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. 1200-1500 RPM. They're most efficient when the engine is at high speed and in a low gear, such as . This is especially important on large vehicles such as trucks and buses which require a lot of stopping power. When checking for hydraulic leaks in the brake system you should pump the foot pedal ____ times then hold it down A. Average the maximum brake control force required for the three snubs. S5.1.4 Fade and recovery. S6.5 Engine. Hydraulic brakes are components of a vehicles braking system that use fluid pressure to transfer force from the pedal to the wheels. For whatever reason, I feel more in control. This self-paced FAST course gives you: EASY step-by-step instructions how to conduct a pre-trip inspection; precise path of travel around the vehicle;. Scope and application. The letters and background of a single common indicator shall be of contrasting colors, one of which is red. 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. A master cylinder shall have a reservoir compartment for each service brake subsystem serviced by the master cylinder. Pressing enter in the search box S5.1.7 Stability and control during braking. 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. Step on the service brake to make sure the bus doesn't pull to either side. Allow a braking distance interval of 1 mi. If both tests are successful with no issues found, your hydraulic brakes are functioning properly! Immediately upon reaching that speed make five stops, each from 30 mph at 10 fpsps for each stop. (including driver and instrumentation). 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. 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. 49 U.S.C. Bendix Hydro-Max Brake System Inspecting 1. (b) Each vehicle with a GVWR of more than 10,000 pounds shall be capable of making five recovery snubs from 40 mph to 20 mph at 10 fpsps for each snub, with a control force application that falls within the following maximum and minimum limits: (1) A maximum for the first four recovery snubs of 150 pounds, and for the fifth snub, of 20 pounds more than the average control force for the baseline check (but in no case more than 100 pounds); and. (d) At vehicle speeds of 20 mph or less, any wheel may lock up for any duration. learn more about the process here. 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. How many seconds should you apply pressure to the brake pedal while doing a hydraulic brake check? user convenience only and is not intended to alter agency intent Disconnect the primary source of power of one subsystem. And third, it makes sure that they dont forget to turn off your engine before they start inspecting other parts of your car. (c) For a vehicle using an electrically-activated parking brake, apply the parking brake by activating the parking brake control. 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 The critical value is determined by measuring the state-of-charge of each propulsion battery at the instant that automatic shut-down occurs and averaging the states-of-charge recorded. Initial brake temperatures before brake applications for subsequent stops are those occurring at the distance intervals. Fastback Top Member 1500 Posts Posted - 04/03/2010 : 04:59:49 AM As part of a routine preventative maintenance program, school bus operators should regularly test their hydraulic brakes. Again, hold your foot on the pedal for a few seconds before releasing it. Make spike stops by applying a control force of 200 lb while recording control force versus time. 0000000859 00000 n 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. The parking brake tests for any vehicle on different grades, in different directions, and for different loads may be conducted in any order. 0000002264 00000 n Bahnhof Stage 1 Clutch Kit Fits GMC C6500 C7500 Topkick 7. 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. (a) (For vehicles with brake power assist units.) Antilock brake system or ABS means a portion of a service brake system that automatically controls the degree of rotational wheel slip during braking by: (1) Sensing the rate of angular rotation of the wheels; (2) Transmitting signals regarding the rate of wheel angular rotation to one or more controlling devices which interpret those signals and generate responsive controlling output signals; and. S7.4.2.1 Burnish. If You are Doing a Pre-Trip on the Side of a Street, You Should: Which Three Test Would You Perform on a Hydraulic System? (a) Passenger cars; (b) vehicles other than passenger cars with GVWR of 10,000 lbs or less; (c) vehicles with GVWR greater than 10,000 lbs; NA = Not applicable. 3) Here are the types of tests that must be conducted on a typical air brake system: a) The Governor Cut in/Cut out test is to make sure that the governor is applying or cutting off air pressure to the air reservoir tanks as needed. At the completion of the stops specified above, deplete the system of any residual brake power reserve capability. 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. S5.2.2 A vehicle of a type described in S5.2.1 at the option of the manufacturer may meet the requirements of S5.2.2.1, S5.2.2.2, and S5.2.2.3 instead of the requirements of S5.2.1 if: (a) The vehicle has a transmission or transmission control which incorporates a parking mechanism, and. If lining thickness at the thinnest point appears to be 3/16 inch (4.76 mm) or less, the pad must be replaced. . (b) For vehicles manufactured on and after September 1, 1999 with GVWRs greater than 10,000 lbs, each message about the existence of a malfunction, as described in S5.3.1(c), shall be stored in the antilock brake system after the ignition switch is turned to the off position and the indicator lamp shall be automatically reactivated when the ignition switch is again turned to the on position. Make three stops from 30 mph at 10 fpsps for each stop. exact, verbatim wording for each component that must be checked;. Linings are assumed adjusted for normal operating clearance in the released position. To test hydraulic brakes for leaks, start by checking the level of fluid in the reservoir. 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. "Published Edition". The drivers seat is often a cushy air suspension seat. 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. 6 0 obj<> endobj S5.1.3.2 Brake power assist units. Reservoirs shall have completely separate compartments for each subsystem except that in reservoir systems utilizing a portion of the reservoir for a common supply to two or more subsystems, individual partial compartments shall each have a minimum volume of fluid equal to at least the volume displaced by the master cylinder piston servicing the subsystem, during a full stroke of the piston. 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. For vehicles equipped with more than one brakepower assist or brakepower unit, conduct tests of each in turn. 0 Friction facing tearout (complete detachment of lining) shall not exceed 10 percent of the lining on any single frictional element. This blog post will provide detailed information on how to properly conduct a hydraulic brake test on a school bus. Determine whether the brake system indicator lamp is activated when the failure is induced. (4) When the supply pressure in a brake power unit drops to a level not less than one-half of the normal system pressure. Third effectiveness (lightly loaded vehicle), 10. 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. Determine the control force, pressure level, or fluid level (as appropriate for the indicator being tested) necessary to activate the brake system indicator lamp. Title 49 was last amended 2/03/2023. Restore the service brake system to normal at completion of this test. (b) Any visible brake fluid or lubricant on the friction surface of the brake, or leakage at the master cylinder or brake power unit reservoir cover, seal and filler openings. Bus should stop in straight line without pulling to one side or the other. Serving Car & Truck Fleet Management Professionals, Serving EV Intenders & Professionals In Commercial & Public Fleets, Serving Corporate, Executive, & Financial Managers Of Large Commercial Fleets, Serving Leaders In Fleet Mobility & Emerging Technology, Serving Public Sector Fleet Professionals, Serving Medium & Heavy Duty Commercial Truck Professionals, Serving Transit Bus, Private Motorcoach, & Passenger Rail Professionals, Serving School & Pupil Transportation Fleet Professionals, Serving Vocational & Service Fleet Professionals. FY TP-131-SB1 pt1. Reverse Lights - clean, not missing or broken . 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