force and hold while checking hydro-boost hose fittings for leaks. Place bus in Neutral and set parking brake. S7.7 Parking brake test. 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. 0000004592 00000 n The advantage of this type of system is that if one circuit should fail, the other can still provide some braking power. Any electromotive force that is applied to the propulsion motor(s) automatically remains in effect unless otherwise specified by the test procedure. Its like asking people what is better Chevy or Ford. I'll tell you soon.. For all other tests during all decelerations, the transmission selector is in the control position, other than overdrive, recommended by the manufacturer for driving on a level surface at the applicable test speed. startxref contact the publishing agency. S7.2 Pretest instrumentation check. With the brakes fully released at all times, drive the vehicle for 2 min at a speed of 5 mph in any combination of forward and reverse directions, through a trough having a water depth of 6 in. S5.1.3.5 Electric brakes. Make sure the vehicle is on the level surface and the air pressure is within the normal operating range (cut-out and cut-in). The force required for actuation of a hand-operated brake system shall be measured at the center of the hand grip area or at a distance of 112 inches from the end of the actuation lever, as illustrated in Figure II. Active Member. Your email address will not be published. 3. Drivers have been required to have a commercial driver's license (CDL) in order to drive certain commercial motor vehicles (CMVs) since April 1, 1992. Air very much does apply the service brake. (Engine may be run up in speed, then throttle closed quickly to attain maximum charge on vacuum assist units.) The wind velocity is zero. or existing codification. A split-second delay in brake reaction is present in all air brake systems. Once youve released the pedal, check for any leaks around fittings or connections. (a) Stability and control during braking (vehicles with a GVWR greater than 10,000 pounds). This content is from the eCFR and is authoritative but unofficial. GMC Topkick front axle complete, hydraulic brakes. Conduct a general check of instrumentation by making not more than 10 stops from a speed of not more than 30 mph, or 10 snubs from a speed of not more than 40 to 10 mph, at a deceleration of not more than 10 fpsps. (e) Unlimited wheel lockup is allowed during partial failure stops, and inoperative brake power or power assist stops. Average the maximum brake control force required for the three snubs. B. Nomenclature changes to part 571 appear at 69 FR 18803, Apr. Where I live (BC Canada) need a special addition to my license for air brakes so I went with hydraulic brakes on my bus. GMC C5500 Topkick A/C Compressor Clutch Parts. Make six stops each from 60 mph, to achieve the average deceleration for each stop as specified in table III. Tail Lights/Brake Lights - clean, not missing or broken . Start the engine and run at idle speed. site when drafting amendatory language for Federal regulations: If your vehicle has hydraulic brakes, its important to check them regularly to ensure they are in good working order. The choice of this option must not be construed as adding to the requirements specified in S5.1.2 and S5.1.3.) First, always put your safety first and be aware of your surroundings. YOU must set the parking brake immediately C. your service brakes will still work, using extra leg power 17. Determine whether the brake system indicator lamp is activated when the RBS is disconnected. Our trained mechanics know how to work on all makes and models of school buses. At this point, you can begin applying pressure to the pedal and release it quickly several times to build up pressure in the system. Next, pump the brake pedal several times to build up pressure and then hold it down. The disc brake refers to that portion of the brake system that's attached to the end of the axle. 0000000516 00000 n S5.4.1 Master cylinder reservoirs. 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. attacks or slurs, hate speech, demonstrably false information, excessive profanity, or that are thinly veiled promotions for a product, will not be approved. Purpose. The Electronic Code of Federal Regulations (eCFR) is a continuously updated online version of the CFR. Use a full brake application for the duration of the stop, with the clutch pedal depressed or the transmission selector control in the neutral position, for the duration of each stop. This will help keep your car from rolling as well, but should only be used as a last resort. S7.4.1.2 Brake adjustment - post burnish. S5.2.2.2 The vehicle's parking brake, with the parking mechanism not engaged, shall be capable of holding the vehicle stationary for 5 minutes, in both forward and reverse directions, on a 20 percent grade. (A) If a separate indicator lamp is provided for gross loss of pressure, the words Brake Pressure shall be used for S5.3.1(a). full text search results I always worked on juice (hydraulic) 4 wheel disk brakes for the most part. S7.7.3 Lightly loaded vehicle. I drove both busses one right after the other 6. As a This standard specifies requirements for hydraulic and electric service brake systems, and associated parking brake systems. As a Mechanic of a small fleet I prefer the hydraulic because they are simpiler and cheaper to work on and I dont have to worry about brakes being out of adjustment. Repeat S7.7.1 or S7.7.2 as applicable except with the vehicle at lightly loaded vehicles weight or at manufacturer's option, for a vehicle with GVWR greater than 10,000 pounds, at lightly loaded vehicle weight plus not more than an additional 1,000 pounds for a roll bar structure on the vehicle. Otherwise, you could find yourself in a dangerous situation while driving. FY TP-131-SB1 pt1. Drive 1 mi at 30 mph after the last fade stop, and immediately follow the recovery procedure specified in S7.11.3.1. 5 - 10 An example would be? 0 For an EV that is equipped with both ABS and RBS that is part of the service brake system, the ABS must control the RBS. S5.3.1 An indicator lamp shall be activated when the ignition (start) switch is in the on (run) position and whenever any of the conditions (a) or (b), (c), (d), (e), (f), and (g) occur: (a) A gross loss of pressure (such as caused by rupture of a brake line but not by a structural failure of a housing that is common to two or more subsystems) due to one of the following conditions (chosen at the option of the manufacturer): (1) Before or upon application of a differential pressure of not more than 225 lb/in2 between the active and failed brake system measured at a master cylinder outlet or a slave cylinder outlet. View the most recent official publication: These links go to the official, published CFR, which is updated annually. 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. S6.5 Engine. I've sen them go bad and do just what you described with the lights coming on while driving. Scope and application. S7.9.2 Repeat S7.9.1 for each of the other subsystems. S5.1 Service brake systems. This is an automated process for Second, it prevents them from accidentally starting your engine (which could be dangerous). title 49 of the Code of Federal Regulations, 7. 2023 School Bus Fleet Magazine, Bobit. Each vehicle shall be manufactured with a parking brake system of a friction type with a solely mechanical means to retain engagement, which shall under the conditions of S6, when tested according to the procedures specified in S7, meet the requirements specified in S5.2.1, S5.2.2, or S5.2.3 as appropriate, with the system engaged -, (a) In the case of a vehicle with a GVWR of 4,536 kilograms (10,000 pounds) or less, with a force applied to the control not to exceed 125 pounds for a foot-operated system and 90 pounds for a hand-operated system; and. 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. developer resources. With vehicle at GVWR, disconnect functional power source, or otherwise render antilock system inoperative. This consists of a warning signal that will come on to alert you before the air pressure in the tanks falls below 60 psi. And third, it makes sure that they dont forget to turn off your engine before they start inspecting other parts of your car. Except where an adjustment is specified, after each brake application accelerate to 40 mph and maintain that speed until making the next brake application at a point 1 mile from the initial point of the previous brake application. Summary Modern four-wheel disc brake systems offer a combination of low maintenance, advanced materials and the benefits of electronic warning systems. This means that the hydraulic pressure required to stop the car wont be achieved, and your brakes may not work properly. 0000000858 00000 n (2) Except for a separate indicator lamp for an anti-lock system, a regenerative system, or an indicator for both anti-lock and regenerative system, the letters and background of each separate indicator lamp shall be of contrasting colors, one of which is red. Electrically-actuated service brakes means service brakes that utilize electrical energy to actuate the foundation brakes. Words in addition to those required by Standard No. trailer S5.1.3.4 Brake power assist and brake power units. 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? S6.3 Tire inflation pressure. S5.5.1 Each vehicle with a GVWR greater than 10,000 pounds, except for any vehicle with a speed attainable in 2 miles of not more than 33 mph, shall be equipped with an antilock brake system that directly controls the wheels of at least one front axle and the wheels of at least one rear axle of the vehicle. If there are no leaks in the system, you should see the needle on the pressure gauge rise steadily during this time. If the power assist fail on a hydraulic brake system A. you will NOT be able to stop the bus B. the hierarchy of the document. Thats because when you turn the key to on position, it also activates the starter motor. (This test is not applicable to a vehicle which has a GVWR of not less than 7,716 pounds and not greater than 10,000 pounds and is not a school bus.). Texas General Knowledge CDL Practice Test. By clicking the submit button below, you are agreeing with Bobit Business Medias Privacy Policy and this outlined level of consent. Top Member, ihthomas665spd If its low, that could indicate a leak as well. (e) For a vehicle with electrically-actuated service brakes, failure of the source of electric power to the brakes, or diminution of state of charge of the batteries to less than a level specified by the manufacturer for the purpose of warning a driver of degraded brake performance. An auxiliary means may be used to accelerate an EV to test speed. Repeat S7.5. (b) At vehicle speeds above 20 mph, one wheel on any axle or two wheels on any tandem may lock up for any duration. (b) For vehicles manufactured on and after September 1, 1999 with GVWRs greater than 10,000 lbs, each message about the existence of a malfunction, as described in S5.3.1(c), shall be stored in the antilock brake system after the ignition switch is turned to the off position and the indicator lamp shall be automatically reactivated when the ignition switch is again turned to the on position. 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. If more than one antilock or variable proportioning brake subsystem is provided, disconnect or render one subsystem inoperative and run as above. b. (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. Each vehicle shall have a brake system indicator lamp or lamps, mounted in front of and in clear view of the driver, which meet the requirements of S5.3.1 through S5.3.5. (With parking brake released.) Tandem axle means a group of two or more axles placed in close arrangement one behind the other with the center lines of adjacent axles not more than 72 inches apart. Unless otherwise specified, the force applied to a brake control is not less than 15 lb and not more than 150 lb. S5.1.1.4 In the fourth effectiveness test, a vehicle with a GVWR of 10,000 pounds or less shall be capable of stopping from 30 and 60 mph within the corresponding distances specified in column I of table II. S6.10 Vehicle position and wheel lockup restrictions. (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. 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. S6.12 Initial brake temperature. Class A Air Brake Test Make sure the air pressure is above 100psi - 120psi. S7.9.6 For an EV with RBS that is part of the service brake system, the tests specified in S7.9.1 through S7.9.3 are conducted with the RBS disconnected and all other systems intact. August 1, 1997 If at a snub condition of 40 to 20 mph, the temperature of the hottest brake exceeds 550 F, make the remainder of the 35 brake applications from the snub condition without regard to brake temperature. (B) The average control force for the baseline check times 0.60. whichever is lower (but in no case lower than 5 pounds). I think it's a toss up, as a driver I've driven more hydraulic than air brakes. 571.105 (S5.2) in effect at the time of manufacture. During each burnish procedure, the propulsion batteries may be charged by an external means or replaced by batteries that are charged to the state of charge recommended by the manufacturer or a state of charge of not less than 95 percent. Pre-trips should only take a few minutes, so make sure youre efficient. If the pedal sinks to the floor, there may be a leak in the system. Test speed cut-out and cut-in ), ihthomas665spd if its low, that indicate. Forget to turn off your engine ( which could be dangerous ) means that hydraulic. Brake pedal several times to build up pressure and then hold it down units. remains effect! 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