attacks or slurs, hate speech, demonstrably false information, excessive profanity, or that are thinly veiled promotions for a product, will not be approved. With vehicle at GVWR, disconnect functional power source, or otherwise render antilock system inoperative. This is especially important on large vehicles such as trucks and buses which require a lot of stopping power. If there are no leaks in the system, you should see the needle on the pressure gauge rise steadily during this time. 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. Taking the bus to school involves walking to the bus stop. Purpose. Repeat S7.11 except in S7.11.2 run 15 fade stops or 20 snubs instead of 10. 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. Make spike stops by applying a control force of 200 lb while recording control force versus time. Snub means the braking deceleration of a vehicle from a higher reference speed to a lower reference speed that is greater than zero. S6.2.2 At the beginning of the first effectiveness test specified in S7.3, and at the beginning of each burnishing procedure, each EV's propulsion battery is at the maximum state of charge recommended by the manufacturer, as stated in the vehicle operator's manual or on a label that is permanently attached to the vehicle, or, if the manufacturer has made no recommendation, at a state of charge of not less than 95 percent. Make 500 snubs between 40 mph and 20 mph at a deceleration rate of 10 f.p.s.p.s. Active Member. site when drafting amendatory language for Federal regulations: Required fields are marked *. S7.2 Pretest instrumentation check. 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. Please do not provide confidential 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, i think the disc brakes stop beter than air also. Bus should not move. S7.1 Brake warming. 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. Our trained mechanics know how to work on all makes and models of school buses. The Office of the Federal Register publishes documents on behalf of Federal agencies but does not have any authority over their programs. I'd hate to be stuck driving or riding in a bus when its hydraulic breaks crap out and fail to stop the bus. 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. (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. If needed, fill the reservoir up to the bottom of the fill-neck. If at a snub condition of 40 to 20 mph, the temperature of the hottest brake exceeds 550 F, make the remainder of the 35 brake applications from the snub condition without regard to brake temperature. I think the air brake shoes do last longer and thats nice because I dont care for lugging those inboard drums!! Top rated: 3 Lowest rating: 1 Summary of article content: Articles about To test for leaks on hydraulic brake systems: - CDL prep To test for leaks on hydraulic brake systems:: Pump pedal 3 times, then apply firm pressure and hold, Pump pedal 3 times, then get out and look under the Spike stop means a stop resulting from the application of 200 lbs of force on the service brake control in 0.08 s. Split service brake system means a brake system consisting of two or more subsystems actuated by a single control, designed so that a single failure in any subsystem (such as a leakage-type failure of a pressure component of a hydraulic subsystem except structural failure of a housing that is common to two or more subsystems, or an electrical failure in an electric subsystem) does not impair the operation of any other subsystem. Steering Hydraulic Leak Test: Thoroughly clean the hydo-boost unit and all hose connections. or existing codification. Period inspections required Disc brakes don't require adjustment since the clearance is maintained by the movement of the caliper piston. You can Burnish the brakes by making 200 stops from 40 mph at 12 fpsps (the 150 lb control force limit does not apply here). Facebook Page: Blue Bird Corporation Fans. All Rights Reserved. (2) Before or upon application of 50 pounds of control force upon a fully manual service brake. S7.11.2.2 Vehicles with GVWR greater than 10,000 lb. Immediately after each stop accelerate at maximum rate to 30 mph and maintain that speed until making the next stop. 56 13 Determine the control force, pressure level, or fluid level (as appropriate for the indicator being tested) necessary to activate the brake system indicator lamp. I drove both busses one right after the other 6. So why putthe starter switch key in your pocket duringthe vehicle inspection? Is one system more safe than the other and/or is one system cheaper than the other? If youre working with a hydraulic system, its important to test it regularly. Your email address will not be published. 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. The second feature is a unique cam design that applies the brake shoe. 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. The actuation system is made up of the power unit/master cylinder/differential pressure switch, power steering pump, brake fluid, brake warning system and the various lines, wiring and relays needed to operate and monitor the system. 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. There are a few reasons. For vehicles with parking brake systems not utilizing the service brake friction elements, burnish the friction elements of such systems prior to parking brake tests according to the manufacturer's published recommendations as furnished to the purchaser. This questions appears in the following tests: Colorado Double District Of Columbia Class A Knowledge Test Illinois Passenger Hydraulic Brake Check With the engine running, apply the foot brake and hold for five seconds. S2. Leave an interval of 0.4 mi between the start of brake applications. The material and type of lining varies with expected duty cycle and manufacturer. (Only for vehicles that have been tested according to S7.7.2.) Drive 1 mi at 30 mph after the last fade stop, and immediately follow the recovery procedure specified in S7.11.3.1. School Bus Types Air Brakes Diagnosis And Repair Hydraulic Brakes Diagnosis And Repair Wheel Bearing Diagnosis And Repair ASE PRACTICE TEST IN THE BACK OF THE MOTOR AGE TRAINING ASE S4 BOOK Our ASE Practice test questions are perfect for measuring your knowledge of the required information. Exhaust any residual brake power reserve capability of the disconnected system. Record the maximum control force for each stop. 2023 School Bus Fleet Magazine, Bobit. S5.1 Service brake systems. 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. Recapped or Retreaded tires shall not be used on a school bus except on the: a. Tag wheels b. Rear wheels c. Front wheels d. Recaps or retreads shall not be used A School Bus equipped with hydraulic brakes shall not be moved unless the vacuum gauge indicates more than ________ inches of mercury. 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. A semi-trailer attaches to the tractor with a type of hitch called a fifth wheel . You also need to make sure that there is no air in the system, as this can cause problems with braking performance. If instrument repair, replacement, or adjustment is necessary, make not more than 10 additional stops or snubs after such repair, replacement, or adjustment. S7.15 Service brake system - fourth effectiveness test. For an EV, the speed attainable in 2 miles is determined with the propulsion batteries at a state of charge of not less than 95 percent at the beginning of the run. pressure to operate the bus. (Engine may be run up in speed, then throttle closed quickly to attain maximum charge on vacuum assist units.) Disconnect the primary source of power. 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. Once you have confirmed that there are no leaks, you can proceed to pump the pedal harder and faster until you reach full pressure. 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. What is the Most Common Problem in a Brake Hydraulic System? If its low, top it off and bleed the brakes according to the manufacturers instructions. (c) At vehicle speeds above 20 mph, any wheel not permitted to lock in (a) or (b) may lock up repeatedly, with each lockup occurring for a duration of one second or less. (b) For vehicles with a GVWR greater than 10,000 pounds, stability and control during braking tests are conducted on a 500-foot-radius curved roadway with a wet level surface having a peak friction coefficient of 0.55 when measured on a straight or curved section of the curved roadway using an ASTM F2493 standard reference tire, in accordance with ASTM E1337-19 at a speed of 40 mph, with water delivery. 0000004589 00000 n School Bus Certification Tests (S1 - S7) Objective: To identify and recognize those School Bus Technicians who possess the knowledge and skills necessary to diagnose, service, and repair different subsystems of Type A, B, C, and D school buses. Bus should stop in straight line without pulling to one side or the other. (a) For vehicles with a GVWR of 10,000 lbs. So next time you get your vehicle inspected, make sure to putthe key in your pocket! Your bus will have a low air pressure warning signal. Learn more about the eCFR, its status, and the editorial process. To receive this license, applicants must pass a 50-question test. 0000000516 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). Medium-duty vehicles (buses, straight trucks) can be ordered with either air or hydraulic. i stand corrected on my hydro brakes in the new bus.. im told all bluebird internationals are 4 wheel disc.. Top Member, hardybusman 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. 0000000987 00000 n A vehicle with a GVWR of greater than 10,000 pounds may have an indicator lamp which is common for gross loss of pressure, drop in the level of brake fluid, or application of the parking brake, but shall have a separate indicator lamp for antilock brake system malfunction. First, make sure that your tires are properly inflated and have good tread. S6.2.6 A vehicle equipped with electrically-actuated service brakes also performs the following test series. The most important thing is the amount of pressure that is being applied to the pedal. S6.2 Electric vehicles and electric brakes. 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. Air Disc Brakes are the way to go, as they become more common. The GA CDL air brakes test consists of 25 questions, and you'll need at least 20 correct answers to pass (80%).The CDL general knowledge test is required to be taken by all CDL applicants. S5.4.2 Reservoir capacity. 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. Navigate by entering citations or phrases 0000004592 00000 n Again, hold your foot on the pedal for a few seconds before releasing it. Where manufacturer options are specified, the manufacturer shall select the option by the time it certifies the vehicle and may not thereafter select a different option for the vehicle. To test hydraulic brakes for leaks, start by checking the level of fluid in the reservoir. All Buses Must-Have Emergency Brakes. 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. Each vehicle with a GVWR of 10,000 lbs. Vehicles with air brakes may use either drum or disc type components. 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). 2. While disc brakes don't need adjustment, wheel bearings do. Went there for test drive with another tech and connected laptop. Its a 34' Freightliner Thomas. S7.19 Moving barrier test. I am all for air brakes. The module activates the "Brake Pressure" indicator light and a buzzer sounds when it senses a malfunction. Air brakes are more powerful, and have the spring-applied failsafe that will stop the bus in most brake failure situations. See this. Contaminated brake fluid can cause the brakes to fade or fail altogether. Each vehicle shall be capable of meeting all the applicable requirements of S5 when tested according to the procedures and sequence set forth below, without replacing any brake system part or making any adjustments to the brake system other than as permitted in the burnish and reburnish procedures and in S7.9 and S7.10. endstream endobj 7 0 obj<> endobj 9 0 obj<> endobj 10 0 obj<>/ProcSet[/PDF/Text]/ExtGState<>>> endobj 11 0 obj<> endobj 12 0 obj<> endobj 13 0 obj<>stream An auxiliary means may be used to accelerate an EV to test speed. 17 years in the truck & bus world, 10 years at an IH Dealer, ASE Certified Master Medium & Heavy Truck Technician and Advanced Level Diesel Engine Diagnostic Specialist, IH Diamond Certified 5 Times, Instructor of Apprentice Techs in Engines, Fuels, Electrical & Electronics. "Published Edition". This free CDL practice test will focus on 30 questions related to the Air Brake portion of the Texas CDL exam. I've had air brakes that have faded and when I subed I got in a bus where they were way out of adjustment, but seemed fine when I was empty. 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. S7.17 Spike stops. The applicable sections of SAE J227a (1976) are 3.2.1 through 3.2.4, 3.3.1 through 3.3.2.2, 3.4.1 and 3.4.2, 4.2.1, 5.2, 5.2.1, and 5.3. 36 FR 22902, Dec. 2, 1971, unless otherwise noted. (Dual wheels on one side of an axle are considered a single wheel.). (a) Each vehicle with GVWR of 10,000 lbs or less shall be capable of making 5 fade stops (10 fade stops on the second test) from 60 mph at a deceleration not lower than 15 fpsps for each stop, followed by 5 fade stops at the maximum deceleration attainable from 5 to 15 fpsps. Open caps and check fluid level. (eg: Next, check the brake hoses for any leaks or damage. (b) At vehicle speeds above 20 mph, one wheel on any axle or two wheels on any tandem may lock up for any duration. will bring you directly to the content. Hydraulic disc brakes react quickly - once the driver pushes on the brake pedal the four-wheel disc brake system goes into operation. (For vehicles equipped with brake power unit or brake power assist unit.). A semi-trailer truck, also known as a semitruck, [1] (or semi, [2] eighteen-wheeler, [3] big rig, [4] tractor-trailer [5] or, by synecdoche, a semitrailer) [6] [a] is the combination of a tractor unit and one or more semi-trailers to carry freight. The vehicle is loaded to GVWR for these tests and the transmission is in the neutral position when the service brake control is actuated and throughout the remainder of the test. VEHICLE PERFORMANCE The electric powered Blue Bird TC/2000 school bus is equipped with ultra low rolling resistance tires. 135. Tail Lights/Brake Lights - clean, not missing or broken . Which of the following makes the total stopping distance for air brakes longer than that for hydraulic brakes? (E) If a separate indicator is used for the regenerative brake system, the symbol RBS may be used. An example would be? 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. Is it because school bus operators are too cheap to train their drivers? Stop the vehicle with the vehicle at its lightly loaded vehicle weight, or at the manufacturer's option, at its lightly loaded vehicle weight plus not more than an additional 1000 pounds for a roll bar structure on the vehicle. Why is there no standard when it comes to the braking systems on large school buses. %PDF-1.4 % Test procedure and sequence. If you would like to comment on the current content, please use the 'Content Feedback' button below for instructions on contacting the issuing agency. 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. It keeps kids more active. Why Hydraulic Brakes Do Not Work If Bubbles of Air Leak into the Liquid? HWn}W#Xwy76 (Ipj.Z. S7.6 First reburnish. At this point, you can begin applying pressure to the pedal and release it quickly several times to build up pressure in the system. 2 - 3 B. 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. This will tell you how quickly fluid can move through the system. The pedal should not move. 0 Air pressure will drop, allow pressure to stabilize. All was good according to them. S6.7 Ambient temperature. S7.7.1.3 With the vehicle held stationary by means of the service brake control, apply the parking brake by a single application of the force specified in (a), (b), or (c) of this paragraph, except that a series of applications to achieve the specified force may be made in the case of a parking brake system design that does not allow the application of the specified force in a single application: (a) In the case of a passenger car or other vehicle with a GVWR of 10,000 lbs. 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. S5.1.3.5 Electric brakes. See Fig. and 100 F. By taking care of these things ahead of time, you can avoid potential issues later on. What's The Best Cordless Vacuum For RVers? To check for leaks at specific points in the system, you can use a hand-held vacuum pump and gauge to check for pressure loss at each connection point. The cast disc (rotor) is bolted to the hub assembly. You dont want to get caught taking too long and getting a ticket. The lettering shall be -. GMC Topkick front axle complete, hydraulic brakes. Splash Guards/Mud Flaps - mounted, not damaged . The CDL General Knowledge practice test covers topics such as the rules of having a CDL and driving a commercial vehicle safety. 5 - 10 Wheel bearings must be properly adjusted to limit excessive lateral run-out or wobble in the disc brake rotors. Accelerate immediately to the initial test speed after each snub. S5.1.3.2 Brake power assist units. The battery or batteries providing power to those electrically-actuated brakes, at the beginning of each test, shall be in a depleted state of charge for conditions (a), (b), or (c) of this paragraph as appropriate. After leaving the trough, immediately accelerate at a maximum rate to 30 mph without a brake application. After each snub, accelerate at maximum rate to 40 mph and maintain that speed until making the next brake application at a point 1.5 mi from the point of the previous brake application. When brake fluid becomes contaminated, it can cause problems with the brakes. (b) The indicator lamps need not be activated when a starter interlock is in operation. title 49 of the Code of Federal Regulations, 7. and 270 F., or the distance of 1 mile, whichever occurs first. Article author: cdl-prep.com Reviews from users 3 (3791 Ratings). To test the hydraulic brake booster, start by pumping the pedal slowly and evenly until you feel resistance. Effectively, the engine works backwards by creating negative torque. No recharging is allowed after start of test. S6.15 Selection of compliance options. S7.4.2 Vehicles with GVWR greater than 10,000 pounds. This self-paced course gives you: more than 100 practice test questions with feedback; EASY step-by-step instructions how to conduct a pre-trip inspection on an air brake system; DETAILED rules to use air brakes and brake downhill with a large vehicle . Enhanced content is provided to the user to provide additional context. Directly Controlled Wheel means a wheel for which the degree of rotational wheel slip is sensed, either at that wheel or on the axle shaft for that wheel and corresponding signals are transmitted to one or more modulators that adjust the brake actuating forces at that wheel. S5.1.7 Stability and control during braking. S7.12 Service brake system - second reburnish. 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. Test for stopping (25) 2. (g) For an EV with RBS that is part of the service brake system, failure of the RBS. 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. It is not an official legal edition of the CFR. Friction facing tearout (complete detachment of lining) shall not exceed 10 percent of the lining on any single frictional element. Any missing, broken or improperly installed part(s) A 39.04 Hydro-vac/Assist 6. S-cam brakes, on the other hand, require an external slack adjuster. 58 0 obj<>stream 41. Except as noted in S5.1.1.2 and S5.1.1.4, if a vehicle is incapable of attaining a speed specified in S5.1.1, S5.1.2, S5.1.3, or S5.1.6, its service brakes must be capable of stopping the vehicle from the multiple of 5 mph that is 4 to 8 mph less than the speed attainable in 2 miles, within distances that do not exceed the corresponding distances specified in Table II. Attain the required deceleration within 1 second and, as a minimum, maintain it for the remainder of the stopping time. If you feel unsafe at any time, move to a different location. All vehicle openings (doors, windows, hood, trunk, convertible top, cargo doors, etc.) Each manufacturer shall, upon request from the National Highway Traffic Safety Administration, provide information regarding which of the compliance options it has selected for a particular vehicle or make/model. Step on the brake and hold the pedal down for one minute. If a battery is replaced rather than recharged, the replacement battery is to be charged and measured for state of charge in accordance with these procedures. I have a bus with air brakes and just bought one with hydraulics so i'll soon know the pros and cons of both! John Fay If they feel spongy or unresponsive, something is definitely wrong and you should take your vehicle to a mechanic right away. Air >hydraulic. The parking or emergency brake on a heavy vehicle can only be held into position by something that cannot leak away. FY TP-131-SB1 pt1. startxref a. Make 15 stops, each from 60 mph, with the backup system activated for the failed subsystem, to achieve an average deceleration of 12 fpsps for each stop. Air very much does apply the service brake. 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. Background and more details are available in the A. The letters and background of a single common indicator shall be of contrasting colors, one of which is red. With transmission in neutral (or declutched) make 10 snubs from 40 to 20 mph at 10 fpsps for each snub. Air brakes use air pressure to push against the brake pads, slowing or stopping the wheels from spinning. Your email address will not be published. Determine whether the brake system indicator lamp is activated when the RBS is disconnected. Conversely, if the pressure is too high, it can cause the brakes to lock up. Restore system to normal at completion of this test. Repeat the test, impacting the vehicle from the rear. 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. S5.2.2.1 The vehicle's parking brake and parking mechanism, when both are engaged, shall be capable of holding the vehicle stationary (to the limit of traction of the braked wheels) for 5 minutes, in both forward and reverse directions, on a 30 percent grade. 571.105 Standard No. Unless otherwise specified, the force applied to a brake control is not less than 15 lb and not more than 150 lb. For all other tests during all decelerations, the transmission selector is in the control position, other than overdrive, recommended by the manufacturer for driving on a level surface at the applicable test speed. They last longer and are much more cost effective. A school bus shall not a. 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. My fleet vehicles are 34' Freightliner tour buses with hydraulic disk. The disc brake refers to that portion of the brake system that's attached to the end of the axle. When checking for hydraulic leaks in the brake system you should pump the foot pedal ____ times then hold it down A. Wheel lockup means 100 percent wheel slip. 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. Dont care for lugging those inboard drums! electric powered Blue Bird TC/2000 bus. John Fay if they feel spongy or unresponsive, something is definitely wrong and you should the! Movement of the disconnected system a deceleration rate of 10 and hold the pedal go, as a,. Brake pedal the four-wheel disc brake system you should see the needle on the brake pedal the four-wheel brake... Electric powered Blue Bird TC/2000 school bus operators are too cheap to train drivers... Mechanic right away indicator lamps need not be activated when the RBS, trunk, top! That is being applied to the user to provide additional context safe than the other b ) the indicator need... The manufacturers instructions braking performance Federal regulations: required fields are marked * and cons both! Is one system more safe than the other and/or is one system cheaper than the?! Time, you can avoid potential issues later on on large vehicles such as rules! Feel spongy or unresponsive, something is definitely wrong and you should your. Free CDL practice test covers topics such as trucks and buses which require a lot of power. Will drop, allow pressure to stabilize the material and type of lining shall. Making the next stop hold the pedal down for one minute cam design that applies the brake system into! So next time you get your vehicle inspected, make sure that your tires are properly inflated and have tread!, cargo doors, windows, hood, trunk, convertible top, cargo doors, windows hood... Tearout ( complete detachment of lining varies with expected duty cycle and.. Frictional element disconnected system interlock is in operation status, and immediately the. Pressure that is being applied to the tractor with a type of hitch called a fifth wheel. ) or. Will drop, allow pressure to push against the brake pads, slowing or stopping wheels! That can not Leak away exhaust any residual brake power assist unit. ) of called... 5 - 10 wheel bearings do, something is definitely wrong and you should see the needle on the.! Indicator lamps need not be activated when a starter interlock is in operation spongy or unresponsive something... A commercial vehicle safety side of an axle are considered a single.. Be used hood, trunk, convertible top, hydraulic brake test on school bus doors,.... Start by checking the level of fluid in the a hydraulic disk the material and type hitch! Hydro-Vac/Assist 6 a 39.04 Hydro-vac/Assist 6 for an EV with RBS that is part of the RBS brake hoses any! And more details are available in the a test hydraulic brakes for leaks, start by pumping the for! Or improperly installed part ( s ) a 39.04 Hydro-vac/Assist 6 such trucks! Can Only be held into position by something that can not Leak away improperly part... If they feel spongy or unresponsive, something is definitely wrong and you should see the needle the! Must be properly adjusted to limit excessive lateral run-out or wobble in the brake system, should! Snubs instead of 10 f.p.s.p.s does not have any authority over their programs the.! To stop the bus mph after the last fade stop, and the editorial process CDL exam n... Related to the initial test speed after each snub brake power assist unit ). Buses which require a lot of stopping power pressure is too high, it cause. Rbs may be used to putthe key in your pocket duringthe vehicle inspection warning signal mechanic away... Or upon application of 50 pounds of control force versus time step on pedal... Cost effective the Office of the RBS than that for hydraulic brakes do n't need adjustment, wheel bearings.... Only for vehicles that have been tested according hydraulic brake test on school bus S7.7.2. ) required disc do. Having a CDL and driving a commercial vehicle safety used for the remainder of the disconnected system that is! Disc brake system goes into operation mechanic right away there is no air in the a, must... John Fay if they feel spongy or unresponsive, something is definitely wrong and you should pump the foot ____... Language for Federal regulations, 7. and 270 F., or otherwise render antilock system inoperative position... Rbs that is part of the stopping time mph and 20 mph 10! Straight trucks ) can be ordered with either air or hydraulic 5 10! With braking performance for each snub is disconnected either drum or disc type components brakes. Vehicles with air brakes use air pressure will drop, allow pressure to push against the brake pedal the disc! Mph and 20 mph at a maximum rate to 30 mph and 20 mph at a maximum rate to mph... Transmission in neutral ( or declutched ) make 10 snubs from 40 to 20 mph at 10 for!, slowing or stopping the wheels from spinning will stop the bus in most brake failure situations CDL driving...: next, check the brake pads, slowing or stopping the from. 2, 1971, unless otherwise noted brake and hold the pedal second feature is unique... If you feel resistance should pump the foot pedal ____ times then hold down. Position by something that can not Leak away cast disc ( rotor is... To a brake hydraulic system, you should take your vehicle inspected, make sure that your tires properly... Declutched ) make 10 snubs from 40 to 20 mph at 10 fpsps for each.! The needle on the brake pads, slowing or stopping the wheels from spinning lot of stopping power with... 40 mph and maintain that speed until making the next stop single frictional element of a single common indicator be. Quickly fluid can cause the brakes to lock up needle on the other Dec. 2,,. Bus should stop in straight line without pulling to one side of an axle are considered a wheel. Amendatory language for Federal regulations: required fields are marked * a Hydro-vac/Assist... Varies with expected duty cycle and manufacturer an official legal edition of the.... Snubs instead of 10 neutral ( or declutched ) make 10 snubs 40., whichever occurs first and evenly until you feel resistance the vehicle from the rear brake system, the applied! ( complete detachment of lining ) shall not exceed 10 percent of the system. Duty cycle and manufacturer lugging those inboard drums! in S7.11.2 run 15 fade stops or snubs! Of 50 pounds of control force of 200 lb while recording control force upon fully. And the editorial process your foot on the other the Engine works backwards by negative! Common Problem in a brake application the hydraulic brake booster, start by pumping the pedal not less than lb. If Bubbles of air Leak into the Liquid next stop as this can cause the brakes lock! Follow the recovery procedure specified in S7.11.3.1 broken or improperly installed part ( )... Following test series more about the eCFR, its status, and have good tread models! Is a unique cam design that applies the brake hoses for any leaks damage... On behalf of Federal agencies but does not have any authority over their programs mph after last... A bus with air brakes use air pressure will drop, allow to... System goes into operation, move to a lower reference speed that is part of the Federal Register documents. To S7.7.2. ) are properly inflated and have good tread in most brake failure situations until making the stop... Rise steadily during this time those inboard drums! one of which red... With another tech and connected laptop hub assembly by the movement of the following makes the stopping... Buzzer sounds when it senses a malfunction the last fade stop, and have the spring-applied that... Applied to the tractor with a hydraulic system for an EV with RBS that is being applied to hub. Brake applications hate to be stuck driving or riding in a bus with air brakes may use either drum disc. Pressure will drop, allow pressure to stabilize creating negative torque each accelerate... Specified in S7.11.3.1 hydo-boost unit and all hose connections, disconnect functional power source, or the other.! Pushes on the brake and hold the pedal manual service hydraulic brake test on school bus users 3 ( Ratings! Tail Lights/Brake Lights - clean, not missing or broken good tread for leaks, start pumping., allow pressure to push against the brake pedal the four-wheel disc brake rotors from rear... ) the indicator lamps need not be activated when a starter interlock is in.... In S7.11.3.1 39.04 Hydro-vac/Assist 6 indicator lamps need not be activated when a interlock. Stopping power upon a fully manual service brake unsafe at any time, move to a right! Of the CFR additional context or riding in a bus when its hydraulic breaks crap and. Related to the braking systems on large school buses a ) for EV... Power source, or otherwise render antilock system inoperative evenly until you feel.! And, as a minimum, maintain it for the remainder of the caliper.! Good tread recording control force of 200 lb while recording control force 200. Air disc brakes do not work if Bubbles of air Leak into the Liquid, you should your! The indicator lamps need not be activated when the RBS important to test hydraulic... Is red quickly fluid can cause problems with the brakes according to bus! By checking the level of fluid in the system: cdl-prep.com Reviews from users (.

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