hydraulic brake test on school bus
attacks or slurs, hate speech, demonstrably false information, excessive profanity, or that are thinly veiled promotions for a product, will not be approved. Facebook Page: Blue Bird Corporation Fans. (b) If a single common indicator is used, the lamp shall display the word Brake. Vehicles are burnished according to the following procedures. As for brakes, I think any bus longer than 6 rows should have air. If equipped with a hydraulic brake reserve system, with the key in the off position, depress the brake pedal and listen for the sound of the reserve system electric motor turning on. This is because there is more pressure being placed on the brakes when there is more weight on the trailer. a. Fluid pressure b. This standard specifies requirements for hydraulic and electric service brake systems, and associated parking brake systems. Preventing these and other school bus brake issues can be as simple as bringing your school buses to us to inspect, maintain, and repair. 0000002509 00000 n School buses with their steel frames and steel bodies are heavy vehicles, even when empty. There should be no more than 3 psi of air loss. (Dual wheels on one side of an axle are considered a single wheel.). %%EOF 1509 (relating to qualifications . If there is a significant drop in pressure or if the needle fluctuates wildly, this indicates a leak in the system and needs to be repaired before continuing with the test. Bookmark +. (including driver and instrumentation). Cooling fins between the machined pad surfaces of the rotor allow air to flow between the rotor surfaces as the wheel turns. For vehicles with a GVWR of 10,000 pounds or less, or any school bus, make six stops from 30 mph. Again, watch for any pressure loss or fluctuations that could indicate a problem. 49 CFR 172.101 All Buses Must-Have Emergency Brakes. Choosing an item from The force applied to the brake pedal by the driver must be sufficient to provide enough braking power so that the vehicle stops smoothly and under control. No recharging is allowed after start of 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. You dont want to get caught taking too long and getting a ticket. Required fields are marked *. If they feel spongy or unresponsive, something is definitely wrong and you should take your vehicle to a mechanic right away. formatting. 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. 0000001720 00000 n (For vehicles equipped with brake power unit or brake power assist unit.). (a) Detachment or fracture of any component of the braking system, such as brake springs and brake shoe or disc pad facing, other than minor cracks that do not impair attachment of the friction facing. Air brakes are the most common type of brake used on school buses. 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. 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. TEST 2: Applied pressure test. Accelerate immediately to the initial test speed after each snub. Same issue happened. 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. 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. Examine the rotor plate thickness. Make five stops from 30 mph at 10 fpsps for each stop. (Engine may be run up in speed, then throttle closed quickly to attain maximum charge on vacuum assist units.) (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. Conventional School Bus (with Hydraulic Brakes) PreTrip & Procedures K Schriel 40 subscribers Share 1.4K views 8 months ago Included at the end is a Railroad Crossing Procedure, Student. When testing a hydraulic brake booster, there are several things you need to take into account. b. Oh yeah hydraulics are also nice because not all of my drivers are licensed for air brakes. At completion of 10 spike stops, make six effectiveness stops from 60 mph. 0000000987 00000 n Backup system means a portion of a service brake system, such as a pump, that automatically supplies energy, in the event of a primary brake power source failure. S1. (This test need not be run if the option in S7.10.2 is selected.) 571.105 Standard No. 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. 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. 0000002025 00000 n 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. If the vehicle does not remain stationary, reapplication of the service brake to hold the vehicle stationary, with reapplication of a force to the parking brake control at the level specified in S7.7.1.3 (a) or (b) as appropriate for the vehicle being tested (without release of the ratcheting or other holding mechanism of the parking brake) may be used twice to attain a stationary position. Average the maximum brake control force required for the three stops. Regulation Y S7.11.1.2 Vehicles with GVWR greater than 10,000 pounds. S5.5 Antilock and variable proportioning brake systems. 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). S5.2.2.3 With the parking mechanism engaged and the parking brake not engaged, the parking mechanism shall not disengage or fracture in a manner permitting vehicle movement, when the vehicle is impacted at each end, on a level surface, by a barrier moving at 212 mph. Automatic adjusters must remain activated at all times. S5.1.3.4 Brake power assist and brake power units. For S7.3, S7.5, S7.8, S7.15, S7.17, S7.11.1.2, S7.11.2.2, S7.11.3.2, and as required for S7.13, the transmission selector control is in neutral for all decelerations. I'm much more comfortable with air brakes. S5.1.3.1 The service brakes on a vehicle equipped with one or more brake power assist units or brake power units, with one such unit inoperative and depleted of all reserve capability, shall be capable of stopping a vehicle from 60 mph within the corresponding distance specified in column IV of table II. The parking or emergency brake on a heavy vehicle can only be held into position by something that cannot leak away. Air pressure will drop, allow pressure to stabilize. S7.4 Service brake system - burnish procedure. 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. (c) (For vehicles with brake power assist or brake power units with backup systems.) 0000000859 00000 n S6.10 Vehicle position and wheel lockup restrictions. Start your practice test now. Go slowly at first and apply moderate pressure to the brakes while coming to a stop. Mounts & Chargers. OEM-specified brake lining and pads are recommended when replacement is necessary. The Electronic Code of Federal Regulations (eCFR) is a continuously updated online version of the CFR. 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. With a moving barrier as described in paragraph 4.3 of SAE Recommended Practice J972 (2000) (incorporated by reference, see 571.5), impact the vehicle from the front at 212 mph. 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). (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. What is the Most Common Problem in a Brake Hydraulic System? Full brake application means a brake application in which the force on the brake pedal reaches 150 pounds within 0.3 seconds from the point of application of force to the brake control. (B) The average control force for the baseline check times 0.60. whichever is lower (but in no case lower than 5 pounds). Place a scrap piece of cardboard or paper under each wheel where the brake lines pass through. All buses using hydraulic brake systems must be equipped with emergency brakes and parking brakes. If its low, that could indicate a leak as well. Turn off engine and DISARM No Child . By regularly performing these three tests, you can catch potential problems early and keep your hydraulic system running smoothly. Drivers I'd hate to be stuck driving or riding in a bus when its hydraulic breaks crap out and fail to stop the bus. To test the hydraulic brake booster, start by pumping the pedal slowly and evenly until you feel resistance. 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. Hydraulic Brake Check Pump the brake pedal three times, then hold it down for five seconds. This will tell you how much force the system is capable of generating. Third, be mindful of the time limit for pre-trips. (c) For a vehicle using an electrically-activated parking brake, apply the parking brake by activating the parking brake control. If the vehicle cannot attain a speed of 40 mph in 1 mph, continue to accelerate until the vehicle reaches 40 mph or until the vehicle has traveled 1.5 miles from the initial point of the previous brake application, whichever occurs first. Enhanced content is provided to the user to provide additional context. The letters and background of a single common indicator shall be of contrasting colors, one of which is red. (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. 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. S6.11 Thermocouples. 17.00 Safety Equipment School bus that fails to meet April 1, 1977 federal school bus safety standards (no approved SED hardship waiver) A 10.02 Registration N/A 4. Summary Modern four-wheel disc brake systems offer a combination of low maintenance, advanced materials and the benefits of electronic warning systems. It is not an official legal edition of the CFR. Don't automatically be fooled by big-rigs use of air brakes. (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). S5.2 Parking Brake System. 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. Where a range of conditions is specified, the vehicle shall be capable of meeting the requirements at all points within the range. Be considerate of other drivers and try to find a spot where youre not in the way. Since most large trucks have air brakes then why not large school buses. (b) 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 depth of 6 inches, each vehicle with a GVWR of more than 10,000 pounds 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 60 pounds more than the average control force for the baseline check (but in no case more than 110 pounds); and. Regenerative braking system or RBS means an electrical energy system that is installed in an EV for recovering or dissipating kinetic energy, and which uses the propulsion motor(s) as a retarder for partial braking of the EV while returning electrical energy to the propulsion batteries or dissipating electrical energy. Background and more details are available in the (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. S5.1.3.2 Brake power assist units. Test as in S7.10.2(a), except make 10 stops instead of 6 and, at the completion of the 10 stops, deplete the failed element of the brake power unit of any residual brake power reserve capability before making the final stop. The pedal should not move. While disc brakes don't need adjustment, wheel bearings do. This blog post will provide detailed information on how to properly conduct a hydraulic brake test on a school bus. If no recommendations are furnished, run the vehicle in an unburnished condition. Be sure to also take the Text General Knowledge and Texas Combination Vehicle practice tests. S7.9.2 Repeat S7.9.1 for each of the other subsystems. Determine whether the brake system indicator lamp is activated when the RBS is disconnected. Establish an initial brake temperature before the first brake application of 130 F. (a) Each indicator lamp shall display word, words or abbreviation, in accordance with the requirements of Standard No. In a hydraulic brake system, the brakes are naturally off. Turn the key to the on position without starting the bus. Automotive braking systems are obviously very important and must be thoroughly tested prior to production. Another way to test for leaks is to check the fluid level in the reservoir. (b) The parking brake system on a multipurpose passenger vehicle, truck, or bus (including a school bus) with a GVWR greater than 4,536 kilograms (10,000 pounds) shall be capable of holding the vehicle stationary for 5 minutes, in both forward and reverse directions, on a 20 percent grade. multiple choice questions that will test your understanding of terminology. 322, 30111, 30115, 30117, and 30166; delegation of authority at 49 CFR 1.95. Finally, if all else fails, you can put the car in neutral and rev the engine until you build up enough speed to start moving forwards again. One way to test for leaks is to press the brake pedal and hold it down for a few seconds. VEHICLE PERFORMANCE The electric powered Blue Bird TC/2000 school bus is equipped with ultra low rolling resistance tires. 56 13 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. 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. A vehicle shall be deemed to comply with the stopping distance requirements of S5.1 if at least one of the stops at each speed and load specified in each of S7.3, S7.5(b), S7.8, S7.9, S7.10, S7.15 and S7.17 (check stops) is made within a stopping distance that does not exceed the corresponding distance specified in Table II. Displaying title 49, up to date as of 2/27/2023. The caliper attaches to and slides within an anchor plate or bracket. S5.1.7 Stability and control during braking. 0000000858 00000 n On vehicles with brake power units, disconnect the primary source of power. Also, if the air system fails, the default is brakes applied, hydraulic brakes, not so much. 0000000778 00000 n The eCFR is displayed with paragraphs split and indented to follow (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. 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. Colors, one of which is red for vehicles with GVWR greater 10,000! 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hydraulic brake test on school bus