The actuation system causes displacement of fluid at a volume and pressure required to cause the foundation brake to apply. 10 Best Printable School Bus Diagram Here are some benefits of using a school bus:1. Pressing enter in the search box S5.4.3 Reservoir labeling - Each vehicle equipped with hydraulic brakes shall have a brake fluid warning statement that reads as follows, in letters at least one-eighth of an inch high: WARNING, Clean filler cap before removing. 0000004589 00000 n S6.2.5 For tests conducted in neutral, the operator of an EV with no neutral position (or other means such as a clutch for disconnecting the drive train from the propulsion motor(s)) does not apply any electromotive force to the propulsion motor(s). When brake fluid becomes contaminated, it can cause problems with the brakes. S5.1.4.1 The control force used for the baseline check stops or snubs shall be not less than 10 pounds, nor more than 60 pounds, except that the control force for a vehicle with a GVWR of 10,000 pounds or more may be between 10 pounds and 90 pounds. Its a 34' Freightliner Thomas. Burnish stops are conducted on any surface. The brakes shall be adjusted three times during the burnish procedure, in accordance with the manufacturer's recommendations, after 125, 250, and 375 snubs. (2) Before or upon application of 50 pounds of control force upon a fully manual service brake. All vehicle openings (doors, windows, hood, trunk, convertible top, cargo doors, etc.) To test the hydraulic brake booster, start by pumping the pedal slowly and evenly until you feel resistance. (a) Each indicator lamp shall display word, words or abbreviation, in accordance with the requirements of Standard No. Pump the brakes until the . Service Brake Test Disengage (push-in) Parking brake and accelerate to 5 mph in a straight line. 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 is especially important on large vehicles such as trucks and buses which require a lot of stopping power. (B) The average control force for the baseline check times 0.60. whichever is lower (but in no case lower than 5 pounds). S6.10.1 For vehicles with a GVWR of 10,000 pounds or less, stops are made with wheel lockup permitted only as follows: (a) At vehicle speeds above 10 mph, there may be controlled wheel lockup on an antilock-equipped axle, and lockup of not more than one wheel per vehicle, uncontrolled by an antilock system. I drove both busses one right after the other 6. Be considerate of other drivers and try to find a spot where youre not in the way. They feel sooooo much more confident in a heavy vehicle. Next, pump the brake pedal several times to build up pressure and then hold it down. Get it fixed before driving. View the most recent official publication: These links go to the official, published CFR, which is updated annually. Air Disc Brakes are the way to go, as they become more common. 5 - 10 S5.6 Brake system integrity. 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. Any missing, broken or improperly installed part(s) A 39.04 Hydro-vac/Assist 6. Top Member, hardybusman (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. Better stopping power. "Published Edition". Your email address will not be published. S7.7.1.4 Following the application of the parking brake in accordance with S7.7.1.3, release all force on the service brake control and commence the measurement of time if the vehicle remains stationary. If everything looks good so far, its time to test-drive your vehicle. Reservoirs shall have completely separate compartments for each subsystem except that in reservoir systems utilizing a portion of the reservoir for a common supply to two or more subsystems, individual partial compartments shall each have a minimum volume of fluid equal to at least the volume displaced by the master cylinder piston servicing the subsystem, during a full stroke of the piston. Why do buses hiss? With vehicle at GVWR, disconnect functional power source, or otherwise render antilock system inoperative. Again, watch for any pressure loss or fluctuations that could indicate a problem. Air very much does apply the service brake. Preventing these and other school bus brake issues can be as simple as bringing your school buses to us to inspect, maintain, and repair. 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 39. If it does, there may be a leak. 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. Since most large trucks have air brakes then why not large school buses. Fig. S7.10 Service brake system - inoperative brake power unit or brake power assist unit test. 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. trailer or less shall be capable of making 10 spike stops from 30 mph, followed by 6 effectiveness (check) stops from 60 mph, at least one of which shall be within a corresponding stopping distance specified in column I of table II. 0000002585 00000 n Hydraulic brakes work by using fluid pressure to go against the brake pads. 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. (For vehicles equipped with brake power unit or brake power assist unit.). The third test is a leaks check. 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. S6.13 Control forces. If your vehicle has hydraulic brakes, its important to check them regularly to ensure they are in good working order. The CamLaster brake has 2 key design differences over traditional S-cam brakes. (when the temperature of components on both ends of an axle are averaged). 1/1.1 As a Choosing an item from Second, make sure youre not blocking traffic when youre doing your pre-trip. S7.3 Service brake system - first (preburnish) effectiveness test. 1 question, Was the hydraulic brakes vacuum boosted or Hydro boosted? 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. 1200-1500 RPM. Two types of brakes can be found on school buses: air and hydraulic. or less, unloaded vehicle weight plus 400 lbs. If needed, fill the reservoir up to the bottom of the fill-neck. (With parking brake released.) Facebook Page: Blue Bird Corporation Fans. Load the vehicle to GVWR, release parking brake, and place the transmission selector control to engage the parking mechanism. S5.1.3.2 Brake power assist units. You can 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. The choice of this option must not be construed as adding to the requirements specified in S5.1.2 and S5.1.3.) YOU must set the parking brake immediately C. your service brakes will still work, using extra leg power 17. . The advantage of this type of system is that if one circuit should fail, the other can still provide some braking power. 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. formatting. Third, be mindful of the time limit for pre-trips. Heres how to test your hydraulic brakes for leaks: 1. 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. (d) The brake system indicator light(s), for compliance with operation in various key positions, lens color, labeling, and location, in accordance with S5.3. After each stop (except the last), accelerate the vehicle immediately at a maximum rate to a speed of 30 mph and begin the next stop. Nomenclature changes to part 571 appear at 69 FR 18803, Apr. Bus should stop in straight line without pulling to one side or the other. Hydraulic or Air Brakes? They all have a big compressor you can tap into for air tools, tire inflaters etc. At completion of 10 spike stops, make six effectiveness stops from 60 mph. (b) In the case of a vehicle with a GVWR greater than 4,536 kilograms (10,000 pounds) not more than 150 pounds for a foot-operated system, and not more than 125 pounds for a hand-operated system. 571.105 Standard No. Choosing an item from Completed. The pedal should not move (lose pressure) during those five seconds. 3 2) Safety procedures usually require the bus driver to use wheel chocks during the air brake check. Bendix Hydro-Max Brake System Inspecting 1. This will give you the best traction possible and help keep your car from rolling. Oklahoma CDL Brake Check Pre-Trip Inspection Parking Brake Check Apply parking brake only and shift into a lower gear. S7.6 First reburnish. Clearance Lights - clean, not missing or broken, ` PT, bPl ,y\BBK- } In Iowa anything over 66 passenger has to be air brakes. But the key to brake safety is still visual inspection and maintaining tolerances that are within manufacturer specifications. Brake power units shall also be charged to maximum accumulator pressure prior to start of test. Regulation Y The vehicle is aligned in the center of the roadway at the start of each brake application. S7.4.1 Vehicles with GVWR of 10,000 lb or less. If it does, theyll know that the starter switch is working properly. Navigate by entering citations or phrases I'd hate to be stuck driving or riding in a bus when its hydraulic breaks crap out and fail to stop the bus. Make spike stops by applying a control force of 200 lb while recording control force versus time. The purpose of this standard is to insure safe braking performance under normal and emergency conditions. 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