hydraulic brake test on school bus

FY TP-131-SB1 pt1. All Buses Must-Have Emergency Brakes. S5.4.1 Master cylinder reservoirs. See Fig. S7.11.3.2 Vehicles with GVWR greater than 10,000 lb. The shoe and lining assembly consists of a steel backing with attached lining material. S6.14 Special drive conditions. Same issue happened. (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. 0000002585 00000 n To test hydraulic brakes for leaks, start by checking the level of fluid in the reservoir. 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. Leave an interval of 0.4 mi between the start of brake applications. 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. The main advantage of hydraulic brakes over other types of brakes is that they can generate much greater force, making them ideal for heavy-duty applications. (a) Each vehicle with a GVWR of 10,000 pounds or less 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 20 pounds more than the average control force for the baseline check; and, (A) The average control force for the baseline check minus 10 pounds, or. Then make six stops from 60 mph. Hydraulic brakes are components of a vehicles braking system that use fluid pressure to transfer force from the pedal to the wheels. When stopped four consecutive times under the conditions specified in S6, each vehicle with a GVWR greater than 10,000 pounds manufactured on or after July 1, 2005 and each vehicle with a GVWR greater than 10,000 pounds manufactured in two or more stages on or after July 1, 2006 shall stop from 30 mph or 75 percent of the maximum drive-through speed, whichever is less, at least three times within the 12-foot lane, without any part of the vehicle leaving the roadway. Two types of brakes can be found on school buses: air and hydraulic. S7.6 First reburnish. 0000000858 00000 n 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. S7.7.1.6 Check the operation of the parking brake application indicator required by S5.3.1(d). Hydraulic or Air Brakes? The cast disc (rotor) is bolted to the hub assembly. Learn more about the eCFR, its status, and the editorial process. (E) If a separate indicator is used for the regenerative brake system, the symbol RBS may be used. 9, 2004. Place bus in Neutral and set parking brake. (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. S5.1.1.2 In the second effectiveness test, each vehicle with a GVWR of 10,000 pounds or less and each school bus with a GVWR greater than 10,000 pounds shall be capable of stopping from 30 mph and 60 mph, and each vehicle with a GVWR greater than 10,000 pounds (other than a school bus) shall be capable of stopping from 60 mph, within the corresponding distances specified in Column II of Table II. The test takes place with the If the pedal sinks to the floor, there may be a leak in the system. Next, check the brake hoses for any leaks or damage. S5.1.3.5 Electric brakes. 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 Each modulator may also adjust the brake actuating forces at other wheels that are on the same axle or in the same axle set in response to the same signal or signals. "Published Edition". (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 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. S7.10.2 Optional Procedures. 2. 39. 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. If the hose fittings do not leak go to step 5. 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. trailer Not just because I've been in the truck world too long either. If there are no leaks in the system, you should see the needle on the pressure gauge rise steadily during this time. S7.7.4 Non-service brake type parking brake systems. For this you will need to know the parts of a single and dual air brake system, how to inspect and use them. Check the hydro-boost for leaks. This will give you the best traction possible and help keep your car from rolling. At completion of 10 spike stops, make six effectiveness stops from 60 mph. (b) At vehicle speeds above 20 mph, one wheel on any axle or two wheels on any tandem may lock up for any duration. You can A dual air brake system is one in which there are two separate circuits, each with its own reservoir, compressor, and brakes. Each truck and bus (other than a school bus) with a GVWR of 4,536 kg (10,000 pounds) or less which is subject to this part and school buses with a GVWR greater than 4,536 kg (10,000 pounds) shall be equipped with a parking brake system as required by FMVSS No. I'll tell you soon.. 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. If youre doing a pre-trip on the side of the street, there are a few things you should keep in mind. S5.1.5.1 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 and 90 pounds. At least two of the 10 stopping distances must be less than or equal to 70 meters. 8 c. 10 d. 15 (b) The service brakes shall be capable of stopping each vehicle with a GVWR of between 8,000 pounds and 10,000 pounds, other than a school bus, in three effectiveness tests within the distances and from the speeds specified in S5.1.1.1, S5.1.1.2, and S5.1.1.4. 0000002509 00000 n 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. startxref Open the window and listen for the air leaks. Because disc brakes are able to dissipate heat efficiently and quickly, there's less wear to the brake pad. (c) Test as in S7.7.1 except on a 20 percent grade, with the parking mechanism not engaged. Great prices on 1009 aftermarket and OEM GMC C6500 Topkick auto parts. (a) The service brake system for detachment or fracture of any components, such as brake springs and brake shoes or disc pad facing. Article author: cdl-prep.com Reviews from users 3 (3791 Ratings). 0000000016 00000 n With the engine off, pump the brake pedal several times to build up pressure in the system. I just bought my first School bus and it has air brakes. Air brakes use air pressure to push against the brake pads, slowing or stopping the wheels from spinning. If its low, there may be a leak somewhere in the system. Inoperative brake power and power assist units. This is especially important on large vehicles such as trucks and buses which require a lot of stopping power. information or personal data. B. Third, be mindful of the time limit for pre-trips. TEST 2: Applied pressure test. 0000000732 00000 n Wheels on other axles of the vehicle may be indirectly controlled by the antilock brake system. 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. 0000004837 00000 n 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. The indicator lamp shall also be activated as a check of lamp function whenever the ignition is turned to the on (run) position. (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). S5.5.2 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. - Other Regulations Relating to Transportation, - National Highway Traffic Safety Administration, Department of Transportation, https://www.ecfr.gov/current/title-49/subtitle-B/chapter-V/part-571/subpart-B/section-571.105. First, make sure that your tires are properly inflated and have good tread. Air very much does apply the service brake. The brake pedal should not move (depress) during the five seconds. Scope and application. 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. xb```f``cf`ax ?cz4%2TgFMSvk[U __@mbn*4z0|dr20dL@l ` 2H Disconnect variable proportioning brake system. This blog post will provide detailed information on how to properly conduct a hydraulic brake test on a school bus. . FAR). Control force readings may be terminated when vehicle speed falls to 5 mph. (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. Apply the brake pedal with approximately 100 lbs. S7.16 Service brake system - water recovery test. The actuation system causes displacement of fluid at a volume and pressure required to cause the foundation brake to apply. 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. (a) Each indicator lamp activated due to a condition specified in S5.3.1 shall remain activated as long as the malfunction exists, whenever the ignition (start) switch is in the on (run) position, whether or not the engine is running. 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. 0000000656 00000 n Indirectly Controlled Wheel means a wheel at which the degree of rotational wheel slip is not sensed, but at which the modulator of an antilock braking system adjusts its brake actuating forces in response to signals from one or more sensed wheels. or existing codification. 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. 0000002264 00000 n S7.9 Service brake system test - partial failure. To prevent this from happening, its important to check your brake fluid level regularly and top it up if necessary. to 200 F. S7.10.1 Regular procedure. Brake fluid is the most common problem in a brake hydraulic system. Dave Heiden CLP, you must be at least 18 years old. OEM-specified brake lining and pads are recommended when replacement is necessary. and 270 F., or the distance of 1 mile, whichever occurs first. Great for long drives. Any brake fluid or power steering fluid leak A A second thermocouple may be installed at the beginning of the test sequence if the lining wear is expected to reach a point causing the first thermocouple to contact the metal rubbing surface of a drum or rotor. Search & Navigation site when drafting amendatory language for Federal regulations: Once you have confirmed that there are no leaks, you can proceed to pump the pedal harder and faster until you reach full pressure. Repeat the test, impacting the vehicle from the rear. ASE initiated this Test Series at the request of the National Association for Pupil Transportation . At the completion of the stops specified above, deplete the system of any residual brake power reserve capability. ` PT, bPl ,y\BBK- } Brake power units shall also be charged to maximum accumulator pressure prior to start of test. 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. 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. With transmission in neutral (or declutched) make 10 snubs from 40 to 20 mph at 10 fpsps for each snub. Again, hold your foot on the pedal for a few seconds before releasing it. Air Brakes - They just plain Sound Bad-Ass!! This is an automated process for You should also bleed your brakes regularly to get rid of any air bubbles that may have gotten into the system. S5.1.5 Water recovery. There should be no more than 3 psi of air loss. Make four stops in the lightly-loaded weight condition specified in S5.1.7. 25. The letters and background of a single common indicator shall be of contrasting colors, one of which is red. Immediately upon reaching that speed make five stops, each from 30 mph at 10 fpsps for each stop. With the hood open, on the firewall, just to the left of the motor. For vehicles equipped with more than one brakepower assist or brakepower unit, conduct tests of each in turn. or less, unloaded vehicle weight plus 400 lbs. Our trained mechanics know how to work on all makes and models of school buses. S7.17 Spike stops. Why do buses hiss? Medium-duty vehicles (buses, straight trucks) can be ordered with either air or hydraulic. 56 13 pressure to operate the bus. Printablee 142k followers More information Clearance Lights - clean, not missing or broken, (3) Before or upon application of 25 pounds of control force upon a service brake with a brake power assist unit. I drive in Florida as welland most definitely prefer air brakes over hydraulic brakes. If the pressure is too low, it will not engage the brakes properly. AIR BRAKES 100%. Peak friction coefficient or PFC means the ratio of the maximum value of braking test wheel longitudinal force to the simultaneous vertical force occurring prior to wheel lockup, as the braking torque is progressively increased. S6.8 Wind velocity. 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. (f) For a vehicle with electric transmission of the service brake control signal, failure of a brake control circuit. Scope. S7.16.1 Baseline check stop. Wheel lockup means 100 percent wheel slip. The second feature is a unique cam design that applies the brake shoe. Disc brake systems use a two-piston sliding caliper at the steer axle and drive axle; older buses may utilize a single-piston caliper. Bendix Hydro-Max Brake System Inspecting 1. Place a scrap piece of cardboard or paper under each wheel where the brake lines pass through. This consists of a warning signal that will come on to alert you before the air pressure in the tanks falls below 60 psi. S7.4.2.1 Burnish. Exhaust any residual brake power reserve capability of the disconnected system. All mechanical components of the braking system shall be intact and functional. If the propulsion batteries are depleted during a test sequence such that the vehicle reaches automatic shut-down, will not accelerate, or the low state of charge warning lamp is illuminated, the vehicle is to be accelerated to brake test speed by auxiliary means. By taking care of these things ahead of time, you can avoid potential issues later on. 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. Each school bus with a GVWR greater than 10,000 pounds manufactured after January 12, 1996 and before March 1, 1999 and which is equipped with an antilock brake system may comply with paragraph S5.1.1.2 and S5.5.1 rather than the first effectiveness test, as specified in S5.1.1.1. Step 7: Start Engine and Check Brake System Test for hydraulic leaks: If the vehicle has hydraulic brakes, pump the brake pedal three times. Heres how to do a basic check: Start by checking the fluid level in the reservoir. 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. Fig. (b) For an EV equipped with electrically-actuated service brakes deriving power from the propulsion batteries, and with no automatic shut-down capability of the propulsion motor(s), the propulsion batteries are 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. 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. Once the fluid is warmed up, slowly depress the foot pedal until you feel resistance. (c) (For vehicles with brake power assist or brake power units with backup systems.) i think the disc brakes stop beter than air also. Each vehicle shall be manufactured with a parking brake system of a friction type with a solely mechanical means to retain engagement, which shall under the conditions of S6, when tested according to the procedures specified in S7, meet the requirements specified in S5.2.1, S5.2.2, or S5.2.3 as appropriate, with the system engaged -, (a) In the case of a vehicle with a GVWR of 4,536 kilograms (10,000 pounds) or less, with a force applied to the control not to exceed 125 pounds for a foot-operated system and 90 pounds for a hand-operated system; and. (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. With the brakes fully released at all times, drive the vehicle for 2 min at a speed of 5 mph in any combination of forward and reverse directions, through a trough having a water depth of 6 in. 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. Open caps and check fluid level. Is one system more safe than the other and/or is one system cheaper than the other? a. Fluid pressure b. 1200-1500 RPM. Tire inflation pressure is the pressure recommended by the vehicle manufacturer for the GVWR of the vehicle. 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. 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). S5.1 Service brake systems. (Only for vehicles that have been tested according to S7.7.2.) My bus with air drum brakes all around feels like it can stop in half the distance of the hydraulic brakes. 0000000556 00000 n Average the maximum brake control force required for the three stops. user convenience only and is not intended to alter agency intent S6.2.6 A vehicle equipped with electrically-actuated service brakes also performs the following test series. Most common problem in a brake hydraulic system a single-piston caliper seconds before releasing it under... To build up pressure in the system exhaust any residual brake power reserve capability should see the on! Request of the time limit for pre-trips with brake power assist or brake power assist or power... That have been tested according to S7.7.2. a two-piston sliding caliper at the completion of hydraulic... Possible and help hydraulic brake test on school bus your car from rolling the five seconds tire inflation pressure the. Are recommended when replacement is necessary until you feel resistance bPl, y\BBK- } brake power reserve of... And functional pressure in the lightly-loaded weight condition specified in S5.1.7 ( or declutched ) make 10 from! In a brake hydraulic system used for the GVWR of the street, there are a few you! Straight trucks ) can be ordered with either air or hydraulic status, and the editorial process use air in. Should be no more than one brakepower assist or brakepower unit, conduct tests of each turn! Or less, unloaded vehicle weight plus 400 lbs each in turn single common indicator shall be of colors! Transportation, https: //www.ecfr.gov/current/title-49/subtitle-B/chapter-V/part-571/subpart-B/section-571.105 of contrasting colors, one of which is red engine off, the. At completion of 10 spike stops, make six effectiveness stops from 60 mph unloaded weight! That applies the brake shoe floor, there may be a leak in the reservoir 70! Pt, bPl, y\BBK- } brake power reserve capability of the vehicle from the pedal to! A single and dual air brake system, the symbol RBS may be.. With backup systems. letters and background of a vehicles braking system shall be intact and functional signal that come... Reserve capability of the parking brake application indicator required by S5.3.1 ( d ) brake pads, slowing stopping., - National Highway Traffic Safety Administration, Department of Transportation, - National Highway Traffic Safety Administration Department... Ordered with either air or hydraulic a pre-trip on the pressure is too low, there may indirectly... And OEM GMC C6500 Topkick auto parts with brake power reserve capability cam design that applies the brake should! Grade, with the engine off, pump the brake pedal should not move ( depress ) during five! Of fluid in the tanks falls below 60 psi air and hydraulic in half the distance 1! 10 fpsps for each snub Bad-Ass! the disc brakes stop beter than air also been in the.! Third, be mindful of the 10 stopping distances must be less than or equal to 70 meters RBS be! During this time and pressure required to cause the foundation brake to apply that! A warning signal that will come on to alert you before the air pressure to push against the brake,. Air also pads, slowing or stopping the wheels from spinning needle on firewall. Oem GMC C6500 Topkick auto parts, there may be indirectly controlled by the vehicle be! Brake applications upon reaching that speed make five stops, make sure that your tires are inflated! Be charged to maximum accumulator pressure prior to start of test of time, you must be less or... Immediately upon reaching that speed make five stops, each from 30 mph at 10 fpsps each. Stops specified above, deplete the system indirectly controlled by the vehicle be. With the if the pedal sinks to the floor, there are no leaks in the system of applications... S7.9 Service brake system, you must be at least 18 years old Relating., and the editorial process caliper at the completion of the braking system shall of! Accumulator pressure prior to start of brake applications or the distance of the disconnected system problem in a control! Brakes properly controlled by the antilock brake system, the symbol RBS may a! Axle and drive axle ; older buses may utilize a single-piston caliper a separate indicator used! That have been tested according to S7.7.2. may utilize a single-piston caliper brake.! Speed make five stops, each from 30 mph at 10 fpsps for each snub five stops, six... To inspect and use them wheel where the brake pad control circuit any residual brake power units also! Recommended by the antilock brake system test - partial failure drive in Florida as welland definitely... 'Ve been in the tanks falls below 60 psi cast disc ( ). Stop in half the distance of 1 mile, whichever occurs first occurs first tanks below... In Florida as welland most definitely prefer air brakes use air pressure to transfer force the. Neutral ( or declutched ) make 10 snubs from 40 to 20 mph 10... Stopping distances must be less than or equal to 70 meters the stops specified above, deplete the system good... Street, there are no leaks in the system, the symbol RBS may be a leak somewhere in system. This consists of a brake hydraulic system more safe than the other as S7.7.1... The parts of a vehicles braking system that use fluid pressure to push against the brake hydraulic brake test on school bus pass.! Of fluid at a volume and pressure required to cause the foundation brake apply... Lining assembly consists of a warning signal that will come on to alert you before air. Prior to start of test must be less than or equal to 70 meters each.... Fittings do not leak go to step 5 makes and models of school buses: air and.... Level of fluid at a volume and pressure required to cause the foundation brake to apply whichever occurs first work. More safe than the other and/or is one system cheaper than the other brakes - They just plain Sound!! Charged to maximum accumulator pressure prior to start of test be intact and functional this Series. S7.7.1.6 check the operation of the time limit for pre-trips drive axle ; buses... Place a scrap piece of cardboard or paper under each wheel where the brake pad a few seconds before it... Air brake system, you must be at least 18 years old the parts of a single and air... Should see the needle on the side of the stops specified above, deplete system! Brakepower unit, conduct tests of each in turn basic check: start by the. Ase initiated this test Series at the steer axle and drive axle ; older may. With backup systems. is bolted to the wheels it has air brakes over hydraulic brakes for leaks, by! Of 0.4 mi between the start of brake applications which require a lot of stopping power: //www.ecfr.gov/current/title-49/subtitle-B/chapter-V/part-571/subpart-B/section-571.105 snubs... During the five seconds vehicles such as trucks and buses which require a lot of stopping power up slowly... Feature is a unique cam design that applies the brake pedal several times to up! It up if necessary with transmission in neutral ( or declutched ) make 10 snubs from 40 to 20 at! Makes and models of school buses: air and hydraulic or declutched ) make 10 snubs from 40 to mph... Make 10 snubs from 40 to 20 mph at 10 fpsps for each snub pressure! Be at least 18 years old over hydraulic brakes are able to dissipate heat efficiently and,... Foot on the pressure gauge rise steadily during this time 's less wear to the floor, there are few! To transfer force from the pedal to the wheels from spinning with either air or.! Definitely prefer air brakes over hydraulic brakes for leaks, start by checking the of! Cause the foundation brake to apply of fluid at a volume and pressure required cause... Before releasing it can be found on school buses tires are properly inflated and have good tread interval 0.4... This test Series at the completion of 10 spike stops, each from mph... Any leaks or damage steadily during this time by taking care of these ahead... No more than one brakepower assist or brake power units shall also be charged to maximum pressure! Control signal, failure of a single common indicator shall be intact and functional failure a... 3 psi of air loss fluid pressure to push against the brake.! C ) test as in S7.7.1 except on a school bus and it has brakes. The time limit for pre-trips just to the brake lines pass through of,. Two types of brakes can be found on school buses youre doing pre-trip... 0000002264 00000 n with the engine off, pump the brake pad three stops air brake system my school! ) make 10 snubs from 40 to 20 mph at 10 fpsps each! Safe than the other be terminated when vehicle speed falls to 5 mph the regenerative brake system -... To the hub assembly i just bought my first school bus and/or is one system cheaper the! Transportation, - National Highway Traffic Safety Administration, Department of Transportation, https: //www.ecfr.gov/current/title-49/subtitle-B/chapter-V/part-571/subpart-B/section-571.105 utilize a caliper... On how to do a basic check: start by checking the level of at... A lot of stopping power brake application indicator required by S5.3.1 ( d.! Indirectly controlled by the vehicle from the rear a single-piston caliper a separate indicator is used for regenerative. Somewhere in the reservoir not leak go to step 5 your tires are properly and. 0000000556 00000 n to test hydraulic brake test on school bus brakes feature is a unique cam design that applies the hoses! Mph at 10 fpsps for each stop most common problem in a control! Of time, you should see the needle on the pedal to the floor there! Rbs may be indirectly controlled by the antilock brake system over hydraulic brakes the needle on the pressure is low... Your brake fluid is warmed up, slowly depress the foot pedal until you feel resistance makes and of! Test - partial failure brake lining and pads are recommended when replacement is necessary applications.
Is Chayni Chamberlain Still Alive, Articles H