School Bus Hydraulic Brake System simple test for leaks..CDL, How Do You Test Hydraulic Brakes for Leaks Cdl, The More You Pull the Lever down the Harder the Trailer Brakes Come on, If Stopped on a Hill, How Can You Start Moving Without Rolling Back, Why Put the Starter Switch Key in Your Pocket During the Vehicle Inspection. This free CDL practice test will focus on 30 questions related to the Air Brake portion of the Texas CDL exam. Reservoirs, whether for master cylinders or other type systems, shall have a total minimum capacity equivalent to the fluid displacement resulting when all the wheel cylinders or caliper pistons serviced by the reservoirs move from a new lining, fully retracted position (as adjusted initially to the manufacturer's recommended setting) to a fully worn, fully applied position, as determined in accordance with S7.18(c) of this standard. 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. So next time you get your vehicle inspected, make sure to putthe key in your pocket! While disc brakes don't need adjustment, wheel bearings do. The brake temperature is measured by plug-type thermocouples installed in the approximate center of the facing length and width of the most heavily loaded shoe or disc pad, one per brake, as shown in figure 1. 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. citations and headings Next, pump the brake pedal several times to build up pressure and then hold it down. At the completion of the stops specified above, deplete the system of any residual brake power reserve capability. I've sen them go bad and do just what you described with the lights coming on while driving. S7.11.1.2 Vehicles with GVWR greater than 10,000 pounds. If everything looks good there, move on to the calipers. S7.11.1.1 Vehicles with GVWR of 10,000 lb or less. Effectively, the engine works backwards by creating negative torque. If there are any leaks, you should see fluid dripping onto the cardboard or paper below. 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. 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. S5.2.2.2 The vehicle's parking brake, with the parking mechanism not engaged, shall be capable of holding the vehicle stationary for 5 minutes, in both forward and reverse directions, on a 20 percent grade. 571.105 Standard No. If youre working with a hydraulic system, its important to test it regularly. Gently pull against the brake by releasing the clutch, and it should hold the vehicle. CDL School Bus Endorsement S Practice Test -3. 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. 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. Check for any leaks at the seals and make sure the pistons are moving freely. trailer Why Hydraulic Brakes Do Not Work If Bubbles of Air Leak into the Liquid? Fig. FY TP-131-SB1 pt1. 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. This will tell you how much force the system is capable of generating. 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. (a) For an EV equipped with RBS, the RBS is considered to be part of the service brake system if it is automatically controlled by an application of the service brake control, if there is no means provided for the driver to disconnect or otherwise deactivate it, and if it is activated in all transmission positions, including neutral. S7.6 First reburnish. 322, 30111, 30115, 30117, and 30166; delegation of authority at 49 CFR 1.95. At this point, stop pumping and hold your foot on the pedal for a few seconds. First, it ensures thatthe inspector can testthe starter switch properly. Second, make sure youre not blocking traffic when youre doing your pre-trip. Second, it prevents them from accidentally starting your engine (which could be dangerous). I have been a medium duty bus tech for decades. S5.1.1.1 In the first (preburnished) effectiveness test, the vehicle shall be capable of stopping from 30 mph and 60 mph within the corresponding distances specified in column I of table II. When youre getting your vehicle inspected, one of the things the inspector will do is test the starter switch. Apply the brake pedal with approximately 100 lbs. 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. 8 c. 10 d. 15 Make four stops, each from 60 mph by a continuous application of the service brake control. Turn the key to the off position. If the pedal sinks slowly or feels spongy, there may be a leak in one of the hoses or seals. If the hose fittings do not leak go to step 5. At completion of 10 spike stops, make six effectiveness stops from 60 mph. Tail Lights/Brake Lights - clean, not missing or broken . force and hold while checking hydro-boost hose fittings for leaks. 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. Finally, remember to do a thorough check of your vehicle before starting your trip. August 1, 1997 Service Brake Test a. %PDF-1.4 % Air very much does apply the service brake. Average the maximum brake control force required for the three stops. Snub means the braking deceleration of a vehicle from a higher reference speed to a lower reference speed that is greater than zero. Article author: cdl-prep.com Reviews from users 3 (3791 Ratings). (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. This content is from the eCFR and is authoritative but unofficial. (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. (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. i stand corrected on my hydro brakes in the new bus.. im told all bluebird internationals are 4 wheel disc.. Burnish stops are conducted on any surface. 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). If the vehicle is equipped with a neutral gear that automatically disables the RBS, the test procedures which are designated to be conducted in gear may be conducted in neutral. The parking brake tests for any vehicle on different grades, in different directions, and for different loads may be conducted in any order. The CamLaster brake has 2 key design differences over traditional S-cam brakes. For vehicles equipped with more than one brake power unit or brake power assist unit, conduct tests of each in turn. 25. ` PT, bPl ,y\BBK- } Drivers S5.1.3.3 Brake power units. S6.2.6 A vehicle equipped with electrically-actuated service brakes also performs the following test series. (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. The parking brake test surface is clean, dry, smooth, Portland cement concrete. "Published Edition". 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, For this you will need to know the parts of a single and dual air brake system, how to inspect and use them. Hydraulic brakes are a vital part of your vehicle, and its important to keep them in good working order. Third, be mindful of the time limit for pre-trips. 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. Validyne model P55 differential pressure . With vehicle at GVWR, disconnect functional power source, or otherwise render antilock system inoperative. The first step is to ensure that the parking brake is completely disengaged. Make six stops from 30 mph. Hydraulic Brake Check With the engine running, apply the foot brake and hold for five seconds. Determine whether the brake system indicator lamp is activated when the RBS is disconnected. (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. S7.16.2 Wet brake recovery stops. 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. Drive for 1.5 mi at 40 mph after the last snub and immediately follow the recovery procedure specified in S7.11.3.2. 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. Maintain control force until vehicle has stopped. (b) For an EV equipped with an RBS that is not part of the service brake system, the RBS is operational and set to produce the maximum regenerative braking effect during the burnishes, and is disabled during the test procedures. This will help keep your car from rolling as well, but should only be used as a last resort. 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. However, if everything seems normal, congratulations your hydraulic brakes are in good shape! Hydraulic disc brakes react quickly - once the driver pushes on the brake pedal the four-wheel disc brake system goes into operation. a. 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. They're most efficient when the engine is at high speed and in a low gear, such as . Drive 1 mi at 30 mph after the last fade stop, and immediately follow the recovery procedure specified in S7.11.3.1. 3. 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