At completion of 10 spike stops, make six effectiveness stops from 60 mph. S6.14 Special drive conditions. Initial brake temperature means the average temperature of the service brakes on the hottest axle of the vehicle 0.2 mi before any brake application. S5.2.1. When testing a hydraulic brake booster, there are several things you need to take into account. Advanced Member, BJ Henderson Burnish stops are conducted on any surface. All was good according to them. 56 13 S7.4.1.1 Burnish. Where manufacturer options are specified, the manufacturer shall select the option by the time it certifies the vehicle and may not thereafter select a different option for the vehicle. However, the options provided in S5.3.1(a) shall not apply to a vehicle manufactured without a split service brake system; such a vehicle shall, to meet the requirements of S5.3.1(a), be equipped with a malfunction indicator that activates under the conditions specified in S5.3.1(a)(4). Restore the service brake system to normal at completion of this test. 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). S7.11 Service brake system - first fade and recovery test. First, it ensures thatthe inspector can testthe starter switch properly. Class A Air Brake Test Make sure the air pressure is above 100psi - 120psi. Steering Hydraulic Leak Test: Thoroughly clean the hydo-boost unit and all hose connections. If you have questions or comments regarding a published document please 49 CFR 172.101 If the initial brake temperature for the first stop in a test procedure (other than S7.7 and S7.16) has not been reached, heat the brakes to the initial brake temperature by making not more than 10 snubs from not more than 40 to 10 mph, at a deceleration not greater than 10 fpsps. 3. 2. Disconnect the primary source of power. Validyne model P55 differential pressure . The letters and background of a separate lamp for an anti-lock system, a regenerative system, or a lamp displaying both an anti-lock and a regenerative system shall be of contrasting colors, one of which is yellow. (2) Before or upon application of 50 pounds of control force upon a fully manual service brake. Why Hydraulic Brakes Do Not Work If Bubbles of Air Leak into the Liquid? Each school bus with a GVWR greater than 10,000 pounds manufactured after January 12, 1996 and before March 1, 1999 and which is equipped with an antilock brake system may comply with paragraph S5.1.1.2 and S5.5.1 rather than the first effectiveness test, as specified in S5.1.1.1. S5.1.2.2 In vehicles not manufactured with a split service brake system, in the event of any one rupture or leakage type of failure in any component of the service brake system the vehicle shall, by operation of the service brake control, be capable of stopping 10 times consecutively from 60 mph within the corresponding distance specified in column IV of table II. S6.13 Control forces. Bookmarked content can then be accessed anytime on all of your logged in devices! xref 117. . S6.1.2 For applicable tests specified in S7.5(a), S7.7, S7.8, and S7.9, vehicle weight is lightly loaded vehicle weight, with the added weight, except for the roll bar structure allowed for trucks and buses with a GVWR greater than 10,000 pounds, distributed in the front passenger seat area in passenger cars, multipurpose passenger vehicles, and trucks, and in the area adjacent to the driver's seat in buses. a. Repeat S7.4, except make 35 burnish stops or snubs. Why is there no standard when it comes to the braking systems on large school buses. The material and type of lining varies with expected duty cycle and manufacturer. If it does, there may be a leak. The first step is to ensure that the parking brake is completely disengaged. Not just because I've been in the truck world too long either. S7.11.3.2 Vehicles with GVWR greater than 10,000 lb. (a) The service brakes shall be capable of stopping each vehicle with a GVWR of less than 8,000 pounds, and each school bus with a GVWR between 8,000 pounds and 10,000 pounds in four effectiveness tests within the distances and from the speeds specified in S5.1.1.1, S5.1.1.2, S5.1.1.3, and S5.1.1.4. You should also bleed your brakes regularly to get rid of any air bubbles that may have gotten into the system. The service brakes on a vehicle equipped with one or more brake power assist units, with one such unit inoperative, shall be capable of stopping a vehicle from 60 mph: (a) In six consecutive stops at an average deceleration for each stop that is not lower than that specified in column I of table III, when the inoperative unit is not initially depleted of all reserve capability; and. (b) A drop in the level of brake fluid in any master cylinder reservoir compartment to less than the recommended safe level specified by the manufacturer or to one-fourth of the fluid capacity of that reservoir compartment, whichever is greater. (c) Unlimited wheel lockup is allowed during spike stops (but not spike check stops), partial failure stops, and inoperative brake power or power assist unit stops. S7.7 Parking brake test. 135. Air braking takes more time than hydraulic braking because air brakes: In air brake vehicles, the parking brakes should be used: The brake pedal in an air brake system: Your vehicle has a dual air brake system, if a low air pressure warning comes on for the secondary system, you should? The first test is a pressure check. (For vehicles only having to meet the requirements of S5.1.1, S5.1.2, S5.1.3, and S5.1.7 in section S5.1, the applicable test procedures and sequence are S7.1, S7.2, S7.4, S7.5(b), S7.5(a), S7.8, S7.9, S7.10, and S7.18. 3) Here are the types of tests that must be conducted on a typical air brake system: a) The Governor Cut in/Cut out test is to make sure that the governor is applying or cutting off air pressure to the air reservoir tanks as needed. 1 CFR 1.1 36 FR 22902, Dec. 2, 1971, unless otherwise noted. All buses using hydraulic brake systems must be equipped with emergency brakes and parking brakes. Pressing enter in the search box 0000000859 00000 n Summary Modern four-wheel disc brake systems offer a combination of low maintenance, advanced materials and the benefits of electronic warning systems. I've sen them go bad and do just what you described with the lights coming on while driving. Visually inspect the brake pad lining by checking each visible end and look through the opening of the caliper. S7.11.1.1 Vehicles with GVWR of 10,000 lb or less. S7.3 Service brake system - first (preburnish) effectiveness test. This content is from the eCFR and may include recent changes applied to the CFR. For EVs having a manual control for setting the level of regenerative braking, the manual control, at the beginning of each burnish procedure, is set to provide maximum regenerative braking throughout the burnish. Each passenger car and each multipurpose passenger vehicle, truck, and bus with a GVWR of 10,000 pounds or less must be capable of meeting the requirements of S5.1.1 through S5.1.6 under the conditions prescribed in S6, when tested according to the procedures and in the sequence set forth in S7. (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. Make three stops from 30 mph at 10 fpsps for each stop. Completed. S6.12 Initial brake temperature. Have you ever wondered why trucks and buses make those funny squeaking and hissing sounds? 8 c. 10 d. 15 (a) Each indicator lamp activated due to a condition specified in S5.3.1 shall remain activated as long as the malfunction exists, whenever the ignition (start) switch is in the on (run) position, whether or not the engine is running. S7.7.3 Lightly loaded vehicle. ` PT, bPl ,y\BBK- } Service on the single- or twin-piston caliper is essentially the same. Air Brakes - They just plain Sound Bad-Ass!! FY TP-131-SB1 pt1. Wear of the service brake must be compensated for by means of a system of automatic adjustment. S5.1.6 Spike stops. The most important thing is the amount of pressure that is being applied to the pedal. Step on Service (foot) brake pedal to stop bus. If more than one antilock or variable proportioning brake subsystem is provided, disconnect or render one subsystem inoperative and run as above. Drive 1 mi at 30 mph after the last fade stop, and immediately follow the recovery procedure specified in S7.11.3.1. Each school bus with a GVWR greater than 10,000 pounds must be capable of meeting the requirements of S5.1.1 through S5.1.5, and S5.1.7 under the conditions specified in S6, when tested according to the procedures and in the sequence set forth in S7. (c) A malfunction that affects the generation or transmission of response or control signals in an antilock brake system, or a total functional electrical failure in a variable proportioning brake system. S7.4.2 Vehicles with GVWR greater than 10,000 pounds. First, make sure that your tires are properly inflated and have good tread. S7.7.4 Non-service brake type parking brake systems. Snub means the braking deceleration of a vehicle from a higher reference speed to a lower reference speed that is greater than zero. Since most large trucks have air brakes then why not large school buses. (3) Transmitting those controlling signals to one or more modulators which adjust brake actuating forces in response to those signals. No further charging of any propulsion battery occurs during any of the performance tests in the test sequence of this standard. S5.4.2 Reservoir capacity. Establish an initial brake temperature before the first brake application of 130 F. Tail Lights/Brake Lights - clean, not missing or broken . Park your car on level ground and set the parking brake. to 200 F. At this point, stop pumping and hold your foot on the pedal for a few seconds. Turn the key to the on position, do not start the truck. I am all for air brakes. I drove both busses one right after the other 6. S7.10 Service brake system - inoperative brake power unit or brake power assist unit test. (b) The parking mechanism must be engaged before the ignition key can be removed. Again, hold your foot on the pedal for a few seconds before releasing it. (including driver and instrumentation); (b) For vehicles with a GVWR greater than 10,000 lbs., unloaded vehicle weight plus 500 lbs. (e) Unlimited wheel lockup is allowed during partial failure stops, and inoperative brake power or power assist stops. 0000002585 00000 n GMC Topkick front axle complete, hydraulic brakes. Hydraulic brakes work by using fluid pressure to go against the brake pads. here. Spike stop means a stop resulting from the application of 200 lbs of force on the service brake control in 0.08 s. Split service brake system means a brake system consisting of two or more subsystems actuated by a single control, designed so that a single failure in any subsystem (such as a leakage-type failure of a pressure component of a hydraulic subsystem except structural failure of a housing that is common to two or more subsystems, or an electrical failure in an electric subsystem) does not impair the operation of any other subsystem. Test for stopping (25) 2. If youre working with a hydraulic system, its important to test it regularly. Conversely, if the pressure is too high, it can cause the brakes to lock up. If equipped with a hydraulic brake reserve (back-up) system, with the key off, depress the brake pedal and listen for the sound of the reserve system electric motor. S7.7.1.5 Following observation of the vehicle in a stationary condition for the specified time in one direction, repeat the same test procedure with the vehicle orientation in the opposite direction on the specified grade. Place bus in Neutral and set parking brake. 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. Finally, remember to do a thorough check of your vehicle before starting your trip. 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. This web site is designed for the current versions of i think the disc brakes stop beter than air also. 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