes in the event the pressure becomes too low. In the event of a total pressure loss the fail-safe will fully engage and stop the vehicle automatically.
However, if the pressure loss is gradual, the SAHR brake may become semi-engaged, generating enough friction to potentially over-heat and destroy the brake. The brakes are wet disc brakes and they have cooling oil in them. The friction required to generate heat is minimal and may not impair vehicle performance, and therefore will go unnoticed by the operator. During a gradual pressure loss, the impending switch will indicate to the operator a warning that the pressure is becoming low and an automatic brake application is impending. Further loss in pressure will result in the accumulator

3 pressure sensor triggering the A.B.A system. They will not destroy them with a fast brake application.
The third sensor, brake pressure sensor, monitors the pressure at the brake and visually indicates to the operator its position, released or applied. If the brake fails to release when a request by the operator is made, the light will indicate the brake as applied.
A.B.A. ¨ Engine Monitoring and Testing Some manufacturers have chosen to monitor the engine oil with regards to the A.B.A.
system. If the engine dies, a drop in engine oil pressure will activate the A.B.A. and put the brakes on. To test the engine oil pressure switch, you would interrupt power to the ECU to simulate an engine failure.
A.B.A. ¨ Transmission Monitoring and Testing The transmission, specifically automatic/semi-automatic, is an integral component in the control of a vehicle speed as it relates to safety. Transmissions that utilize pressure applied clutches for gear selection can fail-unsafe. Disconnection of drive between the engine and the drive wheels can result in a "free-wheel" or neutral condition that removes the dynamic engine braking effect. In a downhill scenario this can result in unexpected acceleration of the vehicle.
Monitoring the pressure that maintains the transmission clutches and therefore the 70 drive/engine connection, and controlling the A.B.A. system has been an industry standard when utilizing such transmissions with unsafe fail modes. Another way to test the transmission ABA would be to add a relay to interrupt power to the ECU to kill the engine.

4 BRIEF SUMMARY OF THE INVENTION
To test these sensors it is necessary to simulate a gradual loss in pressure.
The A.B.A.
testing device (Pendant) of the invention will energize an installed "test solenoid and fixed orifice" to bleed down the charge circuit in a controlled descent. The technician will note the pressure on installed gauges as the test progresses and the pressure loss simulation occurs. The pressures at which the warnings and final brake application occur should correlate with manufacturer's specifications for that vehicle.
Any difference between the pressures noted during the test and the manufacturers specifications, will indicate a requirement for servicing, and may indicate an actual fault in the system.
To test the A.B.A. the testing Pendant includes a means of simulating an engine failure and transmission failure. The automatic application of the emergency SAHR
brake would be the expected result. All indicators should confirm this.
Testing the transmission ¨ A.B.A. control similarly requires the installation of a solenoid and orifice to gradually "bleed" down transmission pressure to point where the sensor indicates a warning and automatic emergency brake application occurs. The coincident pressure on the system gauge would be recorded and compared to the manufacturer's specifications. Another option would be to use a relay to interrupt power to the ECU, simulating an engine failure.
70 These connections within the vehicle are connected to a connector plug which will be mounted typically in the cab of the vehicle. A technician testing that vehicle can simply carry the pendant into that vehicle, plug it in to the connection plug and carry out the necessary tests.

5 The various features of novelty which characterize the invention are pointed out with more particularity in the claims annexed to and forming a part of this disclosure.
For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be made to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
IN THE DRAWINGS
Figure 1 is a schematic circuit diagram showing both the main pressure circuit controlling the brakes and also showing the additional bleed circuits, and the pendant;
DESCRIPTION OF A SPECIFIC EMBODIMENT
Referring to Figure 1, it will be seen that this illustrates in part braking equipment already installed in most heavy machinery especially in the mining industry.
EXISTING EQUIPMENT.
This will comprise the braking system and hydraulic pressure operating system (SAHR), typical on many pieces of heavy earth moving and mining equipment.
The brake operating cylinders are shown generally as (10a), (10b) .
These cylinders contain typically a piston , and a spring (not shown) on one side of the piston. The opposite side of the piston is operated, typically, by hydraulic pressure fluid. So long as the pressure is maintained it will hold the piston to compress the spring. In this condition, the brakes are disengaged and the vehicle can be operated normally. A drop in the pressure will release of the spring and will cause operation of

6 the brakes in known manner.
Hydraulic pressure is supplied from a pressure source (12), typically a pump supplying an accumulator and charge circuit. The hydraulic fluid. is connected to the brakes via the main pressure charge line (14) . The charge line (14) line is connected to a brake solenoid (16) which is controlled by an emergency button (18) typically mounted in a control panel (20) on the dash board of the vehicle.
In the cab there would also be the usual brake pedal (not shown) for normal operation of the brakes which would also connect with the brake solenoid (16).
Typically these will be electrical controls, the electrical lines being shown as (22) The brake solenoid (16) will typically be connected to a hydraulic tank (24).
These components are already present in the vehicle and are typical of SAHR
systems in general. Obviously, in the case of a gas operated system the receptacle would be an accumulator tank.
When braking is required, for example by the driver, or in an emergency situation, then the hydraulic pressure will drop, the pistons will be moved by the springs, and these will then operate the brakes. This is what is known as the typical spring activated hydraulic release (SAHR) system. Other systems may incorporate compressed gas such as nitrogen (not shown). In each case however, the result is generally the same.
So long as the pressure is maintained, the brakes are disengaged and the vehicle can operate.
70 If the pressure is reduced, some braking action will be applied, and if the pressure is discontinued altogether, the vehicle should be brought to a stop.
The vehicle will also have an engine (25) and transmission (26).
However in any system it is possible for some leaks to develop, which have the effect of

7 slowly bleeding off the pressure. When this happens, the springs in the brake cylinders will begin to take over and will cause slight contact between the brakes and the friction elements of the brakes. This may not be noticeable to the operator since it will not interfere with the operation of the vehicle. However, continued operation of the vehicle with the brakes rubbing, will cause the brakes to burn out. For these reasons, testing of the brake systems is mandatory in many jurisdictions. In the past, testing of the systems has required skilled technicians and hours of down time with each machine.
The present invention is directed to providing a more efficient testing system and a system which can be applied to each vehicle on a regular basis, with a minimum of vehicle down time. This will greatly increase the safety of the operation of a fleet of vehicles and at the same time, will also maximize the useful operating time of each vehicle thereby increasing production.
EQUIPMENT TO BE INSTALLED
Referring first of all to the hydraulic system (SAHR), illustrated in the first embodiment in Figure 1, the system according to the invention, will require the installation of a brake bleed line solenoid (40 ), connecting with the main charge line (14) at junction (42).
The bleed solenoid (40) is connected by a bleed line (44) to a controlled bleed orifice (46), and from the orifice ( 46) to the hydraulic tank ( 24,) which is already part of the vehicle brake system.
The bleed solenoid (40 ) is connected by an electric cable (48 ), to the vehicle control;
panel.
The electrical cable (48) and the bleed solenoid (40) , and the bleed line and the bleed orifice (46) will all require installation on a permanent basis in each vehicle, together

8 with the control panel.
In order to simulate a brake or a transmission failure the charge line is connected to an accumulator pressure switch (50), and to an impending brake warning switch (52) .
These two switches are in turn connected via wires (54) and (56) to the vehicle panel (20). Charge valve (57) is connected to pipe (14).
In order to simulate a transmission failure a transmission pressure switch (60 ) is connected to the transmission via pipe (62). This switch is also connected to the vehicle panel via wire (64).
The transmission is further connected to a transmission solenoid (66) via outlet pipe (68) and return pipe (70). This solenoid is connected via wire (72) to the vehicle panel.
All these components will require permanent installation in the vehicle. The vehicle panel (20) will require a brake accumulator pressure lamp (74), a transmission pressure warning lamp (76), an impending brake warning lamp (78), and an engine power lamp (80). Engine (25) will require an oil pressure switch (82) and an engine test relay (84) both being connected to wire (48). Also, relay (84) could test transmission and interrupt power to the ECU to simulate engine failure.
THE TEST PENDANT
The system is completed by means of the test pendant (90). The test pendant incorporates a plurality of separate switches (92, 94, 96). A cable (98) with a plug (100) permits the pendant to be plugged into the connecting receptacle (102) on the vehicle control panel (20 ) in the cab of the vehicle.

9 Once the pendant is plugged in to the receptacle the tests may proceed. By depressing the appropriate button, the technician may signal a slow leak in the brake system itself.
In this test, he will watch the gauges in the cab of the vehicle and see when the brakes are applied, and note down the pressures at which they are applied. If there is any difference between the manufacturers specified pressures and the pressure noted when the impending light comes on, then it indicates a requirement for service.
The technician can also simulate an engine failure, and note the pressures at which the engine oil pressure switch is working, and the brakes are applied in that case.
A technician can also simulate a transmission failure and note the pressures at which 1() the brakes are applied in that case. ABA Relay (86) will apply the brakes if you lose power from any of the three pressure switches.
The foregoing is a description of a preferred embodiment of the invention which is given here by way of example only. The invention is not to be taken as limited to any of the specific features as described, but comprehends all such variations thereof as come within the scope of the appended claims.

10

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS;

1. A. brake testing apparatus for testing automatic pressure released spring operated brake systems on a vehicle having a main pressure line for releasing the brakes ,and comprising;
a bleed solenoid valve in the pressure line and an orifice operable to gradually "bleed"
down pressure and simulate a brake pressure fault;
a brake warning light responsive to a drop in pressure;
a bleed line connection in the main pressure line connected to the brakes;
electrical connections connecting the bleed solenoid valve to a control cable connection mounted in the vehicle; and, a portable control device connectable with said control connection and incorporating at least one switch for operating the bleed solenoid.

2. A brake testing apparatus as claimed in claim 1 and including a transmission test solenoid operable to simulate a transmission failure , and a switch in the control device operable to activate said transmission solenoid.

3. A brake testing apparatus as claimed in claim 1 and including an engine test Relay operable to simulate an engine oil failure and a switch in the control device, operable to activate said engine test Relay.

4. A brake testing apparatus as claimed in claim 2 wherein any of the solenoids are relays.