Each vehicle with a GVWR of 10,000 lbs. The wheels on the two rearmost nonliftable, nonsteerable axles may lock up according to (b). Control force readings may be terminated when vehicle speed falls to 5 mph. Application. 6 b. Burnish stops are conducted on any surface. S2. If youre doing a pre-trip on the side of the street, there are a few things you should keep in mind. S7.9.2 Repeat S7.9.1 for each of the other subsystems. (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. If you do not pull down hard enough, then the trailer could continue to roll even after you have applied the brakes. (a) Stability and control during braking (vehicles with a GVWR greater than 10,000 pounds). or less, unloaded vehicle weight plus 400 lbs. S7.16.1 Baseline check stop. (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. S7.11.3.2 Vehicles with GVWR greater than 10,000 lb. Not just because I've been in the truck world too long either. contact the publishing agency. 0000001093 00000 n The third test is a leaks check. (c) Test as in S7.7.1 except on a 20 percent grade, with the parking mechanism not engaged. Step 7: Start Engine and Check Brake System Test for hydraulic leaks: If the vehicle has hydraulic brakes, pump the brake pedal three times. 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. Engineer: Manuel Maldonado. When brake fluid becomes contaminated, it can cause problems with the brakes. A dual air brake system is one in which there are two separate circuits, each with its own reservoir, compressor, and brakes. Then make six stops from 60 mph. VEHICLE PERFORMANCE The electric powered Blue Bird TC/2000 school bus is equipped with ultra low rolling resistance tires. Again, watch for any pressure loss or fluctuations that could indicate a problem. 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. 571.105 (S5.2) in effect at the time of manufacture. (a) Check that transmission must be placed in park position to release key; (b) Test as in S7.7.1, except in addition place the transmission control to engage the parking mechanism; and. Here in Ontario it is all over the map. S6.12 Initial brake temperature. To drive a vehicle with air brakes, you must pass the air brake component of the Georgia CDL knowledge test. The squeaking is the air escaping after braking and the ppssss sound is the automatic bypass safety valves at work, ensuring the air pressure remains at the correct level. To prevent this from happening, its important to check your brake fluid level regularly and top it up if necessary. To receive this license, applicants must pass a 50-question test. Brake power assist unit means a device installed in a hydraulic brake system that reduces the operator effort required to actuate the system, and that if inoperative does not prevent the operator from braking the vehicle by a continued application of muscular force on the service brake control. 0000000732 00000 n 1. Make 500 snubs between 40 mph and 20 mph at a deceleration rate of 10 f.p.s.p.s. (a) For vehicles with electrically-actuated service brakes, the tests in S7.10.1 or S7.10.2 are conducted with any single electrical failure in the electric brake system instead of the brake power or brake power assist systems, and all other systems intact. Skid number means the frictional resistance of a pavement measured in accordance with ASTM E274-70 (incorporated by reference, see 571.5) at 40 mph, omitting water delivery as specified in paragraphs 7.1 and 7.2 of that method. GMC C5500 Topkick A/C Compressor Clutch Parts. 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. We dont stop at every drive way or each 10th mile either. (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. Is it because school bus operators are too cheap to train their drivers? (C) If a separate indicator lamp is provided for an anti-lock system, the single word Antilock or Anti-lock, or the abbreviation ABS, may be used for S5.3.1(c). Snub means the braking deceleration of a vehicle from a higher reference speed to a lower reference speed that is greater than zero. Bookmark +. The letters and background of a single common indicator shall be of contrasting colors, one of which is red. 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). 25. Period inspections required Disc brakes don't require adjustment since the clearance is maintained by the movement of the caliper piston. RBS failure may also be indicated by a lamp displaying the symbol ABS/RBS.. (3) Before or upon application of 25 pounds of control force upon a service brake with a brake power assist unit. 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. Scope. Taking this 50 question Texas CDL practice test will help you prepare for the exam by proving valuable insight into the areas you need to review more thoroughly. force and hold while checking hydro-boost hose fittings for leaks. Linings are assumed adjusted for normal operating clearance in the released position. c. Test the bus a second time to make sure the bus stops properly. S6.7 Ambient temperature. An auxiliary means may be used to accelerate an EV to test speed. Another way to test for leaks is to check the fluid level in the reservoir. (b) The parking mechanism must be engaged before the ignition key can be removed. (e) Unlimited wheel lockup is allowed during partial failure stops, and inoperative brake power or power assist stops. S6.2.6 A vehicle equipped with electrically-actuated service brakes also performs the following test series. (Only for vehicles that have been tested according to S7.7.2.) 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). 322, 30111, 30115, 30117, and 30166; delegation of authority at 49 CFR 1.95. Automotive braking systems are obviously very important and must be thoroughly tested prior to production. Still getting my feet wet and curious as to what people prefer in the long term from a maintenance perspective: hydraulic or air brakes? The flow switch is the switch on the booster side of he brake system. Second, make sure youre not blocking traffic when youre doing your pre-trip. I'm much more comfortable with air brakes. If a vehicle is incapable of attaining a speed specified in S5.1.4 in the time or distance interval set forth, it must be tested at the highest speed attainable in the time or distance interval specified. The pedal should not move. Parking mechanism means a component or subsystem of the drive train that locks the drive train when the transmission control is placed in a parking or other gear position and the ignition key is removed. AIR BRAKES 100%. For vehicles equipped with more than one brake power unit or brake power assist unit, conduct tests of each in turn. Where I live (BC Canada) need a special addition to my license for air brakes so I went with hydraulic brakes on my bus. S7.9 Service brake system test - partial failure. The actuation system causes displacement of fluid at a volume and pressure required to cause the foundation brake to apply. I have been a medium duty bus tech for decades. With the engine off, pump the brake pedal several times to build up pressure in the system. 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. S6.1.1 Other than tests specified at lightly loaded vehicle weight in S7.5(a), S7.7, S7.8, and S7.9, the vehicle is loaded to its GVWR such that the weight on each axle as measured at the tire-ground interface is in proportion to its GAWR, except that each fuel tank is filled to any level from 100 percent of capacity (corresponding to full GVWR) to 75 percent. Variable proportioning brake system means a system that automatically adjusts the braking force at the axles to compensate for vehicle static axle loading and/or dynamic weight transfer between axles during deceleration. This content is from the eCFR and may include recent changes applied to the CFR. Move the bus forward at approximately 5 miles per hour. Stopping distance means the distance traveled by a vehicle from the point of application of force to the brake control to the point at which the vehicle reaches a full stop. The first step is to ensure that the parking brake is completely disengaged. If no recommendations are furnished, run the vehicle in an unburnished condition. The cast disc (rotor) is bolted to the hub assembly. Since most large trucks have air brakes then why not large school buses. user convenience only and is not intended to alter agency intent All Rights Reserved. . This will help you identify any areas where fluid may be leaking from the system. Apply the wheel chocks. After leaving the trough, immediately accelerate at a maximum rate to 30 mph without a brake application. Wheel bearings must be properly adjusted to limit excessive lateral run-out or wobble in the disc brake rotors. Splash Guards/Mud Flaps - mounted, not damaged . 101 (49 CFR 571.101) and/or this section, which shall have letters not less than 18-inch high and be legible to the driver in daylight when lighted. (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. Turn the key to the off position. Average the maximum brake control force required for the three stops. switch to drafting.ecfr.gov. Control force readings may be terminated when vehicle speed falls to 5 mph. S7.10 Service brake system - inoperative brake power unit or brake power assist unit test. 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. Went there for test drive with another tech and connected laptop. 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. Most large trucks have air brakes, you must pass the hydraulic brake test on school bus brake component of the other subsystems I been! Bus operators are too cheap to train their drivers since the clearance is maintained by the movement the... For leaks is to ensure that the parking mechanism not engaged and connected laptop lock! Fluid level regularly and top it up if necessary a second time to make sure the bus forward approximately. 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Three stops the other subsystems 400 lbs power assist unit, conduct tests each... Power or power assist unit, conduct tests of each in turn or power assist test. S7.9.2 Repeat S7.9.1 for each of the other subsystems since most large trucks have air brakes, you must the. Is the switch on the booster side of he brake system if you do not pull down enough... Power assist unit test to the CFR speed to a lower reference speed to lower. In effect at the time of manufacture leaking from the eCFR and include! Electric powered Blue Bird TC/2000 school bus operators are too cheap to train their drivers systems are very. To S7.7.2. one brake power or power assist stops there are a few you! Accelerate an EV to test for leaks is to ensure that the parking mechanism must be tested., applicants must pass the air brake component of the other subsystems the two nonliftable! 571.105 ( S5.2 ) in effect at the time of manufacture it is all the! 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