Purpose. (c) The service brakes shall be capable of stopping each vehicle with a GVWR greater than 10,000 pounds in two effectiveness tests within the distances and from the speeds specified in S5.1.1.2 and S5.1.1.3. I have a bus with air brakes and just bought one with hydraulics so i'll soon know the pros and cons of both! If it does, theyll know that the starter switch is working properly. I always worked on juice (hydraulic) 4 wheel disk brakes for the most part. Electrically-actuated service brakes means service brakes that utilize electrical energy to actuate the foundation brakes. As part of a routine preventative maintenance program, school bus operators should regularly test their hydraulic brakes. By clicking the submit button below, you are agreeing with Bobit Business Medias Privacy Policy and this outlined level of consent. During each burnish procedure, each propulsion battery is restored to the recommended state of charge or a state of charge of not less than 95 percent after each increment of 40 burnish stops until each burnish procedure is complete. S7.4.2 Vehicles with GVWR greater than 10,000 pounds. To pass, applicants must answer 40 questions correctly. If the pedal sinks to the floor, there may be a leak in the system. Determine the control force, pressure level, or fluid level (as appropriate for the indicator being tested) necessary to activate the brake system indicator lamp. S2. I am all for air brakes. No further charging of any propulsion battery occurs during any of the performance tests in the test sequence of this standard. If both tests are successful with no issues found, your hydraulic brakes are functioning properly! 1 CFR 1.1 %%EOF If you do not pull down hard enough, then the trailer could continue to roll even after you have applied the brakes. It's downstream from the power unit/master cylinder and has responsibility for absorbing energy and dissipating heat generated by stopping the bus. S5.6 Brake system integrity. Braking is all about simple friction and dissipating heat, so the best solution is the one that manages heat best - and that's the disc brake system. 3. (b) At vehicle speeds of 10 mph or less, any wheel may lock up for any duration. Regenerative braking system or RBS means an electrical energy system that is installed in an EV for recovering or dissipating kinetic energy, and which uses the propulsion motor(s) as a retarder for partial braking of the EV while returning electrical energy to the propulsion batteries or dissipating electrical energy. Make 5 stops from 60 mph at 15 fpsps followed by 5 stops at the maximum attainable deceleration between 5 and 15 fpsps for each stop. First, always put your safety first and be aware of your surroundings. The secure and easy all-access connection to your content. %PDF-1.4 % Does this happen in the U.S.A. as well? Required fields are marked *. 322, 30111, 30115, 30117, and 30166; delegation of authority at 49 CFR 1.95. Wheel bearings must be properly adjusted to limit excessive lateral run-out or wobble in the disc brake rotors. Each multipurpose passenger vehicle, truck and bus (other than a school bus) with a GVWR greater than 10,000 pounds must be capable of meeting the requirements of S5.1.1, S5.1.2, S5.1.3, and S5.1.7 under the conditions specified in S6, when tested according to the procedures and in the sequence set forth in S7. Disconnect the primary source of power of one subsystem. Where I live (BC Canada) need a special addition to my license for air brakes so I went with hydraulic brakes on my bus. Another way to test for leaks is to check the fluid level in the reservoir. Engine idle speed and ignition timing settings are according to the manufacturer's recommendations. S7.11.2.1 Vehicles with GVWR of 10,000 pounds or less. The rotors on both front and rear brake groups are protected on the inboard side by splash shields bolted to the wheel end anchor plates. Full brake application means a brake application in which the force on the brake pedal reaches 150 pounds within 0.3 seconds from the point of application of force to the brake control. S5.1.3.5 Electric brakes. Air very much does apply the service brake. Stability and control during braking (braking-in-a-curve test), 8. The flow switch is the switch on the booster side of he brake system. Any electromotive force that is applied to the propulsion motor(s) automatically remains in effect unless otherwise specified by the test procedure. I know we've had some problems in northern wisconsin with the snow icing up in the rear drums, but on the other hand with all the buses now being automatic, you have to set the parking brake overnight with hydraulic and the parking brakes have locked up. Apply the brake control as quickly as possible. When brake fluid becomes contaminated, it can cause problems with the brakes. Heres how to do a basic check: Start by checking the fluid level in the reservoir. Air Disc Brakes are the way to go, as they become more common. Why yes, the ORIGinal CHARGER is a Fastback. Attain the required deceleration within 1 second and, as a minimum, maintain it for the remainder of the stopping time. Except as provided in 5.2.2, the parking brake system on a passenger car and on a school bus with a GVWR of 10,000 pounds or less shall be capable of holding the vehicle stationary (to the limit of traction on the braked wheels) for 5 minutes in both a forward and reverse direction on a 30 percent grade. Displaying title 49, up to date as of 2/27/2023. Hydraulic brakes work by using fluid pressure to go against the brake pads. Loss of fluid from one compartment shall not result in a complete loss of brake fluid from another compartment. For Federal Register citations affecting 571.105, see the List of CFR Sections Affected, which appears in the Finding Aids section of the printed volume and at www.govinfo.gov. Maintain control force until vehicle has stopped. Control force readings may be terminated when vehicle speed falls to 5 mph. Compliance of vehicles manufactured in two or more stages may, at the option of the final-stage manufacturer, be demonstrated to comply with this standard by adherence to the instructions of the incomplete manufacturer provided with the vehicle in accordance with 568.4(a)(7)(ii) and 568.5 of title 49 of the Code of Federal Regulations. S7.7 Parking brake test. What is the Most Common Problem in a Brake Hydraulic System? If the vehicle is equipped with an adjustable engine speed governor, it is adjusted according to the manufacturer's recommendation. 25. Snub means the braking deceleration of a vehicle from a higher reference speed to a lower reference speed that is greater than zero. Spring pressure c. Air pressure d. Any of the above 2. The interval from the start of one service brake application to the start of the next shall be either the time necessary to reduce the initial brake temperature to between 230 F. They last longer and are much more cost effective. Reservoirs, whether for master cylinders or other type systems, shall have a total minimum capacity equivalent to the fluid displacement resulting when all the wheel cylinders or caliper pistons serviced by the reservoirs move from a new lining, fully retracted position (as adjusted initially to the manufacturer's recommended setting) to a fully worn, fully applied position, as determined in accordance with S7.18(c) of this standard. This chapter applies to the course of instruction and physical examination for school bus drivers required by 75 Pa.C.S. are closed except as required for instrumentation purposes. 0000004589 00000 n It is in keeping with a concern for safety that the four-wheel disc brake system has become the brake of choice for the school bus industry. At completion of 10 spike stops, make six effectiveness stops from 60 mph. A vehicle equipped with one or more brake power assist units shall meet the requirements of either S5.1.3.1, S5.1.3.2, or S5.1.3.4 (chosen at the option of the manufacturer), and a vehicle equipped with one or more brake power units shall meet the requirements of either S5.1.3.1, S5.1.3.3, or S5.1.3.4 (chosen at the option of the manufacturer). If the speed attainable in 2 miles is not less than 99 mph, a passenger car shall, in addition, be capable of stopping from the applicable speed indicated below, within the corresponding distance specified in column I of table II. To drive a vehicle with air brakes, you must pass the air brake component of the Georgia CDL knowledge test. (E) If a separate indicator is used for the regenerative brake system, the symbol RBS may be used. (b) Each vehicle with a GVWR greater than 10,000 pounds shall be capable of making 10 fade snubs (20 fade snubs on the second test) from 40 mph to 20 mph at 10 fpsps for each snub. 1509 (relating to qualifications . S5.5.2 In the event of any failure (structural or functional) in an antilock or variable proportioning brake system, the vehicle shall be capable of meeting the stopping distance requirements specified in S5.1.2 for service brake system partial failure. Control force readings may be terminated when vehicle speed falls to 5 mph. However, if the brake is pushed with a great force, it can cause leakage in the cylinder which can be very dangerous for the passengers. (d) Restore systems to normal at completion of these tests. Second, use your emergency brake. (e) Unlimited wheel lockup is allowed during partial failure stops, and inoperative brake power or power assist stops. Bus should stop in straight line without pulling to one side or the other. Bus did brake by itself, but Wabco diagnostics laptop showed that neither parking brake nor service brakes were activated, whereas obviously some brake was applied (And it was not engine brake). 1 Depleted. This is especially important on large vehicles such as trucks and buses which require a lot of stopping power. (a) For an EV equipped with RBS, the RBS is considered to be part of the service brake system if it is automatically controlled by an application of the service brake control, if there is no means provided for the driver to disconnect or otherwise deactivate it, and if it is activated in all transmission positions, including neutral. Repeat S7.6. 39.00 Hydraulic Brakes 2. In a hydraulic brake system, the brakes are naturally off. Make spike stops by applying a control force of 200 lb while recording control force versus time. Why do buses hiss? Not just because I've been in the truck world too long either. Establish an initial brake temperature before the first brake application of 130 F. Beats leaf springs all to hell. to 150 F. Again, hold your foot on the pedal for a few seconds before releasing it. xref c. Test the bus a second time to make sure the bus stops properly. If there are no leaks in the system, you should see the needle on the pressure gauge rise steadily during this time. 2023 School Bus Fleet Magazine, Bobit. Hydraulic disc brakes react quickly - once the driver pushes on the brake pedal the four-wheel disc brake system goes into operation. Turn the key to the on position, do not start the truck. The lettering shall be -. Hydraulic Brake Fluids: Standard regulation on hydraulic brake fluids. S6.12 Initial brake temperature. I'll show you my air brakes if you show me yours. If the pressure is too low, it will not engage the brakes properly. Reverse Lights - clean, not missing or broken . Fill to this level. endstream endobj 57 0 obj<> endobj 59 0 obj<> endobj 60 0 obj<>/ProcSet[/PDF/Text]/ExtGState<>>> endobj 61 0 obj<> endobj 62 0 obj<> endobj 63 0 obj<> endobj 64 0 obj<> endobj 65 0 obj<> endobj 66 0 obj<> endobj 67 0 obj<>stream S7.4.1.1 Burnish. A second thermocouple may be installed at the beginning of the test sequence if the lining wear is expected to reach a point causing the first thermocouple to contact the metal rubbing surface of a drum or rotor. After burnishing, adjust the brakes in accordance with the manufacturer's published recommendations. Each truck and bus (other than a school bus) with a GVWR of 4,536 kg (10,000 pounds) or less which is subject to this part and school buses with a GVWR greater than 4,536 kg (10,000 pounds) shall be equipped with a parking brake system as required by FMVSS No. VEHICLE PERFORMANCE The electric powered Blue Bird TC/2000 school bus is equipped with ultra low rolling resistance tires. Drivers Validyne model P55 differential pressure . If there is a significant drop in pressure or if the needle fluctuates wildly, this indicates a leak in the system and needs to be repaired before continuing with the test. You must pass the air brake component of the stopping time leaf springs all to.! Restore systems to normal at completion of 10 mph or less this chapter applies to the on position do... First brake application of 130 F. Beats leaf springs all to hell by the... Brakes if you show me yours 49 CFR 1.95 they become more common vehicle from a reference. 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