Attain the required deceleration within 1 second and, as a minimum, maintain it for the remainder of the stopping time. Disc brakes are long lasting and provide safe, even stopping. Hydraulic brakes are a vital part of your vehicle, and its important to keep them in good working order. Repeat S7.5. Subscribe to: Changes in Title 49 :: Subtitle B :: Chapter V :: Part 571 :: Subpart B :: Section 571.105. Leave an interval of 0.4 mi between the start of brake applications. 58 0 obj<>stream Completed. The second thermocouple shall be installed at .080 inch depth within 1 inch circumferentially of the thermocouple installed at .040 inch depth. When youre getting your vehicle inspected, one of the things the inspector will do is test the starter switch. S7.9.1 With the vehicle at lightly loaded vehicle weight or at the manufacturer's option for a vehicle with a 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, alter the service brake system to produce any one rupture or leakage type of failure, other than a structural failure of a housing that is common to two or more subsystems. Why yes, the ORIGinal CHARGER is a Fastback. Air brakes are the most common type of brake used on school buses. (b) For EVs with RBS that is part of the service brake system, the tests in S7.10.1 or S7.10.2 are conducted with the RBS discontinued and all other systems intact. FY TP-116-04. I Vote Air Brakes, I agree about that they lock up, and you can't move, instead of that I can't stop. here. I'm a new noob here, but from what I've read. This license is required for driving any legal combination of vehicles, with a gross combination weight rating of 26,001 pounds or more, provided the GVWR of a trailer exceeds 10,000 pounds. S6.2 Electric vehicles and electric brakes. 0000001241 00000 n 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. With the hood open, on the firewall, just to the left of the motor. Its a 34' Freightliner Thomas. will also bring you to search results. Each school bus with a GVWR greater than 10,000 pounds manufactured on or after March 1, 1999 shall be capable of meeting the requirements of S5.1.1 through S5.1.5, under the conditions prescribed in S6, when tested according to the procedures and in the sequence set forth in S7. For centergrooved shoes or pads, thermocouples are installed within one-eighth of an inch to one-quarter inch of the groove and as close to the center as possible. (when the temperature of components on both ends of an axle are averaged). If the speed attainable in 2 miles is not less than 84 mph, a passenger car, or other vehicle with a GVWR of 10,000 lbs., or less, shall also be capable of stopping from 80 mph within the corresponding distance specified in column I of table II. Hydraulic Brakes have hydraulic hoses, tubing, valves, and con- Includes the hydraulic nections leaking, cracked, portion of vacuum actuated pinched, chafed, flat- and compressed-air-over tened, restricted, broken, Open the window and listen for the air leaks. Disc brake systems use a two-piston sliding caliper at the steer axle and drive axle; older buses may utilize a single-piston caliper. Vehicle Hydraulic Brake System Testing. Service Brake Test a. 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. 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). Unless otherwise specified, the force applied to a brake control is not less than 15 lb and not more than 150 lb. This chapter cited in 22 Pa. Code 51.92 (relating to school bus operators); and 67 Pa. Code 231.8 (relating to additions or modifications to 49 CFR). S7.7.1.6 Check the operation of the parking brake application indicator required by S5.3.1(d). If the hose fittings do not leak go to step 5. The batteries may be charged at a more frequent interval if, during a particular 40-stop increment, the EV is incapable of achieving the initial burnish test speed. S5.1.1.2 In the second effectiveness test, each vehicle with a GVWR of 10,000 pounds or less and each school bus with a GVWR greater than 10,000 pounds shall be capable of stopping from 30 mph and 60 mph, and each vehicle with a GVWR greater than 10,000 pounds (other than a school bus) shall be capable of stopping from 60 mph, within the corresponding distances specified in Column II of Table II. S7.3 Service brake system - first (preburnish) effectiveness test. The pedal should not move. S7.7.3 Lightly loaded vehicle. 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. If You are Doing a Pre-Trip on the Side of a Street, You Should: Which Three Test Would You Perform on a Hydraulic System? In the case of vehicles burnished in accordance with S7.4.2.1(a) of this section, reburnish the vehicle by making 35 snubs from 60 to 20 mph, but if the hottest brake temperature reaches 500 F 50 F, make the remainder of the brake applications from the highest snub condition listed in Table IV that will maintain the hottest brake temperature at 500 F 50 F. (1) If separate indicators are used for one or more of the conditions described in S5.3.1(a) through S5.3.1(g) of this standard, the indicator display shall include the word Brake and appropriate additional labeling, except as provided in (c)(1) (A) through (D) of this paragraph. S5.4.1 Master cylinder reservoirs. S7.9.4 (For vehicles with antilock and/or variable proportioning brake systems.) The brake pedal should not move (depress) during the five seconds. Antilock brake system or ABS means a portion of a service brake system that automatically controls the degree of rotational wheel slip during braking by: (1) Sensing the rate of angular rotation of the wheels; (2) Transmitting signals regarding the rate of wheel angular rotation to one or more controlling devices which interpret those signals and generate responsive controlling output signals; and. Still getting my feet wet and curious as to what people prefer in the long term from a maintenance perspective: hydraulic or air brakes? 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. S7.7.1.1 Condition the parking brake friction elements so that the temperature at the beginning of the test is at any level not more than 150 F. Check the fluid level in the hydraulic brake reservoir. If the speed attainable in 2 miles is not less than 84 mph, a passenger car or other vehicle with a GVWR of 10,000 pounds or less shall also be capable of stopping from 80 mph within the corresponding distances specified in Column II of Table II. (b) The service brakes shall be capable of stopping each vehicle with a GVWR of between 8,000 pounds and 10,000 pounds, other than a school bus, in three effectiveness tests within the distances and from the speeds specified in S5.1.1.1, S5.1.1.2, and S5.1.1.4. Two types of brakes can be found on school buses: air and hydraulic. S7.7 Parking brake test. S7.10.2 Optional Procedures. I'll show you my air brakes if you show me yours. Since most large trucks have air brakes then why not large school buses. (b) If a single common indicator is used, the lamp shall display the word Brake. The first test is a pressure check. No further charging of any propulsion battery occurs during any of the performance tests in the test sequence of this standard. 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. Also they use the excuse that if they train the drivers on air brakes then the drivers will just go to another employeer that pays more i.e. If you have questions for the Agency that issued the current document please contact the agency directly. I drove both busses one right after the other 6. 16. Maximum drive-through speed means the highest possible constant speed at which the vehicle can be driven through 200 feet of a 500-foot radius curve arc without leaving the 12-foot lane. 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. . S7.7.1 Test procedure for requirements of S5.2.1 and S5.2.3. For whatever reason, I feel more in control. This will tell you how quickly fluid can move through the system. Finally, remember to do a thorough check of your vehicle before starting your trip. At this point, you can begin applying pressure to the pedal and release it quickly several times to build up pressure in the system. 6 0 obj<> endobj S5.1.5 Water recovery. Control force readings may be terminated when vehicle speed falls to 5 mph. You can S5.1.3.4 Brake power assist and brake power units. You can learn more about the process Hydraulic Brake Check Pump the brake pedal three times, then hold it down for five seconds. There are plenty of pros and cons about the systems. Again, hold your foot on the pedal for a few seconds before releasing it. xref Restore the service brake system to normal at completion of this test. 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. Cooling fins between the machined pad surfaces of the rotor allow air to flow between the rotor surfaces as the wheel turns. This web site is designed for the current versions of 4. 322, 30111, 30115, 30117, and 30166; delegation of authority at 49 CFR 1.95. If everything looks good there, move on to the calipers. Accelerate immediately to the initial test speed after each snub. Conversely, if the pressure is too high, it can cause the brakes to lock up. Second, use your emergency brake. HW[sF~eWJe! 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. Air very much does apply the service brake. (a) Each vehicle with a GVWR of 10,000 pounds or less shall be capable of making five recovery stops from 30 mph at 10 fpsps for each stop, with a control force application that falls within the following maximum and minimum limits: (1) A maximum for the first four recovery stops of 150 pounds, and for the fifth stop, of 20 pounds more than the average control force for the baseline check; and, (A) The average control force for the baseline check minus 10 pounds, or. Displaying title 49, up to date as of 2/27/2023. 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. Average the maximum brake control force required for the three stops. 0000001720 00000 n Second, make sure youre not blocking traffic when youre doing your pre-trip. The parking brake test surface is clean, dry, smooth, Portland cement concrete. Repeat for each subsystem provided. Make four stops, each from 60 mph by a continuous application of the service brake control. a. Fluid pressure b. 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. Be considerate of other drivers and try to find a spot where youre not in the way. Also, if the air system fails, the default is brakes applied, hydraulic brakes, not so much. The second test is a flow check. 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. I couldnt tell exactly on my rears but thought it almost looked drum.. but I guess in 2000 it was not dont that way anymore so I probably have disc on that hydro bus. 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. This is an automated process for - School Bus Conversion Resources School Bus Conversion Resources > Skoolie Tech > Brake Systems and Air Brakes Hydraulic or Air Brakes? Control force readings may be terminated when vehicle speed falls to 5 mph. Air brakes are more powerful, and have the spring-applied failsafe that will stop the bus in most brake failure situations. (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. 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. Each modulator may also adjust the brake actuating forces at other wheels that are on the same axle or in the same axle set in response to the same signal or signals. I'd hate to be stuck driving or riding in a bus when its hydraulic breaks crap out and fail to stop the bus. 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). Hydraulic brakes work on old principal in which the cylinder is filled with the brake oil to build pressure and when the pedal is pushed, it exerts pressure on the wheel to stop the bus. They are also less expensive on a new bus purchase, and many operations are in the mindset of buying cheap to save money up front. 3. (a) (For vehicles with brake power assist units.) Hello, I am Michael Smith, founder of Autopartslife blog, which teaches automotive techniques, solutions, tips, tool reviews, and more. The Electronic Code of Federal Regulations (eCFR) is a continuously updated online version of the CFR. In determining the fully applied worn condition assume that the lining is worn to: (1) Rivet or bolt heads on riveted or bolted linings, or, (2) within one thirty-seconds of an inch of shoe or pad mounting surface on bonded linings, or. (including driver and instrumentation); (b) For vehicles with a GVWR greater than 10,000 lbs., unloaded vehicle weight plus 500 lbs. Drums or rotors are assumed to be at nominal design drum diameter or rotor thickness. We respect your data and privacy. If the propulsion batteries are depleted during a test sequence such that the vehicle reaches automatic shut-down, will not accelerate, or the low state of charge warning lamp is illuminated, the vehicle is to be accelerated to brake test speed by auxiliary means. Make one stop from 60 mph at an average deceleration of not lower than 7 fpsps for passenger cars (equivalent stopping distance 554 feet), or 6 fpsps for vehicles other than passenger cars (equivalent stopping distance 646 feet) and determine whether the control force exceeds 150 pounds. It's also important to lubricate the rails that the caliper moves upon to ensure consistent operation and also to guard against contamination by rust and dirt. At least two of the 10 stopping distances must be less than or equal to 70 meters. Navigate by entering citations or phrases Air pressure will drop, allow pressure to stabilize. Test for stopping (25) 2. This is especially important on large vehicles such as trucks and buses which require a lot of stopping power. My fleet vehicles are 34' Freightliner tour buses with hydraulic disk. I think it's a toss up, as a driver I've driven more hydraulic than air brakes. Air Disc Brakes are the way to go, as they become more common. pressure to operate the bus. 39.00 Hydraulic Brakes 2. For children who are going to be sitting down in the classroom for most of the day, this helps them to do more physical activities. S7.16.1 Baseline check stop. Bahnhof Stage 1 Clutch Kit Fits GMC C6500 C7500 Topkick 7. The test takes place with the Air Brakes - They just plain Sound Bad-Ass!! This will give you the best traction possible and help keep your car from rolling. Electric vehicle or EV means a motor vehicle that is powered by an electric motor drawing current from rechargeable storage batteries, fuel cells, or other portable sources of electrical current, and which may include a non-electrical source of power designed to charge batteries and components thereof. (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. Hydraulic brakes are components of a vehicles braking system that use fluid pressure to transfer force from the pedal to the wheels. 8 0 obj<>stream S5.1.3.2 Brake power assist units. Texas Air Brakes CDL Practice Test. On vehicles with brake power assist units, the unit is charged to maximum prior to start of test. Pressure component means a brake system component that contains the brake system fluid and controls or senses the fluid pressure. Pre-trips should only take a few minutes, so make sure youre efficient. School Bus Test: Standard regulation on school bus pedestrian safety devices - school bus test. 0000000016 00000 n Brake pads are mounted on each side of the rotor and grip the rotor when hydraulic pressure is applied by the hydraulic piston located in the caliper. S7.4.1.1 Burnish. Average the maximum brake control force required for the three stops. Next, firmly apply pressure to the pedal and hold it down for 30 seconds. (B) The average control force for the baseline check times 0.60. whichever is lower (but in no case lower than 5 pounds). S5.1.5.2 (a) After being driven for 2 minutes at a speed of 5 mph in any combination of forward and reverse directions through a trough having a water dept of 6 inches, each vehicle with a GVWR of 10,000 pounds or less shall be capable of making five recovery stops from 30 mph at ten fpsps for each stop with a control force application that falls within the following maximum and minimum limits: (1) A maximum for the first four recovery stops of 150 pounds, and for the fifth stop, of 45 pounds more than the average control force for the baseline check (but in no case more than 90 pounds, except that the maximum control force for the fifth stop in the case of a vehicle manufactured before September 1, 1976, shall be not more than plus 60 pounds of the average control force for the baseline check (but in no case more than 110 pounds). S6.11 Thermocouples. An example would be? 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 or existing codification. Organization and Purpose When brake fluid becomes contaminated, it can cause problems with the brakes. On vehicles with brake power assist units, render the brake power assist unit inoperative, or one of the brake power assist unit subsystems if two or more subsystems are provided, by disconnecting the relevant power supply. S5.1.2.4 For an EV manufactured with a service brake system that incorporates RBS, the vehicle shall be capable of stopping from 60 mph within the corresponding distance specified in Column IV of Table II with any single failure in the RBS, and with all other systems intact. 2004 GMC Topkick/Kodiak Service Manual. S7.13 Service brake system - second fade and recovery test. Keep up with regular maintenance according to your schedule and enjoy safe travels in your school bus! Determine whether the brake system indicator lamp is activated when the RBS is disconnected. S6.15 Selection of compliance options. Heres how to do a basic check: Start by checking the fluid level in the reservoir. S-cam brakes, on the other hand, require an external slack adjuster. Not just because I've been in the truck world too long either. However, at the option of the manufacturer, the following test procedure and sequence may be conducted: S7.1, S7.2, S7.3, S7.4, S7.5(b), S7.6, S7.7, S7.5(a), S7.8, S7.9, S7.10, and S7.18. S7.8 Service brake system test - lightly loaded vehicle (third effectiveness) test. At this point, stop pumping and hold your foot on the pedal for a few seconds. Hydraulic or Air Brakes? c. Test the bus a second time to make sure the bus stops properly. S6.2.1 The state of charge of the propulsion batteries is determined in accordance with SAE Recommended Practice J227a (1976) (incorporated by reference, see 571.5). One feature is a completely internal adjustment system which is designed to continually keep the brake in proper adjustment. S6.14 Special drive conditions. Peak friction coefficient or PFC means the ratio of the maximum value of braking test wheel longitudinal force to the simultaneous vertical force occurring prior to wheel lockup, as the braking torque is progressively increased. (a) For vehicles with a GVWR of 10,000 lbs. and 100 F. A vehicle with a GVWR of 10,000 pounds or less may have a single common indicator lamp. Indirectly Controlled Wheel means a wheel at which the degree of rotational wheel slip is not sensed, but at which the modulator of an antilock braking system adjusts its brake actuating forces in response to signals from one or more sensed wheels. 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Power assist units. of any propulsion battery occurs during any of the Service brake system lamp... Brake pedal should not move ( depress ) during the five seconds an axle are averaged ) stops! Interval of 0.4 mi between the rotor surfaces as the wheel turns schedule and enjoy safe travels in school! System fluid and controls or senses the fluid pressure to transfer force from the pedal for few! This test GVWR of 10,000 lbs versions of 4 foot on the and! To make sure the bus a second time to make sure the bus stops properly it cause... They become more common components on both ends of an axle are averaged ) breaks crap and... May be terminated when vehicle speed falls to 5 mph whatever reason i... Found on school buses: air and hydraulic display the word brake too.
