With transmission in neutral (or declutched) make 10 snubs from 40 to 20 mph at 10 fpsps for each snub. Scope and application. For vehicles equipped with more than one brake power unit or brake power assist unit, conduct tests of each in turn. Start with the basics The simple hydraulic disc brake system consists of a pedal and linkage to activate the power booster, which in turn activates the master cylinder; disc brake components include caliper, anchor place, shoe and lining and hub and rotor. Reflectors -clean, not missing or broken . S5.1.4 Fade and recovery. The pedal should not move (lose pressure) during those five seconds. You dont want to get caught taking too long and getting a ticket. 1 Depleted. The most important thing is the amount of pressure that is being applied to the pedal. full text search results Make four stops if the vehicle is equipped with a split service brake system, or 10 stops if the vehicle is not so equipped, each from 60 mph, by a continuous application of the service brake control. I'll show you my air brakes if you show me yours. S5.1.3.4 Brake power assist and brake power units. In Iowa anything over 66 passenger has to be air brakes. S7.11.2.1 Vehicles with GVWR of 10,000 pounds or less. Average the maximum brake control force required for the three stops. Restore the service brake system to normal at completion of this test. Make four stops, each from 60 mph. 1/1.1 (E) If a separate indicator is used for the regenerative brake system, the symbol RBS may be used. Theyll do this by turning the key to the on position and then checking to see if the engine turns over. As a With vehicle at GVWR, disconnect functional power source, or otherwise render antilock system inoperative. Splash Guards/Mud Flaps - mounted, not damaged . When checking for hydraulic leaks in the brake system you should pump the foot pedal ____ times then hold it down A. The parking brake test surface is clean, dry, smooth, Portland cement concrete. Each vehicle with electrically-actuated service brakes (brake power unit) shall comply with the requirements of S5.1.3.1 with any single electrical failure in the electrically-actuated service brakes and all other systems intact. Ask Your Own Medium and Heavy Trucks Question Apply the brake control as quickly as possible. bluebirdvision Fill to this level. One feature is a completely internal adjustment system which is designed to continually keep the brake in proper adjustment. to 150 F. I am all for air brakes. (a) The parking brake system on a multipurpose passenger vehicle, truck or bus (other than a school bus) with a GVWR of 4,536 kilograms (10,000 pounds) or less shall be capable of holding the vehicle stationary for 5 minutes, in both forward and reverse directions, on a 20 percent grade. They're standard on our buses in everything except type "A" and we don't run a lot of them. the hierarchy of the document. 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. Any missing, broken or improperly installed part(s) A 39.04 Hydro-vac/Assist 6. xref A separate drafting site Class A Air Brake Test Make sure the air pressure is above 100psi - 120psi. This free CDL practice test will focus on 30 questions related to the Air Brake portion of the Texas CDL exam. If air bubbles get into the hydraulic fluid, they can compress when the brake pedal is applied. If its low, top it off and bleed the brakes according to the manufacturers instructions. Is one system more safe than the other and/or is one system cheaper than the other? Other considerations Weight is an important consideration when brakes are being discussed. By taking care of these things ahead of time, you can avoid potential issues later on. After burnishing, adjust the brakes in accordance with the manufacturer's published recommendations. There's nothing more important on any school bus than the braking system. Third effectiveness (lightly loaded vehicle), 10. Maintain control force until vehicle has stopped. Repeat the test, impacting the vehicle from the rear. S6.13 Control forces. While disc brakes don't need adjustment, wheel bearings do. 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. (b) In the case of a vehicle with a GVWR greater than 4,536 kilograms (10,000 pounds), with a force applied to the control not to exceed 150 pounds for a foot-operated system and 125 pounds for a hand-operated system. S7.4.1 Vehicles with GVWR of 10,000 lb or less. 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. Remove old certificate. 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. 0000004592 00000 n Make 10 successive spike stops from 30 mph with the transmission in neutral, with no reverse stops. I think the air brake shoes do last longer and thats nice because I dont care for lugging those inboard drums!! All vehicle openings (doors, windows, hood, trunk, convertible top, cargo doors, etc.) S7.7.1.2 Drive the vehicle, loaded to GVWR, onto the specified grade with the longitudinal axis of the vehicle in the direction of the slope of the grade, stop the vehicle and hold it stationary by application of the service brake control, and place the transmission in neutral. Burnish stops are conducted on any surface. If it does, there may be a leak or other problem. (This test need not be run if the option in S7.10.2 is selected.) It can also cause corrosion in the brake system. Any electromotive force that is applied to the propulsion motor(s) automatically remains in effect unless otherwise specified by the test procedure. The critical value is determined by measuring the state-of-charge of each propulsion battery at the instant that automatic shut-down occurs and averaging the states-of-charge recorded. If it does, there may be a leak. 1509 (relating to qualifications . Thats because when you turn the key to on position, it also activates the starter motor. S5.1.2.3 For a vehicle manufactured with a service brake system in which the brake signal is transmitted electrically between the brake pedal and some or all of the foundation brakes, regardless of the means of actuation of the foundation brakes, 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 any circuit that electrically transmits the brake signal, and with all other systems intact. 58 0 obj<>stream School buses with their steel frames and steel bodies are heavy vehicles, even when empty. (b) Any visible brake fluid or lubricant on the friction surface of the brake, or leakage at the master cylinder or brake power unit reservoir cover, seal and filler openings. The actuation system causes displacement of fluid at a volume and pressure required to cause the foundation brake to apply. S7.4.1.1 Burnish. Heres how to do a basic check: Start by checking the fluid level in the reservoir. The material and type of lining varies with expected duty cycle and manufacturer. A school bus shall not a. Disc brakes are long lasting and provide safe, even stopping. With transmission in neutral (or declutched) make five snubs from 40 to 20 mph at 10 fpsps for each snub. S6.15 Selection of compliance options. Then (for passenger cars) make four stops from either 95 mph if the speed attainable in 2 mi is 99 to (but not including) 104 mph, or 100 mph if the speed attainable in 2 mi is 104 mph or greater. The lettering shall be -. Two types of brakes can be found on school buses: air and hydraulic. If the power assist fail on a hydraulic brake system A. you will NOT be able to stop the bus B. Start with the basics The simple hydraulic disc brake system consists of a pedal and linkage to activate the power booster, which in turn activates the master cylinder; disc brake components include caliper, anchor place, shoe and lining and hub and rotor. Make six stops from 60 mph with vehicle at lightly vehicle weight, or at the 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. The service brakes of a vehicle equipped with one or more brake power assist units or brake power units with a backup system, with one brake power assist unit or brake power unit inoperative and depleted of all reserve capability and with only the backup system operating in the failed subsystem, shall be capable of stopping the vehicle from 60 mph in 15 consecutive stops at an average deceleration for each stop that is not lower than 12 fpsps (equivalent stopping distance 323 feet). 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. Engine idle speed and ignition timing settings are according to the manufacturer's recommendations. S5.1.3 Inoperative brake power assist unit or brake power unit. S7.7.4 Non-service brake type parking brake systems. Why yes, the ORIGinal CHARGER is a Fastback. To avoid engine stall during tests required to be run in gear a manual transmission may be shifted to neutral (or the clutch disengaged) when the vehicle speed decreases to 20 mph. 101 and/or this section and symbols may be provided for purposes of clarity. Each brake power unit reservoir servicing only the brake system shall have a minimum capacity equivalent to the fluid displacement required to charge the system piston(s) or accumulator(s) to normal operating pressure plus the displacement resulting when all the wheel cylinders or caliper pistons serviced by the reservoir or accumulator(s) move from a new lining fully retracted position (as adjusted initially to the manufacturer's recommended setting) to a fully worn, fully applied position. Wear of the service brake must be compensated for by means of a system of automatic adjustment. S7.9.5 For a vehicle in which the brake signal is transmitted electrically between the brake pedal and some or all of the foundation brakes, regardless of the means of actuation of the foundation brakes, the tests in S7.9.1 through S7.9.3 of this standard are conducted by inducing any single failure in any circuit that electrically transmits the brake signal, and all other systems intact. In extreme cases, a complete loss of braking power can occur. S6.14 Special drive conditions. Vehicles with air brakes may use either drum or disc type components. S5.1.1.3 In the third effectiveness test the vehicle shall be capable of stopping at lightly loaded vehicle weight from 60 mph within the corresponding distance specified in column III of table II. Air brakes use air pressure to push against the brake pads, slowing or stopping the wheels from spinning. 3. 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. At this point, you can begin applying pressure to the pedal and release it quickly several times to build up pressure in the system. S7.16.2 Wet brake recovery stops. Bus should not move. S7.4.2.1 Burnish. 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. startxref (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). School Bus 101 9.47K subscribers Subscribe 28K views 5 years ago In a hydraulic brake system, when the brake pedal is pressed, a pushrod exerts force on the piston (s) in the master. Disc brake systems use a two-piston sliding caliper at the steer axle and drive axle; older buses may utilize a single-piston caliper. (c) For a vehicle which has an auxiliary battery (or batteries) that provides electrical energy to operate the electrically-actuated service brakes, the auxiliary battery(batteries) is (are) at (at an average of) not more than five percent above the actual state of charge at which the brake failure warning signal, required by S5.3.1(e) of this standard, is illuminated. Unless otherwise specified, the force applied to a brake control is not less than 15 lb and not more than 150 lb. This standard specifies requirements for hydraulic and electric service brake systems, and associated parking brake systems. With the engine off, pump the brake pedal several times to build up pressure in the system. Is it true that air brakes cost less to maintain? Explanation To test hydraulic brakes, you should pump the brake pedal three times, then apply firm pressure to the brake pedal and hold for five seconds. 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